Path Bac Exam 1

Are there examples of gram stains which are pathognomonic of certain diseases? Given a set of lab values and a specimen of CSF blood, feces, wounds, etc, could you name a disease.

"Normal" Lab Values: WBC: 4,000-12,000 (elevated leukocytes means viral infection) Neutrophils: 2,000-7,500 (elevated neutrophils means bacterial infection) Eosinophils: 40-400 (elevated eosinophils means parasitic infection) CSF glucose: 50-75 (low CSF glucose means bacteria present, they are eating the glucose) CSF protein: 15-45 (higher CSF protein means infection, because the bacteria produce more protein) CSF total nucleated cells: 0-3 (high means bacterial cells present) A red herring: "Strep throat" is a terms often used because it's caused by Streptococcus. Most of the time, it is, but a growing number of cases are caused by a difficult-to-diagnose bacterium, Fusobacterium necrophorum Naegleria fowleri life cycle: Three main stages: Cyst, trophozoite (infectious stage), flagellated Fecal leukocytes: White blood cells in a stool sample, stained with methylene blue Shows that there's blood in the stool and that there is an infection in the intestines Amebic Dysentery: Caused by E. histolytica Trophozoite

Gastroenteritis caused by S. typhimurium and S. enteritis

*M cells* are specialized epithelial cells of the mucosa-associated lymphoid tissues. A characteristic of *M cells* is that they transport antigens from the lumen to cells of the immune system, thereby initiating an immune response or tolerance.

Diseases caused by E. coli?

- Diarrhea - Dysentery - Hemolytic Uremic Syndrome (HUS) - Bladder infections (UTIs) - Septicemia - Pneumonia - Meningitis

E. coli

- E. coli is the most-studied microorganism - It is both a common commensal inhabitant of the GI tract and one of the most important pathogens in humans - The most frequent cause of bloodstream infection and UTIs among Gram-negative banteria is E. coli - Theodor Escherich discovered E. coli in 1885 - E. coli K-12 is normal and there are many types of pathogenic E. coli

Important G- MacConkey+ Lactose+ fermenters from the flow chart?

- Escherichia coli - Klebsiella pneumoniae - Enterobacter spp.

STEC 0157:H7:Kx How many serotypes? What is serotyping? How do you know serotype? What's the lab test for this?

- Over 700 serotypes - Serotyping - based on "the reactivity of highly variable bacterial surface molecules with different antibodies" -O antigen - of LPS (lipopolysaccharide) tells serogroup, -H flagellar antigen tells serotype -K capsule type if the strain has a capsule - latex agglutination test, lab test to test bodily fluids for antibodies or antigens (latex beads with antibodies or antigens are mixed in) - clumping signals a reaction

Membrane ruffling - Salmonella

- Type 3 secretion system - Actin rearrangement - Results in pseudopods which engulf bacteria (force the host to engulf) - looks like a splash of liquid from a droplet hitting a solid surface (membrane ruffling)

Virulence Determinants in Pathogenicity Islands (PAIs)

- group of mobile genetic elements whose discovery has influenced and revised out thinking about genomic stability and the species concept in prokaryotes - These elements play a pivotal role in virulence of bacterial pathogens and are also essential for virulence in pathogens of animals and plants - We review a subgroup of genomic islands, the pathogenicity islands (PAI). Since excellent reviews and original papers have already been published on the molecular structure and evolution of these genetic elements this review emphasizes the contribution of PAI to the development of disease and to the virulence of bacterial pathogens carrying them.

Treatment of ESBL E. coli

-*Parenteral* antibiotic ertapenem *Oral*: Susceptibility rates indicate that Fosfomycin (97%), nitrofurantoin (94%), and pivmecillinam (85%) could be considered important oral treatment options. -Of special concern are associated co resistances to other classes of antimicrobials, which aid the spreading of multi-resistant isolates. CTX-M -lactamase-producing Enterobacteriaceae, which are commonly found in outpatients and isolated from UTIs, are typically also resistant to quinolones, aminoglycosides, and sulfonamides, such as ciprofloxacin, gentamicin, and trimethoprim-sulfamethoxazole, respectively. -This newly detected plasmid encoded resistance was selected by the frequent use of cephalosporins. These bacterial enzymes have been named extended-spectrum -lactamases (ESBL) due to their capacity to inactivate practically all cephalosporins.

Typhoid Pathogenesis Takeaways From Cases in Clinical Microbiology and Infectious Diseases

-A high inoculum (106 CFU/ml) is needed because of this organism's susceptibility to stomach acid. -After the organisms have survived transit through the stomach, they multiply in the small intestine. -They invade the intestinal mucosa of the ileum via M cells. -M cells are specialized epithelial cells that play a role in gut mucosal immunity. -Normally antigens from the lumen of the gut are taken up by these cells and are then processed by antigen-presenting cells in the Peyer's patches -The organism has a series of genes encoding proteins involved in invasion of epithelial and epithelial-like cells. -This series of genes is located in a region of the bacterial chromosome called a pathogenicity island (PAI). -The typhoid bacilli subvert the function of the M cells to invade the Peyer's patches. -Within the Peyer's patches, they are phagocytized by macrophages, where they survive and multiply. -From the Peyer's patches they can be carried to the bloodstream via the lymphatics. -Bacteria enter the Peyer's patches of the intestinal tract mucosal surface by invading M cells — specialized epithelial cells that take up and transcytose luminal antigens for uptake by phagocytic immune cells. -This is followed by inflammation and phagocytosis of bacteria by neutrophils and macrophages and recruitment of T and B cells. -In systemic salmonellosis, such as typhoid fever, Salmonella may target specific types of host cells, such as dendritic cells and/or macrophages that favour dissemination through the lymphatics and blood stream to the *mesenteric lymph nodes* (MLNs) and to deeper tissues.

Drugs or Vaccines for Crohn's disease (CD)

-About 3 million US adults reported having Crohn's disease or ulcerative colitis. -Up to 80,000 US children may have IBD. -Most people with IBD are diagnosed between ages 15 and 35 years. -Treatment usually involves medications, but more severe cases may require surgery. In 2015, an estimated 3.1 million (1.3%) of U.S. adults had ever received a diagnosis of inflammatory bowel disease, and prevalence differed significantly among a number of sociodemographic characteristics, including age, race/ethnicity, education level, employment status, nativity, poverty status, and urbanicity. -Several types of medications may be used to treat IBD: aminosalicylates (anti-inflammatory), corticosteroids (such as prednisone), immunomodulators, and the newest class approved for IBD—the "biologics". Several vaccinations for patients with IBD are recommended to prevent infections. Severe IBD may require surgery to remove damaged portions of the gastrointestinal tract, but advances in treatment with medications mean that surgery is less common than it was a few decades ago. Since Crohn's disease and ulcerative colitis affect different parts of the GI tract, the surgical procedures are different for the two conditions.

The Pathogenic Potential of a Microbe (paper)

-Abstract: Virulence is a microbial property that is realized only in susceptible hosts -There is no absolute measurement for virulence, and consequently it is always measured relative to a standard, usually another microbe or host -This article introduces the concept of pathogenic potential, which provides a new approach to measuring the capacity of microbes for virulence -The pathogenic potential is proportional to the fraction of individuals who become symptomatic after infection with a defined inoculum and can include such attributes as mortality, communicability, and the time from infection to disease -The calculation of the pathogenic potential has significant advantages over the use of the lethal dose that kills 50% of infected individuals (LD50) and allows direct comparisons between individual microbes -An analysis of the pathogenic potential of several microbes for mice reveals a continuum, which in turn supports the view that there is no dividing line between pathogenic and nonpathogenic microbes.

Pathogens must do the following:

-Acquire virulence genes -Sense the environment -Switch virulence genes on and off -Move to the site of infection -Become established -Acquire nutrients -Survive stress -Avoid the host's immune system -Subvert host cytoskeleton and signaling pathways: 1. Salmonella (invasive manipulates the cytoskeleton) goes in the cell 2. E. coli (non-invasive manipulates the cytoskeleton) gets inside by making cytoskeleton come out to bacterial cell 3. Sal. typhimurium manipulates lysosome function to get into the cell -Disseminate to other sites and/or hosts (in some cases) -Be transmitted to a new susceptible host

Treatment of E. coli Meningitis

-Ampicillin (17-78% resistant) -Gentamicin (poor CNS penetration and requires monitoring) -Cefotaxime (good CNS penetration and used instead of gentamicin) -Meropenem (limited use to multidrug resistant organisms (e.g., extended-spectrum beta-lactamase-producing organisms)

Extended-Spectrum B-Lactamses (ESBLs) E. coli

-Antimicrobial resistance in E. coli is consistently highest for antimicrobial agents that have been in use the longest time in human and veterinary medicine, such as ampicillin. -However, in the past two decades increases have been observed in the emergence and spread of multidrug-resistant bacteria, including strains resistant to newer antibiotics such as fluoroquinolones and extended-spectrum cephalosporins (Levy and Marshall 2004). -ESBLs are enzymes that mediate resistance to extended-spectrum (third generation) cephalosporins (e.g., ceftazidime, cefotaxime, and ceftriaxone) and monobactams (e.g., aztreonam) but do not affect cephamycins (e.g., cefoxitin and cefotetan) or carbapenems (e.g., meropenem or imipenem). -Significant risk for Hospital Acquired Infections. -Carbapenens IV or IM Treatments of Choice

Intracellular pathogens

-Can manipulate cytoskeleton (invasive and non-invasive pathogens can do this in different ways) and lysosome function -Lifestyle: 1. Bacterial escape into the cytosol and intracellular movement directed by actin tails. 2. Segregation from the endocytic route and formation of a unique inclusion vacuole by interaction with Golgi-derived vesicles. 3. Segregation from the endocytic route at the early endosome (EE) stage and formation of an endoplasmic reticulum (ER)-like phagosomal compartment. 4. Arrest of phagosome maturation at the EE stage. 5. Segregation from the endocytic route at the late endosome (LE) stage into an Er like phagosome. 6. Transient arrest of phagosome arrest at EE and LE stages. 7. Phagosome maturation completed up to fusion with lysosomes.

Development of vaccines against EHEC

-Development of Stx-based treatments -Neutralizing the effect of the toxin has been one of the strategies to reduce its effect. -Attenuated bacteria and bacterial ghost platform system -Gene regulators (global or specific) are important key players for the expression or silencing of virulence factors in pathogens. In fact, deleting those that promote the expression of specific virulence factors could be useful strategy to attenuate a pathogen. -Protein-based vaccines -chimeric protein constructions have proved to be an attractive approach in recent years. -Plant-based vaccines -In vaccine development, safety is one of the important issues. One approach to reducing the risk of undesired side effects is the use of plant-based vaccines targeting mucosal immunity. -DNA vaccines -DNA vaccines have been used to avoid the use of pathogens or bacterial traces that could lead to the development of disease in the vaccine recipient. -Polysaccharide-based vaccines -Polysaccharides in conjugate vaccine against Haemophilus influenzae type b, pneumococcal and meningococcal bacteremia and meningitis have been successfully used for vaccine development -Improving the adjuvant effect -The suitability of an adjuvant is important in vaccine development to enhance the immunogenicity and reactivity of the antigens in the host immune system. ETEC: the most studied InPEC for vaccine development? Why? Travelers & Children? -Toxin-based vaccines -The transcutaneous route has been used to immunize human volunteers with LT toxin delivered in a skin patch, a strategy designed to avoid the toxic effect of LT and which allows transfer of antigen from the skin to antigen-presenting Langerhans cells and then transport to draining lymph nodes -Autotransporters -Immunoproteomic analysis has also been employed as a strategy for the identification of antigens able to generate an immune response in the host during the process of infection. -Adhesins -Adhesins have been widely employed as target vaccines as several of them are considered to be virulence factors with an important role in colonization and bacterial pathogenesis. -Attenuated bacteria platforms -Some studies have shown that strain ETEC E1392/75-2A confers protection in 75% of human volunteers immunized and challenged with ETEC wild-type strains. -Outer membrane vesicles -Outer membrane vesicles have been largely employed as an antigen delivery system

Early-onset neonatal sepsis (EONS)

-Early-onset neonatal sepsis (EONS): the microorganisms most frequently found to cause of EONS are: *E. coli* and group B streptococcus (GBS): -followed by coagulase-negative staphylococcus, Listeria monocytogenes and Haemophilus influenzae. -Maternal GBS colonization, premature and/or prolonged rupture of membranes, prematurity, maternal UTI and chorioamnionitis, among others, are considered as risk factors associated with EONS.

Salmonella outbreaks

-Eleven people infected with the outbreak strain of Salmonella Typhimurium have been reported from eight states. -One person has been hospitalized and no deaths have been reported. -Epidemiologic and laboratory evidence indicate that contact with pet hedgehogs is the likely source of this outbreak. -In interviews, 10 (91%) of 11 ill people reported contact with a hedgehog. -A common supplier of hedgehogs in this outbreak has not been identified. -The outbreak strain making people sick was identified in samples collected from three hedgehogs in two ill patients' homes in Minnesota.

Gastroenteritis: Symptoms of acute gastroenteritis due to infection with Salmonella can include:

-Enteric: an infection of the gastrointestinal tract -Extra-intestinal: an infection occurring outside the intestine -Gastroenteritis: inflammation of the stomach and large and small intestines that may result in vomiting or diarrhea -Invasive infection: an infection of the bloodstream, bone, joint, brain, or nervous system -Sudden onset of diarrhea (which may be bloody) -Abdominal cramps -Fever (almost always present) -Nausea, vomiting, and headache may occur, though less frequent -Diarrhea may last for several days and lead to potentially severe dehydration, especially in infants and children under 2 years old and in adults over 65 years old. Even after clinical symptoms are no longer obvious, Salmonella bacteria may be found in the stool for several weeks. -Most people with diarrhea due to a Salmonella infection recover completely, although it may be several months before their bowel habits are entirely normal. -Sometimes, Salmonella infection can spread to urine, blood, bones, joints, the brain, or the nervous system, causing symptoms related to that body part or system. Some of these extra-intestinal infections can have long-term effects, depending on which part of the body is infected.

"Typhoid Mary" was Mary Mallon, Irish immigrant living in NYC in the early 1900s.

-First diagnosed "healthy carrier" of S. typhi. -Worked as a domestic servant/cook and was the source of several typhoid fever outbreaks. -Was quarantined but released on the promise that she would never work as a cook again. -She returned to cooking nonetheless under the pseudonym "Mrs. Brown", resulting in another typhoid fever outbreak in NYC. She was "recaptured" and isolated on North Brother Island. She suffered a stroke while living there and died 6 years later. Mary Mallon lived on the Island for a total of 26 years.

What is the cell wall composition of Gram neg vs. pos

-Gram positive cell wall is primarily composed of peptidoglycan, the wall contains teichoic acid -Gram negative cell wall is more complex, includes an outer membrane and contain LPS

Salmonella Mechanisms of Resistance

-In 2011, a Salmonella enterica serovar Anatum clone emerged in Taiwan. During 2016-2017, infections increased dramatically, strongly associated with emergence and spread of multidrug-resistant strains with a plasmid carrying 11 resistance genes, including blaDHA-1. -Because these resistant strains infect humans and food animals, control measures are urgently needed. -Rationale for Drug and Vaccine Development: Unmet Medical Needs

Tir (translocated intimin receptor)

-In order to mediate adhesion, intimin docks onto a protein called the Tir (translocated intimin receptor), itself a bacterial protein encoded in the LEE, that is pre-injected into the host cell surface via the type III secretion system. The intimin-Tir interaction ultimately triggers a re-arrangement of the host cell cytoskeleton into a pedestal structure that enables the intimate association of the pathogen on the host cell surface. The structure of the intimin-Tir interaction domain revealed a crucial role for the C-terminal lectin domain of intimin. -Intimin has been characterized in other attaching and effacing pathogens such as enterohemorrhagic E. coli (EHEC) and Citrobacter rodentium.

Salmonella serotypes

-It's easy to remember Salmonella serotypes names, isn't it? Surely, this is because the naming system of Salmonella serotypes is by far the most scientist friendly. Traditionally, most Salmonella serotypes have been named after geographic locations. -We decided to explore the geographic locations to which Salmonella serotypes refer and describe some unexpected twists in the naming scheme. We found that *93% (n = 1,475) of the 1,585 serotypes could be categorized as geo-serotypes; that is, the name refers to a geographic location.* -The 3 countries with the most geo-serotypes are Germany, the United Kingdom, and the United States. -Other serotype names refer to the name of a person, animal, tribe, or food item or are a composite of symptoms and host. -The Salmonella serotypes naming scheme has had a valuable effect on public health microbiology, and in the current era of fast development of whole-genome sequencing, it should remain a reference.

Steps in Laboratory Testing and Reporting Salmonella

-Laboratory scientists identify Salmonella infection by culturing a patient's sample. If Salmonella bacteria grow, then the diagnosis is confirmed, or in laboratory-terms, "culture confirmed." -Clinical diagnostic laboratories report the test results to the treating clinician and submit Salmonella isolates to state and territorial public health laboratories for serotyping and DNA fingerprinting. -The public health laboratories report the results to CDC's Laboratory-based Enteric Disease Surveillance and to PulseNet -The public health laboratories forward atypical serotypes to CDC's National Salmonella Reference Laboratory for more characterization or confirmation.

Late-onset neonatal sepsis (LONS)

-Late-onset neonatal sepsis (LONS): in contrast to EONS, there is a wide variety of microorganisms associated with LONS: 1. coagulase-negative Staphylococcus & Staphylococcus aureus 2.*E. coli*, Klebsiella pneumoniae, Pseudomonas aeruginosa, Enterobacter cloacae, Candida spp. and GBS. -The risk factors associated with LONS are also different from those associated with EONS and include prematurity, central venous catheterization (more than 10 days), nasal cannula or continuous positive airway pressure use, gastrointestinal tract pathology, exposure to antibiotics and prolonged hospitalization, among others.

Immune defenses can prevent virulence in one or more of seven related ways:

-Limiting the entry of bacteria into the asymptomatic site Ex. skin limits bacteria getting into your body (the asymptmatic site within your body) -Limiting the proliferation of the bacteria in the asymptomatic site Ex. acidic skin pH can prevent bacteria from taking over and growing a lot on your skin (the asymptomatic site) -Increasing the rate of clearance of bacteria and their products from the asymptomatic site Ex. An example could be macrophages clearing out bacteria before they become a problem -Preventing entry of bacteria or their products into the potentially symptomatic site or state -Reducing the rate of proliferation of the bacteria within the potentially symptomatic site or state -Increasing the rate of clearance of bacteria and their products from the potentially symptomatic site or state -Preventing an immune over response to the bacteria or their products in the potentially symptomatic site or state: You don't want your immune system to overreact to something that isn't too bad and make it worse (ex. Super high and damaging fever)

Pathogenesis of neonatal sepsis by E. coli

-Neonatal sepsis is an important but underestimated problem around the world. Neonatal sepsis is defined as disease affecting newborns ≤ 1month of age with clinical symptoms and positive blood cultures. -The incidence of this disease is 1/1000 in normal term neonates and 4/1000 in preterm neonates, increasing up to300/1000 in low weight neonates. Sepsis by bacterial infection is one of the most important causes of morbidity and mortality in newborns in both developed and developing countries (Stoll et al. 2011). -Ascending infection can be described in four main steps: (i) the presence of bacteria in the vagina/cervix; (ii) the bacteria resides in the decidua; (iii) the bacteria colonizes the amnion or the chorion, going through the fetal vessels or crossing the amnion, reaching the amniotic cavity; and (iv) the bacteria enters the fetus through the infected amniotic liquid and reaches the blood. -Many of these bacterial pathogens can frequently be found colonizing the vagina, cervix or rectum of pregnant adult women. Such pathogens may reach the fetus during the late stages of pregnancy by crossing the amniotic membrane or by directly infecting the baby during childbirth. -In the case of early neonatal sepsis (by intrauterine or congenital transmission through the placenta) secondary to bacteria, these microorganisms could arise from a prematurely ruptured amniotic membrane which becomes infected, genuinely infected amniotic liquid (chorioamnionitis), or preterm delivery in a mother colonized by such bacteria, who may have a much higher risk of infecting her offspring due to the immaturity of the neonate's immune system. Preterm delivery constitutes 5%-10% of pregnancies and its occurrence has previously been linked to infection in the genital tract of women during pregnancy -On the other hand, *late-onset neonatal sepsis is defined as infection presented four or more days* after birth and is commonly caused by microorganisms acquired from the *environment rather than from the mother*

What is the difference between serum and plasma

-Plasma is the liquid, cell free part of blood that has been treated with anticoagulants (EDTA) and has fibrinogen present (does not clot the red blood cell in the tube and has a buffy coat of white blood cells and platelets between the plasma and RBCs (non-clotted) -Serum is the liquid part of blood after coagulation of the RBCs, therefore devoid of clotting factors like fibrinogen (RBCs clot with the fibrinogen)

Molecular-based diagnostic tools for Salmonella:

-Plasmid profile analysis. -Pulsed field gel electrophoresis (PFGE) -Polymerase chain reaction (PCR): Polymorphism of 16S-23S spacer region; Arbitrarily primed PCR -These molecular tests are only available in reference laboratories -What is a reference laboratory? PulseNet and Pulsed-Field Gel Electrophoresis (PFGE): -In addition to serotyping, state public health laboratories routinely subtype Salmonella isolates using pulsed-field gel electrophoresis (PFGE) to create a "DNA fingerprint." -The laboratories submit these fingerprint patterns to a dynamic database maintained by PulseNet, a national network of public health and food regulatory agency laboratories coordinated by CDC. -The network includes state health departments, local health departments, and federal agencies (CDC, United States Department of Agriculture's Food Safety and Inspection Service (USDA/FSIS), and the US Food and Drug Administration (FDA)). Next Generation of Laboratory Testing: New methods for diagnosis: -New methods for diagnosis. CDC is also working to adapt its processes to important changes in how Salmonella is diagnosed in patients. -Until recently, culture (laboratory procedures to grow living Salmonella from patient specimens) was the diagnostic standard and the cornerstone of public health surveillance. New methods for subtyping: -New methods for subtyping. PulseNet is working with other Federal and State Agencies to evaluate the use of whole genome sequencing (WGS) to replace PFGE as its standard method for subtyping -Salmonella and other bacteria that cause diarrheal disease. It is hoped that WGS will make the PulseNet process faster, more accurate, and more efficient. Culture independent diagnostic testing (CIDT): -The Food and Drug Administration (FDA) has recently approved new culture independent diagnostic testing (CIDT) methods for diagnosing Salomella infections, but they are not widely used yet. -These new methods do not depend on culturing the specimen, so they do not yield an isolate for serotyping or PFGE. When adopted, these new tests could impact surveillance in a number of ways. PulseNet hopes to develop sequence-based tests that are themselves culture-independent using new systems developed for WGS.

Vaccines - Gastroenteritis

-Poultry vaccine: Megan™Vac 1 targets S. enteritidis -Works for chickens -Does it really break the cycle of Salmonella transmission from animals and humans?

Salmonella Cultures and Serologies

-S. typhi are usually isolated from *cultures of blood or bone marrow* only during the first *2* weeks of illness. -Stool cultures are usually positive during the 3rd to 5th week of the illness. -Urine cultures are often positive. -Serology: S. typhi contain antigens (O and H) that stimulate the host to form the corresponding antibodies. -A four-fold rise in O and H antibody titers in paired specimens acquired 2 weeks apart suggests S. typhi infection.

CDC Salmonella: 10 Symptoms of Salmonella

-Salmonella are bacteria that cause food poisoning, 1.2 million infections and 450 deaths annually in the United States alone. -While the bacteria can affect anyone, infections are more serious in people with underdeveloped or weak immune systems. These include infants and young children, the elderly and those with other serious illnesses like cancer and conditions like HIV. -Salmonella are transmitted to humans through contaminated food and are responsible for a majority of foodborne illnesses. -The bacteria are found in the guts of domestic animals from where they get into milk, meat, eggs and poultry. Salmonella can also get into fruit, vegetables and fish through contamination with animal manure and sewerage. -They may also be transmitted through contact with pets like tortoises, other reptiles, rodents, cats, hedgehogs and dogs. Person to person transmission can also occur due to poor hygiene.

CDC Typhoidal and Nontyphoidal Salmonella

-Salmonella bacteria are classified as either "typhoidal" or "nontyphoidal," based on their serotype. -Typhoidal Salmonella refers to the specific Salmonella serotypes which cause typhoid fever or paratyphoid fever, including Typhi, Paratyphi A, Paratyphi B (see note below), and Paratyphi C: 1. Serotype Paratyphi B is tartrate-negative (unable to ferment tartrate) and causes typhoidal disease. Serotype Paratyphi B var. L(+)tartrate+ is tartrate-positive (able to ferment tartrate) and causes nontyphoidal disease. -Nontyphoidal Salmonella refers to all other Salmonella serotypes13.

Salmonella Serotypes and Typhoid Fever

-Serotypes of Salmonella: 1. These are defined by serotyping based on O-antigen (LPS) and flagellar (H) antigens (Kauffmann-White scheme). -How does Typhoid fever (typhi) differ vs gastroenteritis? -Typhoid fever (also known as enteric fever) is an invasive, systemic clinical syndrome that is typified by high fever and complicated by sepsis and shock, gastrointestinal bleeding or perforation, encephalopathy, and focal metastatic complications such as cholecystitis or hepatitis. -*Host adapted* -Human: S. typhi - typoid fever (*lives only in humans* - in GI tract or bloodstream - highest risk over the last 10 years in Asia, Africa, and Latin america - avoid by vaccination and proper care with food and drinks - carriers and ill shed it in feces) CDC: Persons with typhoid fever usually have a sustained fever as high as 103° to 104° F (39° to 40° C). They may also feel weak, or have stomach pains, headache, or loss of appetite. In some cases, patients have a rash of flat, rose-colored spots. The only way to know for sure if an illness is typhoid fever is to have samples of stool or blood tested for the presence of Salmonella Typhi.

Salmonella Treatments

-Specific antimicrobial therapy shortens the clinical course of enteric fever and reduces the risk for death. -Fluoroquinolones are recommended for empiric treatment of enteric fever in adults, but quinolone resistance is >80% for Typhi and Paratyphi A infections in travelers to South and Southeast Asia, which suggests that treatment failures will occur. -Injectable third-generation cephalosporins are often the empiric drug of choice when the possibility of fluoroquinolone resistance is high. -Azithromycin and ceftriaxone are increasingly used to treat typhoid fever or paratyphoid fever because of the emergence of multidrug-resistant strains, although increasing resistance to azithromycin in Typhi strains has been documented outside the United States. -In contrast, no cases of ceftriaxone resistance have been reported among Typhi and Paratyphi A isolates tested by the CDC National Antimicrobial Monitoring System through 2013. -Additional data on antimicrobial resistance among enteric fever cases in the United States can be found at www.cdc.gov/narmsnow.

Virulence

-The ability of a bacterium to cause infection -Can differ from strain to strain. -Evolution of host/parasite interaction: If symptoms are too severe, then host may die before the organism is spread, or the host may be quarantined thereby preventing spread. -Virulence factors: bacterial product that contributes to pathogenicity (mayem) -Pathogenicity is the ability to cause disease. -Virulence is the relative severity of disease, or the relative ease with which the organism causes disease

CDC Salmonella Genus and Species

-The genus Salmonella is a member of the family Enterobacteriaceae. Like other Enterobacteriaceae, Salmonellae are Gram-negative, rod-shaped bacilli. -The genus Salmonella can be divided into two species: 1. (S. enterica and S. bongori), based on their phenotypic profile. 2. S. enterica can be further divided into six subspecies using their *phenotypic profile.* -The most common serotypes of Salmonella that cause human infection are Enteritidis, Typhimurium, Newport, and Javiana. -These Salmonella serotypes account for about half of culture-confirmed Salmonella isolates reported by public health laboratories

Intimin/Invasin proteins

-The intimin/invasin family of proteins constitutes a set of virulence factors secreted by bacterial pathogens. Both intimin and invasin share a common domain structure and a broad function to promote adherence of the pathogen to host cell surfaces. -The founding member of this protein family was identified in enteropathogenic *Escherichia coli (EPEC)* and initially termed E. coli attaching/effacing protein (EaeA) and is now called the intimin. The eaeA gene encoding intimin is found in the locus for enterocyte effacement (LEE), along with the genes encoding numerous virulence factors including the components of a Type III secretion system.

Treatment of neonatal sepsis

-Treatment of neonatal sepsis consists in ampicillin plus an aminoglycoside, usually gentamicin. -Other antimicrobials used are cefotaxime, vancomycin, metronidazole and piperacillin. The choice of the antibiotic depends on the microorganism associated with sepsis, the susceptibility of the bacterial pathogen, and the prevailing nosocomial infection trends in the nursery.

What are some pitfalls (no-go's) for the Gram Stain

-Treponema, Mycoplasma, Chlamydia, and Rickettsia either lack a cell wall or are too small and can non be visualized by Gram stain. -Bacillus spp. and Clostridium spp. frequently decolorize and appear Gram negative. -Faintly staining Gram-negative rods, such as Campylobacter, Francisella, Brucella, Legionella, Helicobacter, and others, can be counter-stained with carbol fuchsin rather than safranin for better visualization -Organisms that have been treated with antibiotics (particularly with cell-wall acting antibiotics, i.e. beta-lactams) can have distorted appearance, which may complicate their identification. -Older cultures don't stain as well -Bipolar staining (ends stain more than the middle) is a feature most commonly attributed to Yersinia; however, a number of other members of the Enterobacteriaceae can display this feature as well.

E. coli Bacteremia Progressing to Meningitis

-When a high degree of bacteremia occurs, E. coli can successfully crossing the blood-brain barrier previous binding and invasion of the human brain microvascular endothelial cells (HBMECs), causing central nervous system (CNS) inflammation resulting in neonatal meningitis. -Development of neonatal meningitis by E. coli comprises three steps: (i) translocation from the intestine lumen to the bloodstream (but also from urinary tract or the utero); (ii) intravascular survival and multiplication; and (iii) passage of the bacteria through the blood-cerebrospinal-fluid barrier (CSF) and invasion of the arachnoidal space *E. coli is a leading cause of infant meningitis (Neonatal meningitis E. coli) -*Neonatal meningitis E. coli (NMEC) is protected from the host immune response by its K1 capsule and outer-membrane protein A (OmpA).* -Invasion into macrophages may provide a replicative niche for high bacteraemia, allowing the generation of sufficient bacteria to cross the blood-brain barrier (BBB) into the central nervous system. -Attachment of NMEC is mediated by type 1 pili binding to CD48 and OmpA binding to ECGP96. Invasion involves cytotoxic necrotizing factor 1 (CNF1) binding to 67 kDa laminin receptor (67LR; also known as RPSA), as well as type1 pili and OmpA binding their receptors. Treatment of Neonatal Meningitis: -Antibiotic -Penicillin -Ampicillin -for E. coli Klebsiella sp. Gentamicin, Cefotaxime, Meropenem -Vancomycin, Nafcillin

Typhoid Fever

-Without therapy, the illness may last for 3 to 4 weeks and death rates range between 12-30%. -If chemotherapeutically untreatable, gall bladder must be removed -Common sources for gastroenteritis: eggs, meat, milk and milk products. Peanut butter, chocolate, spinach, frozen meat pies, turtles, hedgehogs -Outbreaks often traced to products of bovine origin. -Contaminated milk and milk products. -Marijuana has also been reported as a source of infection. -Turtle, Hedgehogs and reptile pets. -Asymptomatic carriers of the disease -Salmonella typhi: -potential to infect new hosts if untreated. Goes in between epithelial cells, intraluminal replication, continues in cells of RES, necrosis, hemorrhage, perforation of intestinal wall, re-enters bowel -RES: reticuloendothelial system (RES) mononuclear phagocyte system

Salmonella vaccine

-must be refrigerated -administered with cool liquid no warmer than 98.6 F

I will be traveling in under-developed countries. How is infection with ETEC Traveler's Diarrhea treated?

1. Antibiotics can shorten the duration of diarrheal illness and discomfort, especially if given early, but they are usually not required. 2. ETEC is frequently resistant to common antibiotics, including trimethoprim-sulfamethoxazole and ampicillin 3. Because resistance to antibiotics is increasing worldwide, the decision to use an antibiotic should be carefully weighed against the severity of illness and the risk of adverse reactions, such as rash, antibiotic-associated colitis, and vaginal yeast infection 4. Fluoroquinolones (like Ciprofloxacin) have been shown to be effective therapy.

How is infection with ETEC treated?

1. Clear liquids are recommended for persons with diarrhea to prevent dehydration and loss of electrolytes 2. For adults, packaged oral rehydration salts or premixed oral rehydration solutions (both available over-the-counter) may be used, although traditional remedies with salty liquids suck as chicken soup are also effective. 3. Bismuth subsalicylate compounds (Pepto-Bismol) can help reduce the number of bowel movements. 4. Although anti motility agents (Imodium, Lomotil) can effectively relieve ETEC-associated diarrhea and cramps, they may prolong the time it takes the body to rid itself of the toxin -Antimotility medications should be avoided by persons with high fevers or bloody diarrhea, and should be discontinued if diarrhea symptoms persist more than 48 hours

Treatments (Rx) for intestinal E. coli?

1. There is no cure for E. coli 0157:H7. It has to resolve itself. Antibiotics are not advised. They may increase the risk of HUS. 2. Patients should get plenty of rest and drink a lot of water to prevent dehydration. 3. Over-the-counter (OTC) medications for diarrhea are not recommended, as they can slow down the digestive system, undermining the body's ability to eliminate the toxins effeciently.

FDA Approved Infectious Disease Vaccines, No Pathogenic E coli?

24 Bacteria 12 Bacterial Toxoids 63 Viruses 0 Parasites 0 Fungus 27 Diseases

How many serotypes? What are the three antigens?

>700 serotypes O, H, and K antigens

Pathogenicity Island

A large horizontally acquired region of genomic DNA that often encodes virulence factors

Type III Secretion System (T3SS)

A needle-like apparatus that is assembled by pathogenic bacteria for the delivery of bacterial effectors directly into host cells

AIEC

Adherent Invasive E. coli - Crohn's or IBD -Adherent invasive E. coli (AIEC) has been *implicated* as one of the causative agents for Crohn's disease (CD), which is a cause of inflammatory bowel disease (IBD) affecting mainly the small bowel. There is no single causative agent of Crohn's disease (CD) identified, and the current hypothesis is that disease is caused by a combination of factors, including genetics, the intestinal microbiota, environmental factors, and enteric pathogens. -AIEC + genetics + microbiota + environment + enteric pathogens = CD(CDB)? -The AIEC pathotype does not express common virulence factors found in various other pathogenic E. coli strains and the genetic basis for its pro-inflammatory and invasive phenotype is not fully understood

Pathogen Perspective: everything is about survival

Attach to host cell for colonization Evade the host's immune system / persist Obtain iron and other nutrients Disseminate or spread within/to other hosts Produce symptoms of disease It is a battle between the microbe's virulence factors and the host's integrity of defense when a microbe is encountered, has a route of transmission, and a high enough dose. This determines where the host lies between health and morbidity/mortality

Biofilms

Biofilm survival strategy in environment translates to survival strategy in host: -Staph biofilms are normal on skin as part of flora -Staph biofilms on catheters are infections. Life cycle of a biofilm -Attachment -Microcolonies -Make extracellular matrix -Maturation (starting to build the actual biofilm and accumulate the community of bacteria all together) -Dispersion (release from the biofilm) Benefits of biofilm formation -Resistance: Shear Flow, antimicrobials, disinfectants, protozoan grazing -Adaptation: Nutrient deprivation, pH changes, oxygen radicals -Favorable environmental niche -Communal behavior: Protection from disinfection/antibiotics, horizontal gene exchange,nutrient concentration, protection from desiccation, increased metabolic efficiency and diversity, resistance to predation

What are some names of common types of agars for plating pathogens

Blood agar: -Blood agar contains general nutrients and 5% sheep blood. -It is useful for cultivating fastidious (needs specific nutrients) organisms and for determining the hemolytic (ability to eat or break down the blood cells in the agar) capabilities of an organism. -Some bacteria produce exoenzymes that lyse red blood cells and degrade hemoglobin; these are called hemolysins. Bacteria can produce different types of hemolysins 1. Beta hemolysis - complete 2. breakdown (clear zone) 2. Alpha hemolysis - partial breakdown (green discoloration) 3. Gamma reaction - no breakdown (no discoloration or zone) MacConkey agar is a selective agar medium used for the isolation and differentiation of lactose-fermenting and non-fermenting Gram negative rods: -The medium consists of digests of peptones, bile salts, lactose, neutral red, and crystal violet. -Bile salts and crystal violet inhibit the growth of Gram-positive bacteria and some fastidious Gram-negative bacteria. -Colonies that ferment lactose (e.g., Escherichia, Klebsiella, and Enterobacter spp.) produce acid, which causes a red color shift in the neutral red pH indicator and precipitates the bile salts. -Colonies appear red to pink, while nonfermenting colonies (e.g., Proteus, Salmonella, and Shigella spp.) appear yellow, colorless, or translucent. MacConkey agar will typically inhibit Proteus from swarming over the plate. 1. Positive - pink plate 2. Negative - colorless or yellow plate Chocolate agars: -Chocolate agar (CHOC) or chocolate blood agar (CBA) - is a nonselective, enriched growth medium used for isolation of pathogenic bacteria. -It is a variant of the blood agar plate, containing red blood cells that have been lysed by slowly heating to 80°C. Chocolate agar is used for growing fastidious respiratory bacteria, such as Haemophilus influenzae and Neisseria meningitidis. -In addition, some of these bacteria, most notably H. influenzae, need growth factors such as nicotinamide adenine dinucleotide (factor V or NAD) and hemin (factor X), which are inside red blood cells; thus, a growth prerequisite for these bacteria is the presence of red blood cell lysates. -The heat also inactivates enzymes which could otherwise degrade NAD. The agar is named for its color and contains no chocolate products.

DAEC

Diffusely adherent E. coli - diffuse adherence to epithelial cell, watery diarrhea but pathogenicity not conclusively demonstrated DAEC Epidemology & Pathogenicity require more elucidation -DAEC elicits a characteristic signal transduction effect in small bowel enterocytes that manifests as the growth of long finger-like cellular projections, which wrap around the bacteria -The internalization of Afa/Dr DAEC occurs by a mechanism involving lipid rafts and dynamic microtubules (1). Recognition of DAF and/or α₅β₁ integrin by Afa/Dr adhesins and/or invasins plays a pivotal role in bacterial internalization. Internalized Afa/Dr DAEC strains survive within a large vacuole. Diffusely Adherend E. coli (DAEC): -The diffusely adherent E. coli (DAEC) pathotype describes diarrheagenic E. coli strains that attach to cells but do not fall into classical patterns of adherence, such as localized or A/E. -The adhesins of Afa/Dr family have been implicated in DAEC pathogenesis -They have now emerged as a unique group and are considered distinct from other pathotypes, but because of difficulties in classification and identification, the designation of DAEC as a distinct enteric E. coli pathotype requires further epidemiological studies.

Pedestal Formation-EAC is Associated with? What are pedestals?

EPEC & EHEC-HUS Pedestals: -Intestinal cell forms pedestal for bacterium, and infection follows -The bacterium is firmly bound to the intestinal cell surface via the interaction between the Tir and intimin proteins. -Pedestal formation, a very active and striking process, begins -Another intestinal cytoskeletal protein (orange booties) binds to a portion of the bacterial Tir protein that is inside the cell. -Once these proteins bind, long strands of actin (yellow balls) start to form. -The actin filaments build up directly beneath where the bacterium is bound to the intestinal cell. As the actin filaments lengthen, they push the cell membrane upward, and the bacterium becomes perched atop a dramatic pedestal formed by the intestinal cell. -Note: Once many enteropathogenic bacteria have adhered to the intestinal lining, symptoms of the infection (diarrhea) commence.

Types of virulent E. coli

ETEC - Enterotoxigenic - Non-invasive and there are 2 types (LT heat-labile and ST heat-stable) EAggEC-EAEC - Enteroaggregative EIEC - Enteroinvasive EPEC - Enteropathogenic EHEC - Enterohemorrhagic (also is under category of Enteropathogenic)

Conceptual framework of infectious disease

Encounter Entry Spread Multiplication Damage Outcome

EAEC

Enteroaggregative E. coli - watery diarrhea w/ mucus, occasionally bloody, has various adhesions and accessory proteins, enterotoxin and cytotoxin EAEC: - forms biofilm and delivers cytotoxins and enterotoxins - bind to intestinal cells - non-invasive - forms aggregates on surface of cells - ST-like toxin (EAST) Hemolysin - GVVPQ fimbriae - role unclear - AAFs - aggregative adherence fimbriae - Persistent diarrhea in young children w/o inflammation of fever EAEC: -Bind to intestinal cells -Non-invasive -Forms aggregates on surface of cells -ST-like toxin (EAST) Hemolysin -GVVPQ fimbriae - role unclear -AAFs- aggregative adherence fimbriae (AAFs) -Persistent diarrhea in young children w/o inflammation or fever

EHEC/STEC/VTEC

Enterohemorragic E. coli (think Hem=Blood) yy- STEC/VTEC - pathotype is the one most commonly heard about in the new in association with foodbourne outbreak (colon affected and only need low dose of bacteria to infect) EHEC - type I pili - delivers Shiga toxin to do HUS EHEC: -*EHEC = STEC* = O157/O104 -Mixed phenotype with EAE and HUS -Non-invasive, no cell to cell spread -pediatric diarrhea, copious *bloody* discharge (hemorrhagic colitis), intense inflammatory response, -may be complicated by hemolytic uremia *(HUS)* -Mainly food/water borne / Antibiotic treatment of E. coli O157:H7 colitis may stimulate further verotoxin production and thereby increase the risk of *HUS*. -With aggressive treatment > 90% survive acute phase - children/elderly worse prognosis Where does STEC come from? -STEC lives in the guts of ruminant animals, including cattle, goats, sheep, deer, and elk. -The major source for human illnesses is cattle. -STEC that cause human illness generally *do not make animals sick.* -Is there an unmet medical need for a STEC vaccine? -Other kinds of animals, including pigs and birds, sometimes pick up STEC from the environment and may spread it. -So, for the class: Is STEC zoonotic?

EIEC

Enteroinvasive E. coli - mucosal invasion and inflammation of large bowel, watery diarrhea that may progress to bloody, fever (affects colon and lower small intestine) - EIEC - gets into cell through vacuole and then migrates into adjacent cells EIEC: -*EIEC: Enteroinvasive, (mucous, blood)* -No toxins. Does not produce shiga toxin -No known *animal reservoirs* -EIEC invades the colonic epithelial cell, lyses the phagosome and moves through the cell by nucleating actin microfilaments. The bacteria might move laterally through the epithelium by direct cell-to-cell spread or might exit and re-enter the baso-lateral plasma membrane. -Nonfimbrial adhesins, possibly outer membrane protein. Very similar to disease caused by Shigella -Dysentery-like diarrhea, severe inflammation, fever -Invasive phenotype carried on plasmid -Movement with actin based motility

EPEC

Enteropathogenic E. coli -small bowel adherence and epithelial cell effacement by intimin, sever watery diarrhea that may persist, common in infants in developing countries (small intestine only) EPEC: -infantile diarrhea; watery *diarrhea with blood*. Some inflammation, no fever -EPEC adhere to small bowel enterocytes, but destroy the normal microvillar architecture, inducing the characteristic attaching and effacing lesion -Enterocyte attachment and effacement (EAE) Bundle-forming pili /EAE - altered ultrastructure of apical surfaces -Cytoskeletal derangements are accompanied by an inflammatory response and diarrhea: 1. Initial adhesion 2. Protein translocation by type III secretion 3. Pedestal formation. -Sometimes: *Cyto-lethal distending toxin, Cytotoxic necrotizing factors* -Genes found in pathogenicity island Involves a T3SS

ETEC

Enterotoxigenic E. coli - (think T = Traveler's Diarrhea) - acute watery diarrhea, afebrile, low grade fever, occasionally sever, adheres to the small bowel (small intestine only) - ETEC - adherence via type I and IV pili, delivers enterotoxin HST and HLT - Fimbrial adhesions such as CFA I, CFA II, K88, K99 - ETEC adhere to small bowel enterocytes and induce water diarrhea by the secretion of heat-labile (LT) and/or heat-stable (ST) enterotoxins - non-invase - causes watery diarrhea in infants and *travelers* - No inflammation, no fever - CDC does say a fever can occur, but it is rare

Extra-intestinal E. coli infections:

ExPEC Extraintestinal UPEC Europathogenic: Uropathogenic E. coli (UPEC) Virulence Factors: -Urinary Track Infections (UTIs) caused by E. coli -E. coli is the principal cause of UTI which can present as asymptomatic bacteriuria, cystitis and pyelonephritis, as well as prostatitis in men. -Uropathogenic E. coli (UPEC) is the etiological agent in 75% of uncomplicated UTI and 65% of complicated UTI (Flores-Mireles et al. 2015). -UPEC have diverse virulence factors (L¨uthje and Brauner 2014; Subashchandrabose and Mobley 2015), some of them related to pathogenicity islands, regions of DNA that are acquired by horizontal gene transfer. FEMS Micro Reviews, 2016: -These UPEC isolates possess specialized virulence factors: -adhesins -toxins -iron-acquisition systems -polysaccharide coats -invasins that are not present in commensal and intestinal pathogenic strains (Sannes et al. 2004). -In addition, E. coli are the enteric Gram-negative bacilli most frequently found in the genital tract of women, causing vaginal and/or endocervical colonization as well as different infections in pregnant women, such as intra-amniotic and puerperal infection, and neonatal infections, such as early and late neonatal sepsis (Guiral et al. 2011). -*P fimbria - specific galactose dissaccharide that is found on the surfaces uroepithelial cells* Phase variation - after ascension to kidneys/pelvis Siderophores and Hemolysins -Pathogenic mechanisms of extraintestinal Escherichia coli. The different stages of extraintestinal Escherichia coli infections are shown. Uropathogenic E. coli (UPEC) attaches to the uroepithelium through type 1 pili, which bind the receptors uroplakin Ia and IIIa; this binding stimulates unknown signalling that mediate invasion and apoptosis. -Binding of type 1 pili to α3β1 integrins also mediates internalization of the bacteria into superficial facet cells to form intracellular bacterial communities (IBCs) or pods. Sublytic concentrations of the pore-forming haemolysin A (HlyA) toxin can inhibit the activation of Akt proteins and leads to host cell apoptosis and exfoliation. -Exfoliation of the uroepithelium exposes the underlying transition cells for further UPEC invasion, and the bacteria can reside in these cells as quiescent intracellular reservoirs (QIRs) that may be involved in recurrent infections. Summary of Uropathogenic E. coli (UPEC) virulence factors: 1. Adhesins: fimbriae or pili as type 1 fimbriae, P fimbriae (related with renal cells adherence), curli fimbriae, F1c/s fimbriae, F9 and type 3 fimbriae and non-fimbrial adhesins (Afa/Dr adhesins, related with diarrheagic diseases) and autotransporter proteins (Ag43 adhesin and Upa uropathogenic autotransporter protein). These adhesins are responsible for adhesion to both urinary tract epithelial cells and urinary catheters, and promote biofilm formation. 2. Toxins: endotoxin lipopolysaccharide (LPS), α-haemolysin (HlyA), CNF1 (cytotoxic necrotizing factor 1) and SPATEs (serine protease autotransporters of the Enterobacteriaceae) as Sat (Secreted Autotransported Toxin), Pic (Protease Involved in Colonization) or Vat (Vacuolating Autotrasported Protein). These toxins are related to dissemination in tissues, inflammatory response, cytotoxicity and resistance to neutrophils. 3. Iron acquisition mechanisms: Haem receptors (iron Haem uptake regulated by ChuA and Hma) and siderophores (iron chelating molecules as enterobactin, aerobactin, salmochelin and yersiniabactin). Both mechanisms promote the availability of iron in the urinary tract and contribute to survival and persistence in the urinary tract. Zinc acquisition mechanisms are also important. 4. Immune evasion mechanisms: suppression of induction of cytokines and chemokines(due to O antigens of LPS), serum resistance and protection against phagocytes(due to O antigens of LPS and K antigens of capsular polysaccharides) and motility (due to flagella with F antigens). Urinary tract infection, sepsis, and meningitis

Exogenous vs Endogenous Acquisition of Disease

Exogenous: infections acquired from the environment (food, water, air, insects, objects, other humans, etc - "catch" a cold, etc - bodily fluids, fecal-oral route, etc) Endogenous: infections caused by agents in the body (a cut can trigger can infection by Staphylococcus normally found on the skin) Colonization itself is not indicative of infection. Colonization just indicates presence...must be followed by persistence, spread, and signs/symptoms of infectious disease.

Diagnosis: Isolation and identification of the bacterium: Types of Specimens?

Gastroenteritis (Salmonellosis) : (S. typhimurium, S. enteritidis): • nausea • headache • vomiting • abdominal pain • diarrhea (usually without blood Typhoid Fever: incubation period is usually one to two weeks; duration of the illness 4-6 weeks • poor appetite • Headaches • generalized aches and pains • Fever - a sustained fever as high as 103 F-104 F (39 C-40 C). • Lethargy • Diarrhea

Virulence Strategies

General Virulence Factors - specific bacterial components: 1. Adhesion: pili/fimbriae and non fimbiral adhesions 2. Ability to form biofilms 3. Invasins 4. Actin rearrangment 5. Ability to bind to M cells 6.Motility/chemotaxis 7. slgA proteases 8. Ability to acquire iron/iron abstinence 9. Capsules 10. LPS O antigen 11. C5a peptidase 12. Toxins 13. Surface variation Adhesion/Colonization/Altered Environment Usually is a prerequisite for colonization. Normal flora can block adhesion sites. Body tries to "remove unattached bacteria A (rod-like structures) way in which pili (rod-shaped protein structures that extend from bacterial surface) bind to host cell surface molecules (usually carbs). Tip structure is much smaller in reality. B (short structures) way in which afimbrial adhesions (bacterial surface proteins that are not organized in a rod-like structure but instead are shorter and closer to the surface) mediate tight binding between bacteria and host cells C (embedded structures) afimbrial adhesions embedded in surface, no pili (afimbrial adhesins probably mediate tighter binding to host cells than pili - some recognize different substrates such as integrins and cadherins, etc) D (long thin structures) P pili - thin filaments from surface E (rope-like) Type 4 pili - rope like F (curli pili) cuved / thin, aggregative (intertwined coiled structures) Major pili of Gram negatives Type I - rigid fimbriae, can induce hemagglutination Type 2 - similar, no hemagglutination Type 3 - more flexible Type 4 -assembled through a type 2 secretion system, twitching motility Type 5 -similar to type 1 but thinner Curli pili -adherence to matrix proteins Gram positives seem to rely more on non-fimbrial adhesins such as the M proteins (Streptococcus pyogenes has an adhesion that consists of many monomers of M proteins, which mediates attachment to fibronectin, which is a protein found on many host cell surfaces). These non-fimbiral adhesions can inhibit complement fixation, help S. pyogenes avoid phagocyte ingestion, and help bind to a variety of host tissues Toxins/Superantigens Evasion of host defense Enzymes production/Secretion Systems Siderophores/metal acquisition / response Invasion: Uptake/recognition Secretion systems

IBD

Inflammatory Bowel Disease - broad term that describes conditions characterized by CHRONIC inflammation of the gastrointestinal tract

First problem for infection: penetration of physical barriers

Intact skin - microbes can't penetrate skin without help: 1. Vector associated microbes 2. Wounds 3. Microbes aren't known to penetrate intact skin without some aid Mucin layer: a meshwork of protein and polysaccharide that covers mucosal cells layer - not as well understood how microbes traverse this (difficulties collecting samples for microscopy without collapsing the mucin layer): 1. Motility: mucin is not uniform (expelled in thick streams from goblet cells), so mucin layer is probably more like a field of close strands than a solid mat. If bacteria can move between the strands, then they can probably move through mucin (flagellated bacteria are otherwise thought to have trouble moving through the viscous mucin) this would also help them move to the mucosal cell surface as opposed to wandering through the mucin parallel to the cells 2. Chemotaxis through mucin layer Take advantage of M cells phagocytosis: 1. M cells (entry into the Peyer's patches) - normal role in the small intestine is to sample material passing through and then deliver it to the immune system associated with the GI mucosa (M cells are not covered with a thick mucin layer). 2. Some pathogens can use M cells as a "portal" to get to the mucosal layer and then underlying tissues and blood.

Toll-like receptor (TLR)

Membrane bound receptors of the innate immune system that recognize specific pathogen associated molecular patterns

What is OneHealth?

One Health recognizes that the health of people is connected to the health of animals and the environment. -It is a collaborative, multisectoral, and trans-disciplinary approach—working at the local, regional, national, and global levels—with the goal of achieving optimal health outcomes recognizing the interconnection between people, animals, plants, and their shared environment. -A One Health approach is important because 6 out of every 10 infectious diseases in humans are spread from animals.

Peyer's Patches

Organized lymphoid regions of the small intestine monolayer that function in immune surveillance and the generation of a localized immune response

E. coli causes what types of disease and has what phenotypes?

Pathogenic Intestinal E. coli: - 10% of foodborne E. coli STEC cases result in HUS - different strains have acquired different sets of virulence genes resulting in different disease presentations. Many virulence genes are located on Pathogenicity Islands (PAIs) Microbiological phenotypes: - Gram-negative - Facultative anaerobe - Rod-shaped - Aerobic respiration, fermentation, anaerobic respiration - Responds to numerous environmental signals - Highly adaptable - Motility/pili - Predominant facultative organism in human GI tract

Pathogen recognition receptors (PRRs)

Proteins of the innate immune system that recognize pathogen-associated molecular patterns and initiate an innate immune cascade that facilitates pathogen clearance by triggering cytokine and chemokine expression

EHEC = STEC - E. coli 0157 was discovered in 1982. What do you plate E. coli 0157:H7 on?

Selective agars. TC-SMAC/Rainbow/R&F E. coli 0157:H7

STEC

Shiga toxin-producing E. coli - same thing as VTEC/EHEC - watery diarrhea progresses in 0157 to bloody in 1-3 days, abdominal cramps and tenderness, 6% have hemolytic uremic syndrome

Endocytosis

The process by which extracellular particles are engulfed by eukaryotic cells and enclosed in a vesicle

Salmonella as a carrier for other antigens

Ty21a also used as basis to carry foreign antigens -Multiply in Peyer's patches -Induce a potent mucosal immunity Ty21a carrying Shigella plasmid, O antigen of V. cholerae, and tetanus have been tried as vaccines. Ty21a with hepatitis virus and malarial parasites are currently being tested.

E. coli Ahesins:

Type 1 Pili: - on all E.coli strains - bind mannose residues on bladder glycoproteins P fimbriae: - primarily associated with UPEC - not found on non-pathogenic strains - especially in association with kidney infection - binds to specific receptor - globobiose S pili: - associated with neonatal meningitis - same binding pattern as P pili

VTEC

Verotoxin-producing E. coli - same thing as EHEC/VTEC

Is it really true that all intestinal pathogenic E. coli cannot be treated?

Yes, with the exception of Traveler's Diarrhea (ETEC)

What are the two most common inflammatory bowel diseases and what are they cause by? Where do they affect?

ulcerative colitis - Clostridium difficle - large intestine affected Chrone's disease - inflammation affects the entire digestive tract both are caused by abnormal response to the body's immune system AIEC has been implicated