Microbiology Chapter 14

Focal infection

an infection where agents of a local infection enter a blood or lymphatic vessel and spread to other specific parts of the body where they are confined to a specific area(s) of the body --can arise from infections in areas such as the teeth, tonsils or sinuses

Systemic (generalized) infection

an infection where microoorganisms or their products are spread throughout the body by the blood or lymph **An example: measles

Analytical epidemiology

analyzes a particular disease to determine its probable cause --study can be done in 2 ways: 1. Case Control Method --the epidemiologist looks for factors that might have preceded the disease. 2. Cohort Method-- the epidemiologist studies 2 populations: ones that has had contact with the agent causing disease and another that has not

Vectors

animals that carry pathogens from one host to another --arthropods are the most important group --transmit disease by two general methods: Mechanical and Biological transmission

Communicable diseases

any disease that spreads from one host to another either directly or indirectly **An example: Chickenpox, measles, genital herpes, typhoid fever and TB

Notifiable infectious diseases

are diseases for which physicians are required by law to report cases to the US Public Health Service --62 infectious disease have been reported to the national level

Contagious diseases

are diseases that are easily spread from one person to another (Criteria is EASY) **An example: Chickenpox and measles

Zoonoses

are diseases that occur primarily in wild and domestic animals and can be transmitted to humans **An example: Rabies and Lyme disease

Emergin infectious diseases (EID)

are infections that are new or changing, showing an increase in incidence in the recent past or a potential to increase in the near future

Signs

are objective changes the physician can observe and measure --these are apparent to an observer, ex: swelling, fever and paralysis

Carriers

are some people that harbor pathogens and transmit them to others without exhibiting any signs of illness --are an important living reservoirs of infection --some have inapparent infections for which no signs or symptoms are ever exhibited --Other people such as those with latent diseases carry a disease during its symptoms free stages--during the incubation period before symptoms appear or during the convalescent period (recovery)

Bacteriocins

are used in medical microbiology to help identify different strains of bacteria --Such identification helps determine whether several outbreaks of an infectious disease are caused by one or more strains of a bacterium

Nosocomial infection

does not show any evidence of being present or incubating at the time of admission to a hospital; it is acquired as a result of a hospital stay

Period of convalescence

during this time, the person regains strength and the body returns to its prediseased state --Recovery has occured

Period of decline

during this time, the signs and symptoms subside --fever decreases and the feeling of malaise diminishes --during this phase, which may take from less than 24 hrs to several days, the patient is vulnerable to secondary infections

Fomite

general term from any non-living object involved in the spread of infection **An example: tissues, handkerchiefs, towels, bedding, diapers, drinking cups, eating utensils, toys, money and thermometers

Health care-associated infection (HAI)

has been introduced to include infections acquired in settings other than just hospitals --Includes: outpatient health care clinics, nursing homes, rehab centers, in home health centers

Commensalism

in this symbiotic relationship, one of the organisms benefits and the other is unaffected

What does microbial antagonism involve?

involves the competition among microbes --one consequence of this competition is that the normal microbiota protect the host against colonization by potentially pathogenic microbes by competing for nutrients, producing substances harmful to the invading microbes, and affecting conditions such as pH and available oxygen --when this balance between normal microbiota and pathogenic microbes is upset, disease can result

Latent disease

is a disease in which the causative agent remains inactive for a time but then becomes active to produce sumptoms of the disease **An example: Shingles caused by the Varicella virus

Acute disease

is a disease that develops rapidly but lasts only a short time **An example: influenza

Prodromal period

is a relatively short period that follows the period of incubation in some diseases --is characterized by early, mild symptoms of disease such as general headaches and malaise

Droplet transmission

is a third type of contact transmission in which microbes are spread in mucous droplets (Droplet nuclei) that travel only short distances

Sepsis

is a toxic inflammatory condition arising from the spread of microbes, especially bacteria or their toxins from a focus of infection --Predominantly gram negative meaning very hard to treat with antibiotics --Always has an orgin; usually the urinary tract or lungs

Mutualism

is a type of symbiosis that benefits both organisms. **An Example: the large intestine contains bacteria, such as E. coli, that synthesize vitamin K and some B vitamins. These vitamins are absorbed into the bloodstream and distributed for use by body cells.

Parasitism

is a type of symbiosis where one organism benefits by deriving nutrients at the expense of the other --Many disease causing bacteria are parasites

Biological transmission

is an active process and is more complex --an arthropod bites an infected person or animal and ingests some of the infected blood --the pathogens then reproduce in the vector and the increase in the number of pathogens increase the possibility that they will be transmitted to another host.

Primary infection

is an acute infection that causes the initial illness

Subclinical (inapparent) infection

is an infection that does not cause any noticeable illness **An example: Poliovirus and Hep A can be carried by people who never develop the illness

Local infection

is an infection where the invading microorganisms are limited to a relatively small area of the body **An example: boils and abscesses

Diagnosis

is made by evaluation of the signs and symptoms together with lab test results

Noncommunicable disease

is not spread from one host to another

Secondary infection

is one cause by an opportunistic pathogen after the primary infection has weakend the body's defenses --This type of infection of the skin and respiratory tract are common and are sometimes more dangerous than the primary infections **An example: Pneumocystis pneumonia as a consequence of AIDS

Incubation period

is the interval between the initial infection and the first appearance of any signs or symptoms --time of this period depends on the specific microorganism involved AND --its virulence (degree of pathogenicity) the number of infecting microorganisms and the resistance of the host

Mortality Rate

is the number of deaths resulting from a disease in a population in a given period of time in relation to the total population

Morbidity Rate

is the number of people affected by a disease in a given period of time in relation to the total population

Mechanical transmission

is the passive transport of the pathogens on the insect's feet or other body parts --if the insect makes contact with a host's food pathogens can be transferred to the food and later swallowed by the host **An example: Houseflies

Bacteremia

is the presence of bacteria in the blood --bacteria is growing in the blood

Toxemia

is the presences of toxins in the blood **An example: Tetanus

Symbiosis

is the relationship between the normal microbiota and the host --is a relationship between two organisms in at which at leat one organism is dependent on the other

Pathology

is the scientific study of disease

Contact transmission

is the spread of an agent of disease by direct contact, indirect contact or droplet transmission

Period of illness

is the time when the disease is most severe --person exhibits overt signs and symptoms of disease such as fever, chills, muscle pain (myalgia), sensitivity to light (photophobia), sore throat (pharyngitis) lymph node enlargement (lymphadeonapathy) and gastrointestinal disturbances --during this time the number of WBC may increase or decrease --patients immune response and other defense mechanisms overcome the pathogen and ____ ends. --if disease is not successfully overcome or treated the patient dies during this period

Vehicle transmission

is the transmission of disease agents by a medium such as water, food or air --other media include blood and other body fluids, drugs and intravenous fluids

Direct contact transmission

known as person to person transmission --is the direct transmission of an agent by physical contact between its source and a susceptible host; no intermediate object is involved --most common forms are touching, kissing and sexual intercourse

Predisposing factors

makes the body more susceptible to a disease and may alter the course of the disease **An example: -- Gender; females have higher incidence of UTI than males, whereas males have higher rates of pneumonia and meningitis --Genetic background; sickle cell anemia is an example --Climate and weather --Other factors include: inadequate nutrition, fatigue, age, environment, habits, lifestyle, occupation, preexisting illness, chemotherapy, and emotional disturbances

Transient microbiota

may be present for several days, weeks or months and then disappear

Enterococcus spp.

most common cause of surgical wound infections

Staphylococccus aureus

most frequent cause of pneumonia

Indirect contact transmission

occurs when the agent of disease is transmitted from its reservoir to a susceptible host by means of a non-living object

Prevalence

of a disease is the number of people in a population who develop a disease at a specified time, regardless of when it first appeared --takes in account old and new cases --is an indicator of how seriously and how long a disease affects a population

Incidence

of a disease is the number of people in a population who develop a disease during a particular time period --This is an indicator of the spread of the disease

Microbial antagonism

or Competitive exclusion --phenomenon where once established, the normal microbiota can benefit the host by preventing the overgrowth of harmful microorganisms

Normal Microbiota

or normal flora --means that microorganisms establish more or less permanent residence (colonize) but that do not produce disease under normal conditions

Opportunistic pathogens

ordinarily do not cause disease in their normal habitat in a healthy person, but may do so in a diferent environment. **An example: microbes that gain access thru broken skin or mucous membranes can cause thise type of infection. Or if the host is already weakened or compromised by infection, microbes that are ususally harmless cause disease.

Waterborne transmission

pathogens are usually spread by water contaminated with untreated or poorly treated sewage --Diseases include: cholera, shigellosis, leptospirosis

Foodborne transmission

pathogens that are transmitted by foods that are incompletely cooked, poorly refirgerated or prepared under unsanitary conditions --pathoges cause disease such as food poisoning and tapeworm infections

Viremia

refers to the presence of viruses in blood

Airborne transmission

refers to the spread of agents of infection by droplet nuclei in dust that travel more than 1 meter from the reservoir to the host

What do Koch's Postulates do?

show that a specific infectious disease, like anthrax, is caused by a specific microorganism (B. anthracis) that can be isolated and cultured on artificial media --this research provided a framework for the study of the etiology of any infectious disease --used by microbiologists to identify causes of emerging diseases

Morbidity

the incidence of specific notifiable diseases (Sickness)

pathogenesis

the manner in which a disease develops

Coagulase-negative staphylococci

the most common cause of sepsis

Mortality

the number of deaths from diseases

Epidemiology

the science that studies when and where diseases occur and how they are transmitted in populations

Nonliving reservoirs

the two major ___________ of infectious diseas are soil and water --Soil: harbors pathogens like fungi and systemic infections --Water: contaminated by feces of humans and animals harbors several pathogens --Other ______ are foods that are improperly prepared or stored

Herd immunity

this exists when many immune people are present in a community

Candida albicans

urinary tract infections and sepsis

Factors of Nosocomial infections

1. Microorganisms in the hospital environment 2. Compromised (or weakened) status of the host 3. Chain of transmission in the hospital --interaction of all three factors poses a significant risk for infections

Factors contributing to EID

1. New strains of disease/infections 2. A new serovar 3. Widespread and Unwarranted use of Antibiotics 4. Global warming and changin weather patterns 5. Travel of known diseases to new areas 6. Previously unrecognized disease/infections in ppl working in areas undergoing ecological changes 7. Animal control measures 8. Failures in public health measures

Areas of normal microbiota body regions

1. Skin 2. Eyes (Conjunctiva) 3. Nose, Throat and Upper Respiratory System 4. Mouth 5. Large Intestines 6. Urinary and Reproductive Systems

What is pathology concerned with?

1. The cause or Etiology of disease 2. Deals with pathogenesis 3. Structure and Functional changes brought about by a disease and their effects of the body

Koch's Postulates

1. The same pathogen must be present in every case of the disease 2. The pathogen must be isolated from the diseased host and grown in pure culture 3. The pathogen from the pure culture must cause the disease when it is inoculated into a healthy, susceptible lab animal 4. The pathogen must be isolated from the inoculated animal and must be shown to be the original organism

Primary sites of Nosocomial infections

1. UTI 2. Surgical site infection 3. Lower respiratory infections 4. Bacteremia caused by intravenous catheterizations 5. Other (Pg 417)

CDC

Centers for Disease Control and Prevention --a branch of the United States Public Health Service located in Atlanta, GA, is a central source of epidemiological information in the US.

Escherichia coli, Pseudomonas aeruginosa, Enterobacter and Klebsiella pneumoniae

Pneumonia and surgical wound infections

Reservoir of infection

a continual source of the disease organism --Source can be either a living organism or an inanimate object that provides a pathogen with adequate conditions for survival and multiplication and an opportunity for transmission --may be human, animal or non-living

Endemic disease

a disease constantly present in a population **An example: Common cold

Chronic disease

a disease that develops more slowly and the body's reactions may be less severe, but the disease is likely to continue or recur for long periods **An example: Infectious mononucleosis, TB and Hep B

Subacute disease

a disease that is intermediate between acute and chronic **An example: subacute sclerosing panencephalitis (a rare brain disease)

Epidemic diseases

a disease where many people in a given area acquire a certain disease in a relatively short period **An example: Influenza

Sporadic disease

a particular disease occurs only occasionally **An example: Typhoid fever

Syndrome

a specific group of symptoms or signs may always accompany a particular disease group

Septicemia

also called blood poisoning is a systemic infection arising from the multiplication of pathogens in the blood --is a common form of sepsis

Case reporting

an effective way of establishing the chain of transmission --a procedure that requires health care workers to report specified diseases to local, state and national health officials.

Pandemic disease

an epidemic disease that occurs worldwide **An example: Influenza from time to time and AIDS

Experimental epidemiology

begins with a hypothesis about a particular disease, experiments to test the hypothesis are then conducted with a group of people

Clostridium difficile

causes nearly half of all nosocomial diarrhea

Symptoms

changes in body function, such as pain and malaise --these are subjective and not always apparent to an observer

Descriptive epidemiology

entails collecting all data that describe the occurence of disease under study --relative info includes: info about the affected individuals and the place and period in which the disease occured