final exam micro

immunoflurescence

Antibodies with an attached fluorescent marker can be used to identify microbes at the species level Two main kinds of fluorescent antibody techniques for microscopy: •Direct, which detects antigen •Indirect, which detects patient antibody to the pathogen

Overview of the Clinical Microbiology Laboratory

Clinical microbiologist •Rapidly and accurately identify pathogens from clinical specimens •Perform antimicrobial susceptibility testing of these organisms Clinical specimen •Portion or quantity of human material that is tested, examined, or studied to determine the presence or absence of specific microbes

Culture-Based Methods

1. For many bacteria and fungi, obtaining pure culture involves growth on selective or differential media 2. Immunomagnetic beads (IMBs)-small particles coated with antibody targeting a specific microbe; when mixed with a clinical sample, antibody mediates binding of the pathogen to the beads; a magnet is used to pull the beads out of solution to inoculate culture media 3. Classic dichotomous keys are coupled with the biochemical tests for the identification of bacteria

Microbiology Risk Group (RG)

1.Not known to consistently cause disease in healthy adults (for example, Lactobacillus casei, Vibrio fischeri) 2.Associated with human disease; potential hazard if percutaneous injury, ingestion, or mucous membrane exposure occurs (for example, Salmonella typhi, Escherichia coli O157:H7, Staphylococcus aureus) 3.Indigenous or exotic agents with potential for aerosol transmission; disease may have serious or lethal consequences (for example, Coxiella burnetii, Yersinia pestis, herpesviruses) 4.Dangerous/exotic agents that pose high risk of life-threatening disease, aerosol-transmitted lab infections; or related agents with unknown risk of transmission (for example, smallpox virus, Ebola virus, hemorrhagic fever viruses) SDS> Safety Data Sheet

Antigens in vaccines are mixed with an adjuvant to enhance the rate and degree of immunization.

true

MLC is the lowest concentration where drug fail to recover

true

almost al known plant viruses are rna viruses

true

macrophages are phagocytic cells

true

which of followiing lacks sufficent penetrating power for bulk sterilization

uv radiation at 260 nm

who are the following to first observe and describe microorganism

van leeuwenhoek

complete virus particle is called

virion

High Hydrostatic Pressure (HHP)

•Alternative way to preserve food •Applies pressures from 100 to 800 millipascals (mPa) without significant changes in temperature •Highly detrimental to cell membranes •Effective at eliminating eukaryotic microbes •Not as effective at elimination of Gram-positive microbes

Foodborne Illness caused by Bacteria

•Bacteria that cause foodborne illness have some basic characteristics: •Temperature •Growth •Form •Toxin production

Botulism

•Bacteria: Clostridium botulinum •Source: •Incorrectly canned food •Reduced oxygen packaged food •Temperature-abused vegetables, such as baked potatoes •Untreated garlic-and-oil mixtures • •Common Symptoms: •Initially- nausea and vomiting. •Later- weakness, double vision, difficulty in speaking and swallowing. •Preventative Measures: •Hold, cool and reheat food correctly. •Inspect canned food for damage.

Salomonellosis

•Bacteria: Salmonella spp. •Source: •Poultry and eggs •Dairy products •Produce •Common symptoms: •Diarrhea •Abdominal cramps •Vomiting •Fever •Preventative Measures: •Cook poultry and eggs to minimum internal temperatures. •Prevent cross-contamination between poultry and ready-to-eat food.

agent that are static and do not kill infecting microorganis are not useful as chemotherapuetic agents

false

bifidobacterial are gram postive motile and spore forming rods

false

dry heat usually require lower and shorter exposure than mosit heat to achieve same degree of killing

false

immerision oil is used to prevent specimen from drying out

false

larger population generally are killed as rapididly as smaller population

false

the lower genitourinary tract is usually free of micro organisms

false

the lower respotoary has less microflora than the upper

false

the number of microbes that make up the human microbiome is approxietly equal to the number of somatic cells

false

viruses consitute the fourth domain of life in the current biological classification schemes

false there are 3

t cells undergo maturation in the bone marrow

false thymis gland

who is usually credited with discovery of pencillin

fleming

the genus mycobacterium

hard to stain, requires acid-fast stain, tuberculosis and leprosy

blood cell devolpment in bone morrow due to

hemapotatsis

sterilization involves blank all vialable micro

killing or removing

when antispetics and disinfects are compared aintiseptics are

less toxic

acid fast organsims such as myco tb contiain BLANKS constructed from mycolic acid in cell wall

lipids

which of following releases histamine

mast cells and basophilis

The lungs are protected from microorganisms by

mucocilary blanket lysozyme in mucus. phagocytic action of alveolar macrophages.

if the objective lense of microscope is changed without loosing focus

parfocal

viariable cells

pelomoprhic

plasma membrane of eukaryotes contains all except

peptidoglycan

shrinkange phase m away from cell wall when bacterium is placed in hypertonic is called

plasmolysis

which of the following can be used to isolate pure culture of bacteria from mixtures

pour plates, streak plates, all choices

viral capsid protein subunits are called

protomers

The counterstain in the Gram stain is

safranin

the reduction of the microbia polulation to levels are considered safe by public heath stadard are called

santization

The immune system normally discriminates between __________ antigens.

self and nonself

under normal circumstance, the microbiota of the skin is kept in check by

slightly aidic pH

rigid bacteria w helical shape

sprilla

chemotherputic agents are artifcally produced are most specifically refred to as

synthetic

Standard Microbiological Practices

1.Persons must wash their hands after working with potentially hazardous materials and before leaving the laboratory. 2.Eating, drinking, smoking, handling contact lenses, applying cosmetics, and storing food for human consumption must not be permitted in the laboratory. 3.Mouth pipetting is prohibited; mechanical pipetting devices must be used. 4.Policies for the safe handling of sharps (such as needles, scalpels, pipettes, and broken glassware) must be developed and implemented. 5.Procedures must be developed and implemented to minimize the creation of splashes and/or aerosols. 6.Work surfaces must be decontaminated with an appropriate disinfectant after completion of work and after any spill or splash of potentially infectious material. 7.All cultures, stocks, and other potentially infectious materials must be decontaminated using an effective method before disposal. 8.A sign incorporating the universal biohazard symbol must be posted at the entrance to the laboratory when infectious agents are present. The sign may include the biosafety level, name of the agent(s) in use, and the name and phone number of the laboratory supervisor or other responsible personnel. Information should be posted according to institutional policy. 9.Persons must report all injuries incurred in the laboratory to the laboratory supervisor as soon as possible.

which of followung inhibits bacterial growth but doesnt kill bacteria

BacteriostaticAgent

Rapid Methods of Identification

Biochemical kits •API 20E Larger labs also use semi-automated robotic systems to detect microorganisms

chemical based preservation

GRAS—chemical agents "generally recognized as safe" •Include organic acids, sulfite, ethylene oxide gas, and ethyl formate •Sodium nitrite—inhibits spore formation and germination in meats; forms nitrosamines pH •Use of acids can inhibit microbial growth on meat •Impacts effectiveness of chemical preservatives

who developed criteria that be used to establish a caustive link between a particular microorganism and p

Koch

Identification of Microorganisms from Specimens

Preliminary/definitive identification of microbe based on numerous types of diagnostic procedures Direct identification methods: •Culture-based methods •Microscopy and immunofluorescence •Molecular methods

Patient Specimen Evaluation Methods

Rapid test and immunoassays: amino acids, antigen tests, for covid or STI Molecular Testing: protist, bacteria, fungi, virus Biochemical Test: on bacteria and fungi Culture: obtain a pure culture, isolate bacteria that causes disease Microscopy : 90-95% gram negative infectious

Biosafety Level

Recommended guidelines for additional precautions reflect the laboratory's biosafety level (BSL) BSL-1 •Standard microbiology practices •No barriers required; personal protective equipment (PPE): laboratory coats and gloves; eye, face protection, as needed •Laboratory bench and sink required BSL-2 •BSL-1 practice plus: Limited lab access; biohazard warning signs; "sharps" precautions; biosafety manual defining any needed waste decontamination or medical surveillance policies •Biosafety cabinets (BSCs) or other physical containment devices used for all manipulations of agents that cause splashes or aerosols of infectious materials; PPE: laboratory coats, gloves, face and eye protection, as needed •BSL-1 facilities plus autoclave available BSL-3 •BSL-2 practice plus: controlled lab access; all waste decontaminated; lab clothing decontaminated before laundering; baseline serum testing •BSCs or other physical containment devices used for all open manipulations of agents; PPE: protective lab clothing, gloves, respiratory protection as needed •BSL-2 facilities plus self-closing double door, negative air pressure, room exhaust not recirculated, away from access corridors BSL-4 •BSL-3 practice plus: different clothing to enter; shower to exit; decontaminate all material on exit •Class III (glove box) cabinet-based work or Class II (laminar flow) BSC with full-body, positive pressure suit •BSL-3 facilities plus separate building or zone, dedicated heat, ventilation, and air-conditioning system, vacuum, and decontamination systems

drug level required for the clinical treatment of a particular infection

therapetic dose

as the magnification of serioes of object lenses increase working distance

decreases

Specimen Collection

The clinical specimen should: •Represent the diseased area •Be of sufficient quality and quantity •Collected to avoid contamination •Be in a proper container, promptly sent to laboratory •Be obtained before antimicrobial treatment •Be accompanied by a putative diagnosis

Microscopy

Wet-mount, heat-fixed, or chemically fixed specimens can be examined with bright-field or phase-contrast microscopy Stains, like the Gram stain, often used Definitive identification of most fungi is based on the morphology of hyphae or conidia (spores) Protozoa are most often identified based on the morphology of their ova, trophozoites, and cysts Helminths are often visualized in concentrated wet mounts of stool or urine specimens examined for the presence of eggs, larvae, or adult worms

medium that distingues among different groups of bacteria pm basis of their biological charatcer is called a

differential

which of following is liekly to have most toxic side effect to humans

disrupters of cell membrane structures

Human cancer causing viruses most often have a ___________ genome.

dsDNA

the secondary immune respose is stronger than primary

a larger population of lymphocytes reactive to the antigen has devolped

the final outcome of most host-parasite realtionship depends on

all of the choices

which of the folowing is a desirable general charcteristic of anitmicrobal drugs

all of the choices

chemotherapeutic agents are natural products of micro are most specifically refereed to as

antibiotics

which of following choices describes a recombinant vaccine

antigen mixed with nontoxic agent with enhances processing

prevention of infection caused by micro o

antisepsis

lysozyme enzyme that lyses

bacteria

overgrowth of the skin bacterium proprionbacterium acnes may lead to

body odor

protein coat surrounding the viral genome is called

capsid

mechanisms for first line of defense include

chemical barriers, genetic, physical

media containing some ingerdients of unknown chemical compostion are called

complex media

Hemorrhagic colitis

•Bacteria: Shiga toxin-producing Escherichia coli including O157:H7, O26:H11, O111:H8, and O158:NM •Source: •Contaminated food, especially undercooked ground beef, unpasteurized (raw) milk and juice, soft cheeses made from raw milk, and raw fruits and vegetables (such as sprouts) •Contaminated water, including drinking untreated water and swimming in contaminated water •Animals and their environment: particularly cows, sheep, and goats. If you don't wash your hands carefully after touching an animal or its environment, you could get an E. coli infection •Feces of infected people •Common Symptoms: •Severe diarrhea that is often bloody, severe abdominal pain, and vomiting. Usually, little or no fever is present. •Preventative Measures: •Avoid eating high-risk foods, especially undercooked ground beef, unpasteurized milk or juice, soft cheeses made from unpasteurized milk, or alfalfa sprouts. •Use a food thermometer to make sure that ground beef has reached a safe internal temperature of 160° F. •Wash hands before preparing food, after diapering infants, and after contact with cows, sheep, or goats, their food or treats, or their living environment .

Shigellosis

•Bacteria: Shigella spp. •Source: •Food that is easily contaminated by hands, such as salads containing potato, tuna, shrimp, macaroni and chicken. •Food that has made contact with contaminated water, such as produce •Common symptoms: •Bloody diarrhea •Fever (occasionally) •Preventative Measures: •Keep food handlers with the bacteria or diarrhea out of operation •Wash hands •Control flies

Staphylococcal gastroenteritis

•Bacteria: Staphylococcus aureus •Source: •Food that requires handling during prep, including salads (tuna, chicken, macaroni) •Deli meats •Common Symptoms: •Nausea •Vomiting and retching •Abdominal cramps •Preventative Measures: •Wash hands, particularly after touching hair, face or body •Cover wounds on hands and arms •Hold, cool and reheat food correctly

Vibrio gastroenteritis

•Bacteria: Vibrio vulnificus and Vibrio parahaemlyticus •Source: •Oysters from contaminated water •Common symptoms: •Diarrhea •Abdominal cramps and nausea •Vomiting •Low-grade fever and chills •Preventative Measures: •Cook oysters to minimum internal temperatures.

Microbial Product-Based Inhibition

•Bacteriocins •Bactericidal proteins active against related species •Some dissipate proton motive force of susceptible bacteria •Some form pores in plasma membranes •Some inhibit protein or RNA synthesis •For example, nisin from Lactococcus lactis •Used in low-acid foods to inactivate Clostridium botulinum during canning process •For example, bacteriophages that kill Listeria monocytogenes •Sprayed onto ready-to-eat meats prior to packaging

Pathogens need six conditions for growth- FAT TOM

•Food •Acidity •Temperature •temperature danger zone (5°C to 57°C) = where they multiple and grow - 4 hrs •Time •Oxygen •Moisture

High Temperature

•Food heated in special containers (retorts) to 115°C for 25 to over 100 minutes; kills spoilage microbes, but not necessarily all microbes in the food •Spoilage of canned foods may occur due to spoilage before canning, under processing during canning, or leakage of contaminated water into cans during cooling process

Modified Atmosphere Packaging (MAP)

•Gases in stored food affect microbial growth •Shrink-wrap materials and vacuum technology control atmosphere in package •Impermeable to oxygen •High CO2 content packaging can be used to prevent fungal growth •High O2 content packaging produces superoxide anions that inhibit microbial growth

Temperature

•High temperature kills spoilage microbes (vegetive and spore form) , but not necessarily all microbes in food •Low temperature retards but does not stop microbial growth •microorganisms can still cause spoilage with extended storage WHAT IS THE TEMPERATURE DANGER ZONE?

Bacillus Cereus

•Illness: Bacillus cereus gastroenteritis •Reservoir: present in foods and can multiply quickly at room temperature •Incubation period: •Diarrheal: 6-15 hours •Emetic (vomiting): 30 minutes to 6 hours •Treatment: Bed rest and hydration •Source: •Diarrhea Illness- cooked vegetables, meat products, milk •Vomiting Illness- cooked rice dishes, indlucing fried rice and rice pudding •Preventative measures: •Cook food to minimum internal temperatures •Hold food at right temperature •Cool food correctly

Clostridium perfringens

•Illness: Clostridium perfringens gastroenteritis •Source: beef, poultry, gravies and stews •Common symptoms: •Diarrhea •Severe abdominal pain •Not fever or vomiting •Preventative Measures: •Thoroughly cook foods, particularly meat, poultry, and gravies, to a safe internal temperature. •Use a food thermometer •Keep food hot after cooking (at 57˚C or above) •Microwave reheated food thoroughly •Refrigerate perishable foods within two hours (at 5˚C or below) •Divide leftovers into shallow containers and refrigerate immediately. Do not let them cool on the counter.

Listeria monocytogenes

•Illness: Listeriosis •Source: raw meat, unpasteurized dairy products, ready-to-eat food such as deli meat, hot dogs and soft cheese •Common Symptoms •Pregnant women: miscarriage •Fever, stiffneck, confusion, weakness, vomiting (sometimes preceded by diarrhea) •Preventative Measures: •Throw out any product that has passed its use-by or expiration date. •Cook raw meat to minimum internal temperatures. •Prevent cross-contamination between raw or undercooked food and ready-to-eat food. •Avoid using unpasteurized dairy products.

Foodborne Illness caused by Viruses

•Viruses can survive fridge and freezer temperatures •They can't grow in food; but once eaten, can grow inside a person's intestines •Can contaminate both food and water •Can be transferred from: •Person to person •People to food •People to food-contact surfaces

Norovirus

•Illness: Norovirus gastroenteritis •Reservoir: feces of infected individuals •Transmission: person to person, food and water to person, or surface to person •Incubation period: 12 to 48 hours •Treatment: Bed rest and hydration •Source: Produce, shellfish, ready-to-eat foods touched by infected food workers (salads, sandwiches, ice, cookies, fruit), or any other foods contaminated with vomit or feces from an infected person •Common symptoms: Diarrhea, vomiting, nausea,and stomach pain. Diarrhea tends to be watery and non-bloody. Diarrhea is more common in adults and vomiting is more common in children Prevention Measures: •Wash hands frequently with soap and running water for at least 20 seconds, particularly after using the bathroom and before preparing food. •If you work in a restaurant or deli, avoid bare-hand contact with ready-to-eat foods. •Clean and disinfect surfaces contaminated by vomiting or diarrhea (use a bleach-based household cleaner as directed on the label). Clean and disinfect food preparation equipment and surfaces. •If you are ill with diarrhea or vomiting, do not cook, prepare, or serve food for others. •Wash fruits and vegetables and cook oysters and other shellfish thoroughly before eating them. •Wash clothing or linens soiled by vomit or fecal matter immediately. Remove the items carefully to avoid spreading the virus. Machine wash and dry.

Hepatitis A

•Illness: liver disease caused by the hepatitis A virus. •Reservoir: feces of infected individuals •Transmission: food or water contaminated by feces •Incubation period: 28 days average (ranges from 15 to 50 days) •Treatment: vaccine, recommended for ages 12 months and older •Source: Raw or undercooked shellfish from contaminated waters, raw produce, contaminated drinking water, uncooked foods and cooked foods that are not reheated after contact with an infected food handler. •Common symptoms: Fever (mild), general weakness, nausea, dark urine, abdominal pain and jaundice (appears later) •Prevention Measures: •Get vaccinated •Avoid eating oysters or other raw or undercooked shellfish •Keep employees who have jaundice or Hepatitis A out of operation •Wash hands •Minimize bare-hand contact with ready-to-eat foods

Controlling Food Spoilage

•Methods of preservation •goal is to eliminate or reduce the populations of spoilage and disease causing microbes while maintaining food quality •Examples: •Filtration •Pasteurization •Irradiation •Use of antimicrobial agents

Filtration

•Microorganisms can be removed from water, wine, beer, juices, soft drinks, and other liquids by filtration •May better preserve flavor and aroma than pasteurization

Foods That have right FAT TOM

•Milk and dairy products •Eggs •Meat: beef, pork and lamb •Poultry •Fish •Shellfish and crustaceans •Baked potatoes •Heat-treated plant food- cooked rice, beans, vegetables •Tofu or soy protein •Sprouts and sprout seeds •Sliced melons and cut tomatoes •Untreated garlic-and-oil mixtures

Pastuerization

•Pasteurization- take up temp rapidly and hold at specific for amount of time then bring it down •Kills pathogens and reduces number of spoilage organisms •Different pasteurization procedures heat for different lengths of time (shorter heating times result in improved flavor) -Type of Pasteurization -Temperature and Duration of Heating -Products Pasteurized Low-temperature holding (LTH) 68.2°C, 30 minutes Beer, fruit juice, smaller volumes of milk High-temperature short-time (HTST) 72°C, 15 seconds Industry standard for milk and other dairy products in the United States Ultra-high temperature (UHT) 138°C, 3 seconds Milk that does not require refrigeration until opened

Water Availability

•Presence and availability of water affect ability of microbes to colonize food •Food preservation due to drying, increase in solute concentration •Dehydration, such as lyophilization to produce freeze-dried foods, is a common means of preventing microbial growth

Radiation

•Radappertization •Use of ionizing radiation (gamma radiation) to extend shelf life or sterilize meat, seafoods, fruits, and vegetables •Excellent penetrating power •Food not heated nor rendered radioactive •Kills microbes in moist foods by producing reactive oxygen species from water

Low Temperature

•Refrigeration at 5°C slows but does not stop microbial growth •Microorganisms can still cause spoilage with extended storage •Listeria monocytogenes can grow at refrigeration temperature

Microbial Growth and Food Spoilage

•Results from growth of microbes in food •alters food visibly and in other ways, rendering it unsuitable for consumption •Involves predictable succession of microbes •Different foods undergo different types of spoilage processes •Toxins are sometimes produced

Prevention of Illness

•The following steps can help prevent food poisoning (adapted from the U.S. Centers for Disease Control and Prevention). •Shop safely . Bag raw meat, poultry, and fish separately from other food items. Young children can get sick from touching packaged poultry, so don't allow them to touch or play with packages of poultry in your grocery cart. •Prepare foods safely . Wash your hands before and after handling food. Wash fruits, vegetables, and cutting boards. Follow procedures for safe home canning to avoid contamination. •Store foods safely . Cook, refrigerate, or freeze meat, poultry, eggs, fish, and ready-to-eat foods within 2 hours. Make sure your refrigerator is set at 40°F (4°C) or colder. •Cook foods safely . Use a clean meat thermometer to make sure that foods are cooked to a safe temperature. Reheat leftovers to at least 165°F (74°C). Don't eat undercooked hamburger. And be aware of the risk of food poisoning from raw fish (including sushi), clams, and oysters. •Serve foods safely . Keep cooked hot foods hot [140°F (60°C) or above] and cold foods cold [40°F (4°C) or below]. •Follow labels on food packaging . These labels provide information about when to use the food and how to store it. •When in doubt, throw it out. If you aren't sure if a food is safe, don't eat it. Reheating food that is contaminated won't make it safe. Don't taste suspicious food. It may smell and look fine but still may not be safe to eat. •Make smart restaurant choices. •Note the general cleanliness of the facility and staff. If you aren't confident that conditions are sanitary, leave. •Restaurants are inspected by the local health department for cleanliness and proper kitchen procedures. Find out the inspection scores of selected restaurants. (They are sometimes posted in the restaurant.) •Find out if food safety training is regularly provided for staff.

Controlling Food Spoilage

•Time (limit) •Temperature (freezer slowing the growth) (boil will kill it) •Preservation

Pathogens that cause foodborne illness

•Viruses •Bacteria •Parasites •Fungi