Micro Test 1 Material

PowerPoints 1-5

How are microbes classified in the clinical laboratory?

How are microbes classified in the clinical laboratory?

Phenotypical characteristics and Genotypic characteristics

What are phenotypical characteristics?

characteristics that can be observed and can be seen

What are some examples of phenotypical characteristics?

morphology, staining, environmental requirements, nutritional requirements, resistance profiles, antigenic properties

What are genotypical characteristics?

genetic information

What are some example of genotypical characteristics?

DNA base composition, DNA or RNA sequence

What is a species?

Most basic taxonomic group

What is a genus?

Different species with many common phenotypic and genotypic features

What is a subspecies?

share minor characteristics; called biotypes, subtypes, strains, or genotypes

What happens in the cytoplasm?

metabolic processes

What are plasmids?

small, circular extrachromosomal DNA found in bacterial chromosomes

What are the functions of the bacterial cell wall?

1. Provides stability and strength to the bacterial cell

2. Regulates transport of macromolecules in and out of the cell

What are exotoxins secreted by?

living bacterial cell

What are some examples of exotoxins?

Cholera toxin, Toxic Shock Syndrome, Diphtheria Toxin

How do microorganisms adjust to environmental changes?

1. Recombination

2. Mutations

3. Genetic exchange

What is an infection?

bacteria making you sick

What is a pathogen?

organism that has a capability of causing infection

What is normal flora

good bacteria that compete with pathogenic bacteria

What are some advantages of normal flora?

• Attach to receptors on host

• Compete for nutrients

• Stimulate development of immune system

• Produce antimicrobial substances

• Synthesize vitamins

What is a true pathogen?

always causes infection

What is an opportunistic pathogen?

organism that does not typically cause infections but can in certain situations ie immunocompromised

What are some examples of virulence factors?

• Adherence factors

• Capsules

• Endotoxins

• Exotoxins

What is direct mode of transmission?

person to person

What are some examples of direct modes of transmission?

• Congenital

• Hand-to-Hand

• Sexual

• Respiratory droplets or secretions

What is indirect modes of transmission?

when bacteria is transferred from something like an object or animal

What are some examples of indirect transmission?

• Fomites

• Animals, insects, arthropods

• Food

• Water

• Airborne

What is incidence?

Number of those affected in a population

What is prevalence?

Percentage of infected individuals in a population at a given time

What is an Outbreak?

Disproportionately larger number of infected individuals in short period of time

What is endemic?

Disease that consistently present but is limited to a certain area

What is an epidemic?

Sudden increase in disease in certain bacteria

What is a pandemic?

Outbreak of disease across several countries or continents

What is nosocomial?

• Healthcare associated infection

• Acquired in healthcare setting

What is community-acquired?

• Present at time of admission

• Acquired within community

What is colonization?

Presence and multiplication of microorganism in host, with no clinical signs of infection

What is morbidity?

Number cases of disease in population

What is mortality?

Number death from disease in population

What is surveillance?

Collection of data pertaining to disease occurrence

What is an index case?

First case

What is an exposure control plan?

describes risk of exposure to infectious agents and explains exposure reduction methods

What are the factors of exposure control

1. Safety education

2. Universal/Standard precautions

3. Engineering controls

4. Personal protective equipment

5. Postexposure procedures

6. Disposal of hazardous

What are some examples of safety education?

• Orientation for new employees

• Continuing education for current employees

• Safety Manual

What is universal precautions?

• A set of preventative measures designed to reduce risk of transferring HIV, Hep B, and other bloodborne pathogens

• Applies to all blood and body fluids containing visible blood

What is standard precautions?

• Applies to ALL patients

• Designed to reduce risk of ALL infections in healthcare setting

• ALL blood, tissue, body fluids, secretions, excretions (except sweat) are potentially infectious

What is BSL 1

1. No known pathogenic potential

2. Adhere to standard lab techniques

What is BSL 2

• Follow Level 1 practices, plus lab coat, gloves, decontamination of infectious waste, biohazard warning signs

What is BSL 3?

• Follow Level 2 practices, plus special lab clothing, controlled access

• Air movement carefully controlled

What is BSL 4

• Level 3 practice, plus entrance through separate room which street clothing is replaced with lab clothing

• Maximum containment

• Decontamination of all personnel and material before leaving area

What are Biological Safety Cabinets (BSC)?

• Used for any procedures that create aerosols

What is BSC I?

• Open fronted, negative pressure, ventilated cabinet

• Unsterilized air

• Have HEPA filter

What is BSC II?

• Open-fronted, ventilated cabinet

• Sterilizes air entering and circulating within cabinet and exhaust air

• Have HEPA

What is BSC III?

• Highest level of safety

What are examples of Personal Protective Equipment?

• Disposable gloves

• Laboratory gowns

• Eye Protection

• Face masks

What are some protocols with a postexposure plan?

• All laboratory accidents/incidents must be reported

• Appropriate medical treatment given immediately

• Potential exposure to Hepatitis B or HIV should be followed clinically and serologically

• Documentation required

• Review incident and determine preventive measures

What is sterilization?

Destroys ALL pathogens (spores, vegetative cells, fungi, viruses

What is disinfectant?

Destroys or inactivates bacteria, viruses, and fungi (not spores)

What is antiseptic?

Chemical germicide used on skin; not to be substituted for disinfectant

List the organisms most resistant to least resistant to killing agents.

1. Prions

2. Bacterial spores

3. Mycobacteria

4. Nonlipid viruses

5. Fungi

6. Bacteria

7. Lipid viruses

What are the criteria for specimen rejection?

• Received in Formalin

• 24 hour specimen collection

• Sputum with >10 SEC/lpf

• Smear from cervix, vagina, or anus for Neisseria gonorrhoeae

• Improper, nonsterile container

• Specimens for anaerobes that are contaminated with normal flora

What are requirements for GI Tract specimens?

• Fresh stool

• Specimen collected from endoscopy

What are the requirements for blood specimens?

• Collect when patient is febrile

• 2-4 specimens collected from separate venipuncture sites at least one hour apart

• Aerobic & anaerobic bottle

• 20 mL

What are requirements for Urine specimens?

• Clean-catch midstream

• Catheterized

• Always quantitate (perform colony count)

• Inoculate plate with 1 micrometer loop

  • # colonies x 1000 = CFU /mL

Requirements for Cerebrospinal Fluid

• 3rd tube for micro

• No delay

What are the requirements for the genital tract specimens?

• Wet mount for trichomonas vaginalis

• Selective plates for N. gonorrhoeae

What are the requirements for wound and abscess specimens

• Ideal —> collect with needle and syringe

What is a broth?

Media in liquid form

What is an agar?

Gel or semisolid media

What is a colony?

Bacterial population derive from single bacteria cell

What are isolated colonies?

not clustered in one big clump

What is general isolation media?

• Supportive media

• Supports growth on non-fastidious bacteria

What are examples of general isolation media?

• Nutrient agar

• Trypticase soy agar

• Nutrient broth

What is non-selective media?

• Also called enriched media

• Contain nutrient supplement

• Contain 5% defibrinated sheep red blood cells

What are some examples of non-selective media?

• Sheep blood agar

• Chocolate agar

What is sheep blood agar?

See presence of hemolysis by bacteria

What is chocolate agar?

Contain X and V factors for Haemophilus

What is differential media?

Allows grouping of microbes based on colonial appearance

What are some examples of differential media?

• Sheep blood agar

• MacConkey Agar

• Eosin-methylene blue (EMB) agar

What is selective media?

Inhibits growth of all bacteria except those that are sought

What are examples of Selective media

• Hektoen enteric (HE) agar

• Xylose-lysine-deoxycholate (XLD) agar

• Colistin-nalidixic acid (CNA) agar

• Modified Thayer-Martin (MTM) agar

• Salmonella-Shigella (SS) agar

What is enrichment broth?

Liquid media used to inhibit growth of one organism while enhancing that of another organism by providing nutrients

What are examples of enrichment broth

• Gram negative broth

• Thioglycolate broth

• Lim Broth

What is prophylactic therapy?

treating patients who are at high risk for infection

What is empiric therapy?

Patient who has all the symptoms and signs of infection and antibiotic is given to most likely cause or most common cause of infection

What is definitive therapy?

the pathogen has been IDed and the physician knows that the patient is on the correct antimicrobial treatment

What is bacteriostatic?

• Inhibits growth

• Antimicrobial removed —> multiplication

• Successful if patient has effective immune system

What is bactericidal?

• Kills bacteria

• Preferred in serious infections (endocarditis, meningitis, osteomyelitis)

• Neutropenic patients

Are penicillins bacteriostatic or bactericidal?

bactericidal

Are Cephalosporins bacteriostatic or bactericidal?

bactericidal

Are carbapenems bacteriostatic or bactericidal?

bactericidal

Are monobactams bacteriostatic or bactericidal?

bactericidal

Is vancomycin bacteriostatic or bactericidal?

bactericidal (slowly)

Are Fluoroquinolones bacteriostatic or bactericidal?

Bactericidal

Are aminoglycosides bactericidal or bacteriostatic?

bactericidal

Is metronidazole bacteriostatic or bactericidal?

bactericidal

Is daptomycin bacteriostatic or bactericidal?

bactericidal

Are macrolides bacteriostatic or bactericidal?

bacteriostatic

Are tetracyclines bacteriostatic or bactericidal?

bacteriostatic

What is the mode of activity for B-lactam antibiotics?

Inhibits cell wall synthesis by inhibition of enzymes needed for peptidoglycan formation

What is nitrocefin?

Agent used to test for beta lactamase production

What are examples of B-lactam antibiotics?

• Penicillins

• Monobactams

• Carbapenems

• Cephalosporins

What are example(s) of Penicillins?

• Penicillin

• Ampicillin

• Methicillin

• Piperacillin