Exam 1 Flashcards by Tabatha O'Keefe

List the two Gram+ aerobic cocci:

Staphylococcus

Micrococcus

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What differentiates S. aureus from S. epi/sap?

*S. aureus is Coagulase+ and beta hemolytic

+S.epi/sap are Coagulase- and gamma hemolytic

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This media is selective for S. aureus due to what:

Mannitol Salt

Due to increased NaCl and lactose fermentation (yellow halo)

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T/F Staphylococci spp. are Bacitracin resistant:

True

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Staphylococci is lysostaphin ______:

susceptible

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Are Staphylococci spp. microdase + or -?

negative (will stay original color)

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Describe the Gram stain morphology of Staphylococci spp.:

Gram+ grape like clusters (some tetrads and pairs)

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T/F Staphylococci are facultative anaerobes:

True

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What media will Staphylococci spp. grow on:

SBAP
Chocolate
Mannitol Salt (selective)

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What type of growth will S. epi and S. sap show on Mannitol Salt agar:

S. epi: growth but no ferment

* S. sap: growth but varied ferment

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Which bacteria can cause Ritter disease aka Scalded Skin Syndrome:

Staph aureus

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Is Staph aureus coagulase+ for bound factor, free factor, or both:

Both
Confirmed via tube test
(slide test only shows bound factor)

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Gram+, catalase+, coagulase+, medium to large creamy yellow colonies w/ beta hemolysis:

Staph aureus

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Which bacteria causes tampon related TSS:

Staph aureus

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What pathologies can Staph aureus cause:

Ritter disease
TSS
Folliculitis, stye, furuncles
Food poisoning
Impetigo
Bacteremia (catheters)
Endocartitis (can be nosocomial)

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T/F Endocarditis caused by S. aureus can be nosocomial and mortality rate can reach ~50%:

True

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Extracellular enzymes and toxins are associated with what bacteria:

Staph aureus

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This enzyme breaks down fibrinogen into fibrin, and helps protect bacteria from phagocytosis:

Coagulase

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This enzyme dissolves fibrin/clot, enabling infection to spread:

Staphylokinase

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These cause lysis of neutrophils and macrophages, inhibiting phagocytosis:

Leukocidins

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These lyse RBC’s:

Hemolysins
(alpha, beta, gamma, delta all lyse RBC’s)
(all but beta may lyse WBC’s)

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Which hemolysin does not also lyse WBC’s:

Beta

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This enzyme hydrolyzes hyaluronic acid in connective tissues, spreading infection:

hyaluronidase

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Lipase enzymes hydrolyze plasma and skin lipids, enabling organism to colonize this part of the body:

Skin (boils, etc)

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This enzyme hydrolyzes tissue and are prevalent in Ritter's Disease:

Exfoliatins

These enzymes consist of 7 heat stable proteins:

Enterotoxins | A, B, C, C2, D, E, F

Which two enterotoxins are responsible for most food poisoning:

A and B

Which enterotoxin is also known as TSST-1 (toxic shock):

Enterotoxin F is associated with this pathology:

TSS

Enterotoxins A and B are associated with this pathology:

Food poisoning

This cell wall protein is capable of binding IgG molecules at the Fc/Fab region of B cell receptors, impairing opsonization and phagocytosis:

Protein A

What do beta-lactamases do:

They are bacterial enzymes that bind to the beta-lactam ring in antibiotics, making them ineffective

Bullous impetigo is associated with this bacteria and will culture ___:

S. aureus | positive

What differentiates Staph epi from Staph sap:

S. epi: Sensitive to novobiocin | S. sap: Resistant to novobiocin

Which Staph sp is resistant to novobiocin:

Staph saprophyticus

Which Staph sp is NOT nosocomial:

Staph saprophyticus

This bacteria is known to produce biofilm, causing nosocomial infections w/ prosthetics, etc:

Staph epidermidis

This bacteria is the 2nd most common cause of UTI's in females:

Staph saprophyticus

Gram+, Catalase +, Coagulase-, opaque small gray-white colonies, gamma hemolytic, shows growth but NO fermentation of Mannitol salt agar:

Staph epidermidis

Gram+, catalase+, coagulase-, bright white creamy colonies, gamma hemolytic, shows growth and varied degrees of fermentation on Mannitol salt agar:

Staph saprophyticus

T/F Most coagulase- Staph spp are normal flora; thus are common contaminants in clinical specimens:

True

Most frequently encountered coagulase- Staph spp:

Staph epidermidis

What imparts wide range of antibiotic resistance to MRSA:

mecA gene

What are the two forms of MRSA:

* community acquired | * hospital acquired (nosocomial)

What is the treatment for MRSA:

Macrolide antibiotics | clindamyciin or vancomycin

What is used for susceptibility testing of MRSA and why:

Oxacillin or Cefotoxin | *because Methicillin is no longer available in US

What media is selective and differential for MRSA:

BBL CHROMagar MRSA II

What makes BBL CHROMagar MRSA II selective and differential for MRSA:

* Selective: Cefotoxin (inhibits Gram- and yeasts) | * Differential: Chromagen additives (MRSA hydrolyzes chromagen, producing mauve colonies)

Micrococcus is strictly ______:

aerobic

Describe the Gram stain morphology of Micrococcus:

Gram+ tetrads

T/F Micrococcus is normal flora of skin, mucosa, oral pharynx, and is common contaminant of clinical specimens:

True

T/F Micrococcus is highly pathogenic:

False | Is normal flora and common contaminant of clinical specimens

Describe presumptive vs definitive ID of MRSA on BBL CHROMagar:

* Presumptive: mauve colony growth w/in 48 | * Definitive: mauve colony growth w/in 24 hours

Micrococcus spp. is bacitracin ____ and lysostaphin _____:

* Bacitracin susceptible | * Lysostaphin resistant

Colonies of this bacteria on SBAP can be white, tan, yellow, golden yellow, orange, pink:

Micrococcus spp.

This bacteria is strictly aerobic, appears as Gram+ tetrads, microdase+, is bacitracin susceptible, lysostaphin resistant, and colony color is varied:

Micrococcus spp.

List the bacteria included in the group Gram+, Catalase-, Oxidase-:

``` Streptococcus spp. Enterococcus spp. Viridans Strep Leuconostoc Aerococcus Abiotrophia ```

Gram+ cocci are commonly normal flora of upper respiratory tract, but can be pathogenic in _____:

throat

Staph is catalse ___ and Strep is catalase___:

Staph: catalase+ Strep: catalase-

T/F Strep pyogenes can be normal flora:

False. | All Strep spp EXCEPT S. pyogenes can be normal flora

What is the drug of choice for S. pyogenes, S. agalactieae, and groups C, F, G:

Penicillin | if allergy, use erythromycin

Susceptibility testing is indicated for which species of Strep due to resistance:

S. pneumoniae | Viridans Strep

The serologrouping based on surface carbohydrate antigens of various Strep species:

Lancefield group | A, B, C, D, F, G

Which Lancefield groups are clinically significant:

A, B, C, D

What antibiotics are used for susceptibility testing in Strep spp.:

Bacitracin | Optochin

Bile solubility test is positive (turns brown) in this Strep sp?

S. pneumoniae

Which Gram+, catalase- cocci are PYR positive (turns pink) :

Strep pyogenes | Enterococcus sp.

A positive result with this test gives a presumptive ID for Group B strep (agalactieae):

``` Hippurate hydrolysis (positive= purple) ```

The CAMP test is positive in this Gram+, catalase-, aerobic cocci:

Strep agalactieae

What can interfere with the CAMP test:

CO2 (don't use a candle jar)

Is Enterococci pos or neg for Salt Tolerance Test:

positive | turns yellow or turbid

Is Group D Strep pos or neg for Salt Tolerance Test:

negative | stays purple

Describe Gram stain morphology of Strep pyogenes:

Gram+ cocci in chains

What would you do to SBAP when culturing a throat swab:

inoculate plate with SXT antibiotic to inhibit growth of normal flora

Describe colony morphology of Strep pyogenes on SBAP:

gray-white colonies w/ beta hemolysis

What can be a complication of Strep throat in children due to M protein:

Glomerulonephritis) | 95% recover w/ treatment

Necrotizing fasciitis is associated with this bacteria:

Strep pyogenes

TSS with bacteremia and necrotizing fasciitis is associated with this bacteria:

Strep pyogenes

List the 4 virulence factors associated with Strep pyogenes:

Streptolysin O Streptolysin S M protein SPE's

Streptolysin O is oxygen_____, Streptolysin S is oxygen_____:

O: oxygen LABILE (inactived by O2) S: oxygen STABLE

Which Streptolysin is antigenic:

Streptolysin O is antigenic | induces host immune response w/ antibody production

These virulence factors induce lysis of RBC's, WBC's, and platelets:

Streptolysins O and S

Which virulence factor of Strep induces antibody formation and may cause disease post-infection:

M protein

Which diseases can M protein virulence factor cause post-infection with Strep pyogenes:

* Rheumatic fever (fever, endocarditis) | * Glomerulonephritis

This virulence factor associated with S. pyogenes can induce fevers, inflammation, shock, Scarlet fever:

Streptococcal Pyrogenic Exotoxins (SPE's)

What virulence factors cause Rheumatic Fever and Scarlet Fever:

* Rheumatic: M Protein | * Scarlet: SPE's

This can occur from S. pyogenes related SPE's and involves red rash, skin peeling, sore throat, fever:

Scarlet Fever | treat w/ 10 day course antibiotics

Which test would be ordered if recent strep infection suspected and experiencing other disease symptoms such as glomerulonephritis:

ASO (anti- streptolysin O) ***will only show if pt had recent strep infection

Lancefield grouping is done via this test:

latex agglutination

Group B strep:

Strep agalactieae

Which bacteria is associated with respiratory distress, sepsis, pneumonia, meningitis, and death in neonates if mother is not treated:

Strep agalactieae | Group B

T/F Strep agalactieae is beta hemolytic

True

Which Strep species are alpha hemolytic:

``` S. pneumoniae Strep Viridans (occasionally gamma) ```

This bacteria has small gray colonies resembling donuts:

Strep pneumoniae

This bacteria is the leading cause of bacterial pneumonia and meningitis:

Strep pneumoniae | at risk under 2, over 65

PCV13 and PPSV23 are vaccines for what bacteria:

Strep pneumoniae

Does Strep pneumoniae contain any virulence factors:

Yes. C Polysaccharide | impedes phagocytosis

S. sanguis, S. mitis, S. gordonii, S. anginosus, and S. mutans belong to this group:

Strep Viridans

Which species within Strep Viridans is linked to dental caries:

Strep mutans

Do species within Strep Viridans possess group antigens?

No.

Are species within Strep Viridans highly pathogenic?

No. Low virulence, but maybe cause endocarditis and meningitis.

What test differentiates Viridans Strep from Enterococcus and Group D Strep:

Bile Esculin | *is negative in Viridans Strep

This Gram+, catalase- cocci may display alpha, beta, or gamma hemolysis:

Enterococcus spp.

Treatment for Enterococcus spp:

Vancomycin + aminoglycoside

Enterococcus spp is resistant to ____ and ___, and is becoming increasingly resistant to ______:

Cephalosporins and Aminoglycosides Vancomycin (VRE)

VRE:

Vancomycin Resistant Enterococcus

This bacteria used to be named Streptococcus faecalis (Group D Strep), but is now:

Enterococcus faecalis

T/F Enterococcus spp mostly causes nosocomial UTI's, but is also a significant cause of endocarditis:

True

This bacteria is becoming increasingly resistant to Vancomycin:

Enterococcus spp.

Enterococcus spp is ______ for Salt Tolerance test, PYR test, and Pyruvate broth:

Positive

What test differentiates E. faecalis (positive) from E. faecium (negative):

Pyruvate broth

Natural habitat is plants, veggies, dairy:

Leuconostoc spp.

This bacteria is rarely pathogenic, but can cause meningitis, bacteremia in immunocompromised, also linked to nosocomial outbreak in Spain:

Leuconostoc spp.

T/F Only some Leuconostoc spp are resistant to Vancomycin:

False. | ALL Leuconostoc spp. are Vancomycin resistant.

Gram+, Catalase-, PYR-, cocci in chains and pairs, alpha hemolysis, produces CO2 from glucose:

Leuconostoc spp.

Should Leuconostoc spp. first be considered a contaminant in a clinical specimen?

Yes. It is rarely pathogenic.

What is the natural habitat of Leuconostoc spp?

Plants, veggies, dairy

List the 3 organisms for Gram- diplococci, oxidase+:

Neisseria meningitidis Neisseria gonorrhoeae Moraxella catarrhalis

Are there non-pathogenic Neisseria spp that can be normal flora of upper respiratory tract:

yes

The Gram- diplococci grow best under what conditions:

Increased CO2 and humid conditions

Is Neisseria meningitidis normal flora?

Yes, of oropharyngeal/nasopharyngeal mucous membranes.

Presumptive ID of what organism: Gram- diplocci, oxidase+, Strong positive w/ 30% H202:

N. meningitidis

What is required to make a definitive ID of N. meningitidis:

GGAP- and BG- | Must grow on selective agar

What is the treatment for Neisseria meningitidis:

Broad spectrum antibiotic + corticosteroids | IV penicillin still a possibility, but resistance developing

What is the prophylactic treatment for N. meningitidis:

Rifampin

MCV4 and MPSV4 are vaccines against what organism:

N. meningitidis

Diptheria protein can be added to a vaccine to do this:

Large size will elicit stronger immune response (used for healthy young adults)

What media will grow Neisseria meningitidis:

SBAP Chocolate Modified Thayer-Martin (selective) Martin Lewis (selective)

What should be done with specimens of suspected N. meningitidis:

Should be plated immediately to appropriate culture media and transported in CO2 environment

Why do you not want to use cotton swabs for gathering bacterial specimen:

toxic fatty acids present in cotton-- use Dacron swabs instead

JEMBEC, Bio-Bag, and Gono-Pack System are all types of what:

CO2 transport systems

JEMBEC CO2 transport system comes as transport swabs with Amie's Media w/ charcoal. What is the purpose of the charcoal?

Charcoal inhibits toxic fatty acids present in cotton fibers

What are the 1st and 2nd causes of bacterial meningitis in the US:

1) Strep pneumoniae (pneumococcus) | 2) N. meningitidis (meningococcus)

What are the mortality rates for N. meningitidis meningitis, treated vs untreated:

Mortality rate: Treated 10% Untreated 100%

What is the syndrome associated with overwhelming bacteremia caused by Neisseria meningitidis:

Waterhouse-Friderichsen Syndrome

Describe the symptoms of Waterhouse-Friderichsen Syndrome:

Bacteremia w/ N. meningitidis Sudden onset fever, cyanosis, petechiae Bilateral adrenal hemorrhage, shock 20% mortality rate

Bacteria responsible for most cases of newborn meningitis:

Strep agalactieae (Group B)

Bacteria responsible for most cases of meningitis in infants/children:

Strep pneumoniae (pneumococcal)

Bacteria responsible for most cases of meningitis in adolescents/young adults:

Neisseria meningitidis (meningococcal)

Bacteria responsible for most cases of meningitis in older adults:

Strep pneumoniae (pneumococcal)

Strep pneumoniae is the primary bacteria responsible for causing meningitis in these age groups:

Children | Older adults

Can people be asymptomatic carriers of Neisseria gonorrhoeae:

Yes, but it is NEVER normal flora.

Presumptive ID of what bacteria is derived from Gram-, oxidase+ diplococci, glistening non-hemolytic on BAP:

Neisseria gonorrhoeae

What is required for a definitive ID of N. gonorrhoeae:

GGAP+ | remember N. meningitidis is GGAP-

What are the 1st and 2nd most common STD's in the US:

1) chlamydia | 2) gonorrhoeae

Where does N. gonorrhoeae infect in males vs females:

Males: urethra Females: cervix

Gonococcal opthalmia neonatorum:

Occurs in neonates delivered vaginally by N. gonorrhoeae infected mothers; causes blindness

Which 3 agar medias are selective for N. gonorrhoeae?

Modified Thayer Martin Martin Lewis New York City Media

Which two medias are selective for both N. gonorrhoeae and N. meningitidis?

Modified Thayer Martin | Martin Lewis

Does N. gonorrheae require special transport?

Yes. It requires a CO2 environment. | JEMBEC, Bio-Bag, Gono-Pack

What has to be done to N. gonorrhoeae before Gram staining?

Fluids must be centrifuged to concentrate organisms.

Why is presence of Gram- diplococci in vaginal secretions NOT dx for N. gonorrhoeae in females?

Normal flora of female GI/GU tract can resemble Neisseria spp.

What is a definitive ID of N. gonorrhoeae in males?

Gram- diplococci inside PMN's from urethral discharge

Why is it important to do an oxidase test on N. gonorrhoeae even though all three Gram- diplococci are oxidase+?

Can exclude Neisseria spp. and other oxidase- coccobacilli

Medicolegal require this for definitive dx:

two forms of ID via combination of tests

What is required for presumptive ID of N. gonorrhoeae in sexually active adults:

Sample from genital sites | Gram-, oxidase+ diplococci grown on selective media

This process differentiates strains of N. gonorrhoeae based on growth with media with different nutrient sources that allow for subtyping (L-proline, etc):

Auxotyping

Why is auxotyping valuable in N. gonorrhoeae:

valuable epidemiological tool, distinguishes between treatment failure vs reinfection

How would you distinguish between treatment failure vs reinfection of N. gonorrhoeae of a patient:

Auxotyping

13 serotypes exist for N. gonorrhoeae, which are the 5 most encountered in the US?

A, B, C, Y, W135

Which serotypes of N. gonorrhoeae are the most frequent cause of epidemics:

Group A and C

Serogrouping is achieved via this method:

agglutination tests

This is a significant pathogen in sputum, can cause otitis media, sinusitis, and pneumonia:

M. catarrhalis

Gram-, oxidase+, tributyrin hydrolysis+ diplococci:

M. catarrhalis | Neisseria spp are tributyrin hydrolysis-

This colony can be slide across an SBAP culture plate like a hockey puck:

M. catarrhalis

T/F Moraxella catarrhalis is normal flora of upper respiratory tract, possibly female genital tract:

True

Does M. catarrhalis produce beta-lactamase?L

Yes, though beta-lactams remain effective.

What is used to differentiate M. catarrhalis from Neisseria spp. for a definitive dx:

DNase Test Agar | M. catarrhalis is positive = turns green media colorless

What phase does exponential bacterial growth occur:

Log phase

What do prokaryotes have instead of a nucleus?

* Nucleoid containing DNA | * Plasmids containing extrachromosomal DNA

What does the cell envelope consist of in Gram positive bacteria:

* Cell wall (pg, teichoic acids) | * cell membrane (encloses cytoplasm)

What does the cell envelope consist of in Gram negative bacteria:

* Outer membrane * Periplasmic space (pg) * cell membrane (encloses cytoplasm)

List the 3 cellular appendages:

1) capsule 2) fimbriae/pili 3) flagella

This is the outermost layer of both Gram+/-, made of polysaccharides, helps bacteria evade immune system and aids in formation of biofilms:

Capsule

A hardy state that allows bacteria to survive harsh conditions and escape common treatments:

endospores

List the 4 outcomes of bacterial infection:

* Resolution (return to normal) * Restoration of health (w/ lasting effects) * Survival (severely compromised) * Death

What is the goal of the microbiology lab?

To tailor treatment via correct microbial identification.

Ideally, (but maybe not realistic) all specimens should be transported to the lab within ____ hours of collection:

2 hours

What is a holding media:

Amie's and Stuart's | *maintains viability but does not support growth

List the special preservatives for each specimen- Urine: Stool: Blood:

urine--> Boric acid stool--> PVA blood--> anticoagulants (SPS most common)

What specimens have priority in the microbiology lab:

CSF and blood

What stain is used for bacteria that won't stain well with Gram:

Acid Fast | Primary stain is carbolfuchsin

What kind of dilution is a 4 phase plate streak:

semi-quantitative | grade 1+ to 4+

How do you streak for urines:

Streak down the middle and then side to side from initial streak. (quantitative method as loops are calibrated)

Most bacteria are incubated at this tempL

35-37 degrees C

These bacteria can grow under aerobic OR anaerobic conditions:

facultative anaerobes

Chocolate agar- * enriched with: * heat releases: * supports growth of: * incubate with: * can only detect ___ hemolysis:

* BAP hemolyzed red cells by heat * X factor and V factor * N. gonorrhoeae * CO2 * alpha

PEA agar * selective for Gram__ __: * inhibits ___ and ___: * can be enriched with __ for staph and strep:

* selective for Gram+ cocci * inhibits Gram- bacilli and swarming Proteus * enriched with sheep blood

Modified Thayer-Martin Media is highly selective for ____:

N. gonorrhoeae

These can be added to Modified Thayer Martin Media for selectivity- * Colistin, inhibits____: * Vancomycin, inhibits ____: * Nystatin, inhibits ____: * Trimethoprin, inhibits ___:

* Colistin inhibits gram- * Vancomycin inhibits Gram+ * Nystatin inhibits yeasts * Trimethoprim inhibits spreading of Proteus

Modified Thayer-Martin Media is enriched with _____ and _____:

Chocolate agar + hemoglobin

This agar is selective for N. gonorrhoeae, Ureaplasma urealyticum, and Mycoplasma spp.:

New York City agar

XLD agar is selective and differential for _____ and ____:

Salmonella spp. and Shigella spp.

XLD agar contains 3 sugars for fermentation differentiation, acid production turns red media this color:

yellow

How can you tell Salmonella and Shigella apart on XLD agar, since they are both non-fermenters:

Salmonella produces hydrogen sulfide, creating black centers of colonies

LIM broth is prepared from ___ and ___:

Todd Hewitt broth + added antibiotics

LIM is a selective enrichment broth to promote growth of this bacteria:

Strep agalactiae

What is the most widely used enrichment broth in bacteriology:

Thioglycollate broth

This media contains casein, yeast, beef extracts, vitamins, and an agar supplement to make it semi-solid:

Thioglycollate broth

What is the purpose of thioglycollate broth being semi-solid:

to support growth of anaerobes deep in tube

What are the 3 enzyme tests used for Gram+ bacteria:

PYR test Catalase Coagulase

A positive PYR is:

disk turns red 5 minutes after addition of PYR reagent

A positive catalase test is:

bubbling

A positive coagulase test is:

agglutination

A positive PYR test is presumptive ID for ___ and ____:

S. pyogenes and Enterococci

Catalase test is used to differentiate ___ from ____:

Micrococcus (catalase+) | Staphylococci (catalase-)

Coagulase test is used to differentiate ____ from ____:

``` Staph aureus (coagulase+) other Staph spp. (coagulase-) ```

What 3 enzyme tests are used for Gram- bacteria:

Indole Oxidase Urease

Indole test is used for presumptive ID of ____:

E. coli

A positive indole test:

blue color development

This test is used to differentiate among Gram- bacteria:

Oxidase

Microdase test is a modified oxidase test used to differentiate ____ from _____:

Micrococcus (+) | Staphylococcus (-)

A positive oxidase test:

dark purple

Urease test is used to presumptively ID _____:

Proteus spp (positive)

A positive urea test:

slant turns red

The % of people in whom the organism is present actually test positive:

Sensitivity

The % of people without the disease that test negative for the organism:

Specificity

This media is selective for Staph aureus, differential for S. epi and S. sap:

Mannitol Salt Agar

What would the test results be for Enterococcus with- PYR: Salt Tolerance: Pyruvate Broth:

+ + +