microbio quiz study qs for final

what two diseases are usually preceded by infection with GAS

glomerulonephritis, rheumatic fever

the gram stain of a predominant colony in a urine culture shows GPCs, the organism tested was catalase positive. To speciate the MLS could perform

coagulase and novobiocin

a urine culture grows out small, non hemolytic gray colonies in predominance:
GPC, catalase neg, pyrase pos, bile esculin pos, 6.5% salt growth

enterococcus spp

which organism may be positive for slide coagulase but negative for tube coagulase

staphylococcus lugdunensis

which organism is incorreclty paired with disease associatian

none of these

a gpr from a hand wound culture on a farmer grows 3+ gprs that are h2s positivie. what is the most likely id

erysipelothrix rhusiopathiae

which of the following organisms is partially acid fast

nocardia

what organisms is associated with aggressive eye infections

bacillus cereus

which organism is incorrectly matched to its hemolysis pattern

clostridium perfringens: single zone beta hemolysis

what is true about facultative anaerobes

use fermentation to grow in places without oxygen, but use aerobic respiration in place with oxygen

what is important for anaerobic cultures

incubating plates in conditions without oxygen, incubate for 48hrs before checking for growth, plates must be placed back into the anaerobic jar/chamber quickly after work up, draw blood cultures in a set of aerobic and anaerobic

what is true about clostridioides difficile

can cause HAI or community acquired infection, can be diagnosed by PCR and toxin testing, transmitted through spores that are difficult to clean from surfaces, can cause diarrhea or severe colitis after exposure to antibiotics

a male presents to the ER with fever and facial edema and pain with onset 3 days previously. He has had progressive fatigue and dyspnea and tooth extraction 3 days previously. CTA chest and lab test compatible with septic emboli, and cervical CT confirmed a diagnosis of septic thrombophlebitis of the internal jugular vein. What is the most likely pathogen

Fusobacterium necrophorum

a patient presents to pcp with painful swelling in lower jaw. area was surgically drained with purulent discharge containing sulfur granules. gram stain revealed beaded looking, filamentous GPRs, Which organism best fits this clinical scenario

actinomyces

what is the most common method used for identiffuing anaerobic bacteria

Maldi tof

when should diphtheroids be fully identified

from urine as the only isolate with a count greater than 10k cfu/ml, when isolated from sterile sites, if predominant in gram stain or culture

which of the following test results and interpretation do not match

TSI K/A: negative for glucose and lactose fermentation

a lactose fermenter grows out in pure culture from a urine culture. It is non motile, lysine decarb pos, and indole pos. what is the most likely ID

klebsiella oxytoca

which of the following is not an inducible ampC producer

ecoli

match the following bacteria to the expected TSI
Klebsiella aerogenes, shigella sonnei, proteus mirabilis, citrobacter freundii

Klebsiella aerogenes: A/A G neg

shigella sonnei: K/A O neg
proteus mirabilis: K/A G pos

citrobacter freundii: A/A G pos

an organism from a respiratory culture requires v factor but not x factor. It stains as a small GNCB. Which of the following is true

organism is likely normal oral microbiota

what trait is not associated with acinetobacter

tumbling motility

an organism is inoculated to OF tubes for glucose. What is the expected result for an organism that can oxidize glucose but not ferment it?

the mineral overlay tube is green and the open tube is yellow

what organisms are associated with respiratory infection in CF patients

pseudomonas aeruginosa, stenotrophomonas maltophilia

match the GNR to is associated colony morphology
serratia marcescens, stenotrophomonas maltophilia, pseudomonas aeruginosa, acinetobacter baumanii

serratia: red pigment
stenotrophomonas: lavender green
pseudomonas: yellow green pigment
acinetobacter: lavender on mac

what organism will grow yellow colonies of TCBS agar

vibrio cholerae

which organisms are oxidase positive

Eikenella, pasteurella, brucella, bordetella, vibrio, aeromonas, plesiomonas, campylobacter, pseudomonas

what do the HACEK organisms have in common

they are all known to cause infective endocarditis

what types of infections are most commonly associated with vibrio, aeromonas, and plesiomonas

wound and GI infections

which of the following organisms would be most likely to be missed or not seen at all in a direct gram stain

campylobacter

which of the following rapid tests best differentiates slow or late lactose fermenters

ONPG

categorize each organism as lac fermenter or non lac fermenter
ecoli, salmonella enterica, serratia, proteus vulgaris, enterobacter cloacae, morganella, klebsiella, shigella

ecoli: lac fermenter
salmonella enterica typhi: non fermenter

salmonella enterica arizonae: lac fermenter
serratia: non fermenter
proteus vulgaris: non fermenter

enterobacter cloacae: lac fermenter
morganella: non fermenter
klebsiella: lac fermenter
shigella: non fermenter

which of the following organisms does not produce H2S in TSI

shigella sonnei

shigella spp are characteristically…

non motile

an MLS uses too much inoculum when setting up LOTMIC. what test will likely yield a false pos

citrate utilization

the yeast phase can be induced in blastomyces dermatidis in vitro by incubating culture to which temperature

37C

a yeast from a positive blood culture bottle is subcultured on cornmeal and a germ tube is set up. No pseudohyphae were seen after growth on cornmeal or germ tube. Which yeast species?

Candida glabrata

what is true about candida auris

it can colonize the skin, is can be resistant to antifungal drugs, it can withstand some disinfectants

a urease psoitive yeast isolated from an otherwise healthy individuals CSF is mostly likely

cryptococcus neoformas(gatii)

match the yeast to its closest description
candida albicans/dublinensis, candida glabrata, cryptococcus neoformans, rhodotorula mucilaginosa

candida albicans/dublinensis: starring on BA, germ tube pos
candida glabrata: tiny colonies on BA, germ tube neg
cryptococcus neoformans: encapsulated and mucoid, urease pos
rhodotorula mucilaginosa: pink colonies in culture, found in showers that need cleaning

a urine specimen drawn from an indwelling catheter grew four different organisms after 18hrs. what is the best course of action to follow

report mixed flora and hold the plates 3 days in case additional workup is needed for patient care

which of the following is the msot common cause of uncomplicated uti

ecoli

what is true about UTIs

most UTIs are caused by organisms that are normal gut flora

what is not a predisposing factor for UTIs

being a male adult

a BA plate inculated with a .001 ml loops grows 70 colonies of S. aureus. how many cfus/ml should be reported

70,000

which of the following fulfills criteria for culture rejection

urine from a collection bag

50,000 col/ml of a lac fermenting gnr growing in a catheter colelction culture as the only isolate. the organism is motile, citrate positive, and H2S pos. How should it be reported

50,000 col/ml Citrobacter freundii

which of the following specimens are likely the least amount of contamination

subprapubic bladder aspiration

which is the most likely to be a pathogen in a clean catch

90k col/ml enterococcus with 10k mixed flora

what is true about yeast

most are commensal organisms which can act as opportunistic pathogens

what is the purpose of acridine orange stain for blood cultures

to help in visualizing organisms that stain poorly on gram stain

what is the purpose of direct molecular testing from positive blood cultures

to get the organism ID and detect resistance genes quickly

which of the following is most likely due to contamination

¼ bottle pos for staph epidermidis

paired quantitative blood cultures are set up, one from catheter and one from peripheral. The catheter culture grows 100 colonies and the peripheral grows 2 colonies of the same organism

the catheter may be the source of the bacteremia

which of the following are commonly associated with bone marrow infections

salmonella and brucella

which is false about blood culture bottle collection

anaerobic bottle collection is not warranted in most cases

in disk diffusion susceptibility testing, as an antimicrobial agent diffueses away from the disk, the concentration of the antibiotic is…

decreased

how should the image be reported

Resistant to both

what organization primarily provides antibiotic interpretation criteria to US micro labs

CLSI

what resistance strategy is most commonly employed by MRSA

altered drug target

which of the following is considered a species that has a high risk for de-repression of ampC

enterobacter cloacae

what resistance pattern would you expect from an ecoli carrying and NDM1

Cefazolin R, ceftriaxone R, meropenem R

match the antibiotic with its target site

trimethoprim/sulfamethoxazole, vancomycin, ampicillin, rifampin, levofloxacin, clindamycin

trimethoprim/sulfamethoxazole: folate biosynthesis
vancomycin: peptidoglycan
ampicillin: penicillin binding proteins

rifampin: RNA polymerase
levofloxacin: DNA
clindamycin: protein synthesis

the breakpoint for ecoli susceptibility to ampicillin is <8ug/ml. You measure the MIC at 2ug/ml. This means:

the ecoli is susceptible to ampicillin

which of the following would warrant potential infection control precautions in a hospitalized patient with enterococcus faecium infection

vancomycine resistance

which of the following beta lactam drugs will likely have the broadest spectrum of antibacterial activity

imipenem

what is n acceptable level of blood culture contamination

<3%

what is true about burkholderia pseudomallei

it shows poor growth at 24hrs

an organism isolated from the blood of a battle farmer gram stains at tiny GNCBs. it does not appear in culture until day 3 when it grows on BA and CA. which is false

the organism is likely a burkholderia species

which is false about select agents and LRN

sentinel labs are expected to perform full ID of select agents

a 6mo baby has measurable IgG resposne to VZV. what type of non infectious process in the baby may lead to this

passive immunization

what class of antibody is most liekly to be result of a potential false positive result

IgM

what is an important advantage of serology over traditional microbio techniques

it can diagnose infections of non culturable organisms

which of the following can lead to a false negative in serology

immunocompromised patient

of the following, which are not frequently diagnosed using serology

ecoli

which is not a characteristic of campylobacter species

oxidase neg

a stool sample from a pateint with fever and bloody, mucid diarrhea is plated on Hektoen. There are green colonies with blackened center and no orange or purely green colonies. testing should be performed to rule out which pathogen

salmonella enterica

A patient develops profuse, watery diarrhea and abdominal cramps three days after consuming undercooked chicken at a potluck, and a provider writes an order comment indicating that they are concerned for campylobacteriosis. The stool culture should be incubated in which specific set of atmospheric and temperature conditions to increase your odds of isolating this pathogen?

Microaerophilic conditions (5% O₂, 10% CO₂) at 42°C

A hospital epidemiologist is reviewing lab results. A stool sample from a 9-month-old infant on broad-spectrum antibiotics tested positive by PCR for a C. difficile toxin gene. Which of the following represents the most accurate interpretation of this result?

The finding is clinically ambiguous, as asymptomatic colonization with toxigenic C. difficile is very common in children under 2 years old.

Due to very high protein profile similarity, MALDI-TOF based identification is known to be unreliable for differentiating which of the following pairs of enteric organisms, requiring mandatory biochemical follow-up?

Escherichia coli and Shigella spp

Which of the following organisms is most likely to be a GI pathogen?

yellow colony of TCBS agar

Match the agar to the organism it is primarily used to identify:

Hektoen, XLS, CIN, TCBS, MACsorb

Hektoen agar = Salmonella and Shigella

XLD agar = Salmonella and Shigella

CIN agar = Yersinia enterocolitica

TCBS agar = Vibrio spp.

MacConkey Sorbitol = E. coli O157:H7

Which of the following organism pairs is most likely to cause food poisoning symptoms with rapid onset (less than 8 hours)?

Staphylococcus aureus and Bacillus cereus

An enteric gram-negative rod which produces a yellow colony on TCBS agar and can be isolated by culturing in an alkaline peptone broth (pH 8.0-9.0) is:

vibrio cholerae

A female genital gram stain shows 3+ epithelial cells, 4+ Gram variable rods, and 2+ curved Gram negative rods. What is the most likely diagnosis?

bacterial vaginosis

Todd-Hewitt and Carrot broths are used in genital cultures to enrich for which of the following organisms?

streptococcus agalactiae

Which of the following is false about genital infection workups?

Lactobacillus can be a pathogen in a vaginal culture in heavy predominance

Which of the following is true about testing for Neisseria gonorrhoea (GC) in genital specimens?

Nucleic acids amplification testing for GC is often done in conjunction with Chlamydia trachomatis and Trichomonas vaginalis