Intro to Microbiology final

Gram positive rods produce what structure that enables the microbe to protect itself and survive harsh conditions?

Endospore 

What bacterial structure is associated with the virulence and pathogenicity of the microbe?

Capsule (maybe virulence factor??)

What are capnophiles?

Microbes that only grow in CO2

What is the gram stain dependent on the composition of?

The cell wall

What is the primary gram stain?

Crystal violet

What is the mordant in the gram stain process?

grams iodine

What is the decolorizer in the gram stain process?

Acetone/alcohol

What is the counterstain in the gram stain process?

Safranin

What is the name of the structure found on bacteria that is associated with adherence?

Pili

What is the color of lactose fermenters on a MacConkey plate?

Pink

What do LF and NLF look like on MAC?

LF- pink NLF-clear

What is the gram stain of the microbe if it has grown on the MacConkey plate?

GNR

What is the purpose of the candle jar?

Creates a CO2 rich environment

What is the psi, temp, and time needed to perform routine sterilization of artificial culture media by autoclaving?

121 c, 15 PSI, for 15 mins

What type of media is MAC?

Selective differential

What is the McFarland standard we use in order to perform a disc diffusion test?

0.5 McFarland standard

What is the media used for the disc diffusion or Kirby-Bauer susceptibility test?

Mueller hinton agar

If you receive a urethral discharge from a man, what media do you plate?

Chocolate and MTM

What is the definition of bacteriostatic?

Antimicrobial that inhibits growth of the microbe, and relies on the immune system to finish the job

What is the test used to differentiate Staphylococcus saprophyticus from other Coag negative staphs?

Novobiocin disc 

What is the result of the PYR test for Enterococcus faecalis?

Purple- positive

What test do you perform in the lab to differentiate between staph and strep?

Catalase

What discs do we use to identify streptococcus pyogenes?

Bacitracin and PYR

Poor oral hygiene is the condition that is most likely to predispose a person to what GP microbe?

Viridans streptococcus 

What microbe is alpha hemolytic and optochin susceptible?

Streptococcus pneumoniae

What characteristics do all the Enterobacteriaceae microbes have?

GNR, glucose fermentation, oxidase negative, reduces nitrate

What two microbes are predominantly used for oxidase quality control?

E. coli is the negative control, pseudomonas is the positive control

What two microbes are predominantly used for indole quality control?

e.coli is the positive control, klebsiella is the negative

When we isolate N. gonorrhoeae, what is the atmosphere required in order to properly grow the microbe?

Carbon dioxide (CO2)

What type of specimens are used on hektoen plates?

stool

What are the biochemical reactions for Moraxella catarrhalis?

Oxidase positive, motility negative, all CTA sugars are negative

What genus do you suspect if your gram stain is GNC and grows on a chocolate plate?

Neisseria

What is the special media used to isolate E. coli 0157?

SMAC plate

What GNR creates a mucoid lactose positive colony on MacConkey?

Klebsiella pneumoniae

What is the biochemical reactions for Neisseria meningitides?

Oxidase positive, maltose and glucose are positive

What specimen type do we collect for typhoid fever?

blood (culture)

Which microbe has a positive motility at room temperature but a negative motility at 37?

Yersinia

Which of the Enterobacteriaceae family are indole positive?

E. coli, yersinia, and proteus vulgaris

What is the TSI slant that corresponds to the MacConkey plate?

A/A = lactose fermenter. K/K = non fermenter

What is the TSI reaction that corresponds to a Lactose positive Hek media?

A/A

What is the most common cause of urinary tract infection?

Escherichia coli

What is the O antigen?

Polysaccharide found in the cell wall, used for serologic classification of GNR

What is the H antigen?

Flagella

What is the K antigen?

Capsule

What is the typical TSI agar reaction that a nonfermentive GNR produces

K/K

What are the qualifications for an acceptable respiratory culture?

<10 squamous epithelial cells per low power field

What are the qualifications for an unacceptable respiratory culture?

>10 squamous epithelial cells per low power field

When we receive specimens from patients, where in the microbiology laboratory do, we inoculate the culture media?

Biological safety cabinet (BSC) II

What are some examples of enrichment media?

BAP, Chocolate, tryptic soy

What is beta hemolysis?

Complete lysis (clearing) of RBCs

what is alpha hemolysis?

partial lysis (greening) of RBCs

What is gamma hemolysis?

no lysis (no color change) of RBCs

What does a LF on hektoen look like?

Orange-yellow, normal flora

What does a NLF look like on hektoen?

Blue-green, black with H2S, abnormal flora

What is the temperature range for the incubators in the microbiology department

35-37c

What is a facultative anaerobe?

Can grow both aerobically and anaerobically

What is generation time?

The time is takes for a bacteria population to double

If you have 3 plates, BAP, PEA, and a MAC. If you have growth on the BAP and PEA, but no growth on the MAC plate, what is the gram stain of the bacteria?

Gram positive

Describe the logarithmic phase of bacteria.

Bacteria numbers increase logarithmically, population doubles

If you find that a specimen’s gram stain is growing both GNR and GPC, what media would you use in order to isolate the microbe?

CNA for GPC, MAC for GNR 

What media detects the production of H2S?

Hektoen or XLD

It the antibiotic disc does not inhibit the growth; this means the microbe is _________ to the antibiotic

resistant 

List the sterile body sites 

CSF, suprapubic aspirate, pleural fluid, blood, catharized urine

List body sites with normal flora

sputum, nose, stool/feces, vaginal, urine, throat

What antibiotics inhibit protein synthesis?

Aminoglycosides and macrolides

What antibiotics inhibit cell wall synthesis?

Beta lactam and glycopeptide antibiotics

What is the name of the broth media that is used for body fluids? It is able to grow both aerobes and anaerobes

Thioglycollate broth

With regards to the disc diffusion test, as the antimicrobial agent diffuses away from the disc, is the concentration of the antibiotic increased or decreased as it moves away from the disc?

decreases

What microbe is susceptible to the optochin disc test?

Streptococcus pneumoniae

What microbe is resistant to the optochin disc test?

Streptococcus viridans/mutans

What microbe does a positive coagulase test indicate?

Staphylococcus aureus

Which microbe is resistant to novobiocin?

Staphylococcus saphrophyticus

Which microbe is susceptible to novobiocin?

staphylococcus epidermis 

If the zones are too large in the disc susceptibility test, what could cause this type of error

Too shallow agar depth, improper lawn technique, incorrect mcfarland standard (too little microbe)

What is coagulase (Not the test but the enzyme!)?

The enzyme produced by Staphylococcus aureus that converts fibrinogen to fibrin and walls of the organism

What is LIM broth and what cultures do you use it on?

An enrichment media used for vaginal/rectal cultures on pregnant women

What microbe is known to cause acute pharyngitis?

Group A streptococci (pyogenes)

What syndrome do you suspect when a woman presents with a fever, low blood pressure and a cervical specimen reveals GPC in clusters?

toxic shock syndrome 

What microbe is commonly associated with neonatal meningitis and sepsis (A Gram-Positive microbe!)?

Group B streptococcus (Aglactiae)

If you have a sputum sample of a patient with pneumonia, the gram stain is many WBCs and GPC in pairs, what microbe do you suspect? What test would you perform to verify this possibility?

Streptococcus pneumoniae, Optochin

Which group of Streptococcus can lead to acute rheumatic fever and acute glomerulonephritis?

Group A streptococci (Pyogenes)

List group D enterococcus test results

PYR positive, NaCl positive, bile esculin positive

List group D streptococcus (Bovis) test results

Bile exculin positive

Which streptococcus is bacitracin susceptible?

Group A (pyogenes)

Which streptococcus is bacitracin resistant?

Group B (aglactiae)

Which microbe is yellow on a phenol red mannitol salt agar, and what is it fermenting?

Staphylococcus aureus, mannitol 

What does a positive catalase test (bubbling) indicate in a GPC?

staphylococcus

What does a negative catalase test (no bubbling) indicate in a GPC?

streptococcus

Sodium thiosulfate is added to certain types of media to detect what?

It provides sulfur atoms for H2S detection

What is the TSI reaction for a nonfermenter?

K/K

Is the lipopolysaccharide component of the GN cell wall a endotoxin or an exotoxin?

Endotoxin due to lipoplyosaccharide lipid A part

What is exotoxin?

Toxin secreted by bacteria, made of protein

What is the most common mode of transmission for Staphylococcus aureus?

person to person contact (?????)

What is the most common mode of transmission for Group B streptococcus?

Mother-infant transmission

What is the most common mode of transmission for Streptococcus pneumoniae?

Endogenous (from normal flora) or exogenous (through droplets from a carrier)

What is the most common mode of transmission for Coag negative staphylococci?

Person to person: Mucocutaneous barrier breaches, immunosuppression, indwelling prosthetic devices

What are klebsiella pneumoniae’s biochemical reactions?

A/A with gas Urease positive, VP positive, Citrate positive (klebsiella has Unlimited Viscous Colonies)

What are shigellas TSI and LIA reaction?

K/A 

What are salmonellas TSI and LIA reactions?

K/A with H2S

What are Yersinias biochemical reactions?

A/A, indole + urease + Mr + (yersinia instantly understands mercy)