Antimicrobial susceptibility testing
What's the choice of growth medium for antimicrobial susceptibility testing?
Typically Mueller-Hinton
What's the most common coagulase negative staph?
Staphylococcus epidermidis
What's the typical appearance of B. anthracis on BAP?
Ground glass or "medusa" head appearance of colonies.
Microdase test is used to differentiate what type of bacteria?
Differentiates Micrococcus from staphylococci
Whats the ID of this bacteria...
Patient came in complaining of stomach pain and watery diarrhea, his last meal before he started feeling unwell was rice with chicken and a salad
BAP=large, feathery, b-hemolytic
Gram stain= Gram + bacilli
B. cereus
Antibiotic testing is rarely required for which type of bacteria?
Beta hemolytic strep, Neisseria meningitides, Listeria monocytogenes.
What specific gene turns staph aureus into MRSA?
MecA gene
Acinetobacter baumanii, Strenotropomonas maltophilia, Elizabethkingia meningoseptica needs to be differentiated from what other type of bacteria?
Needs to be differentiated from Enterobacteriacea
How do you set up a CAMP test and what is it used for?
Streak a beta-lysin producing strain of S. aureus down the center of a BAP, then streak the test organism across the plate perpendicular to s. aureus, incubate overnight
used to differentiate Group B strep(+) from other streptococcus species(-)
Whats the ID of the bacteria...
pt has destructive periodontitist
BAP= pinpoint, starshaped colonies
Gram stain=small gram-negative bacilli
catalase (+), urea and lactose (-)
Aggregatibacter actinomycetemcomitans
What does S, I, and R stand for and mean when testing for antimicrobial susceptibility?
S(susceptible)=Antimicrobial agent inhibits the growth of the bacteria
I(intermediate)= unable to determine susceptibility
R(resistant) Antimicrobial agent is ineffective
What bacterial infection is common in young, sexually active women?
Staphylococcus saprophyticus
observing umbrella motility in media after overnight incubation is seen in which bacteria?
Its seen in Listeria monocytogenes
The bile solubility test helps differentiate which two species?
streptococcus pneumoniae (+) and alpha hemolytic streptococci (-)
Whats the ID of this specimen....
Gram stain= Gram (+) cocci
Found in blood culture of a pt drawn from arterial line
BAP= Beta hemolytic, white creamy semi large isolates...Slide coagulase (+), catalase (+), PYR(+)
staphylococcus lugdinensis
What does a D-shaped zone indicate during a "D" test?
It indicates inducible clindamycin resistance.
What are some examples of pathogenesis for streptococcus pyogenes?
Hyaluronic acid capsules
streptolysin O, S
exotoxins
F protein
what test is used to differentiate shigella sp. from salmonella?
H2S productions
salmonella is positive
Shigella is negative
What are some species that are generally oxidase positive?
Pseudomonas aeruginosa, Burkholderia spp, Achromobacter spp, Alcaligenes faecalis
Whats the ID of the bacteria?
Pt presents to the ED with discomfort and irritation in her eyes, she wears contact lenses and a yellow/greenish liquid can be seen coming out of her eye.
Gram stain: Gram (-) bacilli
BAP: spready, flat, metallic sheen, B-hemolytic, blue/greenish pigment
Once Identified why must the physician be notified right away?
Pseudomonas aeruginosa
what disk is used as a presumptive identification for streptococcus pneumoniae?
What toxins found in Group A are responsible for hemolysis on BAP?
Streptolysin O and S
What's the optimal temperature range for Pseudomonas, Burkholderia, Alcaligenes, Achromobacter, Sphingomonas
Optimal range is 30-37C
Mesophiles
What media is used to differentiate between strep group D and enterococci?
Bile esculin agar
What's the ID of the bacteria?
A three-week-old female was brought into the ER due to decreased eating, fever and vomiting. according to the mother the baby was born at home with no medical interventions.
Gram stain: Gram + cocci singly
BAP:translucent flat glossy colonies, B-hemolysis, Catalase (-), Hippurate (+), CAMP(+), voges proskauer (-)
Streptococcus agalactiae