Case 49: A surgical patient with a new heart murmur Flashcards
What is the Gram stain of staphylococcus?
Gram +ve cocci in clusters
What is the colonial morphology on HBA subcultured from blood culture for staph.?
White opaque colonies
Growth on O2 and AnO2 (smaller on AnO2)
What is the colonial morphology on MAC subcultured from blood culture for staph.?
Pink tiny colonies
Lactose fermenter
What is the result of catalase and coagulase tests for staph. aureus?
Catalase and coagulase positive
What is the result of catalase and coagulase tests for staph. epidermidis?
Catalase positive
Coagulase negative
Which antimicrobials is staph. aureus susceptible to?
Erythromycin, vancomycin, cefotoxin but not penicillin
Which antimicrobials is staph. epidermidis susceptible to?
Erythromycin, vancomycin but not penicillin or cefotoxin
Which staph. is most likely to infect a wound?
Staph aureus - staph epidermidis doesn’t have the virulence determinants
Which staph. is most likely to cause endocarditis in a patient who has undergone open heart surgery when the catalase coagulase test is negative?
Staph. epidermidis
Which other bacteria can cause endocarditis?
Enterococci, streptococci (GAS and GBS)
Which groups of people are particularly susceptible to staph. induced endocarditis?
Very young - congenital heart disease
People with pacemakers
Surgical patients
What are the potential complications of endocarditis from staph?
Set up vegetations on endocardium, leading to valve damage
Biofilm vegetations may break off and lodge in other places leading to infectious emboli
Which antimicrobial is generally used for Gram -ve bacteria?
Gentamycin
What works synergistically with vancomycin?
Penicillin
What antimicrobial is used for streptococci?
Penicillin with Gentamycin
