Basic EMQsTheme:Causes of diseaseAClostridium perfringensBclostridium difficileCEscherichia coliDHaemophilus influenzaeEStaphylococcus aureusFstreptococcus pyogenesGnone of the above

Select the most likely causative organism for the following infections.

Pelvic sepsis following abdominal hysterectomy

Incorrect - The correct answer is Escherichia coli

Post-operative diarrhoea

Correct

Urinary tract infection after catheterisation

Incorrect - The correct answer is Escherichia coliThe most likely cause of pelvic sepsis is due to E Coli as is most intra-abdominal abscesses. Other causes of pelvic abscesses include pseudomonas spp and Mycobacterium. Again, UTIs are most commonly due to E Coli.Post-operative diarrhoea is most likely a consequence of pseudomembranous colitis due to Clostridium Dificile toxin. Predisposing factors include the use of broad spectrum antibiotics but the condition can also be transmitted.

Theme:Micro-organismsAClostridium perfringensBClostridium difficileCEscherichia coliDHaemophilus influenzaeEStaphylococcus aureusFStreptococcus pyogenesGNone of the above

Select the most likely causative organism for the following infections.

Clostridium perfringens

clostridium diff icile

none of the above

Chronic osteomyelitis after implant surgery

Correct

It is important to have a good idea of what organism is likely to be responsible for a particular infection so that one can tailor the antibiotic therapy accordingly. Chronic osteomyelitis may be caused by many organisms such as Salmonella spp, Mycobacterium but Staphylococcus aureus is the commonest organism.

Gas gangrene

Correct

Gas gangrene is caused by Clostridium perfringens (an anaerobic Gram positive spore forming rod) that is also responsible for food poisoning. Compound contaminated wounds are most susceptible.

Ludwig's angina

Correct

Ludwig's angina is a cellulitic like infection of the floor of the mouth with the gram positive organism, strep pyogenes.

Vincent's angina

Correct

Airway obstruction is a serious sequelae. Vincent's angina is due to an acute gingivitis plus pharyngeal infection and caused by Borrelia vincentii.

 

Theme:AntibioticsAAminoglycosidesBCiprofloxacinCCo-amoxiclav

Staphylococcus aureus

Clostridium perfringens

Streptococcus pyogenes

None of the above

DFusidic acidEPolymyxinsFRifampicinGSulphonamidesHTetracyclines

Select the antibiotic from the above list to which the following pertains:

This agent acts as an inhibitor of nucleic aid synthesis in bacteria.

Incorrect - The correct answer is Rifampicin

Rifampicin inhibits DNA-dependent RNA polymerase of mycobacteria by forming a stable drug-enzyme complex, leading to suppression of initiation of chain formation in RNA synthesis. Rifampicin can inhibit RNA synthesis in mammalian mitochondria, but considerably higher concentration of the drug are required than for the inhibition of bacterial enzyme. Rifampicin is bactericidal for both intracellular and extracellular microorganisms.

This is effective against both aerobic and anaerobic bacteria.

Incorrect - The correct answer is Co-amoxiclav

Co-amoxiclav is an effective broad spectrum penicillin against both Gram positives and Gram negatives. It contains both amoxicillin plus clavulanic acid.

It is used with caution in renal impairment and close monitoring of levels are required.

Correct

Aminoglycosides such as gentamicin are notorious for their renal toxicity and peak and trough concentrations should be measured to avoid toxicity.

 

Aminoglycosides

Polymyxins

Aminoglycosides