A person from village is complaining of development of pustules. Extract from pus has shown gram positive cocci, showing hemolysis, catalase -ye, identified as a group of streptococci. Following test is used:
Bacitracin sensitivity
Novobiocin sensitivity
Optochin sensitivity
Hemolysis
Ans. (a) Bacitracin sensitivity "Sensitivity to bacitracin is employed as a convenient method for differentiating Str. pyogenes from other hemolytic streptococci." Pustule - A vesicle filled with leukocyte. MC cause is virus. MC bacterial cause is Strep. pyogenes. Remember: * Str pyogenes is the etiologic agent in most of the streptococcal skin infection. Vancomycin is the drug of choice. Optochin sensitivity and bile solubility is used to differentiate pneumococci from Strep. viridans group.