07 Jan


Staphylococci and streptococci are referred to as pyogenic (pus-forming) gram-positive cocci.  As a group, they cause abscesses, boils, carbuncle, osteomyelitis, and fatal septicemias.  Staphylococci were originally isolated from pus in wounds but were subsequently demonstrated to be part of the normal flora (microbiota) of the nasal membranes, hair follicles, skin, and perineum in healthy people.  Most humans are carriers of staphylococci.  This is important because in hospitals where 90% of workers can be carriers these bacteria are responsible for many nosocomial (hospital-acquired) infections.  Staphylococcus aureus has developed resistance to many antibiotics including methicillin.  MRSA or methicillin-resistant S. aureus, is a major epidemiological problem in hospitals where it is responsible for a variety of hospital-acquired infections.  To make matters worse,  a strain of MRSA has been isolated from infections in individuals who have not been hospitalized.  This suggests that the resistant bacteria are not unique to hospital environments.