CoNS

  • Coagulase-negative staphylococci are natural inhabitants of human skin, but virtually all infections (except native endocarditis and infections of peritoneal dialysis catheters) are acquired in the hospital.
  • Colonization of patients precedes infection, and patients and hospital personnel are the reservoir of potential pathogens.
  • Potential sites of colonization with resistant S. epidermidis are not as widespread as for S. aureus, but colonization of the intestine has been documented.
  • Hospital-acquired isolates of S. epidermidis are invariably resistant to multiple antibiotics by plasmid-mediated mechanisms, although conjugative resistance was believed to be a factor in the rapid increase in resistance observed during the 1980s.
  • More than 70% of isolates in the United States are now resistant to methicillin.
  • Most strains of S. epidermidis are also resistant to chloramphenicol, clindamycin, macrolides, and tetracyclines.
  • In addition to dependable vancomycin therapy, many S. epidermidis strains remain susceptible to rifampacin and ciprofloxacin, although resistance to both agents can develop rapidly.
  • Resistance to vancomycin has been confirmed for Staphylococcus haemolyticus.