Staphylococcus epidermidis - virulence factors and innate ... - Munin

e.g. patients receiving immune-suppressive therapy, preterm infants, AIDS patients, and drug
abusers (272, 274, 275). S. epidermidis is now considered one the most frequent causes of
nosocomial infections (275) (The Nosocomial Infections Surveillance System (NNIS);
http://www.cdc.gov/ncidod/hip/NNIS/2004NNISreport.pdf).
In immune competent humans, S. epidermidis mainly become pathogenic i) when associated with
indwelling medical devices (biofilm), such as arteriovenous shunts, contact lenses, urinary and
central venous catheters, orthopedic devices, and peritoneal dialysis catheters (272, 276-280) and
ii) in rare cases, when associated with native valve endocarditic (281, 282).
S. epidermidis infections are seldom lethal, but they significantly contribute to morbidity and
health care costs (275, 283).
There are also risks of both under- and over-reporting of S. epidermidis infections, because of
difficulties in finding a common standard to determine clinical relevance of a strain, since
clinically relevant S. epidermidis also are common contaminants of clinical samples.
1.3.3 S. epidermidis – antibiotic resistance
Hospital-acquired S. epidermidis often display resistance against many antimicrobials in use
today, such as methicillin and aminoglycosides (284-289). About 70-90% of all CoNS, both in
Norway and in the rest of the world are resistant to methicillin (284, 290, 291). The methicillin
resistance in staphylococci is mediated by the mecA-gene encoding a penicillin-binding protein
(PBP2a) with reduced affinity for all betalactam antibiotics (292-294). The mecA gene is
integrated in the SCCmec element (292, 295-297). Glycopeptide resistance in S. epidermidis is
still relatively rare (285, 298), and Vancomycin is the drug of choice for methicillin-resistant S.
epidermidis (285). An increasing prevalence of antibiotic resistance in S. epidermidis is partly
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