Incidence and Clinical Significance of Coagulase Negative Staphylococci in Blood

ObjectivesTo investigate the prevalence, distribution, clinical significance and financial impact of blood culture isolates of Coagulase-negative staphylococci (CoNS). Design Retrospective medical record review.MethodsAll patients with positive blood cultures for CoNS obtained between Jan.2008 and Apr. 2009 at Ohud Hospital, a referral hospital at Al Madinah Al Munawara, KSAResultsOf 5263 blood cultures drawn from patients seen at Ohud Hospital,. 593 had positive findings (11.3%). CoNS were isolated in 266 (5.05%) which represents 44.8% of the total positive blood cultures during the study period. Of the 266 positive blood culture patients for CoNS, only 185 medical were available for review. The blood culture contamination rate was 4.7% of the total blood cultures obtained. True bacteremia represented 8.1%. Resistance to Oxacillin was high (75.9%). Vancomycin was used in 36.8% of the patients. 92.9% of the study population was treated by multiple antibiotics. This resulted in additional cost of 3210.2 Saudi Riyals (SR) per patient.ConclusionCoNS are the major microbial contaminant of blood cultures. The most important factors in reducing BC contamination are: strict adherence to the most effective sterile venipuncture techniques by well trained health care workers. Clinical as well as laboratory criteria may help distinguishing true bacteremia from contaminated blood cultures. There is a tendency for clinicians to overuse antibiotics in patients with CoNS from blood cultures. However, as is found in this the vast majority of CoNS are still encountered as contaminants. This should be borne in mind and patients with isolates of CoNS from blood cultures should be carefully evaluated before instituting therapy to avoid unnecessary use of antibiotics, especially Vancomycin and the consequent increase of antibiotic resistance in hospitals.