The significance of coagulase-negative staphylococci bacteremia in a low resource setting

Abstract

Introduction: Coagulase-negative staphylococci (CoNS) are a group of micro-organisms that are increasingly implicated as a cause of significant infection and the leading cause of bloodstream infection (BSI). One important predictor of true BSI is the isolation of CoNS from multiple blood cultures, presuming that the isolates represent the same species. Thus the objective of this study was to determine the significance of repeated CoNS isolated from blood cultures. Methodology: This was a prospective laboratory study which was initiated in June 2007 and lasted until July 2008. CoNS isolates were obtained from patients who had two positive blood cultures within a 14-day interval. CoNS were identified to the species level using an APIStaph, and antibiotics susceptibility testing was performed according to Clinical and Laboratory Standards Institute specifications. Strain relatedness was confirmed using pulsed-field gel electrophoresis. Results: During the study period, 202 CoNS-positive samples were isolated from 101 patients. The most common species isolated was Staphylococcus epidermidis (59.0%), and 83.2% of the patients isolated the same species of CoNS from repeated blood cultures. Among the isolates of the same species, only 40.7% had the same antibiogram. CoNS with the same species and antibiogram had 93.3% probability of belonging to the same strain. Most (65.5%) of the patients were treated with antibiotics, primarily from the glycopeptides group. Conclusion: Speciation and antibiogram of CoNS from repeated blood cultures are adequate in determining the significance of repeated CoNS isolated from blood cultures.

Section’s osseous slice biopsy during major amputation of lower extremity: preliminary results of prospective cohort study

“…We think that the microorganisms spread and were found in SOB earlier until the changes are visible in histopathological or radiological analysis. Repeated positive cultures, isolation of identical species with comparable antibiotic susceptibility profile were considered as strong arguments in favour of a true infection in recent study [ 10 ]. In this study genotyping techniques demonstrated that CoNS exhibiting comparable antibiotic susceptibility patterns had a 93.3 % probability to belong to the same strain [ 10 ].…”

“…Repeated positive cultures, isolation of identical species with comparable antibiotic susceptibility profile were considered as strong arguments in favour of a true infection in recent study [ 10 ]. In this study genotyping techniques demonstrated that CoNS exhibiting comparable antibiotic susceptibility patterns had a 93.3 % probability to belong to the same strain [ 10 ]. In our study in all cases isolated pathogens from SOB and distal site biopsy, which happened to be the same species and antibiogram were compared using genotyping and confirmed the same strain.…”

Cost Savings Realized by Implementation of Routine Microbiological Identification by Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

“…However, traditional methods of identification of Staphylococcus saprophyticus and Staphylococcus lugdunensis required more technologist time and biochemical tests, which delayed identification of these organisms for up to 48 h. Additionally, the Vitek MS provided our laboratory with the ability to identify coagulase-negative Staphylococcus isolates to the species level, which was not done previously. This is beneficial for blood and sterile body fluid isolates to help differentiate between true infection and contamination of blood and sterile body fluid cultures when multiple colonial morphologies were detected (12)(13)(14). For us, these benefits far outweigh the added costs of MALDI-TOF MS. Additionally, some rapid biochemical tests, such as spot indole for Escherichia coli and PYR for Streptococcus pyogenes, may be less expensive than MS.…”