Application of <em>tuf</em> gene sequence analysis for the identification of species of coagulase-negative staphylococci in clinical samples and evaluation of their antimicrobial resistance pattern

Abstract

IntroductionCoagulase-negative staphylococci (CoNS) are normal inhabitants of human skin and mucous membranes. However, CoNS represent one of the major nosocomial pathogens, especially in immunocompromised patients. The increasing incidence of CoNS and mainly methicillin-resistant strains underlines the need for an accurate identification of Staphylococcus isolates at the species level. Analysis of the tuf gene proved to be an accurate tool for the species identification of CoNS. The aims of this study were to identify the CoNS species by tuf gene-based polymerase chain reaction method and sequencing, and to determine the frequency of CoNS clinical isolates resistant to methicillin (MRCoNS) and other antibiotics.MethodsA total of 200 staphylococci isolates were collected from various clinical samples. Phenotyping methods were used for initial identification followed by polymerase chain reaction amplification of tuf gene with subsequent sequencing. The phylogenetic relationships among species were analyzed using the neighbor-joining method based on the partial gene sequence of tuf. Microbroth dilution test was used for screening methicillin resistance, and disk diffusion susceptibility testing was performed for evaluation of antibiotic resistance among the isolates.ResultsIn the present study, 125 isolates were identified as CoNS; among them, Staphylococcus epidermidis 54(43.2%) and Staphylococcus haemolyticus 50 (40.0%) were demonstrated as the most prevalent species. Resistance to methicillin was detected in 54.4% of the CoNS based on microbroth dilution method. In disk diffusion susceptibility testing, the greatest resistance of CoNS was demonstrated for cefoxitin (65.4%), cotrimethoxazole (54.4%), and clindamycin (49.6%), while daptomycin (87.2%) and linezolid (83.2%) showed the greatest effectiveness for CoNS isolates.ConclusionOur results confirmed the predominance of S. epidermidis and S. haemolyticus among CoNS isolates. The high prevalence of MRCoNS strains is a serious concern and strongly suggests the need for control program measures in our hospitals in order to reduce MRCoNS infections, especially in immunocompromised patients.

<p>Antibiotic Resistance and <em>mecA</em> Gene Characterization of Coagulase-negative <em>Staphylococci</em> Isolated from Clinical Samples in Nepal</p>

“…Several studies have identified S. epidermidis as the most commonly isolated CoNS. 22 , 25 – 29 In contrast, some studies have suggested S. capitis 30 and S. hemolyticus 10 , 31 , 32 as the most common CoNS. S. epidermidis is the most common commensal of our skin and mucosa, and contamination through the devices during medical procedures are very common.…”

Carriage ofStaphylococcus schleiferifrom canine otitis externa: antimicrobial resistance profiles and virulence factors associated with skin infection

“…All staphylococcal strains were identified by using both a Vitek 2 system (BioMérieux, France) and 16S rRNA sequencing (Cosmogenetech, Korea). Sequencing of tuf gene was also performed to confirm S. schleiferi isolates [12]. Coagulase production was confirmed as described in previous research [13].…”

Prevalence and antibiotic susceptibility of bacteria isolated in patients affected with blepharitis in a tertiary eye centre in Spain

“…The coagulase-negative Staphylococcus was resistant to oxacillin in almost half of our patients. A study by Khosravi et al 24 supported this result. These authors also described that this bacterium was not susceptible to trimethoprim + sulfamethoxazole, which is in contrast with our data.…”