Abstract
ObjectiveCoagulase-negative staphylococci (CoNS) are as considered opportunistic pathogens which capable of producing several toxins, enzymes and resistance genes. The current study aimed to determine the occurrence of different hemolysins genes and patterns of antibiotic resistance among CoNS species.ResultsThe highest frequency of antibiotic resistance was observed against cefoxitin in 49 isolates (53.8%), and the lowest resistance was against novobiocin in 5 isolates (5.5%). None of the isolates was resistant to vancomycin. The prevalence of hla, hla_yidD, hld, and hlb genes was: 87.9%, 62.6%, 56%, and 47.3%, respectively. The hla/yidD and hld genes were detected in 69.4% of S. epidermidis and the hla gene in 94.6% of S. haemolyticus isolates; the hlb gene was detected in 53.1% of the S. epidermidis isolates. The mecA gene was identified in 50 (55%) of the CoNS isolates. In conclusion, the results of statistical analysis showed that the hld gene had a significant association with resistance to levofloxacin and erythromycin antibiotics, the hlb with clindamycin resistance and the hla/yidD with rifampicin and novobiocin resistance. The results of this study showed that there is a significant relationship between hemolysin encoding genes and antibiotic resistance patterns; therefore, detection of virulence factors associated with antibiotic resistance has become a significant issue of concern.
Highlights
ResultsThe highest frequency of antibiotic resistance was observed against cefoxitin in 49 isolates (53.8%), and the lowest resistance was against novobiocin in 5 isolates (5.5%)
Coagulase-negative staphylococci (CoNS) are considered as opportunistic pathogens that cause a variety of infections, among immunocompromised, long-term hospitalized patients, preterm infants and in patients with indwelling or different implant polymer bodies [1–3]
Antibiotic susceptibility testing The Antibiotic susceptibility testing of 91 CoNS species carried out using the standard disk agar diffusion (DAD) method according to the Clinical and Laboratory Standards Institute (CLSI) guidelines [19]
Summary
Isolation and prevalence of CoNS isolates Of the 91 clinical isolates of CoNS, 49 (53.8), 37 (40.7%) and 5 (5.5%) isolates were recognized as S. epidermidis, S. haemolyticus, and S. saprophyticus, respectively. Our results showed a high frequency of hemolytic activity among CoNS strains isolated from blood, followed by urine, catheter, and wound, respectively. Among the MR-CoNS isolates, the hla gene was the most common with frequency of 90%, followed by the hla_yiD (60%), hld (58%) and hlb genes (48%). A significant association between CoNS species and the occurrence of hld and hla/yiD genes was observed in this study. It was found a meaningful relationship between antibiotic resistance and the presence of the genes for alpha, delta and beta hemolysins
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