Evolution of Antibiotic Resistance of Coagulase-Negative Staphylococci Isolated from Healthy Turkeys in Egypt: First Report of Linezolid Resistance.

Amira A Moawad,Herbert Tomaso,Hafez M Hafez,Uwe Roesler,Omnia Awad,Heinrich Neubauer,Hosny El-Adawy,Helmut Hotzel

doi:10.3390/microorganisms7100476

Amira A Moawad, Herbert Tomaso + Show 6 more

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https://doi.org/10.3390/microorganisms7100476

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Abstract

Coagulase-negative staphylococci (CoNS) are gaining much attention as causative agents of serious nosocomial infections in humans. This study aimed to determine the prevalence and phenotypic antimicrobial resistance of CoNS as well as the presence of resistance-associated genes in CoNS isolated from turkey farms in Egypt. Two hundred and fifty cloacal swabs were collected from apparently healthy turkeys in Egypt. Suspected isolates were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The susceptibility testing of CoNS isolates against 20 antimicrobial agents was performed using the broth microdilution test. The presence of resistance-associated genes like mecA, vanA, blaZ, erm(A), erm(B), erm(C), aac-aphD, optrA, valS, and cfr was determined. Thirty-nine CoNS were identified. All isolates were phenotypically resistant to trimethoprim/sulfamethoxazole, penicillin, ampicillin, and tetracycline. The resistance rates to erythromycin, chloramphenicol, oxacillin, daptomycin, and tigecycline were 97.4%, 94.9%, 92.3%, 89.7%, and 87.2%, respectively. Thirty-one isolates were resistant to linezolid (79.5%). Low resistance rate was detected for both imipenem and vancomycin (12.8%). The erm(C) gene was identified in all erythromycin phenotypically resistant isolates, whereas two resistant isolates possessed three resistance-conferring genes erm(A), erm(B), and erm(C). The cfr and optrA genes were detected in 11 (35.5%) and 12 (38.7%) of the 31 linezolid-resistant isolates. The mecA, aac-aphD, and blaZ genes were identified in 22.2%, 41.9%, and 2.6% of phenotypically resistant isolates to oxacillin, gentamicin, and penicillin, respectively. This is the first study revealing the correlation between linezolid resistance and presence of cfr and optrA genes in CoNS isolates from Egypt, and it can help to improve knowledge about the linezolid resistance mechanism.

Highlights

Coagulase-negative staphylococci (CoNS) are commonly found in animals, humans, food, and the environment
Out of 250 cloacal samples, 39 (15.6 %) CoNS isolates were identified from 12 turkey flocks in five governorates in Egypt using MALDI-TOF MS (Table 4)
The current study showed that CoNS isolated from healthy turkeys had high phenotypic resistance to all β-lactams except imipenem, which is prescribed as one of the first line of defense drugs against clinical infections caused by staphylococci

Summary

Introduction

Coagulase-negative staphylococci (CoNS) are commonly found in animals, humans, food, and the environment. They were believed to be nonpathogenic bacteria until 1980. Thereafter, they have gained more attention as causative agents of serious nosocomial infections in humans [1]. CoNS have a feature of rapid acquisition, possessing, and modification of resistance genes. This feature further promotes the transmission of these genes into different staphylococcal species or even other bacterial genera [1,3]. Infections caused by antibiotic-resistant CoNS have been increasing in humans worldwide. Only few studies have discussed the presence of CoNS in humans and animals in Egypt [4,5,6]

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