Antimicrobial Resistance and Virulence of Methicillin-Resistant Staphylococcus aureus from Human, Chicken and Environmental Samples within Live Bird Markets in Three Nigerian Cities.

Flora Olubunmi Ogundipe,Dennis Hanke,Stefan Schwarz,David Ajiboye Ojo,Aderonke Kofoworola Akintokun,Olajoju Jokotola Awoyomi,Sven Maurischat,Andrea T Feßler,Olufemi Ernest Ojo

doi:10.3390/antibiotics9090588

Abstract

Background: Methicillin-resistant Staphylococcus aureus (MRSA) has emerged as a major threat to public health. This study investigated the occurrence of MRSA in humans, chickens, chicken meat and environmental samples within poultry farms and live bird markets in southwestern Nigeria. Methods: MRSA were isolated using selective culture and tested for antimicrobial susceptibility by broth microdilution. Selected isolates were characterized by whole genome sequencing (WGS). From WGS data, spa, dru, multilocus sequence typing (MLST) and SCCmec types, but also virulence and antimicrobial resistance genes, were identified. Results: Fifty-six MRSA isolates were detected in 734 samples. They showed resistance to β-lactams (100%), tetracycline (60.7%), ciprofloxacin (33.9%), erythromycin (28.6%), gentamicin (32.1%), and trimethoprim/sulfamethoxazole (10.7%). All 30 isolates investigated by WGS carried mecA, dfrG, and tet(38) genes. Other resistance genes detected were blaZ (83.3%), fosB (73.3%), tet(K) (60.0%), aacA-aphD (36.6%), aphA3 (33.3%), msr(A) (30.0%), mph(C) (30.0%), dfrS1 (3.3%), and sat4 (3.3%). Seven spa types (t091, t314, t657, t1476, t2331, t4690 and t12236), four known (dt9aw, dt10ao, dt10cj, and dt11a) and two novel (dt10dr and dt11dw) dru types, as well as five sequence types (ST8, ST121, ST152, ST772 and ST789) were found among the MRSA isolates. All ST121 isolates carried an SCCmec type IV cassette and were not dru-typeable. ST152 and ST121 were found only in specific sample categories within defined locations, while ST8 and ST772 were distributed across most sample categories and locations. Three SCCmec types, IVa, V and Vc, were identified. All MRSA isolates possessed virulence genes including aur, clpP, coa, fnbA, esaA, hly, hla, ica, isdA, srtB, sspA, and vWbp, among others. The toxic shock syndrome toxin gene (tst) was not detected in any isolate, whereas the Pantone–Valentine leukocidin genes lukF-PV/lukS-PV were present in all ST121, all ST772, and all but one ST152 isolates. Conclusion: The results of this study (i) showed that chicken meat is contaminated by MRSA and (ii) suggested that live bird markets may serve as focal points for the dissemination of MRSA within the community.

Highlights

Staphylococcus aureus is an opportunistic pathogen that can cause significant health challenges in humans and animals [1]
Thirty-one of the confirmed isolates originated from chicken meat, 22 isolates were from humans and eight originated from environmental samples (Table 1)
This study showed the presence of Methicillin-resistant Staphylococcus aureus (MRSA) in human, chicken meat and environmental samples from live bird markets/chicken slaughter centers in the study locations

Summary

Introduction

Staphylococcus aureus is an opportunistic pathogen that can cause significant health challenges in humans and animals [1]. Because of the ubiquity of S. aureus, it is difficult to prevent the involvement of the organism as secondary tissue invader following trauma or primary infections [2]. The presence of virulence factors associated with bacterial adhesion, tissue invasion, immune evasion and toxin production may account for the frequent involvement of S. aureus in clinical infections and food poisoning [3]. The emergence and spread of methicillin-resistant S. aureus (MRSA) strains that showed broad spectrum resistance to β-lactam antimicrobial agents, but often resistance to multiple other antimicrobial agents, constitutes a great threat to the usefulness of antimicrobial agents in the treatment of staphylococcal infections, it could lead to an increased risk of infection spread, higher medical cost and sometimes mortality [4]. Methicillin-resistant Staphylococcus aureus (MRSA) has emerged as a major threat to public health. This study investigated the occurrence of MRSA in humans, chickens, chicken meat and environmental samples within poultry farms and live bird markets in southwestern Nigeria

Methods

Results

Discussion

Conclusion