Phenotypic detection, antimicrobial susceptibility and virulence profile of staphylococci in the pig production setting, Makurdi, Nigeria

Abstract

Livestock, particularly pigs, have increasingly been recognized as important reservoirs for zoonotic transmission of pathogenic bacteria, including staphylococci. Livestock production systems in developing countries of sub-Saharan Africa, including Nigeria, are characterized by high misuse/abuse of antimicrobials and a close association between humans and these animals, which promotes the emergence and transmission of resistant and potentially virulent bacteria. In the present study, we investigated the occurrence and characteristics (species distribution, virulence and resistance profile) of staphylococci from smallholder backyard pig farms, slaughter slabs and pig handlers in Makurdi, Nigeria. A total of 330 nasal swabs originating from 300 pigs and 30 in-contact humans were collected and processed. One hundred and thirteen samples [34.2 %; 95 % confidence interval (CI): 29.1–39.6] comprising 103 (34.3 %; 95 % CI: 29.0–40.0) and 10 (33.3 %; 95 % CI: 17.3–52.8 %) samples from pigs and humans, respectively, were positive for staphylococci, yielding 120 isolates (pigs n=110, humans n=10). The 120 isolates were distributed into 15 species with Staphylococcus aureus (n=25) followed by Staphylococcus cohnii (n=19) and Staphylococcus sciuri (n=14) occurring more frequently. All isolates were resistant to β-lactam (100 %) antibiotics. Resistance to some critical antimicrobials, including linezolid (22 %), vancomycin (19.2 %), gentamicin (7.5%) and the fluoroquinolones ciprofloxacin (75.8 %) and enrofloxacin (66.7 %), was also observed. Majority (99.2 %) of the isolates displayed a multidrug resistance phenotype with the AMP-C-CIP-E-ENR-FOX-OX-P-S-SXT-TE phenotype being predominant. Overall, 70 % of the isolates expressed the methicillin resistance phenotype, out of which 20 % (n=17) were MRSA. Resistance to serum bactericidal activity and biofilm production were respectively observed in 45 (100 %) and 5 (11.3 %) of the coagulase-positive staphylococci. Our findings demonstrated the occurrence of a high diversity of staphylococci expressing multidrug resistance and potentially virulent phenotypes among healthy swine and pig handlers in small-scale backyard farms in North-Central Nigeria. These findings underscore the potential role of pig production settings in the emergence and dissemination of potentially virulent staphylococci and the importance of the development of antimicrobial resistance monitoring systems/implementation of control measures in developing countries. Proper hygienic practices and control of indiscriminate use and misuse of antibiotics are recommended.

Occurrence and Antibiotic Sensitivity Patterns of Methicillin-Resistant and Methicillin-Sensitive Staphylococcus aureus in Pigs in Ibadan, Nigeria

“…Antimicrobial susceptibility testing (AST) revealed that the S. aureus isolates, both MRSA and MSSA, demonstrated high levels of resistance (100%) to β-lactam antibiotics including penicillin, ampicillin, and amoxicillin-clavulanic acid. This resistance pattern is similar to the findings reported by Mamfe et al [17], who observed a 100% resistance to βlactam antibiotics by Staphylococci isolates in Makurdi, Nigeria, and this may be attributed to the possibility that the isolates may have acquired the ability to produce β-lactamase due to prolonged antibiotic misuse, thereby, neutralising the antibiotic effects of β-lactams.…”

“…A prevalence of 31.2% (29/93) was obtained which was significantly higher than the 6.5% reported in a previous cross-sectional study conducted by Odetokun et al [16], who used phenotypic and molecular techniques to identify S. aureus from the nasal swabs of slaughtered pigs, goats, cattle, and abattoir workers in Ibadan and Ilorin. Other recent studies that have reported a level of occurrence of Staphylococcus aureus similar to our findings include Mamfe et al [17], who reported a prevalence of 19.1% from the nasal swabs of pigs in Makurdi and Sineke et al [18], reported a prevalence of 29.1% from a combination of samples, particularly pig faecal samples, farm slurry samples, and human nasal swabs in pig production settings in South Africa. The relatively high prevalence observed in the various recent studies points towards the fact that pigs are important carriers of the pathogen and may contribute to the propagation of S. aureus to humans.…”

Epidemiology and Antibiotic Resistance of Staphylococci on Commercial Pig Farms in Cape Town, South Africa

“…The minimum number of samples to be collected (sample size) was estimated to be 163 using a 95% con dence level, an expected methicillin resistance prevalence of 12% (19) and desired precision of 5% (23) in order to describe the prevalence of methicillin-resistant Staphylococcus spp. Differences in the prevalence of SOSA species and antibiotic resistance rates between the two farms were calculated using Fisher exact and Chi squared tests where appropriate.…”

Detection of Methicillin-resistant Staphylococcus aureus (MRSA) resistant to vancomycin and linezolid in bulk tank milk by E-test method

“…MRSA is often analyzed from food and livestock samples (Aires-de-Sousa et al, 2017; Sergelidis and Angelidis, 2017). Besides their resistance to almost all beta-lactam antibiotics, resistance to vancomycin and linezolid, which are considered last resort antibiotics and therefore critical, has become a significant concern for human and animal health for reducing treatment choices of severe infections caused by MRSA (Onaran et al, 2019;Mamfe et al, 2021).…”