SOURCE:

Faculty: Pharmaceutical Sciences
Department: Pharm. Microbio & Biotech

CONTRIBUTORS:

Moses I. Benjamin
Iroha I. R.
Esimone C. O.

ABSTRACT:

The increase in antibiotic-resistant Staphylococcus pseudintermedius among pets and the transfer of S. pseudintermedius from pets to humans threaten veterinary medicine and public health. This study was designed to determine the prevalence, antibiotic susceptibility profiles, and the molecular characteristics of S. pseudintermedius obtained from dogs and humans in Abakaliki, Ebonyi State, Nigeria. One hundred and twelve (112) shelter dogs, 97 dog owners, and 150 non-dog owners were sampled for this study. The 112 swab samples were obtained from three different sites; perineum, nares (nostrils), and mouth while nasal swabs of both the 97 dog owners and 150 non-dog owners were also collected. Swab samples were processed and isolates were identified using standard microbiological procedures. Minimum Inhibitory Concentration (MIC) was determined by broth micro-dilution. Isolates were screened for mecA, mecC, cfr, tetM, tetK, tetL, tetO, sec, siet, exi, and lukD genes by Polymerase Chain Reaction (PCR). Sequencing of tetM genes was also done by direct DNA sequencing. Exactly 99 S. pseudintermedius isolates were recovered from dogs and dog owners while none was recovered from non-dog owners. A total of 86 (76.8 %) dogs were positive for S. pseudintermedius, out of which 46 (53.5 %) were methicillin-resistant S. pseudintermedius (MRSP) strains. In contrast, 13 (13.4 %) dog owners out of the 97 volunteers were positive for S. pseudintermedius. Six (46.2 %) out of the 13 dog owners harboured MRSP strains. The isolates were highly resistant to penicillin (95.3 %) and ampicillin (94.2 %). Resistance was also observed with tigecycline (8.1 %), tetracycline (19.8 %), chloramphenicol (23.1 %), gentamycin (46.5 %), erythromycin (51.2 %), clindamycin (51.2 %), trimethoprim/sulfamethoxazole (51.2 %), levofloxacin (51.2 %), ciprofloxacin (50 %), and moxifloxacin (51.2 %). No resistance to nitrofurantoin, rifampin, vancomycin, quinupristin/dalfopristin, daptomycin, linezolid, and amikacin was observed. None of the isolates from dog owners was resistant to tetracycline. Two isolates from dogs were completely susceptible to all the antibiotics tested. A total of 47 (47.5 %) out of all the 99 isolates from both shelter dogs and humans were methicillin-susceptible S. pseudintermedius (MSSP). The isolates from dogs and dog owners exhibited an average multiple antibiotic resistance index (MARI) value of 0.3. Exactly 97 S. pseudintermedius isolates (Dog = 84, Humans = 13) exhibited 22 different resistance antibiotypes. Ampicillin + penicillin resistance antibiotype (AMPR PENR) was present in 19 out of the 22 resistance antibiotypes observed. Twelve (70.6 %) out of the 17 tetracycline-resistant isolates obtained from dogs harboured tetM gene while none harboured tetL, tetK, and tetO genes. The DNA sequences of the tetM gene for the 12 tetracycline-resistant S. pseudintermedius isolates in our study were deposited in the NCBI database with their respective accession numbers. Cfr resistance gene was not detected among the 17 chloramphenicol-resistant isolates. MecA gene was present in 41 (78.9 %) out of the 52 MRSP isolates. A total of 73 (73.7 %), 2 (2 %), 62 (62.6 %), and 55 (55.6 %) isolates harboured sec, exi, siet, and lukD virulence genes respectively. Conclusively, the S. pseudintermedius isolates from this study were more prevalent in dogs than among dog owners. Isolates were also multi-drug resistant and notably more resistant than those reported in literature. Interestingly, mecA, tetM, sec, siet, exi, and lukD genes encoding various pathogenic factors were the genes harboured by the S. pseudintermedius isolates. There was phenotypic homogeneity in the antibiotic resistance profiles of isolates from both humans and dogs in each of the 69 households that were sampled, thus depicting a possible zoonotic transfer from dogs to their owners. Hence, appropriate hygienic measures such as hand washing after attending to dogs should be adopted. Monitoring of antimicrobial resistance in dogs should be performed routinely and should include control options to avoid the spread of resistance.