Antibacterial resistance in major bacterial communities of a few pig farms and poultries of cameroon: a glance on the diversity of phenotypic related mechanisms

The main objective of the present study was to address phenotypic characterization of resistance mechanisms in bacteria with their trends in poultry and pig farms. More specifically, a few resistance mechanisms were investigated in bacteria isolated from farms in the Western Region of Cameroon. The target traits included extended spectrum beta-lactamase (ESBL), inducible cephalosporinase (IC), high- and low-level penicillinases (HLP and LLP, respectively), high- and low-level cephalosporinases (HLC and LLC, respectively) and inhibitor-resistant penicillinase (IRP) in Gram-negative bacteria. In Gram-positive, they were limited to IC and ESBL. All detections were conducted according to the disk diffusion principles (Kirby-Bauer) with antibiotics that are commonly used for phenotypic detection of resistant traits. A total of 624 isolates from farms in Bafoussam, Bafang, Bandjoun and Kweko (Western Region of Cameroon) underwent the tests. The most common bacteria isolates belonged to Gram-negative bacilli members of the Enterobacteriaceae family (70%). Resistance rates recorded were highest with Amoxicillin and Amoxicillin/Clavulanic-acid. In further details, seven resistance mechanisms were detected; with more than one in the same isolates in some cases. More subtle details highlighted that, their rates broadly varied from 3% with HLC through 67% with LLC, with higher diversity in pig farms. All Serratia spp. expressed LLP while the highest ESBL rate was observed in Salmonella (84.6%). Staphylococci were also found to express ESBL (44%). Overall, HLP, IRP and ESBL-expression appeared first, second and third most frequently detected (67%, 56%, and 50%, respectively). All Staphylococci expressed resistance to Oxacillin (100%) that otherwise reflects resistance to methicillin, while 26.2% of isolates showed resistance to Erythromycin and Clindamycin (indicating constitutive MLSB phenotypes). Altogether, these findings indicated that antibiotic therapy is seriously threatened in the settings; reiterating the need for routine phenotypic tests and to enforce an antibiotic resistance stewardship program in Cameroon.