Nasal Carriage of Methicillin-Resistant Group by Residents of an Urban Informal Settlement in Kenya.

Background: The group constitutes animal-associated bacteria but can comprise up to 4% of coagulase-negative staphylococci isolated from human clinical samples. They are reservoirs of resistance genes that are transferable to but their distribution in communities in sub-Saharan Africa is unknown despite the clinical importance of methicillin-resistant .

Objectives: We characterised methicillin-resistant group isolates from nasal swabs of presumably healthy people living in an informal settlement in Nairobi to identify their resistance patterns, and carriage of two methicillin resistance genes.

Method: Presumptive methicillin-resistant group were isolated from HardyCHROM™ methicillin-resistant media. Isolate identification and antibiotic susceptibility testing were done using the VITEK2 Compact. DNA was extracted using the ISOLATE II genomic kit and polymerase chain reaction used to detect and genes. Results: Of 37 presumptive isolates, 43% (16/37) were methicillin-resistant including - (50%; 8/16), (31%; 5/16) and (19%; 3/16). All isolates were susceptible to ciprofloxacin, gentamycin, levofloxacin, moxifloxacin, nitrofurantoin and tigecycline. Resistance was observed to clindamycin (63%), tetracycline (56%), erythromycin (56%), sulfamethoxazole/trimethoprim (25%), daptomycin (19%), rifampicin (13%), doxycycline, linezolid, and vancomycin (each 6%). Most isolates (88%; 14/16) were resistant to at least 2 antibiotic combinations, including methicillin. The and genes were identified in 75% and 50% of isolates, respectively.

Conclusion: Colonizing group bacteria can carry resistance to methicillin and other therapeutic antibiotics. This highlights their potential to facilitate antimicrobial resistance transmission in community and hospital settings. Surveillance for emerging multidrug resistant strains should be considered in high transmission settings where human-animal interactions are prevalent. Our study scope precluded identifying other molecular determinants for all the observed resistance phenotypes. Larger studies that address the prevalence and risk factors for colonization with group and adopt a one health approach can complement the surveillance efforts.