Antimicrobial susceptibility patterns of Staphylococcus aureus and coagulase negative staphylococci isolated from humans in Nairobi, Kenya

Abstract

Nosocomial infections due to multidrug resistant Staphylococcus aureus are an important health problem worldwide. Antimicrobial resistance prolongs the duration of hospitalization, thereby increasing the cost of patient care. For a long time, methicillin was considered as drug of choice for treatment of penicillin-resistant staphylococcal infections. Emergence of methicillin resistance reduced the available options for treatment of nosocomial and community acquired S. aureus. Normally, such strains are only sensitive to glycopeptides such as vancomycin and teicoplanin. Recent reports show that methicillin resistant S. aureus (MRSA) have become multiply resistant to other drugs such as fluoroquinolones, trimethoprim-sulfamethoxazole (SXT), clindamycin or erythromicin and there are reports of vancomycin resistant strains from different parts of the world. The aim of this study was to determine the susceptibility patterns of Staphylococcus isolates from humans. Drug susceptibility testing of isolates was determined using the disk diffusion method. A total of 110 S. aureus (SA) and 23 coagulase negative staphylococcus (CoNS) isolates from human sources were studied. Both SA and CoNS isolates were completely sensitive to vancomycin. On one hand, there was a comparable high resistance for both SA and CoNS to penicillin G, augmentin and tetracycline. On the other hand, there was significantly high resistance to erythromycin (69.6%), SXT (69.6%), oxacillin (82.6%), ciprofloxacin (52.2%) and clindamycin (39.1%) among CoNS when compared with SA isolates (erythromycin 38.2%, SXT 38.2, oxacillin (33.6%), ciprofloxacin (26.4%), clindamycin 18.2%) with p values 0.0090, 0.0099, 0.0001, 0.0239 and 0.0483, respectively. These high levels of resistance, calls for continuous surveillance studies to monitor for S. aureus infections in the community and hospital settings and the emergence of vancomycin resistant isolates.

Antimicrobial resistance among Enterobacteriaceae, Staphylococcus aureus, and Pseudomonas spp. isolates from clinical specimens from a hospital in Nairobi, Kenya

“…A somewhat lower but substantial proportion of S. aureus isolates (35%) were resistant to one or more tetracyclines, another commonly used class of antimicrobials. This is consistent with findings from other studies that reported levels ranging from 15.5% to 53.4% (Omuse, Kabera & Revathi, 2015;Sangeda et al, 2017;Wangai et al, 2019).…”

“…aureus was the most frequently isolated Gram positive organism, mostly from bloodstream infections and wounds or abscesses, consistent with the findings of other studies (Omuse, Kabera & Revathi, 2015;Sangeda et al, 2017;Wangai et al, 2019). The reported prevalence of MRSA among S. aureus isolates has been quite variable across Africa (Kesah et al, 2003;Falagas et al, 2013), as well as between different facilities within Kenya (Omuse, Kabera & Revathi, 2015;Sangeda et al, 2017;Wangai et al, 2019;Iliya et al, 2020).…”

“…Consistent with findings of other studies in Kenya (Omuse, Kabera & Revathi, 2015;Sangeda et al, 2017;Wangai et al, 2019;Iliya et al, 2020), the majority (56.7%) of S. aureus isolates were resistant to folate pathway inhibitors. A somewhat lower but substantial proportion of S. aureus isolates (35%) were resistant to one or more tetracyclines, another commonly used class of antimicrobials.…”

“…A much lower percentage of S. aureus isolates were MDR (16.7%) compared to Enterobacteriaceae (51%) in the current study. This is also much lower than findings from two other studies in the region, which reported that 63% and 64.8% of S. aureus isolates were MDR (Sangeda et al, 2017;Iliya et al, 2020). However, the criteria used to categorize isolates in the above studies as MDR were different from those used in the current study, limiting comparability.…”

Molecular Ecology of Coral Reef Microorganisms in the Western Indian Ocean coast of Kenya

“…Antibiotic resistant bacteria have been observed widely in aquatic environments following antibiotic contamination from wastewater treatment plants or agricultural runoffs (Schmieder & Edwards, 2012). Avoparcin is a glycopeptide antibiotic that is chemically very similar to vancomycin; there have been earlier concerns about the use of avoparcin in agriculture in various countries as well as Kenya (Bager, Madsen, Christensen, & Aarestrup, 1997; Nilsson, 2012; Raphael, Sam, Anne, Peter, & Samuel, 2017), and it would be reasonable to think it would be the cause of vancomycin resistance gene clusters in coastal waters.…”