Prevalence of multidrug resistant bacteria among clinical isolates at a central pathology laboratory, Muhimbili National Hospital

Abstract

Background: Antimicrobial-resistant is reported to evolve dramatically despite adopting several strategies. An increasing rate of antimicrobial resistance bacteria in resource-limited countries like Tanzania brings both health care costs and mortality. Antibiotic susceptibility testing plays a key role, in attaining proper choice of antimicrobial, and eventually improved treatment outcomes. The ability of the laboratory to identify and reporting of AMR is critical for control of its spread and for improving AMR stewardship. Aim: This study aims at determining the prevalence of multidrug-resistant bacteria among clinical isolates at the central pathology laboratory, Muhimbili Nation Hospital Method: This was a laboratory-based cross-sectional study, conducted from March 2021 to June 2021 at Muhimbili National Hospital (MNH). All specimens processed during a study period were followed to the final identification of bacteria. Isolates were identified using conventional methods and AST was performed following CLSI guidelines. ESBL and MRSA were detected using the double disk method and cefoxitin disk, respectively. MIC for ESBL- PE and MRSA to commonly used antibiotics were detected using the broth dilution method. Data were analysed by Statistical Package for Social Sciences (IBM SPSS) version 23.0. Results: A total of 3549 samples were received and processed at CPL from March to July 2021, and 363(10.2%) clinical isolates were isolated. Out of 363 isolates recovered, 131 were S. aureus and 232 were Gram-negative bacteria. The majority of bacteria were highly resistant to commonly used antibiotics. The overall, prevalence of multi-drug resistance was 45%. MDR was more common in Gram-positive bacteria (57%) compared to gram-negative (44%) P-value = 0.007. The overall prevalence of ESBL among Gram-negative bacteria was 35%, (81/232); while 50.3% (66/131) S. aureus was MRSA. MRSA was significantly resistant to gentamicin, trimethoprim-sulfamethoxazole and ciprofloxacin. MRSA resistance to clindamycin using MIC was low compared by disk diffusion (27.4%) vs (47.5%), p-value = 0.0405. There was a difference in MRSA resistance vi rates to ciprofloxacin on using MIC (52%) and disk diffusion (59%), but not statistically significant. Among ESBL producing isolates rates of resistance to ciprofloxacin (80.3%) and gentamycin (72.7%) was significantly high, p-value = 0.007. There was a significant difference in ESBL resistance rates to ciprofloxacin (89%) using Disk diffusion and MIC (33%) p-value= 0.001. Conclusion This study revealed majority of bacteria were resistant to multiple routinely prescribed antibiotics, and almost half of bacteria were MDR. Nevertheless, the study found, high prevalence of MRSA and ESBL producers among isolates at CPL. Recommendations The observed high proportion of MDR pathogen including ESBL PE and MRSA in our setting call for the need for a clinical microbiology laboratory to enforce the policy for regular screening and reporting for MRSA and ESBL PE.