A multidrug-resistant Stenotrophomonas maltophilia clinical isolate from Kamuzu Central Hospital, Malawi

Background Stenotrophomonas maltophilia is a significant opportunistic pathogen that is associated with high mortality in immunocompromised individuals. In this study, we describe a multidrug-resistant (MDR) S. maltophilia clinical isolate from Kamuzu Central Hospital (KCH), Lilongwe, Malawi. Methods: A ceftriaxone and meropenem nonsusceptible isolate (Sm-MW08), recovered in December 2017 at KCH, was referred to theNational Microbiology Reference Laboratory for identification. In April 2018, we identified the isolate using MALDI Biotyper mass spectrometry and determined its antimicrobial susceptibility profile using microdilution methods. Sm-MW08 was analysed by S1-PFGE, PCR, and Sanger sequencing, in order to ascertain the genotypes that were responsible for the isolate`s multidrug-resistance (MDR) phenotype. Results Sm-MW08 was identified as S. maltophilia and exhibited resistance to a range of antibiotics, including all ß-lactams, aminoglycosides (except arbekacin), chloramphenicol, minocycline, fosfomycin and fluoroquinolones, but remained susceptible to colistin and trimethoprim-sulfamethoxazole. The isolate did not harbour any plasmid but did carry chromosomally-encoded blaL1 metallo-ßlactamase and blaL2 ß-lactamase genes; this was consistent with the isolate's resistance profile. No other resistance determinants were detected, suggesting that the MDR phenotype exhibited by Sm-MW08 was innate. Conclusion : Herein, we have described an MDR S. maltophilia from KCH in Malawi, that was resistant to almost all locally available antibiotics. We therefore recommend the practice of effective infection prevention measures to curtail spread of this organism

Prevalence of Carbapenem Resistance Genes in Acinetobacter Baumannii Isolated From Clinical Specimens Obtained From an Academic Hospital in South Africa

Acinetobacter baumannii is an important cause of hospital-acquired infections. The occurrence of carbapenem resistance that is caused by the carbapenem-hydrolysing class D ?-lactamases and the metallo-?-lactamases (MBLs) limits the range of therapeutic alternatives in treating A. baumannii infections. In this study; two multiplex polymerase chain reactions were performed to screen for both carbapenem-hydrolysing class D ?-lactamases and MBL genes in 97 clinical isolates of A. baumannii. Oxacillinase (OXA)-51 had a prevalence of 83 (81/97); and OXA-23 had a prevalence of 59 (57/97). One isolate was positive for an MBL [Verona integron-encoded metallo ?-lactamases (VIM)]. Therefore; continuous surveillance and monitoring of A. baumannii is crucial because of the high prevalence of antibiotic resistance genes

A Comparative in Vitro Microbiological Evaluation of Generic Meropenem Compounds against the Innovator Compound

Background: Meropenem is a broad-spectrum carbapenem widely used in the treatment of critically ill patients. A generic meropenem product has recently become available in South Africa and we aimed to compare the generic product with the innovator product using established in vitro microbiological testing methods.Method: Comparative minimum inhibitory concentrations (MICs) were determined for 115 clinically relevant isolates using the broth microdilution reference method. Comparative analysis of MIC was done using categorical and essential agreement. A subset of isolates was evaluated using minimum bactericidal concentration (MBC) testing. Results: The overall essential agreement exceeded the international standard of 90. A single major error and six minor errors were detected in 230 comparative MICs. For the 55 Enterobacteriaceae isolates tested; the MIC50 and MIC90 were 0.03 ?g/ml and 0.06 ?g/ml respectively; with no difference between extended-spectrum Beta-lactamase producers (ESBL) and non-ESBL isolates. Bactericidal activity was demonstrated for both generic and innovator products in all isolates tested. For eight of the 11 isolates; the MBC was only twice the MIC.Conclusion: Reference method MIC and MBC testing of a large sample of clinically relevant microorganisms against meropenem has demonstrated comparable in vitro activity between the innovator and generic products. Low MICs and bactericidal activity at concentrations close to the MIC indicate that meropenem remains a useful agent in the treatment of infections caused by ESBL-producing Enterobacteriaceae