Prevalence, phenotypic and genotypic characterization of resistant clinical gram-negative isolates at Kamuzu Central Hospital, Lilongwe Malawi.

Abstract

nterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp. (ESKAPE) pathogens are the leading cause of nosocomial infections worldwide. They are highly virulent, multi-drug resistant (MDR) and therefore difficult to treat posing major public health and clinical challenges globally, particularly in developing countries where resources and microbiology diagnostic services are limited or not available. The aim was to investigate prevalence, phenotypic and genotypic resistant profiles of selected ESKAPE and other important bacterial pathogens isolated from adult patients admitted at Kamuzu Central Hospital (KCH) Escherichia coli and Staphylococcus aureus were the dominant species isolated. Multi-drug resistance and extended spectrum β-Lactamase -production was evident in K. pneumoniae (n=20/29; 69%) and E. coli (49/92; 53%). Pseudomonas aeruginosa was resistant to meropenem but none were carbapenemase producers. MRSA was detected in 10.5% (n=9/86) of S. aureus. These MDR isolates were mostly isolated from pus specimens from the surgical department Genotypically, the CTX-M type (55/60; 92%) and CMY type (16/21) were most prevalent among phenotypically-positive ESBL and pAmpC β-lactamases respectively. Both CTX-M and CMY were most prevalent in E.coli with 71% (15/21) carrying both CTX-M and CMY The most common sequence type in the CTX-M group 1 and CTX-M group 9 positive E.coli was ST410 (n=14/29; 48%) and ST131 (n=5/7; 71%) respectively; all of which contained the blaCTX-M-15 resistance gene. In CMY positive E. coli, ST410 was the most prevalent and all contained blaCMY- 2 resistance gene. All the E.coli isolates carrying both CTX-M and CMY were ST410 and contained both blaCMY- 2 and blaCTX-M-15 resistance genes. All phenotypically confirmed methicillin resistant Staphylococcus aureus (MRSA) contained mecA gene and t064 was most common spa type. Spa type t355 was most common in S. aureus that were negative for mecA gene Findings demonstrate the need for continuous antibiotic resistance surveillance at the hospital to inform antibiotic treatment options. There is also a need for the establishment of antibiotic stewardship programs to sustain the efficacy of antibiotics in Malawi