Prevalence, phenotypic and genotypic characterization of resistant clinical gram-negative isolates at Kamuzu Central Hospital, Lilongwe Malawi.
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Date
2022
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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
Description
Doctoral Degree. University of KwaZulu-Natal, Durban.