Background and Aim: Infectious diseases nowadays are caused by multidrug-resistant bacteria,
making their management both difficult and costly. In Gram-negative bacilli, several enzymes
particularly ESBLs and carbapenemases allow to counteract the antibiotic effect of nearly all β
lactams. This leads to a dilemma for clinicians who increasingly include last-resort drugs in
therapeutic options. The objective of this study is to focus attention on the precarious situation of
antibiotic drugs, even those considered last-resort like colistin. It aims precisely to characterize the
blaCTX-M-G1, blaIPM, blaVIM genes and the mcr gene in Gram-negative bacilli producing ESBL.
Methodology: A total of 60 strains of Gram-negative bacilli isolated from clinical samplesbetween
December 2022 and March 2023 at Shiphra Hospital in Ouagadougou were first subjected to
sensitivity test against β-lactamantibiotics using disc diffusion method. Then a synergy test was
performed for the phenotypic detection of ESBL producers. Finally, a conventional PCR was
performed for isolation of the targeted resistance genes.
Results: Of the 60 strains studied, the sensitivity test showed that 86.67% and 88.33% were
respectively resistant to ceftazidime and cefotaxime. However, most of isolates were found
sensitive to carbapenem drugs. There were 76.67% and 83.33% for meropenem and imipenem
respectively. The synergy test revealed that 76.67% of our strains produced ESBLs.
Electrophoresis of PCR products revealed 89.13% of strains carrying at least one of the resistance
genes studied. All these strains harbored the CTX-M-G1 gene while 6.52% carried also the VIM
gene. The IMP genes and the mcr genes were not detected.
Conclusion: This study showed that several Gram-negative bacilli harbor resistance genes
against last-resort antibiotics at the Schiphra Protestant Hospital. The results obtained raise the
need to regulate the use of antibiotics in order to prevent the emergence of multidrug-resistant
bacteria.

Gram-negative bacilli; ESBL; Muitiplex PCR; CTX-M-1; IMP; VIM; mcr.