Genetic diversity and virulence factors of Gram-negative bacilli isolated at the CHU-Z in Abomey-Calavi/So-Ava (Benin)

Abstract

Nosocomial infections are increasingly recurrent in health facilities and represent a serious public health concern. Apart from patients, health workers are also at high risk of infection. The risk factors associated with this type of infection are still not fully characterized. The present study aimed at characterizing Gram-negative bacillus strains isolated from surfaces and medico-technical equipment at the CHU-Z in Abomey-Calavi/Sô-Ava. 128 samples were collected by dry swabbing in five departments of the Abomey-Calavi University Hospital Center. Identification of the strains and antibiograms were done using the API 20 E Gallery and CASFM recommendations. The pathogenic potential of the isolates was evaluated by i) analyzing the biofilm formation ability and ii) examining the presence of the beta-lactam resistance gene (blaSHV). In addition, E. coli strains were analyzed for their enterohem- orrhagic potential through the screening for the gene encoding for shigatoxin (stx). The proportion of contaminated samples by enterobacteria strains was 23.43%. Twelve species of Gram-negative bacillus were identified with a high predominance of Klebsiella oxytoca (20%), followed by Acinetobacter baumanni (16.66%), Chryseomonas luteola (13.33%). Most strains were resistant to tetracycline (87%) and ceftriaxone (80%). However, most of them were sensitive to norfloxacin (17%), ciprofloxacin (17%), and imipenem (13%). All strains of Escherichia coli, Enterobacter sakazakii, Klebsiella terrigena, Serratia rubidaea, Citrobacter youngae and 50% of Chryseomonas luteola formed biofilm. The results of PCR amplification showed that 6.66% of the strains carry the blaSHV gene and none of E. coli strains have the gene coding for Shigatoxin. These data suggest a significant risk of severe infections or patients and health workers at the CHU-Z in Abomey-Calavi/Sô-Ava. Additional investigations are required to better characterize the presence of pathogenic strains in hospital environment.