University of Khartoum

Phenotypic and Genotypic Characterization of Carbapenems-resistant to Fermentative and Non-Fermentative Gram Negative Bacteria

Phenotypic and Genotypic Characterization of Carbapenems-resistant to Fermentative and Non-Fermentative Gram Negative Bacteria

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Title: Phenotypic and Genotypic Characterization of Carbapenems-resistant to Fermentative and Non-Fermentative Gram Negative Bacteria
Author: M. Elsheikh, Mohamed Elmutasim Abdelhamid
Abstract: Background The spread of carbapenem resistant Enterobacteriaceae has become a major public health problem. Most of carbapenemases genes are plasmid encoded and therefore resistance can easily spread. A high mortality rates is being reported due to infections caused by carbapenem resistant Enterobacteriaceae because of limited treatment options available. The aim of this study is to characterize the phenotypes and genotypes associated with carbapenems-resistant in Gram negative bacilli isolated from Sudanese patients. Methods: This is a cross sectional study carried out in different hospitals in Khartoum State. Three hundreds and seventy clinical isolates of Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii and Pseudomonas aeruginosa form Khartoum state were screened for meropenem resistance by Kirby-Bauer disk diffusion method. The meropenem resistant strains were screened for the presence of carbapenemases by Modified Hodge Test. The meropenem resistant phenotype was also confirmed by automated Vitek2® system. Genes encoding different classes of carbapenemases (blaNDM-1, blaOXA-181/48, blaVIM, blaKPC, blaOXA-23, blaOXA-24, blaOXA-51 and blaOXA-58) were tested in meropenem resistant strains by dual tubed multiplex PCR. In addition to PCR screening and for better characterization of resistance, the whole genomes of four selected multi-drug resistant clinical isolates were sequenced. Results: Screening of the 367 clinical isolates using meropenem disc diffusion method resulted in 36 (9.8%) resistant strains. However only 72% (26/36) isolates were found positive with Modified Hodge Test. Vitek2 Showed 50% (18/36) exhibit¬ed intermediate or resistance designations to imipenem, meropenem or both. In carbapenem resistant bacterial isolates (n=36), the most frequently detected gene was blaOXA-51 27.8 % (10/36), followed by blaNDM-1 and blaOXA-181/48 16.7% (6/36) , while blaKPC and blaOXA-23 were less detected 2.7% (1/36). These genes were mostly detected in Pseudomonas aeruginosa 17 (52%), followed by Klebsiella pneumonia 11(33%), Escherichia coli 3(9%) and Acinetobacter baumannii2(6%). The most frequently determining genes among Pseudomonas aeruginosa were VIM and OXA-51, 14% (5/34) in each. While the most frequently detected gene among Klebsiella pneumoniae was NDM-1 at a rate of 11% (4/36). The overall rate of concordance between phenotypic and genotypic testing was 82.4% for the detection of carbapenemases by Modified Hodge Test and 70.6% by Vitek2. Using genome sequence data, a wide range of antimicrobial resistance genes to major antibiotics classes were predicted, which were in concordance with the phenotypic methods. Conclusion: In response to the high rate of carbapenemases and carbapenem-resistance encoding genes among Enterobacteriaceae in Sudan, nation-wide antibiotics resistance control and monitoring programs are immediately needed. Based on the finding of this study, Tigecycline can still be used as non-beta lactam antibiotic for the treatment of infections caused by carbapenem-resistance gram negative bacteria.
URI: http://khartoumspace.uofk.edu/123456789/26599


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