Isolation, Antibiotic Susceptibility and Molecular Characterization of Resistance Genes in Pseudomonas Isolates from Selected Hospitals in Mombasa County, Kenya.

Abstract

Pseudomonas species are common causes of nosocomial infections. Globally nosocomial infections are among the most important problems complicating health care provision since they are caused by bacteria exhibiting resistance to many antibiotics. Their susceptibility to antibiotics is restricted to merely few drugs, and the occurrence of resistance by initially susceptible strains during therapy occurs at a relatively high frequency. The rate of transmission of Pseudomonas infection increases from 5% in non-hospitalized patients to 20% in hospitalized patients within 72 hours after hospital admission. These infections may be contributed by indwelling catheters, surgical or burn wounds as well as abscess in patients who have been admitted for over 48 hours in the hospital. This study was conducted in two selected hospitals in Mombasa County, coastal region of Kenya. A cross sectional study design was adopted and 192 clinical samples from each study hospital were randomly collected and analyzed. Samples were collected from indwelling catheters, swabs from burn wounds, surgical wounds and abscess as well as tubing’s from patients who had stayed for over 48 hours in the hospital wards or ICU. Specimens were inoculated in MacConkey and Blood agar, and later sub cultured in blood agar for purity. Species identification and antimicrobial susceptibility was analyzed by the Vitek® system. Pseudomonas positive isolates were screened for the presence of Metallo-beta lactamase and fluoroquinolones resistance conferring genes by conventional PCR. Out of the 384 samples, collected 50 were positive for Pseudomonas species. The type of specimens collected included 226 (58.9%) pus swabs, 124 (32.3%) catheter tips, 29 (7.6%) endotracheal tube tips and 5 (1.3%) central venous catheter tips. The predominant isolate identified was Pseudomonas aeruginosa 41 (82%), followed by Pseudomonas fluorescence 3 (6%), Pseudomonas stutzeri 3 (6%), Pseudomonas luteola 2 (4%), and Pseudomonas oleovorans 1 (2%). The relative distribution of the Pseudomonas species amongst the two study facilities was not statistically significant (p= 0.955). Pseudomonas isolates were detected in all the specimen types except central venous catheter tips. Pus swabs recorded the highest Pseudomonas burden n=30 (60%) followed by catheter tips n=11 (22%) and finally endotracheal tubes tips n=9 (18%). Antibiotic susceptibility against 26 drugs used was varying. This study observed that (96%) of Pseudomonas isolates were resistant to Ampicillin while Colistin was the most effective antibiotic. Metallo-betalactamase (MBL) and fluoroquinolone resistance conferring genes were analyzed from twenty (20) Pseudomonas isolates using PCR. VIM was the most prevalent MBL gene observed followed by SPM, SIM, IMP, and GIM. Fluoroquinolone resistant genes ParC and MexR were detected in all the isolates screened in this study. This study is of great importance to the county, as it will outline the suitable antibiogram for the treatment of Pseudomonas infections and serves as a baseline to evaluate the trends in antibiotic resistant genes in the region.