Epidemiological and Molecular Characterization of Multi-Drug Resistant Gram-Negative Bacterial Isolates from Bloodstream Infections Among Patients Admitted at Tikur Anbessa Specialized Hospital, Addis Ababa, Ethiopia

dc.contributor.advisorAdey Desta
dc.contributor.advisorTesfaye Sisay
dc.contributor.advisorGurja Belay
dc.contributor.authorDaniel Beshah
dc.date.accessioned2025-08-17T22:42:27Z
dc.date.available2025-08-17T22:42:27Z
dc.date.issued2024-03
dc.description.abstractBloodstream infections are the major causes of morbidity and mortality worldwide. Alarmingly, Gram-negative bacteria that produce beta-lactamase and carbapenemase are causes for the rapid global spread of multi-drug resistance (MDR), which significantly jeopardizes the efficacy of existing antimicrobial treatments. This research aimed to analyze the microbial profile, antimicrobial susceptibility, genomic diversity, and associated risk factors of Gram-negative bacteria in bloodstream infections. A cross-sectional study was conducted between September 2018 and March 2019 on 1486 bloodstream infection suspected patients. In addition to biochemical identification and antimicrobial susceptibility tests, PCR and WGS were conducted for ESBL, AmpC, MBL and carbapenemase producing resistance genes. The prevalence of bloodstream infection was 417 (28.06%), and the most prevalent bacterial species were Klebsiella pneumoniae (17.6%) and Acinetobacter spp. (11%). Culture positivity was associated with age below 6 years, ICU admission, length of admission > 5 days, temperature greater than 38 oC, instrument usage during medical care, chronic illness, and neonatal incubation. Multi-drug resistance was 95% where 56%, 32% and 7% of the isolates exhibited MDR, XDR, and PDR respectively. Klebsiella pneumoniae and Acinetobacter sp. showed the greatest rates of XDR (37%) and PDR (77%), respectively. Among the 231 phenotypically characterized isolates, 195 (84%) drug-hydrolyzing enzyme producers, 54% and 26% were ESBL and carbapenemase-producer, respectively. Again, Klebsiella pneumoniae was the highest drug-hydrolyzing enzyme-producer bacteria. 176 out of the 195 (76%) were PCR-confirmed resistant bacteria, of which ESBLs, MBLs, carbapenemase, and AmpC-BLs accounted for 53%, 22%, 20%, and 10%, respectively and blaCTX-M, blaFOXM, blaOXA-23, and blaNDM were the highest hits in Klebsiella pneumoniae, (75%), and Escherichia coli (24%). Out of the 142 whole genome sequenced isolates, 1604 genes categorized into 168 resistance classed were identified. A total of 1055 virulence genes were identified belonging to 133 types. The majority of AMR genes and virulent genes were observed in Klebsiella pneumoniae (40%) and E. coli (71%), respectively. Sul2 was the most prevalent gene (%), followed by blaCTX-M-15 (5%), and aph (3'')-Ib (5%). fimH (6%), iutA (6%), and traT (5%) were the most prevalent virulent genes. The most common ESBL producer genes were blaCTX-M-15 (7%) and blaTEM-1B (6%) and the most common AmpC genes were blaCMY-2 (2%) and blaCMY-6 (1%). The highest carbapenemase genes were blaOXA-23 (3%), blaOXA-66 (3%), blaNDM-1 (2%), and blaOXA-1 (2%). In 82 (58%) of the sequenced strains, eight types of gene mutations were identified: parC (30%), gyrA (30%), ramR (1%), rpoB (1%), ompK37 (45%), acrR (43%), and ompK36 (43%) with a total of 220 antimicrobial gene mutations and 956-point mutations. However, 22 (2%) of the mutations were frameshift mutations and the rest 934 were point mutations. Among the 142 drug-resistant strains, 103 (73%) have plasmid mlst, and 108 (76%) have plasmid genes. Resistance to disinfectants like benzalkonium chloride 77(52%) and cetylpyridinium chloride 77(52%) had OqxA 41(29%), OqxB 41(29%), and qacE 49(35%) disinfectant-resistant genes. Like other AMR genes, NICU (B6) still has the leading prevalence of disinfectant resistance genes (22%) followed by C/W (9%) and pediatric hematology (D7) (8%). The study showed AMR has become a significant health hazard of bloodstream infection that most affects neonatal and ICU patients. The alarming result of this study was 7% PDR bacteria. The NICU by ESBL and SICU, General surgery, and caesarian section units by Carbapenemase producer strains were affected. A high burden of ESBL and Carbapenemase was seen in this study The predominant ESBL, MBLs, and Carbapenemase genes were blaCTX-M, blaNDM, and blaOXA-23 respectively. Nine novel drug-resistant bacteria strains were identified. Surgical and inserted medical instruments are the main drug-resistant bacteria transmission roots. Carbapenemase and MBL drug-resistant genes were associated with NICU, general surgery, SICU, and C/S unit which needs infection prevention standard implementation.
dc.identifier.urihttps://etd.aau.edu.et/handle/123456789/6919
dc.language.isoen_US
dc.publisherAddis Ababa University
dc.subjectBloodstream Infections
dc.subjectAntimicrobial Resistance
dc.subjectDrug Resistance Category
dc.subjectDrug Resistance Mechanism
dc.subjectMultidrug Resistance
dc.titleEpidemiological and Molecular Characterization of Multi-Drug Resistant Gram-Negative Bacterial Isolates from Bloodstream Infections Among Patients Admitted at Tikur Anbessa Specialized Hospital, Addis Ababa, Ethiopia
dc.typeThesis

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