Extended-Spectrum Beta-Lactamase Producing Bacteria: Epidemiology, Risk Factors, Diagnostic Methodology, and Antimicrobial Susceptibility Profile: A Prospective Study at a University Hospital in Western Saudi Arabia

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Dalal M. Alashari https://orcid.org/0000-0001-7275-6956
Maha M. Al-Alawi https://orcid.org/0000-0002-2114-2329
Asif A. Jiman-Fatani


Extended-spectrum beta-lactamase, Multidrug resistant, Infections, Clinicians


Objective: To study the prevalence and incidence of extended-spectrum beta-lactamase -producing microorganisms, microbiological characteristics and antimicrobial-susceptibility patterns.

Methods: A prospective study involving all cases of extended-spectrum beta-lactamase -producing microorganisms among all bacteriological samples collected over a 1-year period from 11 November 2015 to 10 November 2016, in the Clinical and Molecular Microbiology Laboratory at King Abdulaziz University Hospital, Jeddah. Detection of extended-spectrum beta-lactamase-producing microorganisms and antimicrobial-susceptibility profiles were done using automated Vitek 2 system. Clinical data such as recent use of antibiotics or invasive devices were investigated as risk factors for multidrug resistance.

Results: The prevalence of extended-spectrum beta-lactamase-producing microorganisms was 5.4% (95% CI = 4.7% – 6.2%); for an incidence = 54 per 1,000 isolates-years. Distribution by species showed 70.0% Escherichia coli, 28.5% Klebsiella pneumoniae and 1.5% Proteus mirabilis. Vitek 2 system showed 6% of false positive ESBL detections by reference to confirmatory E-test. Antimicrobial- susceptibility tests showed that 86.5% of beta-lactamase-producing strains were resistant to ≥ 1 other antimicrobial class and 20% were multidrug resistant. Univariate logistic regression showed that the presence of multidrug resistance was significantly predicted by age (OR = 1.02; P = 0.026), use of urinary catheter (OR = 2.05; P = 0.046) and number of devices used (OR = 1.60; P = 0.046); only age (OR = 1.02; P = 0.022) was significant in the multivariate model.

Conclusion: Clinicians and microbiologists should maintain a high level of alertness and contribute for effective screening and adequate treatment of infections caused by beta-lactamase-producing organisms according to international guidelines and the local epidemiological picture.

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