Antibiograms and characterization of Pseudomonas aeruginosa isolates for Carbapenemase and extended-spectrum β-lactamase production

• Main Author: Briceno, Akiram E.
• Format: text
• Language: English
• Published: Animo Repository 2016
• Subjects: Biology
• Online Access: https://animorepository.dlsu.edu.ph/etd_bachelors/18554
• Institution: De La Salle University

As the threat brought forth by the prevalence of multiple antibiotic resistance of bacteria increases, this study investigated the antimicrobial susceptibility patterns of the Gram negative bacterium Pseudomonas aeruginosa to β-lactam, aminoglycoside and fluoroquinolone antimicrobials using the disc-agar diffusion method. The isolates were likewise characterized for their phenotypic expression of Class A and D Carbapenemases, metallo β-lactamases, and extended-spectrum β-lactamases. A total of 53 isolates were obtained from hospitalized patients of two (2) tertiary level hospitals in Metro Manila from August 2015 to November 2015. Results showed that 23 out of the 53 isolates (43%) were resistant to at least one of the antibiotics tested, with 9 isolates (17%) showing multiple drug resistance, which is defined as the resistance of a bacterium to at least 1 or more agents in 3 or more classes of antimicrobial categories. Resistance to aztreonam, ceftazidime, and the carbapenems were shown by 36%, 30%, and 25% of the isolates, respectively. On the other hand, resistance to the aminoglycosides amikacin, tobramycin and gentamicin were shown by 8%, 15% and 19% of the isolates, respectively. Moreover, 21% and 26% of the isolates were resistant to the fluoroquinolones ciprofloxacin and levofloxacin. The phenotypic screening of carbapenemases using the Modified Hodge test, showed the absence of Class A and D carbapenemase production among the carbapenem-resistant strains. On the other hand, the imipenem-EDTA test showed that only 1 out of 7 (or 14%) of the carbapenem-resistant isolates was positive for metallo-β-lactamase production. The detection of ESBL production using the clavulanate-ceftazidime/aztreonam double-disc synergy test showed positive ESBL production in 10% of the aztreonam and/or ceftazidime resistant isolates.