Philippine Journal of Science
154 No. (1): 13-26, February 2025
ISSN 0031 – 7683
Date Received: 04 Jul 2024

Jennifer Joyce E. Gaytano and Julieta Z. Dungca

Pseudomonas aeruginosa is a notorious nosocomial pathogen owing to its resistance to multiple antibiotics and biofilm formation. This study investigated the effects of 1-wk exposure at different temperatures on the antibiogram and biofilm in P. aeruginosa. A total of 30 isolates from clinical specimens – 14 from wound, six from urine, four from endotracheal aspirate, four from sputum, one from a tissue sample, and one from a cranial cerebrospinal fluid – were collected from a tertiary hospital. The pre-exposure minimum inhibitory concentration (MIC) was measured against the eight antibiotics – namely amikacin (30 μg), gentamicin (10 μg), ciprofloxacin (5μg), piperacillin-tazobactam (100/10 μg), ceftazidime (30 μg), cefepime (30 μg), imipenem (10μg), and meropenem (10 μg). The isolates were then exposed for 1 wk at 24, 37, and 42 °C, afterwhich post-exposure MICs were taken. The biofilm-forming activities after 48 h were determined using the crystal violet assay. MDR- and XDR–P. aeruginosa were recorded in 20 and 17% of the isolates, respectively, mostly to the beta-lactam antibiotics. One isolate was resistant to all eight antibiotics; two were hepta-resistant and hexa-resistant. High carbapenem resistance was observed among isolates (30–43%). Data showed that increasing the temperature from 24 to 42 °C did not significantly affect the MIC (p > 0.05) but had a significant effect on the biofilm formation, with lower temperature (24 °C) favoring enhanced biofilm. In addition, pigment production was observed at 24 °C and became more pronounced at 37 °C but inhibited at 42 °C. In conclusion, exposing P. aeruginosa to increasing temperatures for 1 wk did not cause a significant change in its antibiogram profile. However, the ability of P. aeruginosa to produce bio-pigment and biofilm was found to be temperature dependent. This study underscores the importance of routine antibiotic surveillance for a directed and more efficacious treatment of P. aeruginosa infection and the need to explore effective biofilm-disrupting strategies to mitigate P. aeruginosa colonization in hospital settings.