Abstract
Background: Pseudomonas aeruginosa is an
opportunistic human pathogen. This organism is thought to persist by forming biofilm
within human infections. Bacteria growing in biofilm exhibits increased
resistance to antimicrobial agents. In this study, we examined the effect of
oxygen on the development of biofilm by P. aeruginosa and on the level of its
resistance to the antibiotics. Methods: The P. aeruginosa control
strain group and 45 clinical isolates were cultured and antibiotic
susceptibility testing was performed by disk diffusion agar testing. Biofilm
formations were examined by glass tube assay and were incubated at 37°C under
normoxia (21% oxygen) and hypoxia (1% oxygen). Results: We
observed that hypoxia affects the biofilm formation under hypoxic conditions as
compared to normoxia. Among the antibiotics tested, penicillin, cephalosporin
and carbapnem, all demonstrated decreased susceptibility values under hypoxia compared to normoxia. Conclusion: We established
that hypoxia induced biofilm formation; this suggests that decreased oxygen may
be a critical factor in the bacterial virulence. Moreover, we confirmed a
strong positive correlation between hypoxia and antimicrobial resistance of P. aeruginosa.