Occurrence of a Multidrug Resistant Pseudomonas aeruginosa Strains in Hospitalized Patients in Southwest of Iran: Characterization of Resistance Trends and Virulence Determinants

Pseudomonas aeruginosa is a Gram negative ubiquitous opportunistic organism and one of the more problematic drug-resistant pathogens encountered today.
The aims of the current multicenter research were to assess antibiotic resistance profiles, carbapenemase production, and detection of antibiotic resistance IMP gene as well as virulence factors genes including exoA, algD, lasB, and plcH among the clinical isolates of P. aeruginosa.
A total of 80 nonduplicate isolates of P. aeruginosa were recovered from inpatients. Bacterial identification was done by standard diagnostic tests. Species was confirmed by detection of the exoA gene using the PCR technique. Antimicrobial susceptibility test was performed according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. Carbapenemase production among the isolates was determined by the modified Hodge test. Virulence genes were detected by PCR.
A total of 42 (52.5%) isolates recovered from wound specimens. Colistin was the most effective antibiotic against isolates (97.5% isolates were susceptible) and levofloxacin was the least effective drug (67.5% isolates were resistant). The most common antibiotic resistance pattern was CIPR-CPMR-GEMR (47 isolates). In total, 47 (58.75%) isolates were identified as multidrug resistance (MDR), while 30% of isolates were carbapenemase producer (MHT). Among studied isolates, plcH and lasB genotypes (100% isolates) were the most common virulence gene patterns. Of 80 P. aeruginosa isolates, 39 (48.75%) showed algD, plcH, lasB, and IMP genotype. The blaIMP resistance gene was detected in all MHT positive and MDR isolates.
In our study, the emergence of potentially highly pathogenic and carbapenem-resistant strains in joining with a MDR phenotype is alarming, as a feasible outcome would be a severe clinical result concomitant with critical restrictions in antibiotic therapy.