Molecular diversity, characterization, and antibiogram profile of Pseudomonas aeruginosa infections acquired in hospitals of Thi-Qar province, Iraq

Nosocomial infections, commonly known as healthcare-associated infections (HAI), are infections acquired while getting medical care in a hospital. HAIs can also involve occupational infections that affect staff. Infection happens when a pathogen infects a vulnerable patient host. The etiology of HAI is determined by the source or kind of infection and the pathogen responsible, which can be viral, bacterial, or fungal. In this study, burn, abscess, wound swabs, and urine samples of 150 patients attending Thi-Qar General Hospital in Thi-Qar Province were examined for P. aeruginosa detection, typing, and study of the antibiogram profile. Fifty patients admitted to Intensive Care Unit (ICU), and 100 were selected from different hospital sections (Women's, Men's, Burn, and Emergency sections) in the period of 25-3-2022 to 25-5-2022. Traditional bacteriological methods and Vitek2 were used for confirmation of the species level. Molecular methods (conventional PCR and Sequencing of 16sRNA) were used to confirm identification and detect virulence genes (LasA, LasB, ToxA, and Oprl). Additionally, the genetic diversity was also studied by molecular method (ERIC-PCR) by targeting a specific sequence within the genome of P.aerugionsa. Generally, the total isolation rate of P.aerugionsa was 20/150 (13.3%) of these 6/20(12%) were from ICU and 14/100(14%) from other hospital sections, with no statistical differences (P>0.05). On the other hand, the isolation rate was highest in the Burn section (45%) in comparison with other hospital sections with statistically significant differences (P<0.05). This study clearly demonstrates that 75% of P.aeruginosa infections were nosocomial infections mostly in ICU and Burn sections and 25% were community-acquired infections, with statistical significance (P>0.05). Regarding the virulence profile of P.aeruginosa, the PCR results revealed that all strains harbored at least two virulence genes with the highest prevalent gene being Oprl and LasA genes 20/20(100%) while LasB was found in 12/20(60%) of strains and ToxA gene was found in 65%. Collectively, all strains can be categorized into three genotypes based on the different combinations of virulence genes, the highest prevalent genotype was those strains that carry all studied virulence genes (LasB+, LasA+, ToxA+, and Oprl+) which were detected in 12/20(60%). The other two genotypes (LasB+ and ToxA+) and (LasB) were detected at 6/20(30%) and 2/20(10%) respectively. The genotype LasB-, LasA+, ToxA-, and Oprl+ was distributed throughout all hospital sections except ICU. The amplification of ERIC sequences of all P.aeruginosa isolates revealed that the isolates of Burn, ICU, Women section, and men section showed the same ERIC pattern, while the isolate of the ER section was separated in different ERIC patterns, with similarity matrix 0.785. Additionally, regarding antibiotic susceptibility, the highest resistance against Amikacin and Levofloxacin which not exceeded 40%, and the lowest resistance was found against Augmented and Ppracillin (20%).