Assessment of the antibiotics resistant and biofilm formation of Pseudomonas aeruginosa isolated from Iraqi hospitalized patients

Abstract

Background: Pseudomonas aeruginosa is a leading cause of hospital acquired infections. It has multidrug resistance and high biofilm production leading to difficult treatment.

Objectives: This study aimed to identify P. aeruginosa from clinical samples in Baghdad, Iraq. It also correlated the antibiotic susceptibility to quantitative biofilm production.

Materials and Methods: 150 samples were collected from hospitals of Baghdad by a cross-sectional study. The isolates were identified by culture, biochemical tests and Vitek 2 system. The Kirby-Bauer method (CLSI) was used to test 10 antibiotics. The bio-film formation capacity was examined by crystal violet microtiter plate method at an absorbance of 630 nm.

Results: one hundred isolates, were identified as P. aeruginosa, Infections were found in both sexes. Males made up 54% of cases while females 46% with non-significant P-value (p=0.236) in different age categories. The majority sites of infection from burns in  (29%) and Urine (17%), Sputum and ear swabs each contributed (12%), Wound samples (10%) and Blood (8%) with highly significant (p=0.0001) between sources of infection. The  results for antibiotic susceptibility test Trimethoprim showed the highest resistance (95%) followed by gentamicin (58%), ceftazidime (56%), piperacillin (52%), amikacin (52%), and levofloxacin (45%) in highly significant(p=0.0001). While colistin emerged as the most effective antimicrobial agent with 85% of the isolates being sensitive. Favorable sensitivity was also maintained for norfloxacin (58%), meropenem (52%), and imipenem (48%). The differences between resistance categories were all highly significant (p < 0.0001), indicating a severe resistance burden within the studied strains. 62% percent of isolates showed resistant phenotype with an overwhelming majority being the extensively drug resistant (XDR) phenotype (42%), Multi drug resistant (MDR) in 15% and Pan drug resistant in 5% . The One hundred isolates formed biofilm (100%)  and moderate biofilm producers were predominant (62%) followed by strong 29%, weak 9% . The distribution of isolates by biofilm formation ability and gender shown highly significant in P-value 0.0001 with ratio 63% in males while 37% in females. Also, the biofilm of isolates increased in age categories 41-60, 21-40 37%, 33% respectively. The results also showed the relationship between Biofilm production and clinical sources, the Burn, urine, sputum, and ear swabs isolates showed highly significant in biofilm formation(0.0001 , 0.0079, 0.0094 and 0.0098) respectively.  Across, the results had shown significant P-value in wound and skin swabs (0.0317, 0.0483).While non-significant P-value in  Blood, ETT, Palatal tissue, tissue, stool, pus and cystic fibrosis. Several antibiotics also showed a significant link with biofilm strength. Such as piperacillin and colistin, resistance was significantly higher in stronger biofilm producers (p=0.0084, 0.0087), also the results showed that significant ratio in Norfloxacin, Meropenem (P-value 0.0316, 0.0325). and non-significant results in other antibiotics resistance. The multi-drug resistance classification was correlated with the level of biofilm three core tires formation this overall association was highly significant (p = 0.0001). However, the sensitive isolates group (p = 0.0001), the XDR group (p = 0.0001), and the PDR group (p = 0.0497) showed highly significant relationship while the MDR group non-significant (p = 0.2174). In particular, the majority of the XDR isolates (moderate 28, strong 11 and weak 3) (66.7%, 26.2% and 7.1% respectively) were corroborated the association between the highest level of resistance and strong biofilm formation.

Conclusion: Clinical Pseudomonas aeruginosa isolates showed widespread antibiotic resistance and biofilm formation, highlighting the urgent need for effective antimicrobial stewardship.