Genomic diversity of ß-lactamase producing Pseudomonas aeruginosa in Iran; the impact of global high-risk clones.

BACKGROUND: Hospital-acquired infections caused by multidrug-resistant Pseudomonas aeruginosa incline hospital stay and costs of treatment that resulted in an increased mortality rate. The frequency of P. aeruginosa high-risk clones producing carbapenemases was investigated in our clinical samples. METHODS: In this cross-sectional study, 155 non-repetitive P. aeruginosa isolates were included from different medical centers of Iran. Antibiotic susceptibility testing was determined, and the presence of ß-lactamases were sought by phenotypic and genotypic methods. The clonal relationship of all isolates was investigated, and multi-locus sequence typing (MLST) was used for finding the sequence types of carbapenemase-producers. RESULTS: The agent with highest percent susceptibility rate was recorded for colistin (94.9%). MOX and FOX were found both as low as 1.95% (3/155). The most frequent narrow spectrum ß-lactamase was SHV with 7.7% (12/155) followed by PER, OXA-1, and TEM with the frequency of 7.1% (11/155), 3.2% (5/155), and 1.3% (2/155), respectively. Carbapenemases were detected in 28 isolates (18%). The most frequent carbapenemase was IMP with 9% (14/155) followed by NDM, 8.4% (13/155). OXA-48 and VIM were also detected both per one isolate (0.65%). MLST of carbapenem resistant P. aeruginosa isolates revealed that ST244, ST664, ST235, and ST357 were spread in subjected clinical settings. REP-PCR uncovered high genomic diversity in our clinical setting. CONCLUSION: Clonal proliferation of ST235 strain plays a key role in the propagation of MDR pattern in P. aeruginosa. Our data showed that high-risk clones has distributed in Iran, and programs are required to limit spreading of these clones.

Coexistence of Virulence Factors and Efflux Pump Genes in Clinical Isolates of Pseudomonas aeruginosa: Analysis of Biofilm-Forming Strains from Iran.

BACKGROUND: Biofilm formation and efflux pumps (EPs) correlation play a critical role in the pathogenicity and antibiotic resistance of Pseudomonas aeruginosa. In this study, biofilm formation and EP's collaborative role in clinical isolates of P. aeruginosa infection were investigated. METHODS: Eighty-six (86) P. aeruginosa isolates were collected from different clinical specimens and were confirmed using different biochemical tests. The formation of biofilm was investigated by using a crystal violet assay. Also, EP genes were identified by the PCR method. RESULTS: Based on the results, gentamicin-resistant (n = 50, 66.29%) and ciprofloxacin-resistant (n = 61, 69.66%) strains were the most frequent and colistin (n = 1, 1.12%) and ceftazidime (n = 12, 7.86%) resistant strains were the least prevalent. Furthermore, 22 isolates (31.42%) were MDR, and 11 isolates (12.35%) were XDR strains. Also, 19 isolates (22.47%) were classified as strong biofilm, 29 isolates (21.34%) as moderate biofilm, and 3 (11.23%) isolates as weak biofilm producers. The distribution of the EP genes was as follows: mexA (n = 44, 34.83%), mexB (n = 33, 32.58%), oprM (n = 59, 29.21%), oprD (n = 61, 30.33%), tetA (n = 22, 25.58%), tetR (n = 19, 22.09%), and emrE (n = 21, 24.41%). However, there was a strong significant association between biofilm formation and EPs in P. aeruginosa. Conclusions. In this study, we suggested that the presence of a multidrug resistance efflux pump, MexEF-OprN, significantly reduced P. aeruginosa pathogenicity. In contrast, the presence of the MexAB-OprM and MexCD-OprJ pumps did not affect virulence.

Relationship between biofilm gene expression with antimicrobial resistance pattern and clinical specimen type based on sequence types (STs) of methicillin-resistant S. aureus.

The ica genes in methicillin-resistant Staphylococcus aureus (MRSA) play an important role in biofilm formation. The aim of this study is to define effect of antibiotic resistance and clinical specimens to the expression of ica genes based on their sequence types (STs) and clonal complex (CC). One-hundred (100) S. aureus strain were collected from two teaching therapeutic centers in Hamedan, Iran. Then, the PCR, qPCR, and MLST were used to characterize strains. The results indicated that 29 (29%), 15 (15%), and 5 (5%) strain were strong, mediate, weak biofilm producer, respectively, and the icaA (17%) and icaC (14%) genes were the most abundant. However, two unique STs (3667, 491) in Iran were reported and ST30 and ST11 were the most abundant STs and CC30 and CC5 were observed among MRSA and MSSA strains. High activity in ica locus was observed among strains collected from wound and catheter strains. Also, expression level of icaA gene increased in all strains except ST30 and ST491. Moreover, the highest expression level was observed in CC1, CC7, and CC11. Likewise, activity of the icaC gene was only observed in CC5. Furthermore, the expression of all ica genes in CC5 was significantly correlated with the type of biofilm and the clinical sample. In this study demonstrated that the frequency distribution of STs and CCs in different strains of MRSA was higher than methicillin-sensitive strains. Also, the type of clinical specimen and expression of ica genes played an important role in this abundance.