Pasteur Institute of Iran

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Introduction: Multidrug-resistant (MDR) Pseudomonas aeruginosa isolates are among the common cause of Nosocomial infections. In P. aeruginosa infections, several genes, mexA, and mexB are involved in resistance to antibiotics and pslA, pelA and brlR contribute to biofilm formation. This study aims to investigate the prevalence of these genes in P. aeruginosa isolates and to determine their relationship with biofilm formation, antibiotic resistant, pigment production, and source of infection. Methods: We collected 63 specimens out of 90 samples from patients hospitalized in a hospital affiliated to Shiraz University of Medical Sciences. The specimens belonged to 42 men and 21 women and included urine, sputum, wound, skin, blood, body fluid, and central venous blood (CVB). The samples were cultured on solid media and diagnosed according to standard phenotypic characteristics. Disk diffusion method was used to identify the clinical MDR P. aeruginosa isolates, and the genes pslA, pelA, brlR, mexA, and men were detected by PCR detected. Results: about 25.4% of the clinical isolates were MDR, i.e., resistant to three or more antibiotics. The prevalence of the genes in the clinical isolates was as follows: pslA (92.1%), pelA (68.3%), brlR (93.7%), mexA (95.2%) and mexB (50.8%). The highest and lowest prevalence of drug resistance belonged to ceftriaxone and amikacin, respectively. The highest MDR P. aeruginosa isolates originated from wound, urine and sputum specimens. Conclusion: The presence of MDR isolates correlated significantly with the patients’ gender, the origin of specimens, and bacterial pigment production.  In this study, the detected genes did not significantly correlate with the MDR features of the isolates. J Med Microbiol Infec Dis, 2018, 6 (2): 5 pages.
 
 

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Introduction: Diffusion of antibiotic resistance genes by horizontal gene transfer has led to the fast emergence of multidrug resistance (MDR) among bacteria. Multiple classes of integrons are effective genetic elements which play a significant role in the acquisition and nosocomial dissemination of resistance factors in strains of Gram-negative bacteria, Pseudomonas aeruginosa, and Acinetobacter baumannii. Methods: In this study, 110 sputum samples were collected from hospitalized patients with tract infections. Identification of the isolates was performed by standard biochemical tests. The most frequent Gram-negative isolates were 25 Enterobacteriaceae (62.5%), (9 Enterobacter spp, 11 Citrobacter spp, and 5 Escherichia coli), 6 P. aeruginosa (15%) and 9 Acinetobacter spp (22.5%). Susceptibility of the isolates to antibiotics was carried out by Kirby-Bauer disk diffusion method according to CLSI guidelines, and finally, the class 1 integrons were detected by PCR. Results: Maximum resistance rate among Gram-negative isolates was observed to ceftazidime, co-trimoxazole, and cefotaxime with 89%, 87%, and 82%, respectively. A low-level resistance was recognized for imipenem 32% and gentamicin 34%, while an intermediate level resistance was found against the norfloxacin 40% and ciprofloxacin 44%. Out of 6 P. aeruginosa and 9 A.  baumannii isolates, 2 (33.3%) and 3 isolates (33.3%) were positive for class 1 Integrons, respectively, while all Enterobacteriaceae isolates (100%) were negative for class 1 Integrons. Class 1 integrons were detected among of MDR isolates. Conclusion: Our results showed that monitoring MDR isolates and detection of class 1 integrons in these isolates is necessary for promotion of antibacterial stewardship.

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Introduction: Biofilms are often found in communities of microorganisms in chronic and persistent infections, exhibiting high resistance against antimicrobial agents. Biofilm serves as a barrier, impeding the penetration of drugs and constraining their effectiveness. Multiple methods, such as the Tissue Culture Plate method, Congo Red Agar method, Tube method, bioluminescent assay, and fluorescent microscopic examination, can be used to evaluate biofilm production. Methods: The study included a total of 300 clinical isolates representing a range of bacterial species, including Acinetobacter baumannii (n=9), Coagulase Negative Staphylococcus (n=7), Enterobacter aerogenes (n=7), Enterococcus faecalis (n=15), Escherichia coli (n=137), Klebsiella pneumoniae (n=23), Proteus mirabilis (n=4), Pseudomonas aeruginosa (n=16), Salmonella typhi (n=11), and Staphylococcus aureus (n=68). Associations among isolates capable and incapable of biofilm formation and their multidrug resistance phenotypes were evaluated. Results: Among the 300 clinical isolates tested, 289 isolates (96.3%) exhibited biofilm formation. The most prevalent biofilm-forming organisms were A. baumannii (n=9), Citrobacter koseri (n=1), Coagulase Negative Staphylococcus (CONS) (n=7), E. aerogenes (n=7), E. faecalis (n=15), E. coli (n=137), Klebsiella oxytoca (n=1), K. pneumoniae (n=23), P. mirabilis (n=4), P. aeruginosa (n=16), S. typhi (n=11), S. aureus (n=68), and Streptococcus pneumoniae (n=1). The biofilm-forming isolates demonstrated increased resistance compared to isolates that did not form biofilms. Conclusion: Antimicrobial resistance represents a critical characteristic of infections involving biofilms. The study identified biofilm production in 92.7% of the isolates tested via TCP and in 72.3% of the isolates using the CRA. Furthermore, it was observed that pathogens with multidrug resistance (MDR) exhibited a higher biofilm production tendency than non-producing pathogens.
 

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Introduction: Hospitals are breeding grounds for multidrug-resistant (MDR) bacteria, posing treatment challenges and increasing the risk of spreading "superbugs." This study investigates the prevalence of colistin-resistant bacteria, a last-resort antibiotic, in wastewater from tertiary hospitals in Enugu, Nigeria. Methods: Twenty wastewater samples were collected over three months from two tertiary hospitals in Enugu. A standardized protocol by the American Public Health Association (APHA) was followed. Samples were collected aseptically from key drainage points and transported to the lab within 2 hours. Bacteria were isolated using the pour-plate method and characterized by morphological and biochemical tests, including Catalase, Oxidase, and Glucose Fermentation. Antibiotic susceptibility was assessed using Kirby-Bauer disc diffusion, and colistin resistance was confirmed via broth microdilution. Multiplex PCR detected mcr genes indicating plasmid-mediated resistance. Data were analyzed using SPSS version 23 with Chi-Square and ANOVA tests at a significance level of P < 0.05. Results: Gram-negative bacteria were isolated from 63.1% of samples, with Klebsiella spp. being the most prevalent, accounting for 24.6%. Colistin resistance was phenotypically observed in E. coli (83%), Klebsiella spp. (75%), and Pseudomonas aeruginosa (100%). Genotypically, E. coli harbored mcr-1 (17%) and mcr-3 (83%), while all Klebsiella and Pseudomonas isolates carried multiple mcr genes. Additionally, these bacteria showed resistance to multiple antibiotics, including Septrin, Gentamycin, and Ceftriaxone. Conclusion: The significant presence of colistin-resistant bacteria, especially E. coli and Klebsiella, poses a public health concern, potentially leading to treatment failures and spreading resistance genes. Stricter monitoring of hospital wastewater is necessary to identify emerging resistance trends and improve antibiotic practices in hospitals.