Introduction: Shigellosis is a significant global human health problem, and Shigella is in charge of almost 165 million cases of this disease annually, of whom 163 million cases are in developing countries and 1.5 million cases are in developed countries. The main aims of the current survey were to identify Shigella spp. isolated from diarrheal patients by conventional biochemical tests, determine the antimicrobial susceptibility profiles by disk diffusion method, and detect the ipaH gene using the PCR assay. Methods: The bacterial isolates were identified as Shigella spp. by microbiological tests and were serogrouped by the slide agglutination test. Antimicrobial susceptibility testing was performed using the disk diffusion method. PCR was performed to detect the ipaH gene. Results: The Shigella strains were isolated from 522 patients with various diarrhea, including bloody diarrhea (3%), mucoid plus bloody diarrhea (1.9%), mucoid diarrhea (3.2%), and watery diarrhea (3.2%). Overall, 69 (13.2%) isolates were positive for Shigella spp., of which 34 (49.3%) serotypes were identified as Shigella flexneri, 22 (31.9%) serotypes were identified as Shigella sonnei, 9 (13%) serotypes were identified as Shigella boydii, and 4 (5.8%) serotypes were identified as Shigella dysenteriae. Antibiotic susceptibility tests revealed that the highest resistance percentage was related to ampicillin (82%) and trimethoprim-sulfamethoxazole (77%), and ciprofloxacin and ceftriaxone were the best antibiotics against Shigella isolates. Conclusion: We concluded that Shigella spp. can be considered as an etiological agent of diarrhea in southwest Iran. Since the drug resistance pattern of Shigella differs geographically and over time within a country, continuous and regular surveillance program is necessary.

Background: Legionnaires’ disease is an important public health problem that can cause substantial mortality and morbidity. Legionnaires’ disease-risk estimation may be compromised by uncertainties in Legionella-detection methods. The aim of this study was the detection of L. pneumophila in respiratory specimens of hospitalized patients with respiratory symptoms by culture, PCR, and loop-mediated isothermal amplification (LAMP) methods. Methods: Sputum and bronchoalveolar lavage samples were obtained from patients with pneumonia admitted to teaching hospitals in Ahvaz, Iran from June 2016 to March 2017. Isolation of Legionella spp. was done by culturing the samples directly onto buffered charcoal–yeast extract and modified Wadowsky–Yee agar medium. Then, PCR and LAMP assays were performed for detection of L. pneumophila via its mip gene in respiratory specimens. Results: A total of 100 respiratory specimens were collected. Our results showed that 1% of the samples were culture positive for Legionella spp., and 3% and 7% of samples were positive for L. pneumophila using the mip gene on PCR and LAMP assays, respectively. Conclusion: Legionnaires’ disease should be considered in the diagnosis of pulmonary infectious diseases. Also, the LAMP assay is a faster method with higher sensitivity and specificity than conventional methods, such as PCR and culture, for laboratory diagnosis of Legionnaires’ disease.

Methicillin-resistant Staphylococcus aureus (MRSA) is an important problem associated with significant mortality and morbidity and well known as a predominant bacterial pathogen. The aim of this study was to identify MRSA strains. In this study (June 2018 to June 2019) isolates of S. aureus were obtained from patients referred to teaching hospitals of Ahvaz, Iran. All isolates were confirmed by conventional microbiological methods. In following, antimicrobial susceptibility testing (AST), MRSA screening, PCR detection of MRSA and LAMP assay were performed. Out of a total of 156 staphylococcal isolates, 126 isolates were identified as MRSA. Seventy-two (57.1%) MRSA isolates were recovered from wound. All MRSA isolates were sensitive to vancomycin, linezolid, teicoplanin, quinupristin-dalfopristin, and tigecycline. The results of LAMP showed 100% agreement with PCR. Sensitivity and specificity of the LAMP assays for the mecA genes were 100% and 100%, respectively. The LAMP assay is a rapid and simple method for the identifications of MRSA. Because of its performance without the need for specific instrumentation, this method can be easily employed in medical centers for the detection of mecA.

Hani Burn Hospital of Ahvaz. Antibiotic susceptibility testing was conducted by disk diffusion method according to the CLSI 2017 recommendations. PCR assay was performed by to find beta-lactamase encoding genes. Results: In this study, most clinical specimen was obtained via wound swabs [65 (69.9%)], followed by blood [14 (15.1%)] and biopsy [7 (7.5%)]. Forty-two (45.16%) patients were male and 51(54.84%) were female. High resistance was observed for most of antibiotics especially for gentamicin and ciprofloxacin (Up to 85%), whereas the highest susceptibility was reported for colistin (100.0%), followed by ceftazidime (66.7%). According to PCR results, 16.1% (15), 9.7% (9) and 14.0% (13) of isolates carried blaDHA, blaVEB and blaGES genes, respectively. It also revealed that the blaYEB gene was found to coexist within 2 isolates (2.2%). Conclusions: Antibacterial resistance is high among P. aeruginosa isolates. Colistin is highly active against multi-drug resistant P. aeruginosa isolates. Antimicrobial susceptibility testing can confine indiscriminate uses of antibiotics and resistance increase, and can improve management of treatment....

The management of multidrug-resistant (MDR) and extensively drug-resistant tuberculosis (XDR-TB) presents a main challenge and the drug options for treating these infections are very limited. Linezolid (LNZ) has recently been approved for the treatment of MDR and XDR-TB. But, there are narrow data on genotypic and phenotypic LNZ resistance in clinical isolates. So, we aimed to determine the prevalence of LNZ resistance and to identify the mutations associated with LNZ resistance among clinical MDR-TB isolates. The minimum inhibitory concentration (MIC) values of LNZ for 22 MDR-TB isolates were determined by broth microdilution method. All MDR-TB isolates were sequenced in the rrl and rplC genes conferring LNZ resistance. LNZ resistance was found in 3 (13.6%) of 22 MDR-TB isolates. The MICs of LNZ were 8 μg/mL for two isolates and 16 μg/mL for one isolate. The 421 (A/G) and 449 (T/A) mutations in rplC gene were detected in one of the LNZ-resistant isolates. There was no mutation in rrl gene. The results reveal that the prevalence of LNZ-resistant isolates is 13.6% among MDR-TB isolates and drug susceptibility testing (DST) against LNZ is useful in the management of complicated and drug-resistant cases. However, further studies could identify other possible genetic mechanism of resistance in TB.

Objective: To investigate the pattern of antibiotic resistance and biofilm production capabilities of clinical Acinetobacter baumannii (A. baumannii) isolates in this study. Methods: A. baumannii isolates were collected from Tehran Imam Khomeini Hospital in this cross-sectional study, and the minimum inhibitory concentrations for 16 antibiotics were determined using Vitek2^® systems. All isolates were analyzed for biofilm production, then presence of biofilm-associated genes, and class I and II integron genes. Results: 60 non-replicate A. baumannii isolates were included in this study. The resistance rates reached 100% for aztreonam, cefepime, ceftazidime, ciprofloxacin, piperacillin-tazobactam, piperacillin, ticarcillin, and trimethoprim-sulfamethoxazole. A. baumannii isolates were most sensitive to colistin and rifampicin being the most effective treatments. Multi-drug resistant and extensively drug-resistant isolates accounted for 83.3% and 16.7%, respectively. Of the isolates, 91.6% formed biofilms, categorized as 10% strong, 31.6% moderate, and 50% weak. No correlation was found between antibiotic resistance and biofilm formation. The genes csuE, abaI, and ompA were prevalent, but their distribution was similar across biofilm categories. A relationship between Int1 and biofilm production was noted. Conclusions: The high rates of antibiotic resistance and biofilm formation, alongside the presence of integrons including class I and II, underscore the necessity for ongoing monitoring of A. baumannii. Notably, class I integron presence was significantly linked to biofilm formation. Further research is needed to explore the connection between antibiotic resistance and biofilm production in A. baumannii.