Analysis of Clonal Relationships among Shigella spp. Isolated from Children with Shigellosis in Ahvaz, Iran

Shigellosis is one of the important gastrointestinal bacterial infections, particularly among children of developing countries such as Iran. Antibiotic susceptibility pattern and genetic typing for epidemiological purposes are of significant issues in Shigella infectious control. The aim of this study was to investigate the antibiotic susceptibility and genetic relationship among Shigella strains isolated from children with shigellosis at paediatric hospital in Ahvaz, south west of Iran. This study included all Shigella strains isolated from paediatric patients with diarrhea admitted to Abuzar pediatric hospitals in Ahvaz, during January-June 2015. Shigella isolates were identified using standard microbiological and serological methods. Shigella spp strains also were studied by antimicrobial susceptibility testing and Enterobacterial Repetitive Intergenic Consensus (ERIC) - PCR analysis. Total of 50 Shigella strains were isolated from children with dysentery diarrhea. In total, 31 (62%) were identified as Shigella flexneri, 16(32%) and 3 (6%) were Shigella sonnei and Shigella boydii respectively. High level resistance were detected against ampicillin, trimethoprim-sulfamethoxazole and cephalotine. All isolates were sensitive to ceftriaxone, imipenem gentamicin and amikacin. The results of ERIC-PCR data analysis showed 11 different types of Shigella with four closely-related patterns. S. flexneri was the predominant serogroup of Shigella spp. in children in the referral pediatric hospital in Ahvaz. Ampicillin and trimethoprim-sulfamethoxazole is no longer recommended for shigellosis empirical treatment and should be replaced by other antibiotics such as ceftriaxone or ciprofloxcacin. Diverse but genetically close strains of shigella were responsible for shigellosis in paediatric patients in Ahvaz, south west of Iran.

Multilocus Sequence Typing of the Clinical Isolates of Salmonella Enterica Serovar Typhimurium in Tehran Hospitals

Background: Salmonella enterica serovar Typhimurium is one of the most important serovars of Salmonella enterica and is associated with human salmonellosis worldwide. Many epidemiological studies have focused on the characteristics of Salmonella Typhimurium in many countries as well as in Asia. This study was conducted to investigate the genetic characteristics of Salmonella Typhimurium using multilocus sequence typing (MLST). Methods: Clinical samples (urine, blood, and stool) were collected from patients, who were admitted to 2 hospitals in Tehran between April and September, 2015. Salmonella Typhimurium strains were identified by conventional standard biochemical and serological testing. The antibiotic susceptibility patterns of the Salmonella Typhimurium isolates against 16 antibiotics was determined using the disk diffusion assay. The clonal relationship between the strains of Salmonella Typhimurium was analyzed using MLST. Results: Among the 68 Salmonella isolates, 31% (n=21) were Salmonella Typhimurium. Of the total 21 Salmonella Typhimurium isolates, 76% (n=16) were multidrug-resistant and showed resistance to 3 or more antibiotic families. The Salmonella Typhimurium isolates were assigned to 2 sequence types: ST19 and ST328. ST19 was more common (86%). Both sequence types were further assigned to 1 eBURST group. Conclusion: This is the first study of its kind in Iran to determine the sequence types of the clinical isolates of Salmonella Typhimurium in Tehran hospitals using MLST. ST19 was detected as the major sequence type of Salmonella Typhimurium

Antibacterial and Drug Synergistic Activities of Mentha longifolia Essential Oil Against Shigella flexneri and Shigella sonnei

Background: Microbial infections such as shigellosis are one of the major health challenges in Iran, especially in Khuzestan province in the south west of Iran. Objective: According to the importance of medicinal plants in the treatment of many infectious diseases, and as a valuable alternative for antibiotics, the aim of this research was to assess the antibacterial and drug synergistic activities of the essential oil from Mentha longifolia, a local plant, against Shigella flexneri and Shigella sonnei as the main causes of shigellosis. Materials and Methods: The M. longifolia essential oil was extracted from the leaves. The antibacterial activities of the essential oil against clinical and standard S. flexneri and S. sonnei strains were detected by the disk diffusion and micro-broth dilution methods. Results: The essential oil of M. longifolia had the most significant antibacterial activity against the clinical strain of S. flexneri. Minimum inhibitory concentration (MIC) of 1024 with a concentration of 0.8 mg/mL of essential oil was detected in both the standard and clinical S. flexneri and S. sonnei strains. The essential oil of M. longifolia showed the highest synergistic effect on gentamicin and ampicillin in the clinical isolates of S. flexneri. Conclusion: The results of this study showed that the essential oil of M. longifolia alone or in combination with antimicrobial agents may be useful in the treatment of bacterial infections. In addition, M. longifolia may increase the effect of antibiotics and resolve other antibiotic resistance problems

Molecular analysis of Pseudomonas aeruginosa isolated from clinical, environmental and cockroach sources by ERIC-PCR

Abstract Objective The objective of this study was to investigate the antibiotic susceptibility, virulence factors and clonal relationship among Pseudomonas aeruginosa isolated from environmental sources, hospitalized patients and the surfaces of cockroaches in the ICUs of four hospitals in Hamadan, west of Iran. A total of 237, 286 and 156 bacterial isolates were collected from clinical, environmental and cockroach sources respectively from May to September, 2017. The antimicrobial susceptibility was determined using disk diffusion method. The virulence factors, exotoxins A, S and U were detected by PCR. The genetic linkage of P. aeruginosa isolates were analyzed by Enterobacterial Repetitive Intergenic Consensus (ERIC)-PCR. Results According to our findings, 58 (24.4%), 46 (16%) and 5 (3.25) P. aeruginosa were isolated from clinical, environmental and cockroach samples respectively. The MDR phenotypes were detected in 18 (45%) and 15 (37.5%) of clinical and environmental strains. The environmental isolates harbored more exoA and exoS than did clinical isolates. Genetic diversity was established among P. aeruginosa isolates as 14 different ERIC fingerprints were detected. The clonal relationships was detected among clinical, environmental and cockroach isolates. Our results highlighted the importance of identifying and controlling the potential sources of P. aeruginosa infections in hospitals

Survey of Antibiotic Resistance and Relationship Between Eesterase (estA) Gene with Biofilm Formation in Pseudomonas Aeruginosa Strains Isolated from Burn Patients

Background & Objective: Pseudomonas aeruginosa is known as a major cause of hospital-acquired infections due to its high antibiotic resistance. Biofilm formation is an important virulence factor in P. aeruginosa infections. This pathogen produces extracellular hydrolases such as esterase estA during biofilm formation which can influence the formation and construction of biofilm. The purpose of this study was to detect the antibiotic resistance and distribution of estA gene among biofilm-producing P. aeruginosa strains isolated from burn patients. Materials & Methods: A total of 37 strains of P. aeruginosa were isolated from burn patients in Taleghani hospital in Ahvaz city and identified using standard bacteriological procedures. Antibiotic susceptibility test was performed by disk diffusion method according to the CLSI 2015. Biofilm formation was measured by micro titer plate. Existence of estA gene was detected by PCR. Results: The estA gene existed in 97.3% of isolates and 78.3% of P. aeruginosa isolates produced biofilm. Based on the results of the antibiogram test, highest rate of resistance was observed to piperacillin/ tazobactam (92%) and least resistance was to colistin (8%). Conclusion: According to the results, there was no significant correlations between presence of estA gene and biofilm formation. High level of resistance to antibiotics in P. aeruginosa is considerable

Genotyping and distribution of putative virulence factors and antibiotic resistance genes of Acinetobacter baumannii strains isolated from raw meat

Abstract Background Acinetobacter baumannii strains with multiple antimicrobial resistance are primarily known as opportunistic nosocomial bacteria but they may also be regarded as emerging bacterial contaminants of food samples of animal origin. Here we aimed to study the molecular characteristics of the A. baumanni strains isolated from raw meat samples. Methods A total of 22 A. baumanni strains were isolated from 126 animal meat samples and were genotyped by ERIC-PCR method and by PCR detection of their virulence and antimicrobial resistance determinants. A. baumannii strains with 80% and more similarities were considered as one cluster. Results Sixteen different genetic clusters were found amongst the 22 A. baumanni strains. Of the 22 strains, 12 (54.54%) had similar genetic cluster. A. baumannii strains exhibited the highest percentage of resistance against tetracycline (90.90%), trimethoprim (59.09%), cotrimoxazole (54.54%) and gentamicin (50.00%). TetA (81.81%), tetB (72.72%), dfrA1 (63.63%), aac(3)-IV (63.63%), sul1 (63.63%) and aadA1 (45.45%) were the most commonly detected antibiotic resistance genes. FimH (81.81%), afa/draBC (63.63%), csgA (63.63%), cnf1 (59.09%), cnf2 (54.54%) and iutA (50.00%) were the most commonly detected virulence factors. A. baumannii strains isolated from the chicken meat samples had the highest similarities in the genetic cluster. Conclusions A. baumannii strains with similar genetic cluster (ERIC-Type) had the same prevalence of antibiotic resistance, antibiotic resistance genes and virulence factors. Genetic cluster of the A. baumannii strains is the main factor affected the similarities in the genotypic and phenotypic properties of the A. baumannii strains

Evaluation of antibiotic resistance, toxin-antitoxin systems, virulence factors, biofilm-forming strength and genetic linkage of Escherichia coli strains isolated from bloodstream infections of leukemia patients

Abstract Background One of the most common complications in patients with febrile neutropenia, lymphoma, leukemia, and multiple myeloma is a bloodstream infection (BSI). Objective This study aimed to evaluate the antibiotic resistance patterns, virulence factors, biofilm-forming strength, and genetic linkage of Escherichia coli strains isolated from bloodstream infections (BSIs) of leukemia patients. Methods The study conducted in Iran from June 2021 to December 2022, isolated 67 E. coli strains from leukemia patients’ bloodstream infections in hospitals in two different areas. Several techniques including disk diffusion and broth microdilution were used to identify patterns of antibiotic resistance, microtiter plate assay to measure biofilm formation, and PCR to evaluate the prevalence of different genes such as virulence factors, toxin-antitoxin systems, resistance to β-lactams and fluoroquinolone antibiotics of E. coli strains. Additionally, the genetic linkage of the isolates was analyzed using the Enterobacterial Repeat Intergenic Consensus Polymerase Chain Reaction (ERIC-PCR) method. Results The results showed that higher frequency of BSI caused by E. coli in man than female patients, and patients with acute leukemia had a higher frequency of BSI. Ampicillin and Amoxicillin-clavulanic acid showed the highest resistance, while Imipenem was identified as a suitable antibiotic for treating BSIs by E. coli. Multidrug-resistant (MDR) phenotypes were present in 22% of the isolates, while 53% of the isolates were ESBL-producing with the blaCTX-M gene as the most frequent β-lactamase gene. The fluoroquinolone resistance genes qnrB and qnrS were present in 50% and 28% of the isolates, respectively. More than 80% of the isolates showed the ability to form biofilms. The traT gene was more frequent than other virulence genes. The toxin-antitoxin system genes (mazF, ccdAB, and relB) showed a comparable frequency. The genetic diversity was detected in E. coli isolates. Conclusion Our results demonstrate that highly diverse, resistant and pathogenic E. coli clones are circulating among leukemia patients in Iranian hospitals. More attention should be paid to the treatment and management of E. coli bloodstream infections in patients with leukemia

Genotyping of clinical and environmental multidrug resistant Enterococcus faecium strains

Context: Multidrug resistant (MDR) Enterococcus faecium is a nosocomial pathogen and clonal complex 17 (CC17) is the main genetic subpopulation of E. faecium in hospitals worldwide. Aims: There has thus far been no report of major E. faecium clones in Iranian hospitals. Subjects and Methods: The present study analyzed strains of MDR E. faecium obtained from patients and the Intensive Care Unit environments using pulsed field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) to determine the antibiotic resistance patterns and genetic features of the dominant. Results: clones of E. faecium. PFGE and MLST analysis revealed the presence of 17and 15 different subtypes, respectively. Of these, 18 (86%) isolates belonged toCC17. Most strains in this clonal complex harbored the esp gene and exhibited resistance to vancomycin, teicoplanin, ampicillin, ciprofloxacin, gentamicin, and erythromycin. The MLST results revealed 12 new sequence types (ST) for the first time. Approximately 50% of the STs were associated with ST203. Conclusion: Detection of E. faecium strains belonging to CC17 on medical equipment and in clinical specimens verified the circulation of high-risk MDR clones among the patients and in hospital environments in Iran

Antimicrobial resistance patterns and virulence factors of enterococci isolates in hospitalized burn patients

Abstract Objective The objective of this study was to determine the frequency of the antimicrobial resistance and genes encoding virulence factors of enterococci isolated in hospitalized burn patients in a major burn center in Ahvaz, southwest of Iran. A total of 340 bacterial isolates were collected from the burn center from February 2014 to February 2015. The antimicrobial susceptibility and MIC of vancomycin were determined using the disk diffusion and micro-agar dilution techniques. The genus and species-specific genes, potential virulence genes, and vanA and vanB genes were detected by polymerase chain reaction. Results According to our results, out of the 340 bacterial isolates, 16.4% (n = 56) were identified as enterococci. Out of the 56 enterococcal isolates, 35 (62.5%) were Enterococcus faecalis and 21 (37.5%) were Enterococcus faecium. More than 20% (n = 5) of E. faecium demonstrated resistance to vancomycin. The gelE and asa genes were the most prevalent virulence genes in E. faecalis (48.5%) and E. faecium (43%) isolates. The emergence of vancomycin resistant E. faecium strains which have several virulence factors should be considered as a major cause of concern for burn centers. Control and management of infections induced by enterococci should be regarded as highly important in burn patients