Escherichia coli are remarkably versatile microorganisms and important members of the normal intestinal microbiota of humans and animals. This harmless commensal organism can acquire a mixture of comprehensive mobile genetic elements that contain genes encoding virulence factors, becoming an emerging human pathogen capable of causing a broad spectrum of intestinal and extraintestinal diseases. Nine definite enteric E. coli pathotypes have been well characterized, causing diseases ranging from various gastrointestinal disorders to urinary tract infections. These pathotypes employ many virulence factors and effectors subverting the functions of host cells to mediate their virulence and pathogenesis. This review summarizes new developments in our understanding of diverse virulence factors associated with encoding genes used by different pathotypes of enteric pathogenic E. coli to cause intestinal and extraintestinal diseases in humans.

Escherichia coli are remarkably versatile microorganisms and important members of the normal intestinal microbiota of humans and animals. This harmless commensal organism can acquire a mixture of comprehensive mobile genetic elements that contain genes encoding viru-lence factors, becoming an emerging human pathogen capable of causing a broad spectrum of intestinal and extraintestinal diseases. Nine definite enteric E. coli pathotypes have been well characterized, causing diseases ranging from various gastrointestinal disorders to urinary tract infections. These pathotypes employ many virulence factors and effectors subverting the func-tions of host cells to mediate its virulence and pathogenesis. This review summarizes new de-velopments in our understanding of diverse virulence factors associated encoding genes used by different pathotypes of enteric pathogenic E. coli to cause intestinal and extraintestinal diseases in humans.

Shigella species are the main cause of bacillary diarrhoea or shigellosis in humans. These organisms are the inhabitants of the human intestinal tract; however, they are one of the main concerns in public health in both developed and developing countries. In this study, we reviewed and summarised the previous studies and recent advances in molecular mechanisms of pathogenesis of Shigella Dysenteriae and non-Dysenteriae species. Regarding the molecular mechanisms of pathogenesis and the presence of virulence factor encoding genes in Shigella strains, species of this bacteria are categorised into Dysenteriae and non-Dysenteriae clinical groups. Shigella species uses attachment, invasion, intracellular motility, toxin secretion and host cell interruption mechanisms, causing mild diarrhoea, haemorrhagic colitis and haemolytic uremic syndrome diseases in humans through the expression of effector delivery systems, protein effectors, toxins, host cell immune system evasion and iron uptake genes. The investigation of these genes and molecular mechanisms can help us to develop and design new methods to detect and differentiate these organisms in food and clinical samples and determine appropriate strategies to prevent and treat the intestinal and extraintestinal infections caused by these enteric pathogens.

Background: Cronobacter sakazakii is a new emerging foodborne bacterial pathogen associated with severe lethal diseases such as meningitis, necrotizing enterocolitis, and septicemia in infants and neonates. Powdered infant formula milk (PIFM) has been recognized as one of the main transmission vehicles and contaminated sources of this pathogen. This study aimed to investigate the prevalence rate, genotypic and phenotypic antibiotic resistance profile, and clonal relatedness of C. sakazakii strains isolated from 364 PIFM samples collected from Tehran city, Iran. Methods: Culture-based methods, Kirby–Bauer disk diffusion antibiotic resistance testing, conventional Polymerase Chain Reaction (PCR), and Enterobacterial Repetitive Intergenic Consensus PCR (ERIC-PCR) assays were used in this study to detect and characterize the C. sakazakii isolates. Results: We isolated 25 C. sakazakii strains from PIFM samples (6.86%). The isolates were highly resistant to amoxicillin-clavulanic acid, amoxicillin, ampicillin, cefoxitin, cefepime, erythromycin, ceftriaxone, ciprofloxacin, and chloramphenicol and susceptible to gentamicin, tetracycline, norfloxacin, and azithromycin antibiotics. The blaCTX-M-1 gene was detected in 96% of the isolates. The isolates were categorized into eight distinct clonal types using the ERIC-PCR method, showing a high genetic diversity among the isolates. However, there was a significant correlation between the genotypic and phenotypic antibiotic resistance properties of the isolates. Conclusions: Novel microbial surveillance systems for detecting multi-drug-resistant C. sakazakii are required to control the contamination of this foodborne pathogen in infant foods.

Lymphocyte proliferation assays are widely used to assess the cell-mediated immunity. Current in vitro testing methods that are being used have extensive applications but still more problematic, due to the technical complexity and the needs for specialized equipment and reagents. Electrochemical methods such as cyclic voltammetry represent a very promising tool for the development of label-free in vitro assays of cell proliferation and viability. Here, a novel procedure based on voltammetric behaviours of proliferating cells was fabricated. Results indicated that proliferation in cell cultures and whole blood can be monitored electrochemically using cyclic voltammetry. In the comparison with colorimetric (MTT) assay, cyclic voltammetry gave the best correlation with cell count data over a range of 1200–300,000 cells/well of a microplate. Besides the advantages of short assay duration (4 hours) and the rapidness, the possibility use of fresh blood without further processing, would give more accurate results because cells are monitoring in an intact environment. Cyclic voltammetry assay is an efficient analytical method, which can provide a simple platform for the electrochemical study of lymphocyte proliferation.

Background: Clostridium perfringens is one of the highest prevailing spore-forming foodborne pathogens, which is widely distributed and causes severe disease and outbreaks in humans and animals. Raw meat and poultry are the main vehicles of this pathogen. In this study, we investigated the prevalence, antibiotic resistance pattern, toxin-encoding genes and genetic diversity of C. perfringens isolates from raw whole and minced meat samples purchased from local markets in Qazvin city, Iran (the source of beef cattle production was also located in Qazvin city, Iran). Methods: We used conventional culture-based and Kirby–Bauer disk diffusion and conventional and arbitrary primer PCR methods. Results: A total of 18 C. perfringens strains were isolated from 133 raw meat samples (13.53%). Up to 44.4 and 55.5% of these isolates were detected in raw minced and whole meat samples, respectively. We found that 72.2, 66.6, 61.1, 37.8 and 33.3% of the C. perfringens isolates were resistant to ampicillin, tetracycline, amoxicillin, ciprofloxacin and chloramphenicol antibiotics, respectively. Multidrug resistance was found in 38% of the isolates. Among the four main toxin genes evaluated, the Cpa gene was detected in all isolates, and 61.1% of the isolates were mostly recognized as type A C. perfringens. High levels of genetic diversity were observed among the isolates, and they were classified into five distinct groups. Conclusions: The isolates from whole meat samples were more resistant to antibiotics. However, toxin genes were more detected in the isolates from minced meat samples. Our findings suggest that contamination of raw meat products with multidrug resistant C. perfringens could be regarded as one of the concerning pathogens in these products. Comprehensive monitoring of C. perfringens isolates is strongly recommended.