Mixed infections of Vibrio cholerae O1 Ogawa EL Tor with Shigella dysenteriae

Indole intercepts the communication between enteropathogenic E. coli and Vibrio cholerae

Reported numbers of diarrheal samples exhibiting co-infections or multiple infections, with two or more infectious agents, are rising, likely due to advances in bacterial diagnostic techniques. Bacterial species detected in these samples include Vibrio cholerae (V. cholerae) and enteropathogenic Escherichia coli (EPEC), which infect the small intestine and are associated with high mortality rates. It has previously been reported that EPEC exhibit enhanced virulence in the presence of V. cholerae owing to their ability to sense and respond to elevated concentrations of cholera autoinducer 1 (CAI-1), which is the primary quorum-sensing (QS) molecule produced by V. cholerae. In this study, we examined this interspecies bacterial communication in the presence of indole, a major microbiome-derived metabolite found at high concentrations in the human gut. Interestingly, we discovered that although indole did not affect bacterial growth or CAI-1 production, it impaired the ability of EPEC to enhance its virulence activity in response to the presence of V. cholerae. Furthermore, the co-culture of EPEC and V. cholerae in the presence of B. thetaiotaomicron, an indole-producing commensal bacteria, ablated the enhancement of EPEC virulence. Together, these results suggest that microbiome compositions or diets that influence indole gut concentrations may differentially impact the virulence of pathogens and their ability to sense and respond to competing bacteria.

Increasing antimicrobial resistance among Shigella isolates in the Bushehr, Iran

Antibiotics are drugs used for treatment of infections caused by bacteria. Misuse and overuse of these drugs have contributed to phenomena known as antibiotic resistance. In this research, the antimicrobial resistance of the Shigella has been determined. This descriptive research analyzed registered laboratory data of patients referred to Fatemeh Zahra Hospital of the Bushehr, Iran. Shigella was isolated from their cultured sample from the year 2002-2008. In this study, the total of 121 registered Shigella collected from 2002-2008 were analyzed. There were 62 cases of S. sonnei, 46 cases of S. flexneri, eight cases of S. boydii and five cases of S. dysenteriae among them. Furthermore, two cases of Shigella sonnei were collected from the blood and the rest from the watery stools of the infected patients. The following is the resistance pattern of these organisms; to ciprofloxacin, 4.25%; ceftizoxime, 8.62%; nalidixic acid, 12.12%; co-trimoxazole, 86.13% and to tetracycline, 93.02%. Results ofantibiogram showed that highest rate of drug resistance belongs to tetracycline and co-trimoxazole and the lowest belongs to ciprofloxacin and ceftizoxime. One of the important issue for clinicians, now a day is drug resistance of microorganisms. This phenomenon is increasing due to some factors such as improper use of antibiotics and irrational prescribing. These factors lead to development of new drug resistant species.