Vibrio, a gram negative bacterium consists of more than 70 species of which many are pathogenic. The pathogenic strains are usually associated with gastroenteritis and also infect open wounds that further leads to septicemia. The most important pathogenic vibrio species include V. cholerae, V. parahaemolyticus, V. vulnificus, V. fluvialis and V. mimicus. Cholera is an acute diarrheal illness caused by V. cholerae infecting the small intestine. According to Centers for Disease Control and Prevention (CDC), an estimated 3-5 million cases and over 100,000 deaths occur each year around the world due to cholera. Approximately one in 10 infected person will have profuse diarrhea and other characteristic symptoms (1).
Saltwater bodies and marine habitats serve as the natural reservoirs for these microorganisms as they prefer halophilic environment but they can be also found in freshwater (2). Thus, most of the vibrio infections are related to consumption of contaminated water and uncooked seafood (3). Many studies have revealed that there is association of these vibrios, especially Vibrio parahaemolyticus with many seafoods such as shrimps, crabs, fishes, molluscs etc (4). Consumption of these contaminated seafoods causes severe gastroenteritis in human beings and other animals. V. parahaemolyticus can also be associated with wound infections and septicemia. V. vulnificus is also present in marine environment, estuaries and brackish ponds. Infection by V. vilnificus leads to rapidly expanding cellulitis or septicemia. The microorganism enters the body through wounds and by eating undercooked or raw oysters. The bacteria spread into the bloodstream of people with compromised immune system and cause severe symptoms including blisters, skin lesions, septic shock and even death (5). Though hospitalization and deaths due to V. vulnificus infections are not very common in India, the incidence of V.vulnificus infections has increased tremendously in US and gulf countries. The same is the case with V. mimicus and V. fluvialis. V.mimicus is a non halophilic vibrio which causes sporadic episodes of gastroenteritis and ear infections whereas V. fluvialis is halophilic and causes symptoms similar to that of cholera. The symptoms include diarrhea, vomiting, abdominal pain, dehydration and fever. V.fluvialis also rarely causes wound infections and septicemia. In most cases the infections caused by vibrio can be prevented by proper sanitation and appropriate treatment. The commonly used drugs against non-cholera vibrio infections other gastroenteritis include combination of ceftazidime and doxycycline (6). Other alternative antibiotics include cefotaxime and/or fluoroquinolones. For diarrhea and gastroenteritis, additional oral replacement therapy or intravenous fluid replacement therapy is important to prevent rehydration (7).
Though there are this many antibiotic drugs against vibrio, reports of antibiotic resistance is increasing day by day. Resistance to tetracycline and other antimicrobial agents among V. cholerae has been demonstrated in both in vitro and in vivo experiments. Resistance can be acquired through the accumulation of selected mutations over time, or the acquisition of genetic elements such as plasmids. A likely risk factor for antimicrobial resistance is widespread use of antibiotics (8). Antibiotic resistance by bacteria can also be via structural mechanisms such as biofilm formation and drug …
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