The human pathogenic vibrios – A public health update with environmental perspectives

Abstract

Pathogenic Vibrio species are naturally-occurring bacteria in freshwater and saline aquatic environments. Counts of free-living bacteria in water are generally less than required to induce disease. Increases in number of organisms towards an infective dose can occur as water temperatures rise seasonally followed by growth and concentration of bacteria on higher animals, such as chitinous plankton, or accumulation by shellfish and seafood. Pathogenic Vibrio species must elaborate a series of virulence factors to elicit disease in humans. Activities which predispose diarrhoeal and extraintestinal infections include ingestion of seafood and shellfish and occupational or recreational exposure to natural aquatic environments, especially those above 20 degrees C. Travel to areas endemic for diseases due to pathogenic Vibrio species may be associated with infections. Host risk factors strongly associated with infections are lack of gastric acid and liver disorders. Involvement of pathogenic Vibrio species in cases of diarrhoea should be suspected especially if infection is associated with ingestion of seafood or shellfish, raw or undercooked, in the previous 72 h. Vibrio species should be suspected in any acute infection associated with wounds sustained or exposed in the marine or estuarine environment. Laboratories serving coastal areas where infection due to pathogenic Vibrio species are most likely to occur should consider routine use of TCBS agar and other detection regimens for culture of Vibrio species from faeces, blood and samples from wound and ear infections.

Analysis of some virulence factors ofVibrio vulnificusisolated from Rio de Janeiro, Brazil

“…The evaluations carried out by West [1] indicated that strains of V. vulnificus are more resistant to lysis by complement than are V. parahaemolyticus and V. cholerae, and that during invasion it can activate both the classic and alternate pathways [2].…”

“…Vibrio vulnificus is the most invasive species of the genus Vibrio, with three different clinical syndromes [1]. The first involves progressive infection with a few diarrhoeal symptoms and is characterized by a rapid outset of fulminating septicaemia followed by the appearance of cutaneous lesions with 50 % mortality.…”

“…Patients with hepatic dysfunctions or other syndromes involving iron metabolism appear to be most susceptible to this type of infection [2]. The second, represented by cellulitis, results from the direct contact of wounds or skin lesions with sea ecosystem constituents in both apparently healthy and debilitated patients, and sometimes progresses into septicaemia [1,3]. The third form, seldom found, causes acute self-limited diarrhoea with a low mortality rate [4].…”

“…Other factors have also been reported including the presence of some siderophore-like proteins in the membrane [6], the production of enzymes that damage the surrounding tissues [7,8], and various toxins acting like invasive factors in acute infections [1,3]. An interesting point is that some factors were detected in environmental strains as well as in strains of human origin [9].…”

Isolation and preliminary characterization of bacteriocins produced by Vibrio vulnificus

“…However, gamma radiation kills the treated oysters, which reduces their shelf life (Dixon and Rodrick 1990). Heat may eliminate V. vulnificus (West 1989), but Lowry et al (1989) reported that 67% of raw oysters and 25% of steamed oysters sampled from 18 downtown New Orleans (USA) restaurants contained V. vulnificus. Cold temperatures have also been suggested; however, Hood et al (1983) reported that levels of V. vulnificus increased slightly in oyster shellstock and shucked meat after 7 d at 4°C.…”