Pathogenic Vibrio species isolated from estuarine environments (Ceará, Brazil) - antimicrobial resistance and virulence potential profiles

ABSTRACT Detection of virulent strains associated with aquatic environment is a current concern for the management and control of human and animal health. Thus, Vibrio diversity was investigated in four estuaries from state of Ceará (Pacoti, Choró, Pirangi and Jaguaribe) followed by antimicrobial susceptibility to different antimicrobials used in aquaculture and detection of main virulence factors to human health. Isolation and identification were performed on TCBS agar (selective medium) and dichotomous key based on biochemical characteristics, respectively. Nineteen strains of genus Vibrio were catalogued. Vibrio parahaemolyticus (Choró River) and V. alginolyticus (Pacoti River) were the most abundant species in the four estuaries. All strains were submitted to disk diffusion technique (15 antimicrobials were tested). Resistance was found to: penicillin (82%), ampicillin (54%), cephalotin (7%), aztreonan (1%), gentamicin, cefotaxime and ceftriaxone (0.5%). Five pathogenic strains were chosen to verification of virulence factors. Four estuaries showed a high abundance of species. High number of tested positive strains for virulence is concerning, since some of those strains are associated to human diseases, while others are known pathogens of aquatic organisms.

[Antibacterial activity of essential oils from Artemisia and Cumin plants against Staphylococcus aureus, Escherichia coli and Vibrio cholera]

The emergence of resistance among bacteria makes it necessary to continuously quest for new antimicrobial agents. The present study was performed to evaluate the antibacterial activity of essential oils from Artemisia and Cumin plants. This was an experimental study carried out at the School of Medicine of Tarbiat Modares University [Tehran, Iran] in 2005. Essential oils of Cuminum cyminum, Bunium persicum seeds and aerial parts of Artemisia turcomanica were prepared by hydrodistillation method. Essential oils of A. khorassanica, A. ciniformis, and A. kopetdaghensis were previously obtained and described. The activities of essential oils were evaluated against a clinical isolate of Vibrio cholerae [isolated during the recent outbreak of cholera in Iran], Escherichia coli ATCC25922, a clinical isolate of Staphylococcus aureus, and Staphylococcus aureus ATCC25923 using disc diffusion assay and broth microdilution method for determination of MIC. The components of oils were identified by Gas chromatography coupled with mass spectrometry. Essential oils showed an acceptable level of antibacterial activities. A. khorassanica and A. turcomanica oils demonstrated the highest activity [inhibition zone: 60 mm] followed by A. ciniformis, A. kopetdaghensis, C. cyminum, and B. persicum, respectively. The major constituent in A. turcomanica oil was camphor and that of Cuminum cyminum and Bunium persicum oils was cuminaldehyde. The results of the present study suggested the effects of essential oils against the tested bacteria in vitro, may contribute to the in vivo efficacy of these oils

Hormesis response of marine and freshwater luminescent bacteria to metal exposure

The stimulatory effect of low concentrations of toxic chemicals on organismal metabolism, referred to as hormesis, has been found to be common in the widely used luminescence bioassay. This paper aims to study the hormesis phenomenon in both marine and freshwater luminescent bacteria, named Photobacterium phosphorem and Vibrio qinghaiensis. The effects of Cu (II), Zn (II), Cd (II) and Cr (VI) on luminescence of these two bacteria were studied for 0 to 75 minutes exposure by establishing dose- and time-response curves. A clear hormesis phenomenon was observed in all four testing metals at low concentrations under the condition of luminescence assays.

Antibiogram of Vibrio species isolated from diseased Penaeus monodon [Fab]

Various antibiotics belonging to beta lactum, Rifampicin, Tetracycline, Quinolone, Aminoglycoside and synthetic groups were selected against vibrio species viz. V.fluvialis, V. furnissi, and V. splendidus, isolated from the diseased Penaeus monodon. The study revealed that among 15 antibiotics used, 12 showed sensitivity against V. fluvialis. In Vibrio furnissi among 16 antibiotics tested, 11 showed sensitivity, among 21 antibiotics tested, against V. splendidus, showed sensitivity against 14 antibiotics. Various antibiotics tested, ciprofloxacin was found to be more effective against all the test organisms

Toxigenicity & drug sensitivity of Vibrio mimicus isolated from patients with diarrhoea.

In a total of 720 faecal specimens from patients with secretory diarrhoea, vomiting, dehydration, gastroenteritis, cholera and cholera like illnesses, 18 strains of V. mimicus were isolated as pure culture. These were characterized for various toxin types and virulence factors using conventional in vitro and in vivo assays. Labile and stable toxins were elaborated by 15 and 2 strains respectively by ligated rabbit ileal loop (RIL) and suckling mouse assays. While 15 of the whole cell culture elaborated labile toxin, only 7 strains produced the same when culture filtrate was tested in RIL assay. Culture filtrates of 15 strains exhibited vascular permeability factor (PF) on adult rabbit skin, none of the strains were invasive as indicated by Sereny's test. Culture supernatants of all strains produced a cytotoxic factor to Vero and Chinese hamster ovary cells. Four of the 18 strains (22%) were resistant to multiple drugs (a combination of 3 or more drugs). The results emphasize the significance of continuous screening and identification of V. mimicus and to include in the differential diagnosis of patients with acute diarrhoea.

Role of iron in the virulence of Vibrio vulnificus isolated from Cuddalore coastal waters (India).

V. vulnificus strains isolated from different sources of Cuddalore coastal waters were tested for their virulence activity through their LD50 values in mice. As infections of V. vulnificus have been correlated with pre-existing liver disease and hemochromatosis, the role of iron on virulence was determined using. iron overloaded mice. The LD50 was in the range of 10(4)-10(7) cells in normal mice but 10(1)-10(2) cells in iron-injected mice, thus providing evidence that iron may play a major role in the pathogenesis of V. vulnificus.