PhD Student, University of Fort Hare
This aimed to reveal level of contamination using Vibrio sp as a biomarker and choice of antibiotics
Vibrio infections remain a serious threat to public health. In the last decade, Vibrio disease outbreaks have created a painful awareness of the personal, economic, societal, and public health costs associated with the impact of contaminated water in freshwater resources. We assessed the prevalence of Vibrio species in Great Fish River using standard culture-based and molecular techniques, as well as some selected environmental parameters. Parameters measured includes: pH, temperature, salinity, turbidity, dissolved oxygen (DO) and biological oxygen demand (BOD). The physicochemical qualities ranged as follows: pH (7.5-8.6), temperature (20-26 ºC), salinity (0.13 - 0.60), turbidity (300 – 766 NTU) and dissolved oxygen (6.0- 7.94 mg/L). Statistical analysis showed that pH, temperature, salinity, turbidity, dissolved oxygen were significantly different (P < 0.05). Total Vibrio counts ranged from 0 to 1.1 x102 cfu/ml , 0 to 12.2 x103 cfu/ml, 0 to 14.10 x103 cfu/ml and 0 to 14.4 x103 cfu/ml for point one (P1), Point two (P2), Point three (P3) and Point four (P4) respectively. Molecular confirmation of the presumptive Vibrio species revealed V. cholerae (29%) as predominant species, followed by V. fluvialis (17%), V. vulnificus (10%), and the least was V. parahaemolyticus (8%). The remaining unidentified 36% were alleged to belong to other Vibrio species not covered within the scope of this study. The antibiotic susceptibility profiles of confirmed Vibrio genus isolates recovered from the four rivers revealed that 83% of Vibrio isolates in this study exhibited resistance against three or more antimicrobial agents. The occurrence of Vibrio species in Great Fish River confirms the role of freshwater resources as potential reservoir for this pathogen. We conclude that rural freshwater resources in Chris Hani District Municipality are potential sources of Vibrio pathogens in the aquatic milieu of the rural communities.
Abstract: Vibrio vulnificus is a bacterium responsible for severe gastroenteritis, sepsis and wound infections. Gastroenteritis and sepsis are commonly associated with the consumption of raw oysters, whereas wound infection is often associated with the handling of contaminated fish. Although classical virulence factors of this emerging pathogen are well characterised, there remains a paucity of knowledge regarding the general biology of this species. To investigate the presence of previously unreported virulence factors, we applied whole genome sequencing to a panel of ten V. vulnificus strains with varying virulence potentials. This identified two novel type 6 secretion systems (T6SSs), systems that are known to have a role in bacterial virulence and population dynamics. By utilising a range of molecular techniques and assays we have demonstrated the functionality of one of these T6SSs. Furthermore, we have shown that this system is subject to thermoregulation and is negatively regulated by increasing salinity concentrations. This secretion system was also shown to be involved in the killing of V. vulnificus strains that did not possess this system and a model is proposed as to how this interaction may contribute to population dynamics within V. vulnificus strains. In addition to this intra-species killing, this system also contributes to the killing of inter bacterial species and may have a role in the general composition of Vibrio species in the environment.
Pub.: 01 Nov '16, Pinned: 07 Aug '17
Abstract: There is a growing interest in the role of climate change in driving the spread of waterborne infectious diseases, such as those caused by bacterial pathogens. One particular group of pathogenic bacteria - vibrios - are a globally important cause of diseases in humans and aquatic animals. These Gram-negative bacteria, including the species Vibrio vulnificus, Vibrio parahaemolyticus and Vibrio cholerae, grow in warm, low-salinity waters, and their abundance in the natural environment mirrors ambient environmental temperatures. In a rapidly warming marine environment, there are greater numbers of human infections, and most notably outbreaks linked to extreme weather events such as heatwaves in temperate regions such as Northern Europe. Because the growth of pathogenic vibrios in the natural environment is largely dictated by temperature, we argue that this group of pathogens represents an important and tangible barometer of climate change in marine systems. We provide a number of specific examples of the impacts of climate change on this group of bacteria and their associated diseases, and discuss advanced strategies to improve our understanding of these emerging waterborne diseases through the integration of microbiological, genomic, epidemiological, climatic, and ocean sciences.
Pub.: 16 Nov '16, Pinned: 07 Aug '17