An assessment of potential public health risk associated with the extended survival of indicator and pathogenic bacteria in freshwater lake sediments

Microcosm studies were performed to evaluate the survival of Escherichia coli, Salmonella paratyphi and Vibrio parahaemolyticus in water and sediment collected from the freshwater region of Vembanad Lake (9 35◦N 76 25◦E) along the south west coast of India. All three test microorganisms showed significantly (p < 0.01) higher survival in sediment compared to overlying water. The survival in different sediment types with different particle size and organic carbon content revealed that sediment with small particle size and high organic carbon content could enhance their extended survival (p < 0.05). The results indicate that sediments of the Lake could act as a reservoir of pathogenic bacteria and exhibit a potential health hazard from possible resuspension and subsequent ingestion during recreational activities. Therefore, the assessment of bacterial concentration in freshwater Lake sediments used for contact and non contact recreation has of considerable significance for the proper assessment of microbial pollution of the overlying water, and for the management and protection of related health risk at specific recreational sites. Besides, assessment of the bacterial concentration in sediments can be used as a relatively stable indicator of long term mean bacterial concentration in the water column above

Potential public health significance of faecal contamination and multidrug-resistant Escherichia coli and Salmonella serotypes in a lake in India

To assess the prevalence of faecal coliform bacteria and multiple drug resistance among Escherichia coli and Salmonella serotypes from Vembanadu Lake. Study design: Systematic microbiological testing. Methods: Monthly collection of water samples were made from ten stations on the southern and northern parts of a salt water regulator constructed in Vembanadu Lake in order to prevent incursion of seawater during certain periods of the year. Density of faecal colifrom bacteria was estimated. E. coli and Salmonella were isolated and their different serotypes were identified. Antibiotic resistance analysis of E. coli and Salmonella serotypes was done and the MAR index of individual isolates was calculated. Results: Density of faecal coliform bacteria ranged from mean MPN value 2900 -7100/100ml. Results showed multiple drug resistance pattern among the bacterial isolates. E. coli showed more than 50% resistance to amickacin, oxytetracycline, streptomycin, tetracycline and kanamycin while Salmonella showed high resistance to oxytetracycline, streptomycin, tetracycline and ampicillin. The MAR indexing of the isolates showed that they have originated from high risk source such as humans, poultry and dairy cows. Conclusions: The high density of faecal coliform bacteria and prevalence of multi drug resistant E. coli and Salmonella serotypes in the lake may pose severe public health risk through related water borne and food borne outbreaks

Potential Exposure Risk Associated with the High Prevalence and Survival of Indicator and Pathogenic Bacteria in the Sediment of Vembanadu Lake, India

Prevalence of faecal coliform bacteria and the survival of Escherichia coli, Vibrio parahaemolyticus and Salmonella paratyphi were studied in the water and sediment from Vembanadu Lake in the presence and absence of protozoan predators. The density of faecal coliform bacteria ranged between mean MPN value 5080–9000/100 ml in water and 110,000–988,000/1 g in sediment (p <0.01), which was 110 times greater than in overlying water. The laboratory microcosm studies revealed that E. coli, V. parahaemolyticus and S. paratyphi showed significantly higher survival (p <0.05) potential in sediment than in overlying water both in the presence and absence of protozoan predators. The results indicate that Vembanadu Lake sediment constitutes a reservoir of pathogenic bacteria and exhibits potential health hazard from possible resuspension and subsequent ingestion during recreational activities. Therefore, assessment of bacterial concentration in freshwater lake sediments used for contact and non-contact recreation is of considerable significance for the proper assessment of microbial pollution of the overlying water and the management and protection of related health risk at specific recreational sites. In addition, assessment of the bacterial concentration in sediments can be used as a relatively stable indicator of long-term mean bacterial concentration in the water column above.

Detection and diversity of pathogenic Vibrio from Fiji

Here we investigate the diversity of pathogenic Vibrio species in marine environments close to Suva, Fiji. We use four distinct yet complementary analyses – biochemical testing, phylogenetic analyses, metagenomic analyses and molecular typing – to provide some preliminary insights into the diversity of vibrios in this region. Taken together our analyses confirmed the presence of nine Vibrio species, including three of the most important disease-causing vibrios (i.e. V. cholerae, V. parahaemolyticus and V. vulnificus), in Fijian marine environments. Furthermore, since toxigenic V. parahaemolyticus are present on fish for consumption we suggest these bacteria represent a potential public health risk. Our results from Illumina short read sequencing are encouraging in the context of microbial profiling and biomonitoring. They suggest this approach may offer an efficient and costeffective method for studying the dynamics of microbial diversity in marine environments over time.

Prevalence and Antibiotic sensitivity of Escherichia coli in Extensive Brackish water Aquaculture Ponds

Prevalence and antibiotic resistance of Escherichia coli in the water and sediment samples of brackish water aquaculture ponds adjacent to Cochin backwaters was analysed. More than 50% of the water samples and more than 80% of sediment samples from all the sampling stations were tested positive for £. coli. Risk assessment of the E. coli strains was carried out using multiple antibiotic resistance (MAR) indexing. Majority of the strains were found to be multiple antibiotic resistant suggesting their origin from high risk sources of contamination such as human where antibiotics are frequently used. While none of the £. coli strains were resistant against amikacin, chloramphenicol, streptomycin and trimethoprim, considerable levels of resistance was encountered against ampicillin, erythromycin, penicillin G and vancomycin. High prevalence of £. coli in the water and sediment samples of this extensive brackish water ponds indicates high degree of faecal pollution of this environment. The high risk nature of the strains warrants efficient post harvest and processing measures to avoid health risk to consumers

Studies on the effect of Polycyclic Aromatic Hydrocarbons in the life and activity of Perna spp

In the present study an endeavour has been made to analyse the acute toxicity of WAFs of Bombay High crude and Light Diesel oil on commercially important bivalve species Perna viridis and Perna indica by static bioassay methods. The toxic effects of chemicals in the WAF on the organisms ; their tissues and eventually on rate functions have been elucidated. Marine oil pollution not only affects productivity and quality of marine organisms but also eventually affects the health of human population due to a possible health risk by way of consumption of oil contaminated seafood

Molecular Epidemiology of Escherichia coli isolates from Environmental, Food and Clinical Sources

In the present study diversity of E. coli in the water samples of Cochin estuary were studied for a period of 3 years ranging from January 2010- December 2012. The stations were selected based on the closeness to satellite townships and waste input. Two of the stations (Chitoor and Thevara) were fixed upstream, two in the central part of the estuary namely Bolgatty and Off Marine Science Jetty, and one at the Barmouth. Diversity was assessed in terms of serotypes, phylogenetic groups and genotypes. Two groups of seafood samples such as fish and shellfish collected from the Cochin estuary were used for isolation of E. coli. One hundred clinical E. coli isolates were collected from one public health centre, one hospital and five medical labs in and around Cochin City, Kerala. From our results it was clear that pathogen cycling is occurring through food, water and clinical sources. Pathogen cycling through food is very common and fish and shellfish that harbour these strains might pose potential health risk to consumer. Estuarine environment is a melting pot for various kinds of wastes, both organic and inorganic. Mixing up of waste water from various sources such as domestic, industries, hospitals and sewage released into these water bodies resulting in the co-existence of E. coli from various sources thus offering a conducive environment for horizontal gene transfer. Opportunistic pathogens might acquire genes for drug resistance and virulence turning them to potential pathogens. Prevalence of ExPEC in the Cochin estuary, pose threat to people who use this water for fishing and recreation. Food chain also plays an important role in the transit of virulence genes from the environments to the human. Antibiotic resistant E. coli are widespread in estuarine water, seafood and clinical samples, for reasons well known such as indiscriminate use of antibiotics in animal production systems, aquaculture and human medicine. Since the waste water from these sources entering the estuary provides selection pressure to drug resistant mutants in the environment. It is high time that the authorities concerned should put systems in place for monitoring and enforcement to curb such activities. Microbial contamination can limit people’s enjoyment of coastal waters for contact recreation or shellfish-gathering. E. coli can make people sick if they are present in high levels in water used for contact recreation or shellfish gathering. When feeding, shellfish can filter large volumes of seawater, so any microorganisms present in the water become accumulated and concentrated in the shellfish flesh. If E. coli contaminated shellfish are consumed the impact to human health includes gastroenteritis, urinary tract infections (UTIs), and bacteraemia. In conclusion, the high prevalence of various pathogenic serotypes and phylogenetic groups, multidrug-resistance, and virulence factor genes detected among E. coli isolates from stations close to Cochin city is a matter of concern, since there is a large reservoir of antibiotic resistance genes and virulence traits within the community, and that the resistance genes and plasmid-encoded genes for virulence were easily transferable to other strains. Given the severity of the clinical manifestations of the disease in humans and the inability and/or the potential risks of antibiotic administration for treatment, it appears that the most direct and effective measure towards prevention of STEC and ExPEC infections in humans and ensuring public health may be considered as a priority.