Reliability of mCP method for identification of Clostridium perfringens from faecal polluted aquatic environments

Human Enteric Pathogens in Eight Rivers Used as Rural Household Drinking Water Sources in the Northern Region of South Africa

People living in rural areas still rely on the use of environmental water that is contaminated by human and animal activities. This study assessed the occurrence of human enteric pathogens in rivers that are used by rural communities Vhembe District of South Africa as a source of drinking water covering two seasons (winter and summer) over a one-year period. Water quality was assessed using physico characteristics and indicator organisms (total coliforms, E. coli, Clostridium perfringens). Pathogens tested included bacteria (Pathogenic E. coli, Salmonella-, Shigella- and Vibrio spp.), protozoa (Cryptosporidium- and Giardia spp.), and enteric viruses (Rota-, Noro-, Entero-, and Adenoviruses) while using published molecular protocols. The results showed that the indicator bacteria counts exceeded South African drinking water quality guideline limits and pathogenic E. coli was detected in the samples. No Shigella spp. were isolated, while Vibrio spp. and Salmonella spp. were present; parasites were detected in four rivers and Enteric viruses were predominantly detected in the winter season. The results indicated the poor condition of water and the potential health risks to consumers highlighting the need for implementing river catchment management strategies for continued sustainability in these rivers.

Anaerobic bacteria in wastewater treatment plant

Purpose

The objective of this study was to assess exposure to anaerobic bacteria released into air from sewage and sludge at workplaces from a wastewater treatment plant (WWTP).

Methods

Samples of both sewage and sludge were collected at six sampling points and bioaerosol samples were additionally collected (with the use of a 6-stage Andersen impactor) at ten workplaces covering different stages of the technological process. Qualitative identification of all isolated strains was performed using the biochemical API 20A test. Additionally, the determination of Clostridium pathogens was carried out using 16S rRNA gene sequence analysis.

Results

The average concentration of anaerobic bacteria in the sewage samples was 5.49 × 10⁴ CFU/mL (GSD = 85.4) and in sludge—1.42 × 10⁶ CFU/g (GSD = 5.1). In turn, the average airborne bacterial concentration was at the level of 50 CFU/m³ (GSD = 5.83) and the highest bacterial contamination (4.06 × 10³ CFU/m³) was found in winter at the bar screens. In total, 16 bacterial species were determined, from which the predominant strains belonged to Actinomyces, Bifidobacterium, Clostridium, Propionibacterium and Peptostreptococcus genera. The analysis revealed that mechanical treatment processes were responsible for a substantial emission of anaerobic bacteria into the air. In both the sewage and air samples, Clostridium perfringens pathogen was identified.

Conclusions

Anaerobic bacteria were widely present both in the sewage and in the air at workplaces from the WWTP, especially when the technological process was performed in closed spaces. Anaerobic bacteria formed small aggregates with both wastewater droplets and dust particles of sewage sludge origin and as such may be responsible for adverse health outcomes in exposed workers.

On-line monitoring of Escherichia coli in raw water at Oset drinking water treatment plant, Oslo (Norway)

The fully automated Colifast ALARM^TM has been used for two years for daily monitoring of the presence/absence of Escherichia coli in 100 mL raw water at Oset drinking water treatment plant in Oslo, Norway. The raw water is extracted from 35 m depth from the Lake Maridalsvannet. E. coli was detected in 18% of the daily samples. In general, most samples positive for E. coli were observed during the autumn turnover periods, but even in some samples taken during warm and dry days in July, with stable temperature stratification in the lake, E. coli was detected. The daily samples gave useful additional information compared with the weekly routine samples about the hygienic raw water quality and the hygienic barrier efficiency of the lake under different weather conditions and seasons. The winter 2013/2014 was much warmer than the winter 2012/2013. The monitoring supported the hypothesis that warmer winters with shorter periods with ice cover on lakes, which may be a consequence of climate changes, may reduce the hygienic barrier efficiency in deep lakes used as drinking water sources.

Acid phosphatase test proves superior to standard phenotypic identification procedure for Clostridium perfringens strains isolated from water

Clostridium perfringens is used as an indicator for persistent faecal pollution as well as to monitor the efficacy of water treatment processes. For these purposes, differentiation between C. perfringens and other Clostridia is essential and is routinely carried out by phenotypic standard tests as proposed in the ISO/CD 6461-2:2002 (ISO_LGMN: lactose fermentation, gelatine liquidation, motility and nitrate reduction). Because the ISO_LGMN procedure is time consuming and labour intensive, the acid phosphatase test was investigated as a possible and much more rapid alternative method for confirmation. The aim of our study was to evaluate and compare confirmation results obtained by these two phenotypic methods using genotypically identified strains, what to our knowledge has not been accomplished before. For this purpose, a species specific PCR method was selected based on the results received for type strains and genotypically characterised environmental strains. For the comparative investigation type strains as well as presumptive C. perfringens isolates from water and faeces samples were used. The acid phosphatase test revealed higher percentage (92%) of correctly identified environmental strains (n = 127) than the ISO_LGMN procedure (83%) and proved to be a sensitive and reliable confirmation method.

Freshwater suspended sediments and sewage are reservoirs for enterotoxin-positive Clostridium perfringens

The release of fecal pollution into surface waters may create environmental reservoirs of feces-derived microorganisms, including pathogens. Clostridium perfringens is a commonly used fecal indicator that represents a human pathogen. The pathogenicity of this bacterium is associated with its expression of multiple toxins; however, the prevalence of C. perfringens with various toxin genes in aquatic environments is not well characterized. In this study, C. perfringens spores were used to measure the distribution of fecal pollution associated with suspended sediments in the nearshore waters of Lake Michigan. Particle-associated C. perfringens levels were greatest adjacent to the Milwaukee harbor and diminished in the nearshore waters. Species-specific PCR and toxin gene profiles identified 174 isolates collected from the suspended sediments, surface water, and sewage influent as C. perfringens type A. Regardless of the isolation source, the beta2 and enterotoxin genes were common among isolates. The suspended sediments yielded the highest frequency of cpe-carrying C. perfringens (61%) compared to sewage (38%). Gene arrangement of enterotoxin was investigated using PCR to target known insertion sequences associated with this gene. Amplification products were detected in only 9 of 90 strains, which suggests there is greater variability in cpe gene arrangement than previously described. This work presents evidence that freshwater suspended sediments and sewage influent are reservoirs for potentially pathogenic cpe-carrying C. perfringens spores.