Search Results (19)

Legionella pneumophila (L. pneumophila), the bacteria causing Legionnaires’ disease, a severe pneumonia with high morbidity and mortality globally. The underreporting of this disease is marked particularly in low-income African countries, where data on Legionellosis remains extremely limited. Gauteng, South Africa’s most densely populated province, faces challenges such as rapid urbanisation, limited access to sanitary facilities, and ageing infrastructure, which can compromise drinking water quality by increasing the presence of bacteria within the water distribution systems. Although research on Legionella in South Africa has been conducted, no research has compared its prevalence in urban and rural households in the country. This study examines the presence and distribution of L. pneumophila and amoeba-associated strains in water distribution systems in both urban (Hillbrow and Atteridgeville) and rural (Zandspruit and Melusi) areas in Gauteng province in South Africa. In total, 134 water samples were obtained from tap faucets and storage containers, and 260 biofilm samples were obtained from tap faucets, storage containers, and toilet bowls. Water samples were analysed for Escherichia coli (E. coli) using the IDEXX Colilert^® and for L. pneumophila using the IDEXX Legiolert^TM assay. Both water and biofilm samples were analysed for evidence of amoeba-associated Legionella using the amoeba enrichment technique. The Colilert assay detected total coliforms in 13% of the urban samples and 25% of the rural samples. The Legiolert^TM assay detected L. pneumophila in 52% of urban and 78% of rural samples. Amoeba-associated L. pneumophila was confirmed in 35% of urban samples and 25% in rural samples. The conventional PCR confirmed L. pneumophila in 81% of both urban and rural samples, while real-time PCR detected L. pneumophila in 97% of urban and 100% of rural samples. In total, 111 water and 19 biofilm samples tested positive for the presence of L. pneumophila across the four areas. These results revealed that L. pneumophila is prevalent in both urban and rural water systems in Gauteng. Full article

Background/Objectives: Intensive pig farming is a critical component of food security and economic activity in South Africa; however, it also presents a risk of amplifying antimicrobial resistance (AMR). This study provides genomic insights into antibiotic-resistant Escherichia coli (E. coli) circulating across the pork production chain, using a ‘farm-to-fork’ approach. Methods: A total of 417 samples were collected from various points along the production continuum, including the farm (n = 144), transport (n = 60), and abattoir (n = 213). E. coli isolates were identified using the Colilert-18 system, and their phenotypic resistance was tested against 20 antibiotics. Thirty-one isolates were selected for further characterization based on their resistance profiles and sampling sources, utilizing whole-genome sequencing and bioinformatic analysis. Results: The isolates exhibited varying resistance to critical antibiotics used in both human and animal health, including ampicillin (31/31, 100%), tetracycline (31/31, 100%), amoxicillin–clavulanate (29/31, 94%), chloramphenicol (25/31, 81%), and sulfamethoxazole–trimethoprim (10/31, 33%). Genetic analysis revealed the presence of resistance genes for β-lactams (bla_EC, bla_TEM), trimethoprim/sulfonamides (dfrA1, dfrA5, dfrA12, sul2, sul3), tetracyclines (tetA, tetB, tetR, tet34), aminoglycosides (aadA, strA, aph variants), and phenicols (catB4, floR, cmlA1), most of which were plasmid-borne. Virulome analysis identified 24 genes, including toxins and adhesion factors. Mobile genetic elements included 24 plasmid replicons, 43 prophages, 19 insertion sequence families, and 7 class 1 integrons. The E. coli isolates belonged to a diverse range of sequence types, demonstrating significant genetic variability. Further phylogenomic analysis revealed eight major clades, with isolate clustering by sequence type alongside South African environmental and clinical E. coli strains, regardless of their sampling source. Conclusions: The genetic complexity observed across the pork production continuum threatens food safety and may impact human health. These findings underscore the need for enhanced AMR monitoring in livestock systems and support the integration of AMR surveillance into food safety policy frameworks. Full article

Fecal contamination is a common cause of impairment of surface waters. In monitoring studies, it is usually assessed by measuring concentrations of fecal indicator bacteria such as Escherichia coli (E. coli), a common monitoring target in freshwater systems. In this study, we assess the advantages and disadvantages of two common and previously validated methods for monitoring E. coli concentrations at freshwater beaches: Colilert-18^®, with a turnaround time of ca. 18 h, and real-time quantitative PCR (qPCR), with a turnaround time of ca. 3–4 h. Based on data comprising 3081 pairs of Colilert-18 and qPCR estimates of E. coli concentrations in split samples from Michigan’s annual beach monitoring program in 2019 and 2020, we found that qPCR monitoring detected a high percentage of exceedances of the state’s water quality standard for E. coli contamination that went undetected on the day of sampling with Colilert-18 monitoring because qPCR concentration estimates were available on the day of sampling but Colilert-18 estimates were not. However, Colilert-18 data were more useful than qPCR data for the statistical comparison of contamination levels at different beaches, probably in part because Colilert-18 data showed a much lower percentage of concentration estimates outside the method’s range of quantification. Full article

This study assessed raw vegetable sanitizing in Brazilian schools and identified barriers to standards. This experimental and quantitative study was conducted in 12 school food services in the Federal District (Brazil) public primary education institutions. Microbiological analyses were conducted with vegetable samples (before and after sanitizing) and water used in the sanitization process, collected before the process. The Petrifilm^®E. coli/Coliform Count Plates and COLIlert methods were used to evaluate vegetables and water samples, and a checklist of good practices was applied in each school food service to identify barriers to proper sanitization. Thirty-five samples of raw vegetables were offered to students, 32 samples of water, and 17 hygiene processes were evaluated. The results indicate that 76.5% (n = 13) of hygiene processes were considered unsatisfactory, with an average increase of 5.8 log CFU g⁻¹ (DV = 7.4) in the initial microbial load in 47.1% (n = 8) of the evaluated processes; moreover, 33.3% (n = 6) of the samples exceeded the tolerable limit, with an average value above 1.5 × 10³ CFU/g. Attention to food handler training and necessary organizational changes is essential to ensure safe food and promote healthy student eating habits, highlighting the importance of strengthening basic hygiene practices and following the parameters for sanitizing vegetables. Full article

Heavy metal and microbial pollution in groundwater raises health concerns due to its adverse effects. This study aimed to assess the health risks associated with heavy metal and bacterial pollution in groundwater in Mankweng. Heavy metals and Escherichia coli were detected using inductively coupled plasma mass spectrophotometry and a Colilert system, respectively. The heavy metal pollution index (HPI) and non-carcinogenic and carcinogenic risks were computed. The β-Poisson dose–response model was employed to predict the probability of E. coli infection. The metals’ concentrations were all within the permissible limits of the South African National Standard (SANS). However, Pb levels at sites E and G exceeded the World Health Organization (WHO) guideline (≤0.01 mg/L). HPI values were all less than 100, indicative of low contamination. The hazard quotient values were all less than 1, except for vanadium. The cumulative cancer risk ranged between 3.06 × 10⁻⁵ and 1.81 × 10⁻⁴ and between 3.55 × 10⁻⁵ and 2.20 × 10⁻⁴ for adults and children, respectively. E. coli was only detected at site L. The annual risk of E. coli infection exceeded the WHO risk limit of 10⁻⁴. The results underscore the need for the regular monitoring of groundwater. Full article

There is a lack of groundwater quality monitoring, especially in developing countries like South Africa. This study aimed to evaluate borehole water quality. Groundwater was analysed for pH, dissolved oxygen (DO), temperature, electrical conductivity (EC), total dissolved solids (TDSs), turbidity, chemical oxygen demand (COD), nitrogen (N), sulphate (SO₄²⁻), fluoride (F⁻), chloride (Cl⁻), calcium (Ca²⁺), magnesium (Mg²⁺), potassium (K⁺), and sodium (Na⁺) using a multi-parameter device, spectrophotometer, turbidity meter, and inductively coupled plasma optical emission spectrophotometer. Total coliforms and Escherichia coli were quantified using the Colilert system. The water quality index (WQI) was calculated using the arithmetic weighting method. The parameters ranged as follows: pH (6.71–7.94), DO (2.19–7.79 mg/L), EC (379.67–1317.33 µS/cm), TDSs (190–659 mg/L), temperature (16.75–22.31 °C), turbidity (0.17–3.21 NTU), COD (9–50 mg/L), F⁻ (0.17–2.09 mg/L), Cl⁻ (36.1–184.55 mg/L), N (0.64–28.56 mg/L), SO₄²⁻ (27.18–112.13 mg/L), K⁺ (1.71–21.77 mg/L), Ca²⁺ (29.59–134.59 mg/L), Mg²⁺ (16.72–110.78 mg/L), and Na⁺ (38.52–170.63 mg/L). One borehole was polluted with E. coli (9 MPN/100 mL) and 25% were contaminated with coliforms beyond 10 MPN/100 mL. The WQI ranged from 50.430 to 190.220. The results underscore the importance of regular monitoring of groundwater. Full article

Quantitatively assessing fecal indicator bacteria in drinking water from limited resource settings (e.g., disasters, remote areas) can inform public health strategies for reducing waterborne illnesses. This study aimed to compare two common approaches for quantifying Escherichia coli (E. coli) density in natural water versus the ColiPlate™ kit approach. For comparing methods, 41 field samples from natural water sources in Kentucky (USA) were collected. E. coli densities were then determined by (1) membrane filtration in conjunction with modified membrane-thermotolerant E. coli (mTEC) agar, (2) Idexx Quanti-Tray^® 2000 with the Colilert^® substrate, and (3) the Bluewater Biosciences ColiPlate kit. Significant correlations were observed between E. coli density data for all three methods (p < 0.001). Paired t-test results showed no difference in E. coli densities determined by all the methods (p > 0.05). Upon assigning modified mTEC as the reference method for determining the World Health Organization-assigned “very high-risk” levels of fecal contamination (>100 E. coli CFU/100 mL), both ColiPlate and Colilert exhibited excellent discrimination for screening very high-risk levels according to the area under the receiver operating characteristic curve (~89%). These data suggest ColiPlate continues to be an effective monitoring tool for quantifying E. coli density and characterizing fecal contamination risks from water. Full article

Antibiotic resistance profiles of Escherichia coli were investigated in an intensive pig production system in the uMgungundlovu District, South Africa, using the ‘farm-to-fork’ approach. Four hundred seventeen (417) samples were collected from pig and pig products at different points (farm, transport, and abattoir). E. coli was isolated and enumerated using the Colilert^® 18/Quanti-Tray^® 2000 system. Ten isolates from each Quanti-tray were selected randomly and putatively identified on eosin methylene blue agar. Real-time PCR targeting the uidA gene was used to confirm isolates to the genus level. The Kirby–Bauer disc diffusion method was used to determine the isolates’ antibiotic susceptibility profiles against 20 antibiotics. A total of 1044 confirmed E. coli isolates were obtained across the three critical points in the food chain. Resistance was observed to all the antibiotics tested with the highest and lowest rates obtained against tetracycline (88.5%) and meropenem (0.2%), respectively. Resistance was also observed to chloramphenicol (71.4%), ampicillin (71.1%), trimethoprim-sulfamethoxazole (61.3%), amoxicillin-clavulanate (43.8%), cephalexin (34.3%), azithromycin (23.9%), nalidixic acid (22.1%), cefoxitin (21.1%), ceftriaxone (18.9%), ciprofloxacin (17.3%), cefotaxime (16.9%), gentamicin (15.5%), cefepime (13.8%), ceftazidime (9.8%), amikacin (3.4%), piperacillin-tazobactam (1.2%), tigecycline (0.9%), and imipenem (0.3%). Multidrug resistance (MDR) was observed in 71.2% of the resistant isolates with an overall multiple antibiotic resistance (MAR) index of 0.25, indicating exposure to high antibiotic use environments at the farm level. A high percentage of resistance was observed to growth promoters and antibiotics approved for veterinary medicine in South Africa. Of concern was resistance to critically important antibiotics for animal and human use and the watch and reserve categories of antibiotics. This could have adverse animal and human health consequences from a food safety perspective, necessitating efficient antibiotic stewardship and guidelines to streamline antibiotic use in the food-animal production chain. Full article

There is a need for accessible and low-cost microbiological water quality testing in contexts where diarrheal illness is a major public health concern. In most cases, the quantification of Escherichia coli and other microbial indicators by conventional culture methods requires an incubation step for processed samples at specific temperatures for bacterial growth over a prescribed time. However, incubators can be the most expensive equipment required for such microbial analyses, limiting the number and scope of water quality testing available in low-resource contexts. In this study, a low-cost incubator was developed using a locally available expanded polystyrene (EPS) foam cooler, with two water bottles filled with hot water to heat incubator to a target of 35 °C. The EPS incubator performance was validated by processing 150 water samples in duplicates using the Colilert Quanti-tray/2000 system, incubated in either the EPS incubator or a standard laboratory incubator set at 35 °C. Statistically significant correlations of results indicated that the quantification of E. coli was comparable between both methods. Risk categorizations from standard and EPS incubation results agreed for 141 of 150 (94%) samples, with zero false negatives. In addition to being reasonably mobile the EPS incubator would reduce the cost of such water quality testing, thus potentially increasing the scope of water quality testing coverage. Full article

The disposal of municipal solid wastes in landfills represents a major threat for aquifer environments at the global scale. The aim of this study was to explore how groundwater geochemical characteristics can influence the microbial community functioning and the potential degradation patterns of selected organic substrates in response to different levels of landfill-induced alterations. Groundwaters collected from a landfill area were monitored by assessing major physical-chemical parameters and the microbiological contamination levels (total coliforms and fecal indicators—Colilert-18). The aquatic microbial community was further characterized by flow cytometry and Biolog EcoPlates^TM assay. Three groundwater conditions (i.e., pristine, mixed, and altered) were identified according to their distinct geochemical profiles. The altered groundwaters showed relatively higher values of organic matter concentration and total cell counts, along with the presence of fecal indicator bacteria, in comparison to samples from pristine and mixed conditions. The kinetic profiles of the Biolog substrate degradation showed that the microbial community thriving in altered conditions was relatively more efficient in metabolizing a larger number of organic substrates, including those with complex molecular structures. We concluded that the assessment of physiological profiling and functional diversity at the microbial community level could represent a supportive tool to understand the potential consequences of the organic contamination of impacted aquifers, thus complementing the current strategies for groundwater management. Full article

Development of sensitive methods for the determination of E. coli bacteria contamination in water distribution systems is of paramount importance to ensure the microbial safety of drinking water. This work presents a new sensing platform enabling the fast detection of bacteria in field samples by using specific antibodies as the biorecognition element and dark field microscopy as the detection technique. The development of the sensing platform was performed using non-pathogenic bacteria, with the E. coli DH5α strain as the target, and Bacillus sp. 9727 as the negative control. The identification of the captured bacteria was made by analyzing the dark field microscopy images and screening the detected objects by using object circularity and size parameters. Specificity tests revealed the low unspecific attachment of either E. coli over human serum albumin antibodies (negative control for antibody specificity) and of Bacillus sp. over E. coli antibodies. The system performance was tested using field samples, collected from a wastewater treatment plant, and compared with two quantification techniques (i.e., Colilert-18 test and quantitative polymerase chain reaction (qPCR)). The results showed comparable quantification capability. Nevertheless, the present method has the advantage of being faster, is easily adaptable to in-field analysis, and can potentially be extended to the detection of other bacterial strains. Full article

Background: Young children exhibit a high susceptibility to several diarrhoea-causing bacterial microorganisms. In this study, the prevalence of fecal contamination on children’s toys was determined using total coliform and E. coli as bacterial fecal indicators. The prevalence of diarrhoeagenic E. coli strains were used as an indication of the potential health risks. Materials and Methods: A cross-sectional descriptive study was carried out for 3 months in rural communities in the Vhembe district, Limpopo province of South Africa. Nonporous plastic toys (n = 137) used by children under 5 years of age in households and day care centres (DCCs) from rural villages were collected for assessment. New toys (n = 109) were provided to the households and DCCs and collected again after 4 weeks. Microbiological assessment was carried out using the Colilert^® Quanti-Tray/2000 system. Diarrhoeagenic E. coli strains were identified using a published multiplex PCR protocol. Results: Water, sanitation and hygiene (WASH) conditions of the children in the households and DCCs were assessed. Statistical analysis was used to identify the relationship between fecal contamination of the existing and introduced toys. All the existing and introduced toy samples, both from DCCs and households, tested positive for total coliform counts and 61 existing and introduced toy samples tested positive for E. coli counts. Diarrhoeagenic E. coli strains identified included EHEC, ETEC, EPEC, EIEC and EAEC. Conclusions: The results indicated that water, sanitation and hygiene conditions could be responsible in the contamination of children’s toys and the transmission of diarrhoea to young children. Full article

In many regions where drinking water supply is intermittent and unreliable, households adapt by storing water in cisterns or rooftop tanks. Both intermittent supply and stored water can be vulnerable to contamination by microorganisms with deleterious health effects. The Metropolitan Zone of Guadalajara is a rapidly growing urban center with over five million residents where household storage is nearly ubiquitous. This pilot study was conducted in July 2018 to examine the microbiological quality of drinking water in Guadalajara. Samples were tested for free available chlorine residual, total coliform bacteria, and Escherichia coli. A survey on access to water and public perspectives was also conducted. Water exiting rooftop tanks exceeded regulatory limits for total coliform levels in half of the homes studied. Piped water arriving at two homes had total coliform levels that far exceeded regulatory limits. No E. coli were detected in any of the samples. Only 35% of homes had a chlorine residual between the recommended 0.2 and 1.5 mg/L. Many homes reported unpleasant odors and colors. Only 7% of residents drank the piped water. Future studies are needed, especially during April and May when many homes reported a higher disruption to water service. Full article

Water resources, especially safe, potable water, are limited for many Haitians. In areas where shallow groundwater is available, many household water needs such as laundry, bathing, and cooking are supplied by hand–dug wells. In order to better understand the water quality and prevalence of these household wells, 35 hand–dug wells were surveyed and sampled near the Hôpital Albert Schweitzer in Deschapelles, Haiti. Water samples were collected and tested for fecal coliform and Escherichia coli using the IDEXX Colilert–18 method. Of the samples collected, 89 percent were determined unsafe to use as a drinking water source based on the World Health Organization standard of 1.0 colony–forming unit (cfu) E. coli per 100 mL. Sixty–six percent of the wells exceeded recreational/body contact standards for the state of Michigan (130 cfu/100 mL). Some of these wells were deemed suitable for conversion to a new well type called in situ filtration (ISF) wells. In situ filtration wells are installed with an internal sand filter pack, PVC casing, pump, and cap which seals the well from surface contamination and provides additional water treatment as water is pumped. Previous ISF installations have reduced E. coli to safe drinking water levels within 90 days. Full article

Human burial in cemeteries facilitates the decomposition of corpses without posing a public health danger. However, the role of cemeteries as potential environmental reservoirs of drug-resistant pathogens has not been studied. Thus, we investigated cemeteries as potential environmental reservoirs of multi-drug resistant (MDR) pathogenic Escherichia coli. E. coli isolates were obtained from water samples (collected from surface water bodies and boreholes in three cemeteries) after isolation using the Colilert^® 18 system. Pathogenic potentials of the isolates were investigated using real-time polymerase chain reactions targeting seven virulence genes (VGs) pertaining to six E. coli pathotypes. The resistance of isolates to eight antibiotics was tested using the Kirby–Bauer disc diffusion method. The mean E. coli concentrations varied from <1 most probable number (MPN)/100 mL to 2419.6 MPN/100 mL with 48% of 100 isolates being positive for at least one of the VGs tested. Furthermore, 87% of the isolates were resistant to at least one of the antibiotics tested, while 72% of the isolates displayed multi-drug resistance. Half of the MDR isolates harboured a VG. These results suggest that cemeteries are potential reservoirs of MDR pathogenic E. coli, originating from surrounding informal settlements, which could contaminate groundwater if the cemeteries are in areas with shallow aquifers. Full article