Waterborne epidemic outbreak of Shigella sonnei gastroenteritis in Santa Maria de Palautordera, Catalonia, Spain

Mitigation of T3SS-mediated virulence in waterborne pathogenic bacteria by multi-electrode cylindrical-DBD plasma-generated nitric oxide water

S. enterica, S. flexneri, and V. parahaemolyticus bacteria are globally recognized to cause severe diarrheal diseases, consisting of Type III Secretion System (T3SS) effectors that help in bacterial infection and virulence in host cells. This study investigates the properties of multi-electrode cylindrical DBD plasma-generated nitric oxide water (MCDBD-PG-NOW) treatment on the survival and virulence of S. enterica, S. flexneri, and V. parahaemolyticus bacteria. The Colony Forming Unit (CFU) assay, live/dead cell staining, lipid peroxidation assay, and bacteria morphological analysis showed substantial growth inhibition of bacteria. Moreover, to confirm the interaction of reactive nitrogen species (RNS) with bacterial membrane biotin switch assay, DAF-FM, and FTIR analysis were carried out, which established the formation of S-nitrosothiols in the cell membrane, intracellular accumulation of RNS, and changes in the cell composition post-PG-NOW treatment. Furthermore, the conventional culture-based method and a quantitative PCR using propidium monoazide showed minimal VBNC induction under similar condition. The efficiency of bacteria to adhere to mammalian colon cells was significantly reduced. In addition, the infection rate was also controlled by disrupting the virulent genes, leading to the collapse of the infection mechanism. This study provides insights into whether RNS generated from PG-NOW might be beneficial for preventing diarrheal infections.

Infectious Diseases Associated with Hydrometeorological Hazards in Europe: Disaster Risk Reduction in the Context of the Climate Crisis and the Ongoing COVID-19 Pandemic

Hydrometeorological hazards comprise a wide range of events, mainly floods, storms, droughts, and temperature extremes. Floods account for the majority of the related disasters in both developed and developing countries. Flooding alters the natural balance of the environment and frequently establish a favorable habitat for pathogens and vectors to thrive. Diseases caused by pathogens that require vehicle transmission from host to host (waterborne) or a host/vector as part of their life cycle (vector-borne) are those most likely to be affected by flooding. Considering the most notable recent destructive floods events of July 2021 that affected several Central Europe countries, we conducted a systematic literature review in order to identify documented sporadic cases and outbreaks of infectious diseases in humans in Europe, where hydrometeorological hazards, mainly floods, were thought to have been involved. The occurrence of water-, rodent-, and vector-borne diseases in several European countries is highlighted, as flooding and the harsh post-flood conditions favor their emergence and transmission. In this context, strategies for prevention and management of infectious disease outbreaks in flood-prone and flood-affected areas are also proposed and comprise pre- and post-flood prevention measures, pre- and post-outbreak prevention measures, as well as mitigation actions when an infectious disease outbreak finally occurs. Emphasis is also placed on the collision of floods, flood-related infectious disease outbreaks, and the evolving COVID-19 pandemic, which may result in unprecedented multi-hazard conditions and requires a multi-hazard approach for the effective disaster management and risk reduction.

Biodiversity of New Lytic Bacteriophages Infecting Shigella spp. in Freshwater Environment

Bacteriophages, viruses that infect and replicate within prokaryotic cells are the most abundant life forms in the environment, yet the vast majority of them have not been properly reported or even discovered. Almost all reported bacteriophages infecting the Enterobacteriaceae family, with Escherichia coli being the major subject of studies, have been isolated from wastewater, sewage, and effluent resources. In the present study, we focused on the distribution and biodiversity of Shigella phages in an aquatic ecosystem. While no Shigella bacteria was recovered from the Yangtze River, three lytic phages were isolated from this ecosystem and were subjected to biological, morphological, and genomic characteristics. Comparative genomics and phylogenetic analyses demonstrated that vB _SflM_004 isolate belongs to Myoviridae family, Felixounavirus genus of Ounavirinae subfamily, vB_SdyM_006 was classified under the same family, however, it is suggested to be in a new genus under Tevenvirinae subfamily with some other related bacteriophages. vB_SsoS_008 phage belongs to the Siphoviridae family, Tunavirus genus, Tunavirinae subfamily. The phages did not harbor any genes involved in the lysogenic cycles and showed a high temperature and pH stability. The biodiversity of the isolated phages highly suggests that continued isolation on non-model members of Enterobacteriaceae family is necessary to fully understand bacteriophage diversity in aquatic environments.

Weather and gastrointestinal disease in Spain: A retrospective time series regression study

BACKGROUND

A few studies in high-income countries have investigated the relationship between ambient temperature and/or precipitation and the occurrence of gastroenteritis. In most of the cases, hot temperatures and heavy precipitation events have been related to increases in infections. This is of concern as climate change predictions indicate an increase of those extreme events. Our aim was to evaluate the association between meteorological variables and daily gastroenteritis hospitalizations in Spain for the period 1997-2013.

METHODS

We obtained data on all hospitalizations which occurred in Spain for the study period from administrative databases and selected those with gastroenteritis as the main diagnosis. Meteorological data was obtained from the European Climate Assessment & Dataset. Daily counts of hospitalizations were linked to meteorological variables in a retrospective ecological time series study using quasi-Poisson regression models with overdispersion and applying the Distributed Lag Non-linear Model (DLNM) framework.

RESULTS

Both high and cold temperatures increased the risk of gastroenteritis hospitalizations (relative risk (RR) = 1.21, 95% confidence interval (CI): 1.09, 1.34; and RR = 1.07, 95% CI: 1.00, 1.15, respectively), whereas heavy precipitation was found protective for those hospitalizations (RR = 0.74, 95% CI: 0.63, 0.86). Hot temperatures increased hospitalizations for gastroenteritis classified as foodborne or idiopathic but not those in the group of Others, which were composed mainly of infections by rotavirus and were associated with cold temperatures.

CONCLUSIONS

Our findings suggest an important role of ambient temperatures, especially hot temperatures, in increasing gastroenteritis hospitalizations, while the exposure to heavy precipitation events pose opposite and unexpected effects on these infections.

A Waterborne Outbreak of Shigella sonnei with Resistance to Azithromycin and Third-Generation Cephalosporins in China in 2015

Here, we report for the first time a waterborne outbreak of Shigella sonnei in China in 2015. Eleven multidrug-resistant (MDR) S. sonnei isolates were recovered, showing high resistance to azithromycin and third-generation cephalosporins in particular, due to an mph(A)- and bla_CTX-M-14-harboring IncB/O/K/Z group transmissible plasmid of 104,285 kb in size. Our study highlights the potential prevalence of the MDR outbreak of S. sonnei in China and its further dissemination worldwide with the development of globalization.

Variation of Bacterial Communities with Water Quality in an Urban Tropical Catchment

A major challenge for assessment of water quality in tropical environments is the natural occurrence and potential growth of Fecal Indicator Bacteria (FIB). To gain a better understanding of the relationship between measured levels of FIB and the distribution of sewage-associated bacteria, including potential pathogens, in the tropics this study compared the abundance of FIB (Total coliforms and E. coli) and the Bacteroidales (HF183 marker) with bacterial community structure determined by next-generation amplicon sequencing. Water was sampled twice over 6 months from 18 sites within a tropical urban catchment and reservoir, followed by extraction of DNA from microorganisms, and sequencing targeting the V3-V4 region of the 16S rRNA gene. Multivariate statistical analyses indicated that bacterial community composition (BCC) varied between reservoir and catchment, within catchment land-uses, and with E. coli concentration. Beta-regression indicated that the proportion of sequences from sewage-associated taxa (SAT) or pathogen-like sequences (PLS) were predicted most significantly by measured levels of E. coli(log MPN/100 mL) (χ² > 8.7; p < 0.003). In addition, SAT were significantly predicted by log HF183 levels (χ²=13.1; p = 0.0003) while PLS were not. Our study suggests that measurements of E. coli concentration could be useful in predicting samples enriched in sewage-associated and pathogen-like bacteria in tropical environments despite the potential for nonconservative behavior.

Safe drinking water and waterborne outbreaks

The present work compiles a review on drinking waterborne outbreaks, with the perspective of production and distribution of microbiologically safe water, during 2000-2014. The outbreaks are categorised in raw water contamination, treatment deficiencies and distribution network failure. The main causes for contamination were: for groundwater, intrusion of animal faeces or wastewater due to heavy rain; in surface water, discharge of wastewater into the water source and increased turbidity and colour; at treatment plants, malfunctioning of the disinfection equipment; and for distribution systems, cross-connections, pipe breaks and wastewater intrusion into the network. Pathogens causing the largest number of affected consumers were Cryptosporidium, norovirus, Giardia, Campylobacter, and rotavirus. The largest number of different pathogens was found for the treatment works and the distribution network. The largest number of affected consumers with gastrointestinal illness was for contamination events from a surface water source, while the largest number of individual events occurred for the distribution network.

Shigellosis Outbreak in Al Batinah South Governorate, Oman: Case-control study

OBJECTIVES

An outbreak of acute gastroenteritis due to Shigella flexneri occurred in August 2012 in the catchment area of the Wadi Sahtan Health Center in Rustaq, Al Batinah South Governorate, Oman. The aim of this study was to discover possible causes of this outbreak in the villages of Fassa, Rogh and Amk and to measure the risk of exposure among cases and controls.

METHODS

A case-control study was conducted in September 2012 in Fassa, Rogh and Amk. All households in the three villages were interviewed. Case and control households were compared to determine possible exposure avenues, including place of residence, source of drinking water, hand hygiene levels and practices related to drinking water, food preparation and environmental sanitation.

RESULTS

Residing in Fassa (P <0.0001; odds ratio [OR] = 4.86, 95% confidence interval [CI] = 2.22-10.63) and average hand hygiene practices (P = 0.008; OR = 13.97, 95% CI = 1.58-123.36) were associated with an increased risk of contracting shigellosis. No significant differences were found with regards to the other exposure avenues.

CONCLUSION

This was the first study conducted in Oman regarding an outbreak of shigellosis in a community setting. The only variables that significantly impacted the risk of acute gastroenteritis were residing in Fassa and average hand hygiene practices. The source of the outbreak could not be identified. However, septic tank sanitation and water and food consumption practices were not satisfactory in the studied villages. These need to be addressed to prevent similar outbreaks of acute gastroenteritis in this region in the future.

Environmental monitoring of bacterial contamination and antibiotic resistance patterns of the fecal coliforms isolated from Cauvery River, a major drinking water source in Karnataka, India

The present study focuses prudent elucidation of microbial pollution and antibiotic sensitivity profiling of the fecal coliforms isolated from River Cauvery, a major drinking water source in Karnataka, India. Water samples were collected from ten hotspots during the year 2011-2012. The physiochemical characteristics and microbial count of water samples collected from most of the hotspots exhibited greater biological oxygen demand and bacterial count especially coliforms in comparison with control samples (p ≤ 0.01). The antibiotic sensitivity testing was performed using 48 antibiotics against the bacterial isolates by disk-diffusion assay. The current study showed that out of 848 bacterial isolates, 93.51% (n = 793) of the isolates were found to be multidrug-resistant to most of the current generation antibiotics. Among the major isolates, 96.46% (n = 273) of the isolates were found to be multidrug-resistant to 30 antibiotics and they were identified to be Escherichia coli by 16S rDNA gene sequencing. Similarly, 93.85% (n = 107), 94.49% (n = 103), and 90.22% (n = 157) of the isolates exhibited multiple drug resistance to 32, 40, and 37 antibiotics, and they were identified to be Enterobacter cloacae, Pseudomonas trivialis, and Shigella sonnei, respectively. The molecular studies suggested the prevalence of bla TEM genes in all the four isolates and dhfr gene in Escherichia coli and Sh. sonnei. Analogously, most of the other Gram-negative bacteria were found to be multidrug-resistant and the Gram-positive bacteria, Staphylococcus spp. isolated from the water samples were found to be methicillin and vancomycin-resistant Staphylococcus aureus. This is probably the first study elucidating the bacterial pollution and antibiotic sensitivity profiling of fecal coliforms isolated from River Cauvery, Karnataka, India.

Low compliance with national guidelines for preventing transmission of group 1 nationally notifiable infectious diseases in Korea

PURPOSE

This study was performed to evaluate the compliance with, and adequacy of, the Korean national guidelines which had been recommended until 2011 for isolation of patients with group 1 nationally notifiable infectious diseases (NNIDs), namely cholera, typhoid fever, paratyphoid fever, shigellosis, and enterohemorrhagic Escherichia coli (EHEC) infection.

MATERIALS AND METHODS

We evaluated the clinical and microbiological characteristics of confirmed cases of group 1 NNIDs and compliance with the guidelines in 20 Korean hospitals nationwide in 2000-2010. We also compared the Korean guidelines with international guidelines.

RESULTS

Among 528 confirmed cases (8 cases of cholera, 232 of typhoid fever, 81 of paratyphoid fever, 175 of shigellosis, and 32 EHEC infections), strict compliance with the Korean guideline was achieved in only 2.6% to 50.0%, depending on the disease. While the Korean guidelines recommend isolation of all patients with group 1 NNIDs, international guidelines recommend selective patient isolation and screening for fecal shedding, depending on the type of disease and patient status.

CONCLUSION

Compliance with the previous national guidelines for group 1 NNIDs in Korea was generally very low. Further studies are needed to evaluate whether compliance was improved after implementation of the new guideline in 2012.

Measuring underreporting and under-ascertainment in infectious disease datasets: a comparison of methods

BACKGROUND

Efficient and reliable surveillance and notification systems are vital for monitoring public health and disease outbreaks. However, most surveillance and notification systems are affected by a degree of underestimation (UE) and therefore uncertainty surrounds the 'true' incidence of disease affecting morbidity and mortality rates. Surveillance systems fail to capture cases at two distinct levels of the surveillance pyramid: from the community since not all cases seek healthcare (under-ascertainment), and at the healthcare-level, representing a failure to adequately report symptomatic cases that have sought medical advice (underreporting). There are several methods to estimate the extent of under-ascertainment and underreporting.

METHODS

Within the context of the ECDC-funded Burden of Communicable Diseases in Europe (BCoDE)-project, an extensive literature review was conducted to identify studies that estimate ascertainment or reporting rates for salmonellosis and campylobacteriosis in European Union Member States (MS) plus European Free Trade Area (EFTA) countries Iceland, Norway and Switzerland and four other OECD countries (USA, Canada, Australia and Japan). Multiplication factors (MFs), a measure of the magnitude of underestimation, were taken directly from the literature or derived (where the proportion of underestimated, under-ascertained, or underreported cases was known) and compared for the two pathogens.

RESULTS

MFs varied between and within diseases and countries, representing a need to carefully select the most appropriate MFs and methods for calculating them. The most appropriate MFs are often disease-, country-, age-, and sex-specific.

CONCLUSIONS

When routine data are used to make decisions on resource allocation or to estimate epidemiological parameters in populations, it becomes important to understand when, where and to what extent these data represent the true picture of disease, and in some instances (such as priority setting) it is necessary to adjust for underestimation. MFs can be used to adjust notification and surveillance data to provide more realistic estimates of incidence.

Characterization and complete genome sequence of the Shigella bacteriophage pSf-1

Shigellosis is a global health problem, and Shigella flexneri is the major cause of this disease. In this study, we isolated a virulent Siphoviridae bacteriophage (phage), pSf-1, that infects S. flexneri. This phage was isolated from the Han River in Korea and was found to infect S. flexneri, Shigella boydii, and Shigella sonnei. One-step growth analysis revealed that this phage has a short latent period (10 min) and a large burst size (86.86 PFU/cell), indicating that pSf-1 has good host infectivity and effective lytic activity. The double-stranded DNA genome of pSf-1 is composed of 51,821 bp with a G + C content of 44.02%. The genome encodes 94 putative ORFs, 71 putative promoters, and 60 transcriptional terminator regions. Genome sequence analysis of pSf-1 and comparative analysis with the homologous Shigella phage Shfl1 revealed that there is a high degree of similarity between pSf-1 and Shfl1 in 54 of the 94 ORFs of pSf-1. The results of this investigation indicate that pSf-1 is a novel Shigella phage and that this phage might have potential uses against shigellosis.

Quality of piped and stored water in households with children under five years of age enrolled in the Mali site of the Global Enteric Multi-Center Study (GEMS)

Water, sanitation, and hygiene information was collected during a matched case-control study of moderate and severe diarrhea (MSD) among 4,096 children < 5 years of age in Bamako, Mali. Primary use of piped water (conditional odds ratio [cOR] = 0.45; 0.34-0.62), continuous water access (cOR = 0.30; 0.20-0.43), fetching water daily (cOR = 0.77; 0.63-0.96), and breastfeeding (cOR = 0.65; 0.49-0.88) significantly reduced the likelihood of MSD. Fetching water in > 30 minutes (cOR = 2.56; 1.55-4.23) was associated with MSD. Piped tap water and courier-delivered water contained high (> 2 mg/L) concentrations of free residual chlorine and no detectable Escherichia coli. However, many households stored water overnight, resulting in inadequate free residual chlorine (< 0.2 mg/L) for preventing microbial contamination. Coliforms and E. coli were detected in 48% and 8% of stored household water samples, respectively. Although most of Bamako's population enjoys access to an improved water source, water quality is often compromised during household storage.

Standardization and international multicenter validation of a PulseNet pulsed-field gel electrophoresis protocol for subtyping Shigella flexneri isolates

Shigella flexneri is one of the agents most frequently linked to diarrheal illness in developing countries and often causes outbreaks in settings with poor hygiene or sanitary conditions. Travel is one of the means by which S. flexneri can be imported into developed countries, where this pathogen is not commonly seen. A robust and discriminatory subtyping method is needed for the surveillance of S. flexneri locally and regionally, and to aid in the detection and investigation of outbreaks. The PulseNet International network utilizes standardized pulsed-field gel electrophoresis (PFGE) protocols to carry out laboratory-based surveillance of foodborne pathogens in combination with epidemiologic data. A multicenter validation was carried out in nine PulseNet laboratories located in North and South America, Europe, and Asia, and it demonstrated that a new protocol is highly robust and reproducible for subtyping of S. flexneri. This protocol, already approved for PulseNet laboratories, applies NotI and XbaI as primary and secondary restriction enzymes, respectively, under electrophoresis conditions of initial switch time of 5 s to final switch time of 35 s, at 6 volts/cm.

Weather, water quality and infectious gastrointestinal illness in two Inuit communities in Nunatsiavut, Canada: potential implications for climate change

Climate change is expected to cause changes in precipitation quantity, intensity, frequency and duration, which will subsequently alter environmental conditions and might increase the risk of waterborne disease. The objective of this study was to describe the seasonality of and explore associations between weather, water quality and occurrence of infectious gastrointestinal illnesses (IGI) in two communities in Nunatsiavut, Canada. Weather data were obtained from meteorological stations in Nain (2005-2008) and Rigolet (2008). Free-chlorine residual levels in drinking water were extracted from municipal records (2005-2008). Raw surface water was tested weekly for total coliform and E. coli counts. Daily counts of IGI-related clinic visits were obtained from health clinic registries (2005-2008). Analysis of weather and health variables included seasonal-trend decomposition procedures based on Loess. Multivariable zero-inflated Poisson regression was used to examine potential associations between weather events (considering 0-4 week lag periods) and IGI-related clinic visits. In Nain, water volume input (rainfall + snowmelt) peaked in spring and summer and was positively associated with levels of raw water bacteriological variables. The number of IGI-related clinic visits peaked in the summer and fall months. Significant positive associations were observed between high levels of water volume input 2 and 4 weeks prior, and IGI-related clinic visits (P < 0.05). This study is the first to systematically gather, analyse and compare baseline data on weather, water quality and health in Nunatsiavut, and illustrates the need for high quality temporal baseline information to allow for detection of future impacts of climate change on regional Inuit human and environmental health.

Shigellosis outbreak linked to canteen-food consumption in a public institution: a matched case-control study

On 13 November 2009, the authorities of Flemish Brabant, Belgium, received an alert concerning a potential outbreak of Shigella sonnei at a public institution. A study was conducted to assess the extent, discover the source and to implement further measures. We performed a matched case-control study to test an association between shigellosis and canteen-food consumption. Water samples and food handlers' faecal samples were tested. The reference laboratory characterized the retrospectively collected Shigella specimens. We found 52 cases distributed over space (25/35 departments) and time (2 months). We found a matched odds ratio of 3·84 (95% confidence interval 1·02-14·44) for canteen-food consumption. A food handler had travelled to Morocco shortly before detection of the first laboratory-confirmed case. Water samples and food handlers' faecal samples tested negative for Shigella. Confirmed cases presented PFGE profiles, highly similar to archived isolates from Morocco. Foodborne transmission associated with the canteen was strongly suspected.