Bromine and Chlorine Disinfection of Cryptosporidium parvum Oocysts, Bacillus atrophaeus Spores, and MS2 Coliphage in Water.

Conventional water treatment practices utilizing chemical disinfection, especially chlorination, are considered generally effective in producing microbiologically safe drinking water. However, protozoan pathogens such as oocysts of Cryptosporidium parvum are very resistant to chlorine, which has led to consideration of alternative disinfectants for their control. Free bromine, HOBr, has not been evaluated extensively as an alternative halogen disinfectant for inactivation of Cryptosporidium parvum in drinking water or reclaimed water for non-potable uses. Bromine is a versatile disinfectant consisting of different chemical forms with persistent microbicidal efficacy under varied water quality conditions and is effective against a range of waterborne microbes of health concern. The objectives of this study are to (1) compare the efficacy of free bromine to free chlorine at similar concentrations (as milligrams per liter) for disinfection of Cryptosporidium parvum oocysts, Bacillus atrophaeus spores, and MS2 coliphage in a model buffered water and (2) evaluate the kinetics of inactivation of these microorganisms using appropriate disinfection models. Overall, at a target concentration of ∼5 mg/L, bromine averaged 0.6 log (73.8%) reductions of C. parvum oocyst infectivity after 300 min (CT: 1166 min·mg/L) and produced up to a 0.8 log reduction disinfectant activity. An ∼5.0 mg/L chlorine dose increased oocyst infectivity by only 0.4 log (64%) after 300 min (CT: 895 min·mg/L). Bacillus atrophaeus spores and MS2 coliphage treated with bromine and chlorine were reduced by 4 log10 (99.99%) for both disinfectants over the duration of the experiments.

Evidence Map and Systematic Review of Disinfection Efficacy on Environmental Surfaces in Healthcare Facilities.

Healthcare-associated infections (HAIs) contribute to patient morbidity and mortality with an estimated 1.7 million infections and 99,000 deaths costing USD $28-34 billion annually in the United States alone. There is little understanding as to if current environmental surface disinfection practices reduce pathogen load, and subsequently HAIs, in critical care settings. This evidence map includes a systematic review on the efficacy of disinfecting environmental surfaces in healthcare facilities. We screened 17,064 abstracts, 635 full texts, and included 181 articles for data extraction and study quality assessment. We reviewed ten disinfectant types and compared disinfectants with respect to study design, outcome organism, and fourteen indictors of study quality. We found important areas for improvement and gaps in the research related to study design, implementation, and analysis. Implementation of disinfection, a determinant of disinfection outcomes, was not measured in most studies and few studies assessed fungi or viruses. Assessing and comparing disinfection efficacy was impeded by study heterogeneity; however, we catalogued the outcomes and results for each disinfection type. We concluded that guidelines for disinfectant use are primarily based on laboratory data rather than a systematic review of in situ disinfection efficacy. It is critically important for practitioners and researchers to consider system-level efficacy and not just the efficacy of the disinfectant.

Chitosan Coagulation Pretreatment to Enhance Ceramic Water Filtration for Household Water Treatment.

Viruses are major contributors to the annual 1.3 million deaths associated with the global burden of diarrheal disease morbidity and mortality. While household-level water treatment technologies reduce diarrheal illness, the majority of filtration technologies are ineffective in removing viruses due to their small size relative to filter pore size. In order to meet the WHO health-based tolerable risk target of 10-6 Disability Adjusted Life Years per person per year, a drinking water filter must achieve a 5 Log10 virus reduction. Ceramic pot water filters manufactured in developing countries typically achieve less than 1 Log10 virus reductions. In order to overcome the shortfall in virus removal efficiency in household water treatment filtration, we (1) evaluated the capacity of chitosan acetate and chitosan lactate, as a cationic coagulant pretreatment combined with ceramic water filtration to remove lab cultured and sewage derived viruses and bacteria in drinking waters, (2) optimized treatment conditions in waters of varying quality and (3) evaluated long-term continuous treatment over a 10-week experiment in surface waters. For each test condition, bacteria and virus concentrations were enumerated by culture methods for influent, controls, and treated effluent after chitosan pretreatment and ceramic water filtration. A > 5 Log10 reduction was achieved in treated effluent for E.coli, C. perfringens, sewage derived E. coli and total coliforms, MS2 coliphage, Qß coliphage, ΦX174 coliphage, and sewage derived F+ and somatic coliphages.