Evaluation of media for simultaneous enumeration of total coliform and Escherichia coli in drinking water supplies by membrane filtration techniques

This study evaluated three different dehydrated media for simultaneous detection and enumeration of total coliform （TC） and Escherichia coil in drinking water samples with a standard membrane filtration procedure. The experiment indicated that the differential coliform agar （DCA） medium was the most effective among the tested media in enumerating TC and E. coil, without the need for extensive accompanying confirmation tests. The results for DCA medium were highly reproducible for both TC and E. coil with standard deviation of 6.0 and 6.1, respectively. A high agreement （82%） was found between DCA and m-Endo media on 152 drinking water samples in terms of TC positive. The DCA medium also reduced concealment of background bacteria.

Antimicrobial Resistant Coliforms in Tap Water with Low Free Residual Chlorine Levels in Two Hospitals: Case Study in Gaza, Palestine

Universal access to safe water, whether at households or health centres, is central to achieving the sixth sustainable development goal by 2030. A hospital-based survey was conducted to screen for antimicrobial resistance among coliforms in samples collected from tap water (n = 54) at surgical wards in Gaza and to investigate the association with free residual chlorine and pH levels. Total coliforms (TC) were detected in 48.1% (26/54) of tested samples and FCs were detected in 25.9% (14/54). Free residual chlorine test ranged from zero to 0.2 mg/l (average: 0.08 mg/l), of which more than half of the samples (53.7%) 29/54 showed no free residual chlorine. The mean value of free residual chlorine in samples tested positive for growth on m-Endo (0.03) was lower than the mean for negative samples (0.14). The pH values were within the acceptable range (average: 7.6) and there was a statistically significant variation between the mean of pH values for samples tested positive on m-Endo (7.29) and that tested negative (7.84). Among coliform positive samples, 23.1% (6/26) had coliform isolates with resistance patterns. More than two-thirds of antimicrobial resistant (AMR) isolates were resistant to amikacin, ceftazidime, ceftriaxone, and imipenem. Moreover, 50% of the isolates were resistant to piperacillin-tazobactam. One-third (33.3%) of isolates were resistant to cefoxitin, and fosfomycin, 16.7% were resistant to ciprofloxacin, and nitrofurantoin. Intermediate resistance was shown in 16.7% of the isolates to cefoxitin and ciprofloxacin. The ESBL and carbapenem resistance genes detected in isolates were TEM (66.7%), NDM (33.3%), OXA (25%), blaCTXM (16.7%), and blaCTXM-3 (16.7%). The finding highlighted the level of contamination with AMR coliform in samples collected from tap water and pointed out the importance of managing water safety through identifying the main source of contamination, in addition to maintaining proper water disinfection at healthcare facilities for the patient, staff and environmental safety.

Microbiological Quality of Freshly Prepared, Packaged Fruit and Milk Juices Sold in Cafés, Shops, and Supermarkets in Hargeisa, Somaliland

Background: Due to their delicious taste, high nutritional content, and health benefits, fruit juices are well-known drinks in many countries and are now an essential component of the modern diet. Objective: Determining the microbiological quality of both packaged and freshly made fruit and milk juices. Method: The spread-plate approach was employed to isolate and count the bacteria. 90 ml of sterile peptone water were blended with 10 ml of well-mixed, packed, and freshly made fruit juices. The samples were sequentially diluted (101 - 105) in accordance with the Indian Manual of Food Microbiological Testing Methods. Results: From eight samples of imported packaged fruit and milk juice, the average of total coliform, staphylococci, and viable bacterial counts were zero, 1.39 × 102, and 2 × 102 CFU/ml, respectively. In contrast, from three samples of locally produced fruit and milk juice, the average of total coliform, staphylococci, and viable bacterial counts were zero, 5.83 × 102, and 2.73 × 103 CFU/ml, respectively. Four samples of handmade prepared fruit and milk juices had a mean of total coliform, staphylococci, and viable bacterial count of 1.441 × 104, 4.1 × 103, and 2.35 × 105 CFU/ml, respectively. Conclusion: 33.3% of the results from microbiological analysis of freshly made fruit and milk juices met the permissible range of the Revised Microbiological Standards for Fruit and Vegetables and Their Products, which were published in 2018 and as well as the Hong Kong Center for Food Safety, whereas 66.7% of the microbiological analyses of freshly prepared fruit and milk juices were above the permissible reference range of GSO standard 2000. 12.5% of the investigated imported and packed fruits and milk juices had one failed test (TSC), which was above the acceptable limit, 87.5% of the tested samples of fruit and milk juices fulfilled the necessary standards of TCC, TVBC, and TSC. 100% of the tested locally manufactured fruit and milk juices complied with TSC, TCC, and TVBC requirements. All investigations showed that freshly made fruit and milk juices were heavily contaminated (Total viable bacterial count, total coliform count, and total staphylococcus count). .

Kinetics of Treated Domestic Sewage Disinfection through Catalytic Oxidation with H2O2

The inactivation of bacterial cells through catalyzed oxidation using hydrogen peroxide as the primary oxidant agent is dependent on a series of factors, such as the concentration of the catalyst, the rate of hydroxyl radical formation in the controlled decomposition of the oxidant agent, and the concentration and toxicity of hydrogen peroxide. The objective of this study was to develop a mathematical model able to predict the kinetics of the inactivation Escherichia coli and total coliforms cells present in treated domestic sewage through catalytic peroxidation. The catalyst used was iron oxide supported on mineral coal （called CP）, and the effects of the operational conditions, including hydrogen peroxide concentration and dosage of catalyst, were evaluated. The results showed that the disinfection kinetics of the treated domestic sewage is dependent on the concentrations of hydrogen peroxide and catalyst dosage. The kinetic model was shown to be able to predict the behavior of the inactivation kinetics of the bacterium Escherichia coli ATCC-25922 when different concentrations of hydrogen peroxide （75 and 100 mg·L^-1） were used, regardless of the catalyst dosage.

Assessment of Water Microbiologic Pollution in Durres＇s Marine Harbour Basin, Albania

The aim of this study is to assess the water microbiologic pollution in Durres＇s Harbour basin and to compare it with European standards. The comparison of heterotrophs and total coliforms level in sampling are the essence of this research. The object of this study is done in four sampling areas of Durres＇s Harbour basin. In order to compare the level of water microbiologic pollution in four areas of Durres＇s Harbour basin, control area is also studied which is a beach area near the Harbour named Apollonia Beach. The sampling areas were： Ferry Terminal （FT）, Fishery Harbor （FH）, East Zone （EZ）, Fuel Quay （FQ） and Apollonia Beach （AB）, respectively. The period of sample-taking was July-October 2008. The strategy used for this purpose consisted in water insemination with coverage method by means of Petri＇s plates according to respective dilutions in culture media Plate Count Agar （PCA） for heterotrophs and MacConkey for total coliforms. The number of colonies that are formed determines the number of cells at the moment of water insemination, the number of heterotrophs in culture media PCA, respectively. The number of pink and red colonies that were formed determines the number of cells at the moment of water insemination, the number of total coliforms in culture media MacConkey, respectively. The measure ofheterotrophic bacteria and total coliforms used is Colony-Forming Units （CFU）/100 mL seawater. （AB） is within European standards. The richest area with heterotrophs is （FH）, which confirms the fact that it is the most polluted microbiologic area in the Harbour basin of Durres. The richest area with total coliforms is （FT）. The poorest area with heterotrophs and total coliforms is （FQ）.

The Bacterial Load of Hospital Discharges(Sidi Kacem,Morocco)

Fecal microorganisms, which are indicators or pathogens, have an optimum growth in the specific conditions of the internal environment animal or human. Therefore, when issued by a host, they result in sudden and drastic changes in the environment. This study aims at bacteriological characterization of the effluent from the provincial hospital in Sidi Kacem. And it shows that the effluent from the hospital contributing to non-regulatory standards ultimately reaches the environment (river wadi floor, animal, vegetable...). The results of bacteriological analyses (Total Coliforms, Fecal Coliforms) about sewage from the provincial hospital depending on the day of rest and work in the city of Sidi Kacem are presented with means respectively 557 × 104 and 328 × 104 in the rest and working days 555 × 104, 342 × 104 and the much higher maximum working days from the day of rest are 64 × 105 and 42 × 105. The results obtained show that the rate of bacteria (CT-CF) exceeds standards recommended by CNS (1994) and WHO (1996, 1997). These results have adverse effects on human life, animal, environment and ecosystem in general.

Evaluating Drinking Water Treatment Methods in the Njala University and Neighboring Mokonde Communities in Southern Sierra Leone

Rural communities in sub-Saharan Africa (SSA) are always faced with the challenge of securing safe water for beneficial uses. Most communities lack a centralized water supply system and, thus, each residence utilizes the treatment method that they can afford. This study evaluated three treatment methods for drinking water in the Njala University and Mokonde communities in southern Sierra Leone. In the perceived natural treatment, residents in the Mokonde community believe that groundwater has been purified by the soil media and, hence, does not require further treatment. In the conventional treatment, the Njala University Water Works use sand filtration and chlorine disinfection to treat water from the Taia River. The third treatment method, first flush diversion, was introduced by Njala University researchers in 2014. We studied the populations of coliform bacteria and E. coli in untreated and treated water samples to determine if each of the treatment methods supported the beneficial use of drinking. This study concludes that the natural filtration does not remove pathogens in the well water. Even though the first flush and conventional treatments were efficient in reducing microbial populations in the water, the World Health Organization’s 100% removal guideline was not achieved most of the time. Therefore, all three treatment methods did not support the beneficial use of drinking. Further treatment was needed to render the water potable.