Levels Of Indicator Microorganisms Research Articles

Kvaliteta mora za kupanje na plažama u Kaštelima (Hrvatska) u razdoblju primjene Direktive o upravljanju kvalitetom vode za kupanje 2006/7/EC

We analyzed and discussed bathing water quality at 11 official bathing sites in Kaštela (Croatia) in the period 2009-2022. The results showed spatial and temporal variations in quality. The worst bathing water quality was in the eastern part of the area, at beaches Torac, Kamp and Gojača. Levels of indicator microorganisms at identified sources of fecal pollution near these beaches indicate a significant load of fecal material to these areas. The observed decrease in annual fecal indicator bacteria exceedances, while not statistically significant, indicates a trend toward improvement in water quality. The number of sites with worse annual and final assessment showed a decreasing trend only since 2017 and 2020, respectively, which is not a ‘sufficient’ time period to draw a clear conclusion about the trend. The improvements are probably the result of intensive work in recent years to improve the sewage system in the area. In the annual and final assessment, bathing sites from Kaštela with ‘poor’ water quality accounted on average for more than 27% of all waters with ‘poor’ quality in Croatia. This implies that additional efforts are needed to eliminate the sources of fecal pollution in the area.

Effects of Using an Alternative Bedding Composition on the Levels of Indicator Microorganisms and Mammary Health in Dairy Farm Conditions

The aim of this study was to compare an improved bedding composition with conventional straw bedding under farm conditions, regarding its effects on the influence of indicator microorganisms on the hygiene levels of cubicle floors and the occurrence of mastitis in dairy cows. Dairy cows were housed in newly built stalls divided into two parts, each with four subsections, and bedded cubicles arranged in three rows. Five stall subsections from each 9-bedded cubicle were selected for study, and 30 dairy cows were monitored according to the time intervals of bedding treatment for cubicles. In the first subsection (control), the cows were housed in bedded cubicles layered with straw up to a height of 20 cm. Sections 2–5 had alternative bedding (AB) as follows: fresh AB, AB 1 month old, AB 2 months old, and AB 3 months old, which were bedded one day before (fresh) and 1–3 months before the actual observation period, respectively. The alternative bedding per one cubicle consisted of ground limestone (100 kg), water (80 L), recycled manure solids (RMS; 15 kg), and straw (25 kg). After laying, the bedding was treated with a concrete selector to provide strength and sufficient resistance. A total of 180 bedding and 600 quarter milk samples were taken simultaneously from all five monitored subsections for microbiological determination. Comparing classical straw bedding with the alternate bedding showed a stabilizing effect by keeping the bedding thickness up to the floor barrier level, which had a beneficial effect by reducing the level of fecal contamination in the rear of the cubicle. Fecal coliforms and fecal streptococci were found to be reduced in one-day-old bedding as well as after the first, second, and third months. By evaluating the health status of the mammary glands, a positive effect was noted in reducing the occurrence of subclinical mastitis, which was reflected in a reduced number of infected quarters in the group of cows housed in cubicles for three months after use of improved bedding.

Salmonella, Listeria monocytogenes, and Indicator Microorganisms on Hass Avocados Sold at Retail Markets in Guadalajara, Mexico

Hass avocados may become contaminated with Salmonella and Listeria monocytogenes at the farm and the packing facility or later during transportation and at retail. In Mexico, avocados are frequently sold in bulk at retail markets, where they are stored at room temperature for several hours or days and exposed to potential sources of microorganisms. These conditions may favor the entry, adhesion, survival, and biofilm formation of Salmonella and L. monocytogenes. The aim of this study was to determine the occurrence of Salmonella, L. monocytogenes, and other Listeria species and the levels of indicator microorganisms on the surface of avocados sold at retail markets. A total of 450 samples (Persea americana var. Hass) were acquired from retail markets located in Guadalajara, Mexico. One group of 225 samples was evaluated for the presence of Salmonella and for enumeration of aerobic plate counts, yeasts and molds, Enterobacteriaceae, coliforms, and Escherichia coli. The other 225 samples were processed for isolation of L. monocytogenes and other Listeria species. Microbial counts (log CFU per avocado) were 4.3 to 9.0 for aerobic plate counts, 3.3 to 7.1 for yeasts and molds, 3.3 to 8.2 for Enterobacteriaceae, 3.3 to 8.4 for coliforms, and 3.3 to 6.2 for E. coli. Eight samples (3.5%) were positive for Salmonella. Listeria spp. and L. monocytogenes were detected in 31 (13.8%) and 18 (8.0%) of 225 samples, respectively. Listeria innocua, Listeria welshimeri, and Listeria grayi were isolated from 7.6, 1.3, and 0.9% of samples. These results indicate that avocados may carry countable levels of microorganisms and could be a vehicle for transmission of Salmonella and L. monocytogenes.

Comparative reduction of Giardia cysts, F+ coliphages, sulphite reducing clostridia and fecal coliforms by wastewater treatment processes

ABSTRACTAdvanced wastewater treatment processes are applied to prevent the environmental dissemination of pathogenic microorganisms. Giardia lamblia causes a severe disease called giardiasis, and is highly prevalent in untreated wastewater worldwide. Monitoring the microbial quality of wastewater effluents is usually based on testing for the levels of indicator microorganisms in the effluents. This study was conducted to compare the suitability of fecal coliforms, F+ coliphages and sulfide reducing clostridia (SRC) as indicators for the reduction of Giardia cysts in two full-scale wastewater treatment plants. The treatment process consists of activated sludge, coagulation, high rate filtration and either chlorine or UV disinfection. The results of the study demonstrated that Giardia cysts are highly prevalent in raw wastewater at an average concentration of 3600 cysts/L. Fecal coliforms, F+ coliphages and SRC were also detected at high concentrations in raw wastewater. Giardia cysts were efficiently removed (3.6 log10) by the treatment train. The greatest reduction was observed for fecal coliforms (9.6 log10) whereas the least reduction was observed for F+ coliphages (2.1 log10) following chlorine disinfection. Similar reduction was observed for SRC by filtration and disinfection by either UV (3.6 log10) or chlorine (3.3 log10). Since F+ coliphage and SRC were found to be more resistant than fecal coliforms for the tertiary treatment processes, they may prove to be more suitable as indicators for Giardia. The results of this study demonstrated that advanced wastewater treatment may prove efficient for the removal of Giardia cysts and may prevent its transmission when treated effluents are applied for crop irrigation or streams restoration.

Microbial safety considerations of flooding in primary production of leafy greens: A case study

This study evaluated the effects of a flood event, floodplain and climatic parameters on microbial contamination of leafy greens grown in the floodplains. Additionally, correlations between pathogenic bacteria and levels of indicator microorganisms have been also determined. To diagnose the microbial contamination after the flood event, sampling was carried out in weeks 1, 3, 5 and 7 after the flooding in four flooded lettuce fields. To assess the impact of flooding on the microbial contamination of leafy greens, indicator microorganisms (coliforms, Escherichia coli and Enterococcus) and pathogenic microorganisms (Salmonella spp., VTEC (E. coli O157:H7 and other verocytotoxin producing E. coli, O26, O103, O111, O145) and Listeria monocytogenes) were evaluated. Irrigation water, soil and lettuce samples showed levels of coliforms and E. coli higher than 5 and 3logcfu/g or 100mL, respectively when sampled 1week after flooding. However, bacterial counts drastically declined three weeks after the flooding. Climatic conditions after flooding, particularly the solar radiation (6–8MJ/m2), affected the survival of bacteria in the field. L. monocytogenes was not detected in lettuce samples, except for 2 samples collected 3weeks after the flooding. The presence of Salmonella was detected in irrigation water, soil and lettuce by multiplex PCR one week after the flooding, but only 2 samples of soil and 1 sample of water were confirmed by colony isolation. Verotoxigenic E. coli was detected in soil and lettuce samples by multiplex PCR. Therefore, the implication of flood water as the source of VTEC contamination of soil and lettuce was not clear. E. coli counts in irrigation water were positively correlated with those in lettuce. A significant correlation (P<0.005) was found between the presence of pathogens and E. coli counts, highlighting a higher probability of detection of pathogens when high levels of E. coli are found. The results obtained in the present study confirm previous knowledge which defined flooding as a main risk factor for the microbial contamination of leafy greens.

Evaluating the Dilution of Wastewater Treatment Plant Effluent and Viral Impacts on Shellfish Growing Areas in Mobile Bay, Alabama

The U.S. Food and Drug Administration (FDA) provides guidance to state shellfish control authorities on establishing prohibitive closure zones in proximity to wastewater treatment plant (WWTP) discharges with the purpose of minimizing the exposure of molluscan shellfish to health hazards posed by bacterial and viral pathogens present in wastewater effluents. For more than 25 years, the FDA has recognized conditional area management as an option to minimize the size of a prohibitive closure zone, and to enlarge the size and productivity of shellfish growing areas. To use this option, the FDA has recommended achieving a 1,000:1 dilution of effluent within the perimeter of the prohibited closure zone. Using newly available analytical methods and hydrographic equipment, the FDA is undertaking studies to determine whether its 1,000:1 dilution recommendation is supported by the findings. From 2007 through 2009, the FDA conducted field investigations to assess the impacts of wastewater effluent from a large municipal WWTP that discharges into Alabama's Mobile Bay. The dilution of the effluent in the bay was ascertained by conducting a hydrographic dye study using rhodamine WT tracer dye. Submersible fluorometers fastened to oyster cages at sentinel stations were used to determine continuously the dilution of the dye-tagged effluent throughout a 4-day study period. In addition, dilution and dispersion of the dye-tagged effluent was tracked throughout Mobile Bay by fluorometric measurements made while conducting boat transects. The microbiological impacts of the wastewater on molluscan shellfish were assessed by testing oysters placed in cages at sentinel stations at various distances along the anticipated path of the effluent. Levels of fecal coliforms, Escherichia coli, male-specific coliphage, and norovirus genogroups I and II were determined. Norovirus genogroup II was detected in oysters that were located as far as 5.74 km from the discharge, an area in close proximity to the calculated 1,000:1 dilution line. Results also showed that the levels of indicator microorganisms and viral pathogens in the shellfish inversely correlated with increased dilutions of the wastewater effluent in Mobile Bay.

Bacterial and viral pathogens in live oysters: 2007 United States market survey.

Two samples of market oysters, primarily from retail establishments, were collected twice each month in each of nine states during 2007. Samples were shipped refrigerated overnight to five U.S. Food and Drug Administration laboratories on a rotating basis and analyzed by most probable number (MPN) for total and pathogenic Vibrio parahaemolyticus and V. vulnificus numbers and for the presence of toxigenic V. cholerae, Salmonella spp., norovirus (NoV), and hepatitis A virus (HAV). Levels of indicator organisms, including fecal coliforms (MPN), Escherichia coli (MPN), male-specific bacteriophage, and aerobic plate counts, were also determined. V. parahaemolyticus and V. vulnificus levels were distributed seasonally and geographically by harvest region and were similar to levels observed in a previous study conducted in 1998-1999. Levels of pathogenic V. parahaemolyticus were typically several logs lower than total V. parahaemolyticus levels regardless of season or region. Pathogenic V. parahaemolyticus levels in the Gulf and Mid-Atlantic regions were about two logs greater than the levels observed in the Pacific and North Atlantic regions. Pathogens generally associated with fecal pollution were detected sporadically or not at all (toxigenic V. cholerae, 0%; Salmonella, 1.5%; NoV, 3.9%; HAV, 4.4%). While seasonal prevalences of NoV and HAV were generally greater in oysters harvested from December to March, the low detection frequency obscured any apparent seasonal effects. Overall, there was no relationship between the levels of indicator microorganisms and the presence of enteric viruses. These data provide a baseline that can be used to further validate risk assessment predictions, determine the effectiveness of new control measures, and compare the level of protection provided by the U.S. shellfish sanitation system to those in other countries.

The effect of sampling time on the levels of micro-organisms recovered from broiler carcasses in a commercial slaughter plant

Changes in the levels of indicator micro-organisms and Listeria on broiler carcasses were determined at various stages of commercial broiler slaughter and processing. In addition, the effect of time of day that sampling was carried out within the plant on the microbial profile of samples was evaluated. Counts of total aerobic organisms (37°C and 22°C), Enterobacteriaceae, E. coli and Staphylococcus aureus on broiler skin samples were consistently lower on samples obtained during evening visits to the co-operating broiler slaughter plant when compared with corresponding morning samples. Counts of S. aureus were significantly lower for both morning and evening samples taken following final carcass rinsing when compared to pre-evisceration equivalents ( P<0.05). The number of total viable aerobic bacteria, Enterobacteriaceae and E. coli in scald tank water samples taken early each morning prior to processing start-up were significantly lower than corresponding samples obtained after flocks had been processed where an average of 3912 and 42 475 birds had been processed on morning and evening visits, respectively ( P<0.05). The prevalence of Listeria on broiler skin samples consistently increased for both morning and evening samples through the various stages of processing. For example, the prevalence on samples taken in the morning following defeathering, final carcass rinsing, in-line chilling and final carcass chilling was 10%, 40%, 56% and 72%, respectively. The most frequently recovered species of Listeria from these samples were L. innocua (86%), L. monocytogenes (6%), L. grayi (6%) and L. seeligeri (2%).