Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 61
Filtrar
Más filtros

Tipo del documento
Intervalo de año de publicación
1.
J Environ Sci (China) ; 146: 241-250, 2024 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-38969452

RESUMEN

The dynamics of the composition and antibiotic resistance of the fecal coliform bacteria (FCB) in a typical wastewater treatment plant (WWTP) were investigated concerning the seasonal changes. Results showed that WWTP could remove the FCB concentration by 3∼5 logs within the effluent of 104∼105 CFU/L, but the antibiotic resistant rate of FCB species increased significantly after WWTP. The dominant FCB changed from Escherichia coli in the influent (∼73.0%) to Klebsiella pneumoniae in the effluent (∼53.3%) after WWTP, where the Escherichia coli was removed the most, while Klebsiella pneumoniae was the most persistent. The secondary tank removed the most of FCB (by 3∼4 logs) compared to other processes, but increased all the concerned antibiotic resistant rate. The potential super bugs of FCB community showing resistance to all the target antibiotics were selected in the biological treatment unit of WWTP. The FCB showed the highest multiple antibiotic resistance (92.9%) in total which even increased to 100% in the effluent. Klebsiella has the highest antibiotic resistant rate in FCB, with a multiple antibiotic resistance rate of 98.4%. These indicated that the Klebsiella pneumoniae not just Escherichia coli should be specially emphasized after WWTP concerning the health risk associated with FCB community.


Asunto(s)
Escherichia coli , Heces , Eliminación de Residuos Líquidos , Aguas Residuales , Aguas Residuales/microbiología , Eliminación de Residuos Líquidos/métodos , Heces/microbiología , Escherichia coli/efectos de los fármacos , Antibacterianos/farmacología , Enterobacteriaceae/efectos de los fármacos , Enterobacteriaceae/aislamiento & purificación , Farmacorresistencia Bacteriana , Microbiología del Agua , Klebsiella pneumoniae/efectos de los fármacos
2.
Anal Bioanal Chem ; 413(20): 5003-5011, 2021 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-34132819

RESUMEN

A simple and rapid polymerase chain reaction (PCR)-based lateral flow assay (LFA) was developed for multiplex detection of hygiene indicator bacteria. Specifically, new PCR primers were designed for accurately detecting Escherichia coli, coliform bacteria, and total bacteria, and the results obtained as a colorimetric signal (generated by the accumulation of gold nanoparticles at distinct test zones on flow strips) could be identified by the naked eye in <10 min after the completion of PCR. The proposed LFA system did not exhibit any cross-reactivities with 8 distinct bacterial strains and can detect down to 1 colony forming unit (CFU)/mL. Furthermore, three species of cultured bacteria (Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa) inoculated onto sterilized ham were successfully analyzed using the LFA system, which demonstrated that this system shows sufficient sensitivity and specificity for food hygiene monitoring. The speed and simplicity of this LFA make it suitable for use in the food industry as part of routine screening analysis.


Asunto(s)
Bacterias/clasificación , Bacterias/aislamiento & purificación , ADN Bacteriano/química , Microbiología de Alimentos , Cartilla de ADN , Oro , Nanopartículas del Metal/química , Tiras Reactivas , Reproducibilidad de los Resultados , Sensibilidad y Especificidad
3.
J Appl Microbiol ; 130(5): 1721-1729, 2021 May.
Artículo en Inglés | MEDLINE | ID: mdl-32966644

RESUMEN

AIMS: This study was designed to analyse the prevalence of class 1 and class 2 integron integrase genes among antibiotic-resistant coliform bacteria isolated from paper currency circulating in Pakistan. METHODS AND RESULTS: A total of 500 individual currency notes were collected from different food vending sites at Lahore, Pakistan. Bacterial population were identified by biochemical and PCR techniques. Antimicrobial susceptibility testing was performed by disc diffusion assay. The highest bacterial population on currency was found from street vendors and butcher shops. Escherichia coli was found to be the most prevalent coliform bacteria followed by Klebsiella sp. and Enterobacter sp. PCR amplification of antimicrobial resistance gene showed the presence of ampC, blaTEM , blaNDM-1 , qnrA, tet(A) and tet(B) genes among coliform isolates. A total of 47 integron integrase bearing strains of coliform bacteria were analysed. Sequence analysis showed the presence of dfrA1-aadA1, dfrA1, dfrA5, dfrA7, aadA1, aadA4 cassette arrays in class 1 integron and dfrA1-sat2-aadA1 in class 2 integrase genes. CONCLUSION: Circulating currency was heavily contaminated with antimicrobial-resistant coliform bacteria bearing class 1 and class 2 integron integrase genes. SIGNIFICANCE AND IMPACT OF THE STUDY: This study describes a potential threat of severe bacterial infections due to improper hand hygiene and community sanitation when dealing with the currency notes.


Asunto(s)
Farmacorresistencia Bacteriana , Enterobacteriaceae/clasificación , Enterobacteriaceae/genética , Integrasas/genética , Integrones/genética , Papel , Antibacterianos/farmacología , Proteínas Bacterianas/genética , Comercio , ADN Bacteriano , Enterobacteriaceae/efectos de los fármacos , Higiene , Pruebas de Sensibilidad Microbiana , Pakistán , Reacción en Cadena de la Polimerasa
4.
Food Microbiol ; 100: 103860, 2021 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-34416960

RESUMEN

Beef can easily be contaminated with bacteria during the meat production chain. In this work, we studied the contamination levels of mesophilic aerobic bacteria (MAB) and thermotolerant coliform bacteria (TCB) on raw beef surfaces from small shops in Helsinki, Finland and meat markets in Benin City, Nigeria. We also investigated the prevalence of Salmonella, Campylobacter, Yersinia, Shiga toxin-producing Escherichia coli (STEC), Listeria, and cephalosporin-resistant E. coli (CREC). In total, one hundred unpacked raw beef samples from Finland and Nigeria were collected in 2019. The median MAB and TCB counts were significantly (P < 0.001) higher on beef from Nigeria than from Finland. The median MAB and TCB counts in Nigeria were 7.5 and 4.0 log10 cfu/cm2, respectively, and 6.5 and 2.8 log10 cfu/cm2 in Finland, respectively. Most (94%) Nigerian samples were unacceptable according to limits set by the EU. Beef samples from meat markets in Benin City were significantly (P < 0.05) more frequently contaminated with Salmonella, STEC, and CREC than beef samples from small shops in Helsinki. Salmonella, STEC, and CREC were isolated from 30, 36, and 96% of Nigerian samples, respectively, and from <2, 12, and 2% of Finnish samples, respectively. Our study demonstrates a significant difference between the bacterial contaminations of raw beef in Nigeria and Finland, along with a possible misuse of cephalosporins in animal husbandry in Nigeria.


Asunto(s)
Bacterias/aislamiento & purificación , Contaminación de Alimentos/análisis , Carne/microbiología , Animales , Bacterias/clasificación , Bacterias/genética , Bacterias/crecimiento & desarrollo , Bovinos , Finlandia , Microbiología de Alimentos , Nigeria
5.
Environ Monit Assess ; 193(6): 339, 2021 May 14.
Artículo en Inglés | MEDLINE | ID: mdl-33988761

RESUMEN

About one-half of the homes on First Nations (FN) reserves in Manitoba, Canada, receive piped water from a water treatment plant (WTP). Many other homes (31%) are equipped with cisterns that are filled by a water truck, and our objective was to determine how the use of cisterns affects drinking water safety relative to drinking water piped directly to homes from the WTP. The study included belowground concrete cisterns, belowground fiberglass cisterns, and aboveground polyethylene cisterns stored in insulated shelters, and all the data collection methods showed that the tap water in homes with cisterns were relatively more contaminated with coliform bacteria than the tap water in piped homes. The frequency and severity of Escherichia coli and total coliform contamination were numerically greater in drinking water samples from belowground concrete and fiberglass cisterns than in piped water samples in each community, and the contamination of belowground cisterns by coliform bacteria was greatest in late spring. As well, data obtained under the Access to Information Act showed no statistical differences in the percent of satisfactory samples (no detects) between 2014 and 2018, suggesting no clear indication of improved water quality in any of the Tribal Councils in which these three and other communities are a member off. Our results point to the need for additional treatment of drinking water in homes supplied by belowground concrete or fiberglass cisterns and replacement of belowground cisterns with aboveground cisterns or piped water to reduce the risk of water-borne illnesses.


Asunto(s)
Agua Potable , Canadá , Agua Potable/análisis , Monitoreo del Ambiente , Manitoba , Microbiología del Agua , Abastecimiento de Agua
6.
Artículo en Inglés | MEDLINE | ID: mdl-30633653

RESUMEN

Decentralized wastewater management based on vertical flow constructed wetlands (VFCWs) can be an effective solution for minimizing sanitation problems also in urban landscapes, especially when considering rapidly expanding cities in developing countries. Yet, the mass implementation of VFCWs in urbanized areas first needs improvement of a few design drawbacks - among them, the control of infection hazard is of primary importance. Therefore, in this study, the possibility of mitigation of the VFCW-derived infection hazard was assessed, through analysis of bacteriostatic properties of top filtration layer materials, according to clinical experiences based on "safe" antimicrobial surfaces. The experiment was carried out on a daily operating VFCW. Coliform bacteria survival rates were measured for known VFCW construction materials such as Pinus bark, gravel, slag, charcoal and LECA. The calculated die-off rates expressed as 12-h first-order inactivation coefficients ranged between 6.91 h-1 (slag/summer) and 0.58 h-1 (Pinus bark/autumn). The obtained die-off curves showed charcoal, Pinus bark and LECA to have little bacteriostatic properties - even occasionally providing conditions promoting the growth of the coliform population. Meanwhile, slag and gravel were strictly inhibiting bacteria growth, reducing the population up to 99% within the first 3 h of contact time. The research showed that it is possible to significantly mitigate the infection hazard of VFCW by means of proper top-layer substrate material, similar or equal to slag or gravel.


Asunto(s)
Enterobacteriaceae/crecimiento & desarrollo , Aguas Residuales , Purificación del Agua/métodos , Humedales , Carbón Orgánico/química , Arcilla/química , Recuento de Colonia Microbiana , Filtración , Viabilidad Microbiana , Corteza de la Planta/química , Estaciones del Año , Aguas Residuales/química , Aguas Residuales/microbiología
7.
Environ Monit Assess ; 191(8): 516, 2019 Jul 27.
Artículo en Inglés | MEDLINE | ID: mdl-31350602

RESUMEN

In this study, the concentrations of nine typical antibiotics, including sulfadiazine (SD), sulfamerazine (SMR), sulfamethazine (SM2), sulfamethoxazole (SMZ), ofloxacin (OFX), ciprofloxacin (CIP), trimethoprim (TMP), oxytetracycline (OTC), and tetracycline hydrochloride (TC), were detected in the Yitong River by solid-phase extraction high-performance liquid chromatography. The concentrations of the antibiotics were analyzed. Additionally, an improved immobilized substrate enzyme substrate method (DST-enzyme substrate method) was developed and used to evaluate the antibiotic resistance of coliform bacteria to OFX, CIP, enrofloxacin (ENR), TC, sulfisoxazole (SOX), and TMP in the Yitong River. The results showed that the concentrations of the nine antibiotics ranged from nd (not detected) to 1.361 µg/L. The detection rate and concentration of OFX were the highest, followed by CIP, and the detection rate and concentration of SM2 and OTC were the lowest. The detection rate and concentrations of antibiotics were higher in August and November than those in May. The antibiotics were mainly distributed in the livestock sewage discharge and suburban domestic sewage discharge areas. Moreover, the drug resistance of total coliform bacteria to fluoroquinolones, sulfonamides, tetracyclines, and TMP varied with season.


Asunto(s)
Antibacterianos/análisis , Farmacorresistencia Bacteriana/efectos de los fármacos , Enterobacteriaceae/efectos de los fármacos , Monitoreo del Ambiente/métodos , Ríos/química , Contaminantes Químicos del Agua/análisis , China , Enterobacteriaceae/genética
8.
J Clean Prod ; 184: 798-805, 2018 May 20.
Artículo en Inglés | MEDLINE | ID: mdl-29789757

RESUMEN

Providing safe fecal sludge (FS) sanitation has remained an important goal of global communities because of the high risks imposed on human health of the exposure to un-sanitized FS. This study used lactic acid fermentation as a pre-treatment technology to evaluate the sanitization effect of lactic acid bacteria (LAB) on FS. A combination of fermented rice flour and brown sugar was used as the medium to prepare LAB, and fecal coliforms were used as the indicator organisms. The addition of a LAB suspension grown in fermented rice flour and brown sugar to FS was studied to evaluate the survival of fecal coliforms. The pH decreased during ongoing lactic acid fermentation after the addition of the LAB suspension. The results revealed that fecal coliforms in reactors containing 1:1 and 2:1 w/w of FS and LAB suspension decreased to half of the initial concentration within seven days of the treatment process in comparison with that of the control reactor. Viable plate counts of 0.6 × 108, 0.9 × 108, and 2.4 × 108 CFU/100 mL were recorded from reactors 1:1, 2:1, and the control, respectively. The total elimination of the fecal coliforms below the detection limit (<3 log 10 CFU/100 mL) was observed in both reactors after 15-17 days, whereas the number of fecal coliforms remained at 2.3 × 108 CFU/100 mL in the control reactor. The fecal coliforms were eliminated because of the acidification caused by the LAB during the incubation time. The final pH in the treatment reactors 1:1 and 2:1 was 3.7 and 3.9. While the final pH in the control reactor was 7.91. The results revealed that the bacterial pathogens in FS can be completely eliminated through a low-cost technique and a simple lactic acid fermentation process.

9.
Bull Exp Biol Med ; 162(6): 781-783, 2017 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-28432491

RESUMEN

The dynamics of microbial biofilm formation by standard strain and by clinical strains of uropathogenic coliform bacteria was investigated in vitro and the effect of sublethal concentrations of the polymer compound polyazolidinammonium modified with iodine hydrate ions on the initial stages of biofilm formation was assessed. Treatment of immunological plate wells with the polymeric compound prevented film formation, especially in case of clinical E. coli strain carrying FimH virulence gene.


Asunto(s)
Antibacterianos/farmacología , Azoles/farmacología , Biopelículas/efectos de los fármacos , Polímeros/farmacología , Compuestos de Amonio Cuaternario/farmacología , Escherichia coli Uropatógena/efectos de los fármacos , Antibacterianos/síntesis química , Azoles/síntesis química , Adhesión Bacteriana/efectos de los fármacos , Biopelículas/crecimiento & desarrollo , Violeta de Genciana , Yodo/química , Pruebas de Sensibilidad Microbiana , Polímeros/síntesis química , Compuestos de Amonio Cuaternario/síntesis química , Escherichia coli Uropatógena/patogenicidad , Escherichia coli Uropatógena/fisiología , Virulencia
10.
Anal Bioanal Chem ; 408(14): 3715-25, 2016 05.
Artículo en Inglés | MEDLINE | ID: mdl-27002609

RESUMEN

In this study, we demonstrate that the combination of an enzymatic method (based on Colilert-18 medium) and gas chromatography-differential mobility spectrometry (GC-DMS) can reduce the time required for detection of coliform bacteria (including Escherichia coli) from 18 to 2.5 h. The presented method includes the incubation (~2.5 h) of the sample containing coliform bacteria in Colilert-18 medium. The incubation time of 2.5 h is required for the activation of the ß-galactosidase enzyme. Produced during the incubation biomarker o-nitrophenol (ONP) can be detected by means of GC-DMS within just 200 s. The detection limit for ONP was 45 ng (on-column). The method developed in this work provides significantly shorter analysis time compared with standard methods, and can be potentially adapted to the field conditions. Therefore, this method is a promising tool for an early detection of coliform bacteria (including E. coli). Graphical Abstract Fast detection of coliform bacteria by means of GC-DMS.


Asunto(s)
Cromatografía de Gases/métodos , Enterobacteriaceae/aislamiento & purificación , Análisis Espectral/métodos , Límite de Detección
11.
Environ Monit Assess ; 188(2): 89, 2016 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-26769702

RESUMEN

Fecal contamination of surface waters is a significant problem, particularly in rapidly developing coastal watersheds. Data from a water quality monitoring program in southwest Brunswick County, North Carolina, gathered in support of a regional wastewater and stormwater management program were used to examine likely modes and sources of fecal contamination. Sampling was conducted at 42 locations at 3-4-week intervals between 1996 and 2003, including streams, ponds, and estuarine waters in a variety of land use settings. Expected fecal sources included human wastewater systems (on-site and central), stormwater runoff, and direct deposition by animals. Fecal coliform levels were positively associated with rainfall measures, but frequent high fecal coliform concentrations at times of no rain indicated other modes of contamination as well. Fecal coliform levels were also positively associated with silicate levels, a groundwater source signal, indicating that flux of fecal-contaminated groundwater was a mode of contamination, potentially elevating FC levels in impacted waters independent of stormwater runoff. Fecal contamination by failing septic or sewer systems at many locations was significant and in addition to effects of stormwater runoff. Rainfall was also linked to fecal contamination by central sewage treatment system failures. These results highlight the importance of considering multiple modes of water pollution and different ways in which human activities cause water quality degradation. Management of water quality in coastal regions must therefore recognize diverse drivers of fecal contamination to surface waters.


Asunto(s)
Monitoreo del Ambiente , Heces , Microbiología del Agua , Contaminación del Agua/análisis , Animales , Humanos , North Carolina , Estanques , Lluvia , Ríos , Aguas del Alcantarillado , Urbanización , Agua , Contaminación del Agua/estadística & datos numéricos , Calidad del Agua/normas
12.
Trop Anim Health Prod ; 48(2): 451-9, 2016 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-26719295

RESUMEN

This study aimed to assess the degree of contamination of bulk tank milk (BTM) by Staphylococcus spp. and coliform bacteria and to identify major milking practices that help perpetuate them in dairy cattle herds in São Miguel Island. In July 2014, BTM was sampled and a survey concerning local milking practices was conducted on 100 herds. Semi quantitative multiplex polymerase chain reaction detected coagulase-negative staphylococci, Escherichia coli, Staphylococcus aureus, and other coliform bacteria (Klebsiella oxytoca, Klebsiella pneumoniae, and Serratia marcescens) in 100, 75, 59, and 35 % of BTM, respectively. According to multivariable univariate models, on herds not using hot water for cleaning the milking machine and teat liners, there was at least 3.4 more odds (P < 0.01) to have S. aureus or coliform bacteria contamination in BTM. The likelihood of finding S. aureus in BTM was higher (P < 0.001) on herds without high hygiene during milking, when milking mastitic cows at the end, on abrupt cessation of milking at dry-off, and official milk control implementation. The glove use also favored (odds ratio (OR) 5.8; P < 0.01) the detection of coliform bacteria in BTM. Poor milking practices identified in this study should be avoided in order to decrease S. aureus and coliform bacteria contamination of BTM. Other factors associated with milk quality in São Miguel Island also should be further investigated.


Asunto(s)
Crianza de Animales Domésticos , Mastitis Bovina/epidemiología , Leche/microbiología , Animales , Azores/epidemiología , Bovinos , Industria Lechera , Escherichia coli/aislamiento & purificación , Femenino , Klebsiella/aislamiento & purificación , Mastitis Bovina/microbiología , Mastitis Bovina/transmisión , Prevalencia , Factores de Riesgo , Serratia marcescens/aislamiento & purificación , Staphylococcus aureus/aislamiento & purificación
13.
J Avian Med Surg ; 30(2): 187-95, 2016 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-27315388

RESUMEN

Nine Humboldt penguins ( Spheniscus humboldti ), between 1 and 1.5 years old and kept at Zoo Dresden, developed local and systemic infections with various opportunistic pathogens within a period of 4 months. Affected birds died peracutely without preceding symptoms or showed various clinical signs, including separation from conspecifics, reduced food intake, lethargy, dyspnea, swelling of the salt glands, and ocular discharge. One bird showed central nervous signs, including seizures. Pathologic examination of deceased birds revealed severe necrotizing inflammation of the mucous membranes and deep structures of the glottis, trachea, nasal sinus, and conchae and granulomatous inflammation of the salt glands. Further findings were airsacculitis, pneumonia, hepatitis, conjunctivitis, and myositis. Pseudomonas aeruginosa was the predominant pathogen in 7 cases. Six penguins died or were euthanatized, whereas 3 penguins that received systemic antibiotic treatment with tobramycin (10 mg/kg IM q24h for 10 days) showed rapid clinical improvement. Insufficient turnover rate of the filtration system, biofilm formation on pipe surfaces, and other factors are assumed to have promoted pathogen buildup in the pool water and subsequent infection.


Asunto(s)
Enfermedades de las Aves/microbiología , Infecciones por Pseudomonas/veterinaria , Pseudomonas aeruginosa/aislamiento & purificación , Spheniscidae , Administración Oral , Animales , Animales de Zoológico , Antibacterianos/uso terapéutico , Antifúngicos/uso terapéutico , Enfermedades de las Aves/tratamiento farmacológico , Enfermedades de las Aves/patología , Resultado Fatal , Femenino , Fluoroquinolonas/administración & dosificación , Fluoroquinolonas/uso terapéutico , Itraconazol/uso terapéutico , Masculino , Fármacos Neuroprotectores/uso terapéutico , Infecciones por Pseudomonas/tratamiento farmacológico , Infecciones por Pseudomonas/microbiología , Infecciones por Pseudomonas/patología , Silimarina/uso terapéutico , Tobramicina/uso terapéutico , Xantinas/uso terapéutico
14.
Bull Environ Contam Toxicol ; 95(5): 599-605, 2015 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-26347459

RESUMEN

The impact of coastal pollution was studied using edible oysters, Crassostrea rivularis as an indicator at two sites viz., North Wandoor (NW) and Phoenix Jetty (PJ) in Port Blair, Andaman. The hydrographic parameters showed that nitrite, nitrate and phosphate concentration were less and dissolved oxygen were more at NW compared to PJ. The oysters were collected from the study sites and biochemical, microbial, mineral profiles and ATPase activities were estimated. ATPase activity was inhibited in the gill tissue of oysters (p<0.05) of PJ sample. Total microbial load in the water and oyster, and coliform bacteria (MPN) in the water were significantly (p<0.05) higher at PJ compared to the NW. There was no significant difference (p>0.05) in the mineral profile of water collected from both the sites. However, calcium and magnesium were more in the oysters collected from NW (p<0.05), and Cu, Zn and Cd were more in PJ samples (p<0.05).


Asunto(s)
Crassostrea , Monitoreo del Ambiente/métodos , Metales Pesados/análisis , Contaminantes Químicos del Agua/análisis , Adenosina Trifosfatasas/metabolismo , Animales , Crassostrea/química , Crassostrea/microbiología , Enterobacteriaceae/aislamiento & purificación , Branquias/química , Branquias/metabolismo , Branquias/microbiología , India , Minerales/análisis , Nitratos/análisis , Nitritos/análisis , Microbiología del Agua
15.
Sci Total Environ ; 912: 169506, 2024 Feb 20.
Artículo en Inglés | MEDLINE | ID: mdl-38123084

RESUMEN

This study focused on the removal of the total coliforms, fecal coliforms and four target antibiotics in the dissolved ozone flotation (DOF) thickening sludge process. Additionally, the thickened effluent chromaticity and its effect on thickened sludge hydrolysis process were investigated. Ozonation in the DOF process could inactivate coliforms by oxidizing cellular components and destroying genetic material, as well as altering the chemical structure of antibiotics, leading to the degradation of antibiotics. At an O3 dosage of 16 mg/g TS, the concentration of total coliforms and fecal coliforms decreased by 2.2 log and 2.4 log, corresponding to an overall removal rate of 99.4 % and 99.7 %, respectively. The total degradation rate of four target antibiotics (tetracycline (TC), oxytetracycline (OTC), norfloxacin (NOR), ofloxacin (OFL)) were 66.5 %, 68.8 %, 53.3 % and 57.5 %, respectively. The chromaticity removal rate of the thickened effluent reached 95 %. Analysis of fluorescence spectra indicated alterations in the fluorescence properties of dissolved organic matter, resulting in a decrease in fluorescence intensity by ozonation. The thickened sludge had higher hydrolysis rates, resulting in a greater production of volatile fatty acids (VFAs). This was mainly attributed to the increased amount of soluble protein and carbohydrate in the substrate after DOF treatment, which was more conducive for the rapid conversion of hydrolysis into VFAs during the initial stage. These results provided new ideas for upgrading and transforming the thickening process of wastewater treatment plants (WWTPs).


Asunto(s)
Antibacterianos , Ozono , Ozono/química , Aguas del Alcantarillado/química , Tetraciclina , Bacterias
16.
J Hazard Mater ; 480: 135987, 2024 Sep 27.
Artículo en Inglés | MEDLINE | ID: mdl-39353273

RESUMEN

Antimicrobial-resistant bacteria, selected by antimicrobial agent use in livestock, are emerging and their spread to crops from feces via composting represents a public health concern as they are ultimately transmitted to humans. In this study, we investigated Escherichia coli and other ampicillin (AMP)-resistant coliform spread conditions in field soil and dent corn, an agricultural crop, on a livestock-derived compost-applying farm. No AMP-resistant E. coli was detected in any samples of field soil and dent corn. In contrast, AMP-resistant and extended-spectrum ß-lactam (ESBL) producing coliforms were consistently present in field soil and dent corn during the entire study period. In particular, extremely high AMP-resistant coliform levels were detected in dent corn stems and roots. AMP-resistant coliform detection in crops is pivotal and raises significant concerns regarding antimicrobial-resistant bacterial spread. Furthermore, AMP-resistant coliform isolate identification defined Enterobacter bugandensis and Enterobacter asburiae as the dominant species among AMP-resistant coliforms, both tested positive for ESBL production. This means that high concentrations of AMP-resistant coliforms are to be present on farms where crops are grown. However, we identified no common species among the AMP-resistant coliforms in the compost, field soil, and dent corn samples. Therefore, the initial hypothesis of the compost being the source of antimicrobial-resistant bacteria was not confirmed. Although their source remains unknown, a certain antimicrobial-resistant bacterial concentration could nonetheless be detected in the field.

17.
Lett Appl Microbiol ; 57(6): 547-53, 2013 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-23952651

RESUMEN

UNLABELLED: The performance of chromogenic coliform agar (CCA) for the enumeration of Escherichia coli and coliform bacteria was validated according to ENV ISO 13843 using pure cultures and naturally contaminated water samples. The results indicate that for the detection of E. coli and coliform bacteria, respectively, the method is sensitive (94 and 91%), specific (97 and 94%), selective (selectivity -0·78 and -0·32) and efficient (96 and 92%). Relative recovery of E. coli and coliform bacteria on CCA in comparison with tryptone soy agar (TSA) was good (104 and 94% in mean, >80 and >70% in all cases), and repeatability and reproducibility were sufficient. The linear working range was defined for 10-100 total target colonies per 47-mm membrane filter. A high precision of the method was confirmed by low overdispersion in comparison with Poisson distribution. The robustness of the method with respect to the variable incubation time of 21 ± 3 h was found to be low, because an incidental increase in presumptive colonies especially between 18 and 21 h was observed. In conclusion, the CCA method was proved as a reliable method for the quantification of E. coli and coliform bacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: The international standard for the detection and enumeration of E. coli and coliform bacteria by membrane filtration (ISO 9308-1) is currently under revision and will be published in 2014. In the new standard, lactose-triphenyl tetrazolium chloride (TTC) agar will be replaced by a CCA. A performance validation of this revised method according to ENV ISO 13843 is presented in this study to determine fundamental data on its applicability and to provide reference data for secondary validation by users of this method.


Asunto(s)
Recuento de Colonia Microbiana/métodos , Enterobacteriaceae/crecimiento & desarrollo , Escherichia coli/crecimiento & desarrollo , Agar/química , Compuestos Cromogénicos , Recuento de Colonia Microbiana/instrumentación , Recuento de Colonia Microbiana/normas , Enterobacteriaceae/aislamiento & purificación , Escherichia coli/aislamiento & purificación , Reproducibilidad de los Resultados , Microbiología del Agua
18.
Waste Manag Res ; 31(9): 925-36, 2013 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-23836101

RESUMEN

A study was conducted to investigate the levels of plant nutrients, heavy metals, parasites and fecal coliform bacteria in Bangkok-produced sewage sludge and finished compost products for potential agricultural application, as well as to compare the quality of compost under different composting conditions. The results indicated that digested sewage sludge had high fertilizing values for organic matter (19.01 ± 0.09%), total nitrogen (2.17 ± 0.07%), total phosphorus (2.06 ± 0.06%) and total potassium (1.16 ± 0.22%), but it was contaminated with human pathogens, including fecal coliform bacteria, viable helminthes egg and active forms of parasite cysts. Thus, fresh sewage sludge should not be disposed on land unless it has undergone pathogen reduction. It is proven that the quality of the sludge mixed with grass clippings at a ratio of 6:1 volume/volume after having passed a windrow composting process for 8 weeks can be classified as class A biosolids as the levels of remaining fecal coliforms were < 3 most probable number g(-1) dry solid and all human parasites were destroyed. Concentrations of organic matter, total nitrogen, total phosphorus and total potassium in the finished compost were 16.53 ± 1.25%, 1.39 ± 0.06%, 0.42 ± 0.10% and 1.53 ± 0.05% respectively. The total copper concentration was rather high (2291.31 ± 121.77 mg kg(-1)), but all heavy metal concentrations were also well below the United States Environmental Protection Agency pollutant limits for land application. The finished compost products can be considered as a soil conditioner as they have relatively low essential plant nutrient concentrations. It is recommended to be initially used for gardening and landscaping to ensure safety utilization.


Asunto(s)
Monitoreo del Ambiente , Contaminantes Ambientales/análisis , Reciclaje/métodos , Aguas del Alcantarillado/química , Administración de Residuos/métodos , Agricultura/métodos , Animales , Helmintos/aislamiento & purificación , Aguas del Alcantarillado/microbiología , Aguas del Alcantarillado/parasitología , Suelo/química , Suelo/parasitología , Microbiología del Suelo
19.
Sci Total Environ ; 872: 161932, 2023 May 10.
Artículo en Inglés | MEDLINE | ID: mdl-36796696

RESUMEN

Access to safe drinking water in rural Bangladesh remains a perpetual challenge. Most households are exposed to either arsenic or faecal bacteria in their primary source of drinking water, usually a tubewell. Improving tubewell cleaning and maintenance practices might reduce exposure to faecal contamination at a potentially low cost, but whether current cleaning and maintenance practices are effective remains uncertain, as does the extent to which best practice approaches might improve water quality. We used a randomized experiment to evaluate how effectively three approaches to cleaning a tubewell improved water quality, measured by total coliforms and E. coli. The three approaches comprise the caretaker's usual standard of care and two best-practice approaches. One best-practice approach, disinfecting the well with a weak chlorine solution, consistently improved water quality. However, when caretakers cleaned the wells themselves, they followed few of the steps involved in the best-practice approaches, and water quality declined rather than improved, although the estimated declines are not consistently statistically significant. The results suggest that, while improvements to cleaning and maintenance practices might help reduce exposure to faecal contamination in drinking water in rural Bangladesh, achieving widespread adoption of more effective practices would require significant behavioural change.


Asunto(s)
Arsénico , Agua Potable , Escherichia coli , Calidad del Agua , Pozos de Agua , Arsénico/análisis , Bangladesh , Abastecimiento de Agua
20.
Water Res ; 244: 120494, 2023 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-37611356

RESUMEN

Microbial water quality is routinely examined using the fecal indicator bacteria Escherichia coli, coliform bacteria and enterococci. Several practical cases in German drinking water distribution systems indicated invertebrates such as insects or gastropods as a source for the microbiological deterioration. Therefore, we examined three genera of Gastropoda (Arion, Helix and Cepaea) for the presence of fecal indictor bacteria in excreta using standard methods. Enterococci and coliform bacteria were detected in high concentrations (mean values of 1.5 × 106 and 6.3 × 106 per gram feces, respectively). E. coli was also detected, still specification revealed that what was assigned by standard ISO-methods to be E. coli was indeed a novel species of Buttiauxella, exhibiting ß-D-glucuronidase activity, thus, explaining the false-positive results. Microbiome analyses confirmed the cultural results. Enterobacteriaceae were dominant in the samples, yet only very few sequences could be assigned to Escherichia. Our study suggests, that enterococci and coliform bacteria are an integral component in the gastropod microbiome, whereas E. coli might be derived from other sources with gastropods being a vector. The results further indicate, that the current concept of fecal indicator bacteria needs to be extended, as not only humans and homeothermic animals could be a source for fecal indictor bacteria, but also gastropods need to be taken into consideration.


Asunto(s)
Agua Potable , Escherichia coli , Animales , Humanos , Microbiología del Agua , Bacterias , Enterobacteriaceae , Enterococcus , Heces/microbiología , Monitoreo del Ambiente
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA