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1.
Prevalence and Antimicrobial Resistance of Thermophilic Campylobacter spp. from Cattle Farms in Washington State 下载免费PDF全文
Wonki Bae Katherine N. Kaya Dale D. Hancock Douglas R. Call Yong Ho Park Thomas E. Besser 《Applied microbiology》2005,71(1):169-174
The prevalence of thermophilic Campylobacter spp. was investigated in cattle on Washington State farms. A total of 350 thermophilic Campylobacter isolates were isolated from 686 cattle sampled on 15 farms (eight dairies, two calf rearer farms, two feedlots, and three beef cow-calf ranches). Isolate species were identified with a combination of phenotypic tests, hipO colony blot hybridization, and multiplex lpxA PCR. Breakpoint resistance to four antimicrobials (ciprofloxacin, nalidixic acid, erythromycin, and doxycycline) was determined by agar dilution. Campylobacter jejuni was the most frequent species isolated (34.1%), followed by Campylobacter coli (7.7%) and other thermophilic campylobacters (1.5%). The most frequently detected resistance was to doxycycline (42.3% of 350 isolates). Isolates from calf rearer facilities were more frequently doxycycline resistant than isolates from other farm types. C. jejuni was most frequently susceptible to all four of the antimicrobial drugs studied (58.8% of 272 isolates). C. coli isolates were more frequently resistant than C. jejuni, including resistance to quinolone antimicrobials (89.3% of isolates obtained from calves on calf rearer farms) and to erythromycin (72.2% of isolates obtained from feedlot cattle). Multiple drug resistance was more frequent in C. coli (51.5%) than in C. jejuni (5.1%). The results of this study demonstrate that C. jejuni is widely distributed among Washington cattle farms, while C. coli is more narrowly distributed but significantly more resistant. 相似文献
2.
Impact of an Urban Effluent on Antibiotic Resistance of Riverine Enterobacteriaceae and Aeromonas spp. 总被引:2,自引:0,他引:2 下载免费PDF全文
Marisol Goi-Urriza Michle Capdepuy Corinne Arpin Nathalie Raymond Pierre Caumette Claudine Quentin 《Applied microbiology》2000,66(1):125-132
In order to evaluate the impact of an urban effluent on antibiotic resistance of freshwater bacterial populations, water samples were collected from the Arga river (Spain), upstream and downstream from the wastewater discharge of the city of Pamplona. Strains of Enterobacteriaceae (representative of the human and animal commensal flora) (110 isolates) and Aeromonas (typically waterborne bacteria) (118 isolates) were selected for antibiotic susceptibility testing. Most of the Aeromonas strains (72%) and many of the Enterobacteriaceae (20%) were resistant to nalidixic acid. Singly nalidixic acid-resistant strains were frequent regardless of the sampling site for Aeromonas, whereas they were more common upstream from the discharge for enterobacteria. The most common resistances to antibiotics other than quinolones were to tetracycline (24.3%) and beta-lactams (20.5%) for Enterobacteriaceae and to tetracycline (27.5%) and co-trimoxazole (26.6%) for Aeromonas. The rates of these antibiotic resistances increased downstream from the discharge at similar degrees for the two bacterial groups; it remained at high levels for enterobacteria but decreased along the 30-km study zone for Aeromonas. Genetic analysis of representative strains demonstrated that these resistances were mostly (enterobacteria) or exclusively (Aeromonas) chromosomally mediated. Moreover, a reference strain of Aeromonas caviae (CIP 7616) could not be transformed with conjugative R plasmids of enterobacteria. Thus, the urban effluent resulted in an increase of the rates of resistance to antibiotics other than quinolones in the riverine bacterial populations, despite limited genetic exchanges between enterobacteria and Aeromonas. Quinolone resistance probably was selected by heavy antibiotic discharges of unknown origin upstream from the urban effluent. 相似文献
3.
Prevalence and Antimicrobial Resistance of Campylobacter spp. and Salmonella Serovars in Organic Chickens from Maryland Retail Stores 总被引:3,自引:0,他引:3 下载免费PDF全文
Retail organic (n = 198) and conventional (n = 61) chickens were analyzed. Most organic (76%) and conventional (74%) chickens were contaminated with campylobacters. Salmonellae were recovered from 61% of organic and 44% of conventional chickens. All Salmonella enterica serovar Typhimurium isolates from conventional chickens were resistant to five or more antimicrobials, whereas most S. enterica serovar Typhimurium isolates (79%) from organic chickens were susceptible to 17 antimicrobials tested. 相似文献
4.
Effect of Conventional and Organic Production Practices on the Prevalence and Antimicrobial Resistance of Campylobacter spp. in Poultry 总被引:2,自引:0,他引:2 下载免费PDF全文
Taradon Luangtongkum Teresa Y. Morishita Aaron J. Ison Shouxiong Huang Patrick F. McDermott Qijing Zhang 《Applied microbiology》2006,72(5):3600-3607
Intestinal tracts of broilers and turkeys from 10 conventional broiler farms and 10 conventional turkey farms, where antimicrobials were routinely used, and from 5 organic broiler farms and 5 organic turkey farms, where antimicrobials had never been used, were collected and cultured for Campylobacter species. A total of 694 Campylobacter isolates from the conventional and organic poultry operations were tested for antimicrobial resistance to nine antimicrobial agents by the agar dilution method. Although Campylobacter species were highly prevalent in both the conventional and organic poultry operations, the antimicrobial resistance rates were significantly different between the organic operations and the conventional operations. Less than 2% of Campylobacter strains isolated from organically raised poultry were resistant to fluoroquinolones, while 46% and 67% of Campylobacter isolates from conventionally raised broilers and conventionally raised turkeys, respectively, were resistant to these antimicrobials. In addition, a high frequency of resistance to erythromycin (80%), clindamycin (64%), kanamycin (76%), and ampicillin (31%) was observed among Campylobacter isolates from conventionally raised turkeys. None of the Campylobacter isolates obtained in this study was resistant to gentamicin, while a large number of the isolates from both conventional and organic poultry operations were resistant to tetracycline. Multidrug resistance was observed mainly among Campylobacter strains isolated from the conventional turkey operation (81%). Findings from this study clearly indicate the influence of conventional and organic poultry production practices on antimicrobial resistance of Campylobacter on poultry farms. 相似文献
5.
Cloacal swabs collected from 264 ring-billed gulls (Larus delawarensis) at four sites near Montréal, Canada were cultured for the presence of Salmonella spp., Campylobacter spp. and Listeria spp. All birds were apparently healthy when captured or killed. Of all birds examined, 8.7%, 15.9% and 9.5%, respectively, were infected with Salmonella spp., Campylobacter spp. and Listeria monocytogenes. Overall, 29.9% of gulls sampled harbored one or more of these bacteria. Gulls probably play only a minor role in the epizootiology of these bacteria. 相似文献
6.
The study investigated the prevalence of Campylobacter spp. in Finnish cattle at slaughter and carcass contamination after slaughter. During the period January to December 2003, bovine rectal fecal samples (n=952) and carcass surface samples (n=948) from 12 out of 15 Finnish slaughterhouses were examined. In total, campylobacters were detected in 31.1% of fecal samples and in 3.5% of carcass surface samples. Campylobacter jejuni was isolated from 19.5%, Campylobacter coli from 2.2%, and presumptive Campylobacter hyointestinalis from 10.8% of fecal samples. Campylobacters were detected in 4.4% and 37.4% of the fecal samples examined both by direct culture and by enrichment (n=730), respectively, suggesting a low level of campylobacters in the intestinal content. A slightly increasing trend was observed in the overall prevalence of campylobacters towards the end of summer and autumn. Seventeen different serotypes were detected among the fecal C. jejuni isolates using a set of 25 commercial antisera for serotyping heat-stable antigens (Penner) of C. jejuni by passive hemagglutination. The predominant serotypes, Pen2 and Pen4-complex, were isolated from 52% of the fecal samples. Subtyping by pulsed-field gel electrophoresis (SmaI) yielded 56 and 20 subtypes out of 330 fecal and 70 carcass C. jejuni isolates, respectively. MICs of ampicillin, enrofloxacin, erythromycin, gentamicin, nalidixic acid, and oxytetracycline for 187 C. jejuni isolates were determined using a commercial broth microdilution method. Sixteen (9%) of the isolates were resistant to at least one of the antimicrobials tested. Resistance to nalidixic acid was most commonly detected (6%). No multiresistance was observed. 相似文献
7.
Prevalence of Campylobacter spp. in Cattle in Finland and Antimicrobial Susceptibilities of Bovine Campylobacter jejuni Strains 总被引:1,自引:0,他引:1 下载免费PDF全文
The study investigated the prevalence of Campylobacter spp. in Finnish cattle at slaughter and carcass contamination after slaughter. During the period January to December 2003, bovine rectal fecal samples (n = 952) and carcass surface samples (n = 948) from 12 out of 15 Finnish slaughterhouses were examined. In total, campylobacters were detected in 31.1% of fecal samples and in 3.5% of carcass surface samples. Campylobacter jejuni was isolated from 19.5%, Campylobacter coli from 2.2%, and presumptive Campylobacter hyointestinalis from 10.8% of fecal samples. Campylobacters were detected in 4.4% and 37.4% of the fecal samples examined both by direct culture and by enrichment (n = 730), respectively, suggesting a low level of campylobacters in the intestinal content. A slightly increasing trend was observed in the overall prevalence of campylobacters towards the end of summer and autumn. Seventeen different serotypes were detected among the fecal C. jejuni isolates using a set of 25 commercial antisera for serotyping heat-stable antigens (Penner) of C. jejuni by passive hemagglutination. The predominant serotypes, Pen2 and Pen4-complex, were isolated from 52% of the fecal samples. Subtyping by pulsed-field gel electrophoresis (SmaI) yielded 56 and 20 subtypes out of 330 fecal and 70 carcass C. jejuni isolates, respectively. MICs of ampicillin, enrofloxacin, erythromycin, gentamicin, nalidixic acid, and oxytetracycline for 187 C. jejuni isolates were determined using a commercial broth microdilution method. Sixteen (9%) of the isolates were resistant to at least one of the antimicrobials tested. Resistance to nalidixic acid was most commonly detected (6%). No multiresistance was observed. 相似文献
8.
Amy R. Sapkota Lance B. Price Ellen K. Silbergeld Kellogg J. Schwab 《Applied microbiology》2006,72(4):3069-3071
Organoarsenicals are commonly used for growth promotion in U.S. poultry production. Susceptibilities to arsenite, arsenate, and the organoarsenical roxarsone were measured in 251 Campylobacter isolates from conventional and antimicrobial-free retail poultry products. Isolates from conventional poultry products had significantly higher roxarsone MICs (z = 8.22; P < 0.0001). 相似文献
9.
Dante Poggi Priscila Oliveira de Giuseppe Mathieu Picardeau 《Applied and environmental microbiology》2010,76(14):4882-4885
We measured the frequency of appearance of spontaneous mutants resistant to gentamicin, kanamycin, streptomycin, and spectinomycin in saprophytic and pathogenic Leptospira strains. The mutations responsible for the spontaneous resistance to streptomycin and spectinomycin were identified in the rpsL and rrs genes, respectively. We also generated a gentamicin resistance cassette that allows the use of a third selectable marker in leptospires. These results may facilitate further advances in gene transfer systems in Leptospira spp.Our understanding of leptospiral pathogenesis depends on reliable genetic tools for fully characterizing genes of interest. Significant advances in genetics of Leptospira spp. have been made over the last few years (8, 11). For generating antibiotic resistance genetic markers, our group focused on antibiotics other than those used therapeutically. We therefore excluded the use of β-lactams, as they are used to treat leptospirosis, which is an emerging disease with more 500,000 severe cases occurring annually (8). Plasmid DNA can be introduced into Leptospira by electroporation (2, 21) or conjugation (16). In 1990, Saint Girons et al. used the replication origin of the LE1 leptophage (22) to generate a plasmid that was able to replicate autonomously in both the saprophyte Leptospira biflexa and Escherichia coli (21). They used resistance to kanamycin (Kan), which was conferred by a gene from the Gram-positive bacterium Enterococcus faecalis, as a genetic marker to select for introduced DNA. Another marker, a spectinomycin (Spc) resistance cassette from Staphylococcus aureus, was also used as a selectable marker in Leptospira spp. (1). Further studies have used Spc and Kan markers to screen for transformants resulting from plasmid replication or chromosomal integration in leptospires (8, 11). As the proportion of allelic-exchange mutants is low and as chromosomal integration generally occurs through a single recombination event, a plasmid containing the rpsL wild-type gene as a counterselectable marker in a streptomycin (Str)-resistant strain of L. biflexa (due to a mutation in rpsL) was also used to eliminate clones harboring the plasmid and/or clones that have integrated the plasmid through a single-crossover event (9, 17, 20). 相似文献
10.
A. Patriarchi B. Maunsell E. O'Mahony Á. Fox S. Fanning J. Buckley D.J. Bolton 《Letters in applied microbiology》2009,49(3):305-310
Aim: The aim of this study was to investigate the prevalence of Campylobacter species in a subset of intensive poultry flocks by examining samples collected in geographically disparate areas on the island of Ireland.
Methods and Results: Faecal, water and environmental samples were collected from the interior of poultry houses on nine farms. Three cultural methods were used for Campylobacter isolation: direct plating, enrichment culture and a recovery method for emerging Campylobacter spp. Presumptive Campylobacter isolates were confirmed using biochemical tests and further identified to species level by multiplex PCR. All flocks sampled in this study were found to be contaminated with Campylobacter at the time of sampling. Structural and air samples taken from the interior of broiler houses were also found to be Campylobacter positive. All water samples were found to be Campylobacter negative. The Campycheck method was used for the isolation of emerging Campylobacter spp.
Conclusions: Campylobacter spp. were recovered (as contaminants) from the poultry house interior, air and environmental samples in all intensive poultry flocks surveyed.
Significance and Impact of the Study: This study highlights the need for improved biosecurity on selected poultry farms. 相似文献
Methods and Results: Faecal, water and environmental samples were collected from the interior of poultry houses on nine farms. Three cultural methods were used for Campylobacter isolation: direct plating, enrichment culture and a recovery method for emerging Campylobacter spp. Presumptive Campylobacter isolates were confirmed using biochemical tests and further identified to species level by multiplex PCR. All flocks sampled in this study were found to be contaminated with Campylobacter at the time of sampling. Structural and air samples taken from the interior of broiler houses were also found to be Campylobacter positive. All water samples were found to be Campylobacter negative. The Campycheck method was used for the isolation of emerging Campylobacter spp.
Conclusions: Campylobacter spp. were recovered (as contaminants) from the poultry house interior, air and environmental samples in all intensive poultry flocks surveyed.
Significance and Impact of the Study: This study highlights the need for improved biosecurity on selected poultry farms. 相似文献
11.
S. Zhao G. H. Tyson Y. Chen C. Li S. Mukherjee S. Young C. Lam J. P. Folster J. M. Whichard P. F. McDermott 《Applied and environmental microbiology》2016,82(2):459-466
The objectives of this study were to identify antimicrobial resistance genotypes for Campylobacter and to evaluate the correlation between resistance phenotypes and genotypes using in vitro antimicrobial susceptibility testing and whole-genome sequencing (WGS). A total of 114 Campylobacter species isolates (82 C. coli and 32 C. jejuni) obtained from 2000 to 2013 from humans, retail meats, and cecal samples from food production animals in the United States as part of the National Antimicrobial Resistance Monitoring System were selected for study. Resistance phenotypes were determined using broth microdilution of nine antimicrobials. Genomic DNA was sequenced using the Illumina MiSeq platform, and resistance genotypes were identified using assembled WGS sequences through blastx analysis. Eighteen resistance genes, including tet(O), blaOXA-61, catA, lnu(C), aph(2″)-Ib, aph(2″)-Ic, aph(2′)-If, aph(2″)-Ig, aph(2″)-Ih, aac(6′)-Ie-aph(2″)-Ia, aac(6′)-Ie-aph(2″)-If, aac(6′)-Im, aadE, sat4, ant(6′), aad9, aph(3′)-Ic, and aph(3′)-IIIa, and mutations in two housekeeping genes (gyrA and 23S rRNA) were identified. There was a high degree of correlation between phenotypic resistance to a given drug and the presence of one or more corresponding resistance genes. Phenotypic and genotypic correlation was 100% for tetracycline, ciprofloxacin/nalidixic acid, and erythromycin, and correlations ranged from 95.4% to 98.7% for gentamicin, azithromycin, clindamycin, and telithromycin. All isolates were susceptible to florfenicol, and no genes associated with florfenicol resistance were detected. There was a strong correlation (99.2%) between resistance genotypes and phenotypes, suggesting that WGS is a reliable indicator of resistance to the nine antimicrobial agents assayed in this study. WGS has the potential to be a powerful tool for antimicrobial resistance surveillance programs. 相似文献
12.
Takako Taniguchi Elpita Tarigan Hiroyuki Sato Chiho Kaneko Naoaki Misawa 《EcoHealth》2021,18(2):241-249
EcoHealth - A total of 55 samples of intestinal contents from 28 raccoon dogs (Nyctereutes procyonoides) and 27 badgers (Males anakuma) in Miyazaki prefecture, Japan, were examined for the presence... 相似文献
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14.
Bae W Kaya KN Hancock DD Call DR Park YH Besser TE 《Applied and environmental microbiology》2005,71(1):169-174
The prevalence of thermophilic Campylobacter spp. was investigated in cattle on Washington State farms. A total of 350 thermophilic Campylobacter isolates were isolated from 686 cattle sampled on 15 farms (eight dairies, two calf rearer farms, two feedlots, and three beef cow-calf ranches). Isolate species were identified with a combination of phenotypic tests, hipO colony blot hybridization, and multiplex lpxA PCR. Breakpoint resistance to four antimicrobials (ciprofloxacin, nalidixic acid, erythromycin, and doxycycline) was determined by agar dilution. Campylobacter jejuni was the most frequent species isolated (34.1%), followed by Campylobacter coli (7.7%) and other thermophilic campylobacters (1.5%). The most frequently detected resistance was to doxycycline (42.3% of 350 isolates). Isolates from calf rearer facilities were more frequently doxycycline resistant than isolates from other farm types. C. jejuni was most frequently susceptible to all four of the antimicrobial drugs studied (58.8% of 272 isolates). C. coli isolates were more frequently resistant than C. jejuni, including resistance to quinolone antimicrobials (89.3% of isolates obtained from calves on calf rearer farms) and to erythromycin (72.2% of isolates obtained from feedlot cattle). Multiple drug resistance was more frequent in C. coli (51.5%) than in C. jejuni (5.1%). The results of this study demonstrate that C. jejuni is widely distributed among Washington cattle farms, while C. coli is more narrowly distributed but significantly more resistant. 相似文献
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A discriminant equation based on bill-depth and total head- and bill-length is provided to sex adult Black-headed Gulls Larus ridibundus . This equation is used to sex birds of known age. Relationships between age and morphometrics and between age and the black extent on the wing are then investigated both in males and females. Size of birds did not change with age but the black extent on the wing tended to decrease with age in both sexes. The tendency to become lighter with age may he an expression of senescence. 相似文献
17.
Chuanwu Xi Yongli Zhang Carl F. Marrs Wen Ye Carl Simon Betsy Foxman Jerome Nriagu 《Applied and environmental microbiology》2009,75(17):5714-5718
The occurrence and spread of antibiotic-resistant bacteria (ARB) are pressing public health problems worldwide, and aquatic ecosystems are a recognized reservoir for ARB. We used culture-dependent methods and quantitative molecular techniques to detect and quantify ARB and antibiotic resistance genes (ARGs) in source waters, drinking water treatment plants, and tap water from several cities in Michigan and Ohio. We found ARGs and heterotrophic ARB in all finished water and tap water tested, although the amounts were small. The quantities of most ARGs were greater in tap water than in finished water and source water. In general, the levels of bacteria were higher in source water than in tap water, and the levels of ARB were higher in tap water than in finished water, indicating that there was regrowth of bacteria in drinking water distribution systems. Elevated resistance to some antibiotics was observed during water treatment and in tap water. Water treatment might increase the antibiotic resistance of surviving bacteria, and water distribution systems may serve as an important reservoir for the spread of antibiotic resistance to opportunistic pathogens.The occurrence and spread of antibiotic-resistant bacteria (ARB) are pressing public health problems worldwide, and aquatic ecosystems are a recognized reservoir for ARB and antibiotic resistance genes (ARGs) (4, 6, 8, 11, 12, 15, 39). Naturally occurring ARB and ARGs in the aquatic environment are selected for and enriched for by antibiotics found in sewage and agricultural runoff, which result from the widespread and increased use of antibiotics (4, 11, 12, 15, 38). Historically, concerns about the microbial quality of drinking water have focused on the occurrence of pathogens in drinking water distribution systems (5, 34). However, the presence of trace levels of antibiotics and ARB in source water and finished drinking water may also greatly affect public health and is an emerging issue for the general public and the drinking water industry (3, 30). Although several studies have detected ARB in drinking water systems (2, 3, 20, 30, 38), most previous studies focused on cultivable bacteria and/or indicator organisms. Little is known about the fate of ARGs in drinking water systems, and it was recently proposed that ARGs are emerging contaminants (24).We used culture-dependent methods and molecular techniques to investigate the prevalence and dynamics of heterotrophic ARB and ARGs in a drinking water source (source RW-P) and treated drinking water (source DW-P) (see Materials and Methods in the supplemental material). We tested water from a drinking water plant located in Michigan and tap water from several small cities located in Michigan and Ohio (sources TW-1, TW-2, TW-3, and TW-4). Two independent samples were collected each time at each collection site at three different times, and we used four replicates from each sample for tests. We tested bacterial resistance to the following antibiotics: amoxicillin (amoxicilline), chloramphenicol, ciprofloxacin, gentamicin, rifampin (rifampicin), sulfisoxazole, and tetracycline. We also examined the presence of eight ARGs, including beta-lactam resistance genes (blaTEM and blaSHV), chloramphenicol resistance genes (cat and cmr), sulfonamide resistance genes (sulI and sulII), and tetracycline resistance genes (tetO and tetW).Total heterotrophic plate counts (HPC) were determined using R2A agar without added antibiotics. The water treatment process reduced the total HPC from 9.9 × 106 CFU/100 ml in source water to 68 CFU/100 ml in treated drinking water, indicating that there was efficient removal and/or deactivation of total HPC (Table (Table1).1). In contrast, the total 16S rRNA gene copy number decreased from 3.4 × 107 copies/100 ml in source water to 1.6 × 106 copies/100 ml in treated drinking water (Fig. (Fig.1).1). The discrepancy between the reduction in the HPC and the reduction in the total 16S rRNA gene copy number suggests that the final disinfection step effectively inactivated bacteria but most of the dead or damaged cells were still present in finished drinking water. The number of HPC in tap water ranged from 3.44 × 102 to 6.1 × 104 CFU/100 ml water, values that are lower than those for source water but significantly higher than those for treated drinking water, indicating that there is regrowth of bacteria in drinking water distribution systems. The copy numbers of total 16S rRNA genes in tap water ranged from 2.45 × 105 to 1.02 × 107 copies/100 ml water. The higher levels suggested by the 16S rRNA data are consistent with results of previous studies demonstrating that only 5 to 10% and 1% of bacteria in wastewater and soil, respectively, can be cultivated or identified by culture-based methods (9, 37). A significant correlation (P < 0.05, R2 = 0.78) was found between the 16S rRNA gene copy number and the total HPC if treated drinking water (DW-P) data were not included (Fig. (Fig.1).1). This suggests that cultivable bacteria in drinking water represent only a small portion of the total bacterial biomass. Including treated drinking water (DW-P) data resulted in a distorted correlation, suggesting that a large proportion of the 16S rRNA genes present came from dead and/or damaged cells. The levels of total heterotrophic bacteria were significantly higher in tap water (TW-1) than in treated drinking water (DW-P), indicating that there was bacterial regrowth in the water distribution system.Open in a separate windowFIG. 1.Heterotrophic bacteria and the 16S rRNA gene in different water samples. (A) Copy numbers of the 16S rRNA gene and numbers of heterotrophic bacteria (CFU) in 100 ml water. (B) Correlation (P < 0.05, R2 = 0.78) between the copy number of the 16S rRNA gene and the number of heterotrophic bacteria in different water samples (without the data for DW-P). RW-P, source water from the drinking water treatment plant; DW-P, finished drinking water from the drinking water treatment plant; TW-1, tap water from the city where the drinking water treatment plant is located; TW-2, TW-3, and TW-4, tap water from three towns in Michigan and Ohio close to the city where the TW-1 drinking water treatment plant is located. The statistical analysis was done using six samples for each type of water sample. Lg, log10.
Open in a separate windowaPrevalence was defined as the percentage of resistant HPC in the total HPC. The statistical analysis was done using six samples for each type and four technical replicates for each sample.bRW-P, source water from the drinking water treatment plant; DW-P, finished drinking water from the drinking water treatment plant; TW-1, tap water from the city where the drinking water treatment plant is located; TW-2, TW-3, and TW-4, tap water from three towns in Michigan and Ohio close to the city where the TW-1 drinking water treatment plant is located.cSignificantly different from RW-P.dSignificantly different from DW-P.The prevalence of HPC resistant to antibiotics was determined using R2A agar containing amoxicillin (4 mg/liter), chloramphenicol (16 mg/liter), ciprofloxacin (2 mg/liter), gentamicin (8 mg/liter), rifampin (2 mg/liter), sulfisoxazole (256 mg/liter), or tetracycline (8 mg/liter). Some groups of heterotrophic bacteria were resistant to all of the antibiotics at the concentrations tested in all water samples (Table (Table1).1). In the source water, 14.4% of the HPC were resistant to gentamicin and 1.7% were resistant to tetracycline. The resistance of HPC to amoxicillin, chloramphenicol, and rifampin was significantly higher (P < 0.01) in treated drinking water than in source water, while the resistance to sulfisoxazole was significantly lower (P < 0.01). Compared to treated drinking water (DW-P), the resistance of HPC to tetracycline in tap water was significantly greater and the resistance to amoxicillin was significantly lower (P < 0.01). The resistance to chloramphenicol and rifampin remained higher than the resistance in source water. The prevalence of HPC antibiotic resistance in tap water samples collected from other cities varied, but the resistance of HPC to rifampin was particularly high in all tap water samples.A number of previous studies have reported that ARB are common in drinking water (2, 3, 19, 25, 33). We added to these studies by testing water both before and after treatment, as well as tap water. Although the bacterial concentration was effectively lower during water treatment, the prevalence of resistance to amoxicillin, rifampin, and chloramphenicol nevertheless increased significantly.Several studies have discovered that chlorine, an agent widely used for disinfection, selects for ARB (2, 3, 9, 16, 33, 37). Armstrong et al. (2, 3) found that there was a significant increase in the proportion of multidrug-resistant (MAR) bacteria following flash mixing with chlorine. Murray et al. (16) demonstrated that the proportion of bacteria resistant to ampicillin and cephalothin (cefalotin) in sewage increased significantly following chlorination, and they observed a significant increase in the proportion of MAR strains during chlorination in laboratory experiments. Other studies demonstrated that the susceptibility of ARB to a disinfectant and the susceptibility of antibiotic-susceptible bacteria to a disinfectant are similar (7, 28), indicating that disinfection does not select ARB but instead induces the development of antibiotic resistance. Armstrong et al. (2, 3) suggested that stress-tolerant bacteria selected by chlorination might be more antibiotic resistant, and one study found that suboptimal chlorine treatment of drinking water selected for MAR Pseudomonas aeruginosa (33).The mechanism of chlorine-induced antibiotic resistance in bacteria is unknown. It is possible that chlorine can increase expression of the multidrug efflux pumps, leading to resistance to disinfection by-products as well as antibiotics. The drinking water treatment plant that we sampled used monochloramine as a disinfectant. No previous study has reported the effects of monochlroamine disinfection on ARB, but our results suggest that monochlromaine disinfection may have an effect similar to that of chlorine disinfection.Real-time PCR was used to quantify ARGs (including cat, cmr, blaTEM, blaSHV, sulI, sulII, tetW, and tetO) in collected water samples. All ARGs tested were detected in all water samples, except for the tetO and tetW genes, which were detected only in source water (Fig. (Fig.2).2). The copy number of each ARG in 100 ml water was calculated and normalized to the copy number of the total 16S rRNA genes to determine the relative abundance of each ARG in the water samples. Compared to the copy number in finished water, the copy number of ARGs in tap water was significantly greater (P < 0.001), except for the blaSHV gene, whose copy number was not significantly different (P = 0.124); the tetO and tetW genes were not detected in the drinking water sample after treatment. In terms of the relative abundance of ARGs in bacterial populations, all ARG/16S rRNA gene ratios were less than −3 log. Compared to source water, treated drinking water had a higher abundance of the cat and blaSHV genes (P < 0.001) but a lower abundance of the sulI gene (P < 0.001) (Fig. (Fig.2).2). No significant difference in any other ARG was found. After distribution, no significant change was observed in any ARG, except that the abundance of the blaTEM gene was significantly increased (P < 0.01) compared with the abundance in treated drinking water (DW-P) or in tap water (TW-1) (Fig. (Fig.2).2). The ARGs were also present in tap water samples collected from other cities. The similarity of the abundance of ARGs in the different tap water samples is quite remarkable (Fig. (Fig.2).2). The relative abundance of all ARGs was similar to that in the TW-1 tap water sample, except that the relative abundance of sulII and blaSHV was lower in the TW-2 and TW-3 tap water samples (Fig. (Fig.22).Open in a separate windowFIG. 2.Quantities of ARGs in different water samples. The bars indicate the copy numbers of the resistance genes normalized to the 16S rRNA gene copy number, and the symbols indicate the absolute copy numbers of ARGs in 100 ml water. RW-P, source water from the drinking water treatment plant; DW-P, finished drinking water from the drinking water treatment plant; TW-1, tap water from the city where the drinking water treatment plant is located; TW-2, TW-3, and TW-4, tap water from three towns in Michigan and Ohio close to the city where the TW-1 drinking water treatment plant is located. The statistical analysis was done using six samples for each type of water sample. Lg, log10.The quantities of individual ARGs were not significantly correlated with either HPC counts or 16S rRNA genes (data not shown), indicating that the ARGs tested were not evenly distributed among the bacterial populations in the water samples. However, the overall trends in quantity were similar for some ARGs and ARB. For example, in source water, treated drinking water, and tap water (TW-1), the number of heterotrophic bacteria resistant to amoxicillin, chloramphenicol, and sulfisoxazole corresponded to the proportion of genes coding for resistance to these antibiotics (blaSHV, cat, and sulI, respectively).Bacteria may inherit resistance to some antibiotics or can develop resistance via spontaneous mutation or the acquisition of resistant genes (35). The acquisition of a resistant gene via horizontal gene transfer is the most common and easiest way for bacteria to develop antibiotic resistance both in the environment and in a host (26, 29). Many bacteria transmit ARGs, and these ARGs were recently proposed to be emerging contaminants because of their widespread occurrence in aquatic ecosystems (13, 21, 22, 24). Plasmid-mediated blaTEM and blaSHV are the most common genes coding beta-lactamases and “extended-spectrum” beta-lactamases, a major cause of resistance to beta-lactams, and they are increasingly being found in different settings worldwide (14, 23). The enzymes encoded by these genes confer unequivocal resistance to ampicillin, amoxicillin, ticarillin, and carbenicillin (32, 36). We detected blaTEM and blaSHV genes in all but one water sample, which is evidence that these genes are distributed widely in drinking water systems. The selective increases in the levels of both genes in tap water due to either water treatment or regrowth within drinking water distribution systems suggest that the spread of at least some beta-lactam-resistant determinants may occur through drinking water distribution systems.Both tetO and tetW are tetracycline resistance genes encoding ribosomal protection proteins. Both of these genes are common in intestinal and rumen environments (1, 31); thus, their presence may indicate fecal contamination (22). If the tetO and tetW genes truly represent the level of fecal contamination, our results show that drinking water treatment was effective for eliminating and controlling fecal contamination.The most frequent cause of bacterial resistance to chloramphenicol is enzymatic inactivation by acetylation of the drug via different types of chloramphenicol acetyltransferases encoded by cat genes (17), but other mechanisms, such as efflux systems, may also contribute to chloramphenicol resistance (18). The proportion of cat genes increased significantly following water treatment, suggesting that the drinking water treatment did not effectively remove or inactivate the chloramphenicol-resistant bacterial population. On the other hand, the cmr gene, an efflux pump gene related to chloramphenicol resistance, showed little variation in different water sources.Sulfonamides act as competitive inhibitors of the enzyme dihydropteroate synthase in the folic acid pathway of bacterial and some eukaryotic cells. sulI and sulII encode alternative sulfonamide-resistant dihydropteroate synthases in gram-negative clinical bacteria, and both genes commonly occur (often at roughly the same frequency) in sulfisoxazole-resistant gram-negative clinical isolates (10). The drinking water treatment process significantly decreased the abundance of the sulI gene but had no significant influence on the sulII gene.In summary, we found heterotrophic ARB and ARGs in all finished water and tap water tested, although the amounts were small. The size of the general population of bacteria followed the order source water > tap water > finished water, indicating that there was regrowth of bacteria in drinking water distribution systems; elevated resistance to some antibiotics was observed during water treatment and in tap water. We show that the quantities of most ARGs are greater in tap water than in finished water and source water. The increased levels of ARGs and specialized groups of ARB in tap water compared to finished water and source water suggest that water treatment could increase the antibiotic resistance of surviving bacteria and/or induce transfer of ARGs among certain bacterial populations. Water distribution systems could serve as an incubator for growth of certain ARB populations and as an important reservoir for the spread of antibiotic resistance to opportunistic pathogens. Drinking water treatment processes and distribution systems can impact the spread of antibiotic resistance. Rusin et al. (27) estimated that the risk of infection by bacteria in drinking water was as low as 7.3 per billion people for exposure to low levels of Aeromonas and as high as 98 per 100 patients receiving antibiotic treatment exposed to high levels of Pseudomonas (27). Whether exposure to ARB results in an increased risk to the general public, particularly individuals with compromised immune systems, the very young, the very old, or individuals with chronic conditions, is not known and deserves further study. Future research should identify factors accounting for the selective increase in antibiotic resistance and develop new methods and approaches to reduce accumulation of such resistance. 相似文献
TABLE 1.
Prevalence of ARB HPC in source water, finished drinking water, and tap water from four townsaSampleb | Total HPC (CFU/100 ml) | % of total HPC resistant to:
| ||||||
---|---|---|---|---|---|---|---|---|
Amoxicillin | Ciprofloxacin | Chloramphenicol | Gentamicin | Rifampin | Sulfisoxazole | Tetracycline | ||
RW-P | 1.19 × 106 | 11.67 ± 4.39 | 11.60 ± 5.92 | 4.17 ± 1.93 | 14.42 ± 5.52 | 10.85 ± 3.57 | 7.46 ± 3.87 | 1.66 ± 0.80 |
DW-P | 68 | 39.55 ± 9.79c | 4.77 ± 4.71 | 19.45 ± 5.60c | 21.96 ± 14.43 | 47.98 ± 17.99c | 1.17 ± 1.14c | 1.50 ± 1.24 |
TW-1 | 1.6 × 104 | 15.22 ± 2.73d | 9.99 ± 4.76 | 13.96 ± 3.70c | 13.40 ± 1.73 | 62.00 ± 8.96c | 3.34 ± 1.21 | 3.78 ± 0.93c,d |
TW-2 | 6.04 × 104 | 3.02 ± 0.19 | 13.14 ± 0.48 | 5.49 ± 0.47 | 4.67 ± 0.21 | 28.10 ± 1.72 | 7.85 ± 0.67 | 0.08 ± 0.01 |
TW-3 | 3.44 × 102 | 4.07 ± 0.17 | 0.18 ± 0.07 | 0.75 ± 0.39 | 2.18 ± 0.62 | 82.15 ± 1.50 | 0.33 ± 0.03 | 0.98 ± 0.38 |
TW-4 | 2.46 × 103 | 14.33 ± 1.74 | 0.18 ± 0.05 | 2.05 ± 0.04 | 9.76 ± 0.34 | 14.23 ± 1.69 | 0.12 ± 0.001 | 0.04 ± 0.002 |
18.
Atanassova V Reich F Beckmann L Klein G 《FEMS immunology and medical microbiology》2007,49(1):141-145
One hundred and forty-four samples of chilled turkey meat from six flocks, taken directly from the slaughterhouse, and 100 samples of turkey meat retail products were examined. Over one-quarter (29.2%) of the tested samples from the slaughterhouse were Campylobacter positive, showing high variability in the flocks. The lowest percentage of Campylobacter-positive samples was found in flocks I and III (8.3%), whereas, in flock VI, 91.7% of the samples were Campylobacter positive. Turkey meat retail products showed a prevalence of 34% for Campylobacter. Heat-treated meat was negative for Campylobacter. Quantitative studies of the samples taken at the slaughterhouse revealed a mean log range of 1.9-2.5 CFU g(-1)Campylobacter spp. Results from the quantification of retail products gave a mean log value of 2.1 CFU g(-1). 相似文献
19.
Effects of Climate on Incidence of Campylobacter spp. in Humans and Prevalence in Broiler Flocks in Denmark 总被引:1,自引:0,他引:1 下载免费PDF全文
Mary Evans Patrick Lasse Engbo Christiansen Michael Wain Steen Ethelberg Henrik Madsen Henrik Caspar Wegener 《Applied microbiology》2004,70(12):7474-7480
Campylobacter infections are increasing and pose a serious public health problem in Denmark. Infections in humans and broiler flocks show similar seasonality, suggesting that climate may play a role in infection. We examined the effects of temperature, precipitation, relative humidity, and hours of sunlight on Campylobacter incidence in humans and broiler flocks by using lag dependence functions, locally fitted linear models, and cross validation methods. For humans, the best model included average temperature and sunlight 4 weeks prior to infection; the maximum temperature lagged at 4 weeks was the best single predictor. For broilers, the average and maximum temperatures 3 weeks prior to slaughter gave the best estimate; the average temperature lagged at 3 weeks was the best single predictor. The combined effects of temperature and sunlight or the combined effects of temperature and relative humidity predicted the incidence in humans equally well. For broiler flock incidence these factors explained considerably less. Future research should focus on elements within the broiler environment that may be affected by climate, as well as the interaction of microclimatic factors on and around broiler farms. There is a need to quantify the contribution of broilers as a source of campylobacteriosis in humans and to further examine the effect of temperature on human incidence after this contribution is accounted for. Investigations should be conducted into food consumption and preparation practices and poultry sales that may vary by season. 相似文献