Occurrence of Potential Pathogens in Water Containing Ornamental Fishes

The bacterial population of the water supplied with ornamental fish purchased from retail outlets was examined qualitatively and quantitatively. As many as 10(9) viable aerobic organisms per 100 ml were present, with fecal coliform counts as high as 10(5) per 100 ml. Citrobacter, Escherichia, Pseudomonas, and Vibrio were isolated from 75% or more of the samples, whereas Aeromonas, Alcaligenes, Enterobacter, Flavobacterium, and Streptococcus were isolated from 45 to 65% of the samples. Pseudomonas aeruginosa, Edwardsiella tarda, and Klebsiella pneumoniae were also isolated.     

traT gene sequences, serum resistance and pathogenicity-related factors in clinical isolates of Escherichia coli and other gram-negative bacteria

The R6-5 plasmid-specified outer membrane protein, TraT protein, has previously been shown to mediate resistance to bacterial killing by serum. Colony hybridization with a 700 bp DNA fragment carrying most of the traT gene was used to examine the prevalence of traT in Gram-negative bacteria, particularly strains of Escherichia coli, isolated from clinical specimens. traT was found in isolates of E. coli, Salmonella, Shigella and Klebsiella, but not in Pseudomonas, Aeromonas or Plesiomonas, nor in the few isolates of Enterobacter, Proteus, Acinetobacter, Citrobacter, Serratia or Yersinia that were examined. It was detected in a significantly higher proportion of the E. coli strains isolated from the blood of patients with bacteraemia/septicaemia or from faeces of patients with enteric infections (50-70%) than in that of strains isolated from normal faeces (20-40%). The incidence of traT in strains isolated from cases of urinary tract infections was variable. traT was found to be frequently associated with production of the K1 capsule and with the carriage of ColV plasmids, but not with the carriage of R plasmids, nor with serum resistance or the production of haemolysin.     

Faculative Anaerobic Bacteria in the Digestive Tract of Chum Salmon (Oncorhynchus keta) Maintained in Fresh Water Under Defined Culture Conditions

The bacterial flora in the digestive tract of chum salmon growing in fresh water under defined and controlled culture conditions was examined both qualitatively and quantitatively. The predominant species present in the digestive tract were identified as Aeromonas, with Aeromonas hydrophila being the most common isolate. These aeromonads were not isolated from the diet. Other bacterial species commonly isolated included Bacillus, Enterobacter, nonpigmented pseudomonads, Micrococcus, and Acinetobacter. These species were also isolated from the diet or tank water. As many as 10-8 viable bacteria per g (wet weight) of digestive tract plus contents were counted. After 75 days of starvation, 10-6 viable bacteria were counted, whereas fish fed a sterile feed contained 10-5 viable bacteria per g (wet weight) of digestive tract plus contents.     

产超广谱β-内酰胺酶细菌的种类及耐药分析

目的：为预防和治疗质粒介导的超广谱β-内酰胺酶（ESBL）细菌感染提供依据。方法：采用E-test法对可疑细菌进行ESBL检测,用K-B法做药物敏感试验,用WHONET4进行分析。结果：在890株革兰阴性杆菌中检出ESBL44株,其中大肠埃希菌18株、肺炎克雷伯菌10株、阴沟肠杆菌9株、费劳地枸椽酸杆菌3株、嗜水气单胞菌2株、鼠伤寒沙门菌1株、液化沙雷菌1株,对亚胺培菌、呋喃妥因、阿米卡星、环丙沙星的敏感率分别为100%、68.2%、29.5%、25.0%。结论：产ESBL细菌分布广泛、阳性率高、易借助耐药质粒传播,具有较高的交叉耐药性和多重耐药性。     

Pollution indicator bacteria associated with municipal raw and drinking water supplies.

A total of 3819 bacterial cultures isolated from municipal water samples were identified using a combination of Enterotubules and confirmatory media. Frequency distributions for the different genera or groups of bacteria were similar for raw water and drinking water isolations, except for Escherichia organisms which doubled their frequency in raw water. Differences between the membrane filter (MF) and presence-absence (P-A) test with regard to types of organisms isolated were limited to Klebsiella organisms which were preferentially cultured from MF plates. Members of the genus Enterobacter were isolated more than twice as frequently as any of the other coliform genera dealt with in this study. Aeromonas organisms were detected almost as often as such individual genera as Escherichia, Citrobacter, or Klebsiella. Although non-lactose fermenting colonies (false-negatives) of the coliform genera would not be detected by the MF technique, their lack of detection would likely be offset by the Aeromonas colonies (false-positives). At least 25% of the coliform isolates were either anaerogenic or non-lactose fermenters and would therefore go undetected by the most probably number (MPN) technique.     

Nitrogen-deficient Medium in the Differential Isolation of Klebsiella and Enterobacter from Feces

On a nitrogen-deficient agar medium, the tribe Klebsielleae formed large, glistening, mucoid colonies which were easily distinguished from other colony types. Of 113 Klebsielleae isolates from human feces which were characterized, Klebsiella accounted for 88% of the total; 75% were K. pneumoniae; K. ozaenae (13%) was isolated from one individual only. The remaining strains (12%) were identified as Enterobacter cloacae. Counts (for the tribe) ranged from 10(2) to 10(6), with a median of 10(4); 9 of 53 stool specimens were negative. K. pneumoniae was also isolated from 6 of 41 frozen foil-pack foods. Anaerobic studies at room temperature and 37 C revealed no appreciable differences from aerobic plates. The nitrogen-deficient medium appeared better than E M B for isolation of Klebsielleae when they were present in low numbers relative to other coliforms; slime production by Klebsielleae concomitant with minimal growth of other bacteria is involved.     

Identification of strains isolated as total and fecal coliforms and comparison of both groups as indicators of fecal pollution in tropical climates

This study was undertaken to better characterize the groups of total coliforms (TC) and fecal coliforms (FC) and to evaluate both groups as indicators of fecal contamination of drinking well water in a tropical climate (The Ivory Coast, West Africa). Isolated colonies obtained as TC or FC on membrane filters were identified using the API-20E system. From the well water samples, 58 golden-green colonies with a metallic sheen isolated on Endo medium (TC) were identified as Escherichia coli (55%), Enterobacter (26%), Klebsiella (14%), Proteus (3%), and Citrobacter (2%). Among 132 colonies isolated on Endo medium as non-TC (not showing the characteristic golden metallic sheen), 10% were identified as E. coli. The 196 blue colonies isolated on M-FC medium at 44.5 degrees C (FC) were identified as E. coli (66%), Klebsiella (12%), Enterobacter (10%), Citrobacter (5%), Salmonella (3%), Serratia (3%), Proteus (2%), and Yersinia (0.5%). Among 24 nonblue colonies on M-FC medium, none were identified as E. coli. Of the colonies isolated from human feces, E. coli represents 92% of the TC and 89% of the FC. Although these results are limited, they tend to confirm the greater specificity of the fecal coliform technique over that of total coliform for the detection of fecal contamination of untreated well water. From the results presented here and the observations of other workers, it is suggested that the use of FC instead of TC should be considered as the method of choice for determining drinking water pollution of untreated groundwater supplies.     

Development and evaluation of a PCR method for diagnosis of Salmonella enteric fever, based on DNA sequences of the hilA gene

Typically, diagnosis of enteric fever due to Salmonella spp. is by bacterial isolation from blood culture; however, the blood culture method is slow, not always available, and not informative in patients with antibiotic treatment. Salmonella spp. uses the hilA gene (component of the pathogenicity island I) to invade epithelial cells and produce infection. Using the hilA gene sequence a PCR test was designed to detect Salmonella in blood samples. The sensitivity (S), specificity (SP), positive predictive value (PPV) and negative predictive value (NPV) of the PCR method were obtained by testing the blood samples from 34 patients with suspected of enteric fever. Presence of S. typhi was confirmed by blood culture. Blood samples were also tested from 35 patients with infections due to other non-Salmonella pathogens, again corroborated by blood culture (Klebsiella pneumoniae, 9; Serratia marcescens, 5; Escherichia coli, 4; Pseudomonas aeruginosa, 9; Providencia alcalifaciens, 4; Enterobacter cloacae, 4). Control samples were obtained from 150 healthy volunteers. The S, SP, PPV and NPV for the PCR method were all 100%. The lowest number of colony forming units/ml detected by PCR in blood samples was 10.     

Comparative study of the prevalence and clinical profiles of diarrheas due to Aeromonas and other enteric pathogens

The prevalence of Aeromonas spp. and other enteric pathogens in stool specimens from diarrheic and non-diarrheic patients was studied over a 12 month period (January to December, 1986). Except for the absence of fever, all the clinical features in Aeromonas diarrhea were comparable to those associated with other diarrheagenic agents. These features included abdominal pain (30%), vomiting (24.5%), fever (31.5%), dehydration (9.5%) and hematochezia (19.5%). Aeromonas spp. were more frequently isolated from patients with gastroenteritis (2.5%) than from control patients (1.0%) (P less than 0.05). Isolates were recovered more often during the dry months (66.7%), than during the wet months (33.3%). Among the enteric pathogens isolated, Aeromonas spp. (2.5%) ranked next to Esch. coli (14.5%) and Shigella spp. (6.3%) in prevalence. Other bacterial isolates included Plesiomonas shigelloides (1.5%) Vibrio spp. (1.0%), Yersinia enterocolitica (1.0%) and Salmonella spp. (1.8%).     

重庆地区成人感染性腹泻病原学分析

目的 研究重庆地区成人感染性腹泻患者的病原学特点.方法 采用MICROSCAN系统进行粪便细菌培养,用ELISA和多重PCR方法进行病毒检测.结果 130例腹泻标本中,检出细菌阳性17例,包括沙门菌属7例,志贺菌属5例,副溶血弧菌3例和嗜水气单胞菌2例.病毒检测中,单重感染30例,双重感染10例,三重感染1例.A组轮状病毒检出率为3.85％ (5/130),B轮状病毒检出率为3.85％ (5/130),C组轮状病毒检出率为15.4％ (20/130),诺如病毒检出率为9.23％ (12/130),星状病毒检出率为4.62％(6/130),札如病毒检出率为3.08％ (4/130),腺病毒检出率为0.77％(1/130).结论 重庆地区成人腹泻患者中,沙门菌和志贺菌为细菌感染的主要菌种,轮状病毒和诺如病毒为病毒感染的主要病原体.     

Differentiation of Serratia from Enterobacter on the Basis of Nucleoside Phosphotransferase Production

Precoated cellulose thin-layer chromatograms were used to detect the production of guanosine 5'-phosphate from guanosine and p-nitrophenylphosphate by whole-cell preparations. One-hundred per cent of Serratia (163 strains) and 84% of E. liquefaciens (15 of 18 strains) produced the nucleotide. All other Enterobacter (23 strains), Klebsiella (10 strains), and E. coli (10 strains) were negative for the production of this nucleotide. The entire test procedure could be carried out in 4 hr. It is proposed that E. liquefaciens is more closely related to Serratia than Enterobacter and that reclassification of these organisms should be investigated.     

Comparison of frequency and susceptibility to antimicrobials of bacterial strains of the family Enterobacteriaceae isolated from patients hospitalised in intensive care units

The aim of the study was estimation of frequency and susceptibility to antimicrobial agents of gram-negative rods isolated from clinical specimens obtained from patients requiring intensive care, with emphasis on profile of the unit. The analysis comprised strains of gram-negative rods isolated from patients of two intensive care units (ICUs) of a tertiary care hospital (1200 beds). Identification of cultured isolates was done using automated VITEK and API systems (bioMerieux, France). Susceptibility to antimicrobial agents was tested by a disk-diffusion method according to the NCCLS recommendations. In total the analysis comprised 722 strains of gram-negative rods. In blood cultures predominated strains of Enterobacter spp. (42.5%) and Klebsiella pneumoniae (37.5%). In cultures of clinical specimens other than blood 41.6% comprised strains of Klebsiella pneumoniae, 14.8% Escherichia coli and 14.4% Proteus mirabilis. Frequency of multi-drug resistant strains of bacteria of the family Enterobacteriaceae was much higher among blood isolates in comparison to strains cultured from other clinical specimens. There was a relatively high percentage of strains of Enterobacteriaceae susceptible to piperacillin and tazobactam (69.0%) and ceftazidime (54.6%). Conclusions: 1. All strains were susceptible to carbapenems. 2. There was a relatively high percentage of strains of gram-negative rods susceptible to piperacillin/tazobactam and ceftazidime. 3. Bacteria isolated from blood cultures were characterised by a much higher percentage of resistant strains in comparison to other specimens. 4. Longer stay in ICU promoted selection of strains resistant to antimicrobials.     

Isolation and 16S rRNA sequence analysis of the beneficial bacteria from the rhizosphere of rice

The present study deals with the isolation of plant growth promoting rhizobacteria (PGPR) from rice (variety NIAB IRRI-9) and the beneficial effects of these inoculants on two Basmati rice varieties. Nitrogen-fixing activity (acetylene-reduction activity) was detected in the roots and submerged shoots of field-grown rice variety NIAB IRRI-9. Estimation of the population size of diazotrophic bacteria by ARA-based MPN (acetylene reduction assay-based most probable number) in roots and shoots indicated about 10(5)-10(6) counts/g dry weight at panicle initiation and grain filling stages. Four bacterial isolates from rice roots and shoots were obtained in pure culture which produced phytohormone indoleacetic acid (IAA) in the growth medium. Among these, three isolates S1, S4, and R3 reduced acetylene to ethylene in nitrogen-free semi-solid medium. Morphological and physiological characteristics of the isolates indicated that three nitrogen-fixing isolates S1, S4, and R3 belonged to the genus Enterobacter, while the non-fixing isolate R8 belonged to the genus Aeromonas. 16S rRNA sequence of one isolate from root (R8) and one isolate from shoot (S1) was obtained which confirmed identification of the isolates as Aeromonas veronii and Enterobacter cloacae, respectively. The 1517-nucleotide-long sequence of the isolate R8 showed 99% similarity with Aeromonas veronii (accession No. AF099023) while partial 16S rRNA sequence (two stretches of total 1271 nucleotide length) of S1 showed 97% similarity with the sequence of Enterobacter cloacae (accession No. AJ251469). The seedlings of two rice varieties Basmati 385 and Super Basmati were inoculated with the four bacterial isolates from rice and one Azospirillum brasilense strain Wb3, which was isolated from wheat. In the rice variety Basmati 385, maximum increase in root area and plant biomass was obtained in plants inoculated with Enterobacter S1 and Azospirillum Wb3, whereas in the rice variety Super Basmati, inoculation with Enterobacter R3 resulted in maximum increase of root area and plant biomass. Nitrogen fixation was quantified by using 15N isotopic dilution method. Maximum fixation was observed in Basmati 385 with the inoculants Azospirillum Wb3 and Enterobacter S1 where nearly 46% and 41% of the nitrogen was derived from atmosphere (%Ndfa), respectively. In general, higher nitrogen fixation was observed in variety Basmati 385 than in Super Basmati, and different bacterial strains were found more effective as inoculants for the rice varieties Basmati 385 and Super Basmati.     

Profiles of the utilization of 20 amino acids as the only source of nitrogen and carbon in bacteria of the genera Klebsiella, Enterobacter, Serratia, Escherichia

The profiles of the utilization of 20 protein amino acids in 118 Klebsiella pneumoniae sub- sp. pneumoniae, K. oxytoca, K. planticola, K. mobilis, Enterobacter cloacae, Serratia marscescens, S. liquefaciens, Escherichia coli strains isolated from clinical material were studied. The utilization of amino acids was determined on minimal saline agar containing amino acid as the only source of nitrogen and carbon; the results were evaluated after 72-hour incubation at 37 degrees C. 17 profiles of amino-acid utilization were thus determined, most of them genus-specific in enterobacteria: Klebsiella (profiles No. 1--6, 9, 10), Enterobacter (No. 11--13), Serratia (No. 14--16), Escherichia (No. 17). The full coincidence of amino-acid utilization profiles in bacteria of K. mobilis (No. 1, 6) and K. pneumoniae subsp. pneumoniae with out of such profiles in bacteria of the genera Enterobacter, Serratia, Escherichia was established, which confirmed that K. mobilis (formerly Enterobacter aerogenes) belonged to the genus Klebsiella.     

Enterobacteriaceae, coliforms, faecal coliforms and salmonellas in raw ewes' milk

Thirty-nine samples of freshly drawn ewes' milk collected at 13 farms, and 120 samples of raw ewes' milk collected on arrival at a dairy were examined. Farm samples had geometric mean counts of 4.4 X 10(2) Enterobacteriaceae/ml, 3.9 X 10(2) coliforms/ml and 2.0 X 10(2) faecal coliforms/ml, whereas the respective mean counts were 6.2 X 10(3)/ml, 5.4 X 10(3)/ml and 1.3 X 10(3)/ml for dairy samples. Salmonellas were not detected by enrichment procedures in any of the 159 samples examined. Escherichia coli (47.5% strains), Enterobacter cloacae (17.7%), Ent. agglomerans (11.3%), Hafnia alvei (6.5%) and Klebsiella oxytoca (6.0%) were the predominant species in 434 Enterobacteriaceae strains isolated from farm samples. Levels and species of Enterobacteriaceae found in the present work in raw ewes' milk imply a considerable risk of early blowing in cheese-making from unpasteurized milk.     

Classification of enterobacteria based on overall similarity

Krieg, R. E. (Iowa State University, Ames), and W. R. Lockhart. Classification of enterobacteria based on overall similarity. J. Bacteriol. 92:1275-1280. 1966.-A numerical study was made of 53 organisms, representing 12 genera of the family Enterobacteriaceae and 4 members of the genus Aeromonas. A total of 105 features was determined for each culture. Matching coefficients were computed, and the organisms were sorted into phenetic groups by use of the "highest-link" criterion. The genera Enterobacter (Aerobacter), Escherichia, Citrobacter, Arizona, Shigella, and Salmonella formed a single, large cluster with little or no evidence of subdivisions into tribes or genera. Paracolobactrum and Klebsiella were joined to the large group as subclusters. Members of the genera Erwinia and Serratia formed separate, distinct clusters related to the large group at a lower level of similarity. At a still lower level were appended Aeromonas, Proteus, Providencia, and some individual species from other genera. These organisms were no more closely related to one another than to the larger group.     

Use of 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside for the isolation of beta-galactosidase-positive bacteria from municipal water supplies

A new medium, mX-Gal, has been developed for the membrane filter enumeration of beta-galactosidase-positive bacteria in municipal water supplies. mX-Gal medium contains the chromogenic beta-galactosidase substrate 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside (X-Gal). All Aeromonas, Citrobacter, and Enterobacter strains isolated from raw water on mX-Gal medium were beta-galactosidase positive. In contrast, only 10 to 20% of these strains produced a red colony with a metallic sheen on m-Endo agar LES medium. Of 674 chlorinated water samples analyzed for total coliforms on m-Endo agar LES medium and for beta-galactosidase-positive bacteria on mX-Gal medium, 18 that were negative for coliforms on m-Endo agar LES showed beta-galactosidase-positive bacteria on mX-Gal. Of a total of 50 beta-galactosidase-positive bacteria isolated from these samples, 76% were identified as Aeromonas hydrophila.     

2002年至2007年太原地区儿童细菌性腹泻病原菌分布及耐药分析

目的了解太原地区近6年儿童细菌性腹泻病原菌分布及耐药情况。方法对临床诊断细菌性腹泻病,便培养已分离到病原菌1080例作回顾性分析,分析其病原菌的分布及耐药情况。结果埃希菌属486株（45％）,居于首位,前5位的病原菌依次为埃希菌属、肠球菌属、酵母样真菌、志贺菌属、假单胞菌属。各年均以大肠埃希菌为主要检出菌,志贺菌逐年减少。年龄分布中,婴儿的构成比最高（44．4％）。埃希菌属、志贺菌属、假单胞菌属、沙门菌属、气单胞菌属此5种杆菌对13种抗生素的平均耐药率依次为舒普深、痢特灵、头孢他啶、庆大霉素、环丙沙星、头孢哌酮、头孢曲松、丁胺卡那、头孢噻肟、诺氟沙星、头孢呋辛、哌拉西林、头孢唑啉。从埃希菌属近6年的耐药性变迁资料可以看出,对13种抗生素的耐药率均有不同程度上升。结论传统的致病菌志贺菌属、沙门菌属较少,而肠球菌属、假单胞菌属、枸橼酸杆菌属、克雷伯杆菌属、肠杆菌属、酵母样真菌等条件致病菌肠炎占有相当比例。各种致病菌的耐药性增加,第三代头孢除头孢他啶的耐药率较低外,其余都较高。提示应严格掌握抗生素用药指证,合理选用抗生素。     

Characterization of Ornithine Decarboxylase-Positive, Nonmotile Strains of the Klebsiella-Enterobacter Group

Thirty-seven strains of ornithine decarboxylase-positive, nonmotile Klebsiella-Enterobacter organisms isolated from 36 patients were studied by biochemical and serological testing. Five strains gave biochemical reactions which conformed closely to those of Escherichia coli; three strains gave positive Quellung reactions to specific Klebsiella antisera. (Two of these were thought to be Enterobacter in spite of this typing reaction.) The remaining 29 strains were classified as Enterobacter. These results demonstrate the necessity of doing both an ornithine decarboxylase test and a motility test to differentiate Klebsiella from Enterobacter. Had only a motility test been done, they all would have been called Klebsiella.     

Acetylene reduction (nitrogen fixation) by enterobacteriaceae isolated from paper mill process waters

Using selective media containing galactitol, over 130 Enterobacteriaceae have been isolated from paper mill process waters collected from different localities. These bacteria were extensively characterized and tested for acetylene-reducing (nitrogen-fixing) activity under anaerobic conditions. High activity was found in representatives of Klebsiella pneumoniae, Enterobacter aerogenes, Enterobacter cloacae, Erwinia herbicola, Citrobacter freundii, Citrobacter intermedius, and Escherichia coli. Under argon, nitrogenase synthesis was generally not repressed by 5 mM l-glutamate, l-aspartate, l-leucine or Casamino Acids (0.5 g/liter). In many strains, both the specific activities (nanomoles of C(2)H(4) per minute per milligram of protein) and the activities (nanomoles of C(2)H(4) per minute) had considerably declined after 24 h. In three selected strains, activity in intact cells grown under nitrogen was unaffected by the presence during assay of 10 mM l-amino acids or ammonium acetate. All of the strains examined were tolerant towards inactivation of nitrogen-fixing activity by 1.8% (vol/vol) oxygen during assay, and inactivation by up to 10% oxygen was partly reversible. Representatives of the six taxa synthesized nitrogenase in stirred aerobic cultures, though the protein concentrations attained were lower than under anaerobic conditions. It seems reasonable to suggest that under natural conditions, nitrogen fixation is able to contribute significantly to the nitrogen economy of the cells.