Antimicrobial Resistance of Escherichia coli O157 Isolated from Humans, Cattle, Swine, and Food

A total of 361 Escherichia coli O157 isolates, recovered from humans, cattle, swine, and food during the years 1985 to 2000, were examined to better understand the prevalence of antimicrobial resistance among these organisms. Based on broth microdilution results, 220 (61%) of the isolates were susceptible to all 13 antimicrobials tested. Ninety-nine (27%) of the isolates, however, were resistant to tetracycline, 93 (26%) were resistant to sulfamethoxazole, 61 (17%) were resistant to cephalothin, and 48 (13%) were resistant to ampicillin. Highest frequencies of resistance occurred among swine isolates (n = 70), where 52 (74%) were resistant to sulfamethoxazole, 50 (71%) were resistant to tetracycline, 38 (54%) were resistant to cephalothin, and 17 (24%) were resistant to ampicillin. Based on the presence of Shiga toxin genes as determined by PCR, 210 (58%) of the isolates were identified as Shiga toxin-producing E. coli (STEC). Among these, resistance was generally low, yet 21 (10%) were resistant to sulfamethoxazole and 19 (9%) were resistant to tetracycline. Based on latex agglutination, 189 (52%) of the isolates were identified as E. coli O157:H7, among which 19 (10%) were resistant to sulfamethoxazole and 16 (8%) were resistant to tetracycline. The data suggest that selection pressure imposed by the use of tetracycline derivatives, sulfa drugs, cephalosporins, and penicillins, whether therapeutically in human and veterinary medicine or as prophylaxis in the animal production environment, is a key driving force in the selection of antimicrobial resistance in STEC and non-STEC O157.     

Antimicrobial resistance of Escherichia coli O157 isolated from humans, cattle, swine, and food

A total of 361 Escherichia coli O157 isolates, recovered from humans, cattle, swine, and food during the years 1985 to 2000, were examined to better understand the prevalence of antimicrobial resistance among these organisms. Based on broth microdilution results, 220 (61%) of the isolates were susceptible to all 13 antimicrobials tested. Ninety-nine (27%) of the isolates, however, were resistant to tetracycline, 93 (26%) were resistant to sulfamethoxazole, 61 (17%) were resistant to cephalothin, and 48 (13%) were resistant to ampicillin. Highest frequencies of resistance occurred among swine isolates (n = 70), where 52 (74%) were resistant to sulfamethoxazole, 50 (71%) were resistant to tetracycline, 38 (54%) were resistant to cephalothin, and 17 (24%) were resistant to ampicillin. Based on the presence of Shiga toxin genes as determined by PCR, 210 (58%) of the isolates were identified as Shiga toxin-producing E. coli (STEC). Among these, resistance was generally low, yet 21 (10%) were resistant to sulfamethoxazole and 19 (9%) were resistant to tetracycline. Based on latex agglutination, 189 (52%) of the isolates were identified as E. coli O157:H7, among which 19 (10%) were resistant to sulfamethoxazole and 16 (8%) were resistant to tetracycline. The data suggest that selection pressure imposed by the use of tetracycline derivatives, sulfa drugs, cephalosporins, and penicillins, whether therapeutically in human and veterinary medicine or as prophylaxis in the animal production environment, is a key driving force in the selection of antimicrobial resistance in STEC and non-STEC O157.     

Experimental Infection of the Gray Garden Slug, Deroceras reticulatum (Müller), By the Holotrichous Ciliate Tetrahymena pyriformis (Ehrenberg)

SUMMARY. To determine whether Tetrahymena pyriformis could infect Deroceras reticulatum and become morphologically modified in the same way as the parasitic phase of T. limacis , 50 slugs were exposed for 10 days to an amicronucleate clone of T. Pyriformis and 50 were exposed for the same period of time to a micronucleate clone. The slugs were then transferred to clean containers for another 10 days, to allow ciliates which had entered the slugs either to persist and multiply or, in the case of transitory infections, to disappear. An additional 50 slugs were kept in a control group for 20 days. All of the slugs had been collected at a single locality in which natural infections by T. limacis had not been noted, and were maintained in separate one-half pint milk bottles throughout the experimental period.
Of the slugs exposed to the amicronucleate clone, 40 survived to the end of the experimental period, and 15 were infected. Of those exposed to the micronucleate clone, 42 survived, and 5 were infected. Forty-three of the slugs in the control group survived, and none were infected by ciliates. In some of the slugs infected by T. pyriformis , hundreds of ciliates were noted. The infections were apparently limited to the digestive gland, intestinal tract, and fluid around the viscera. Ciliates recovered from slugs were in general smaller than those growing in thriving cultures, but morphologically were typical T. pyriformis. None were observed to have a proportionately smaller cytostome or apiculate anterior end characteristic of the parasitic phase of T. limacis.     

Antibiotic Resistance of Vibrio anguillarum,in Relation to Serovar and Plasmid Contents

A total of 520 Vibrio anguillarum strains, isolated from fish and the environment, were tested for their sensitivity to 20 different antibiotics. Most isolates were of European origin. The results were compared with data on the O-serogroup and plasmid contents. All strains were sensitive to neomycin, spectinomycin, nitrofurantoin, flumequine and oxolinic acid, while most strains were sensitive to streptomycin, Oxytetracycline, chloramphenicol, sulphonamides, trimethoprim, sulphonamides with trimethoprim, nalidixan, rifampicin, novobiocin and O/129. A major part of the strains were resistant to the macrolides, spiramycin and lincomycin. For ampicillin, cephalothin, and Colistin marked differences were recorded with respect to O-serogroup. Most O1 strains were resistant to Colistin and sensitive to ampicillin and cephalothin, while most O2 strains were sensitive to Colistin but resistant to ampicillin and cephalothin. Some antibiotic resistant strains carried plasmids but no conjugation experiments were carried out to detect possible R factors.     

DNA relatedness among species of Enterobacter and Serratia.

Species of Enterobacter and Serratia were examined for deoxyribonucleic acid relatedness to Klebsielleae, to atypical erwiniae, and to other members of Enterobacteriaceae. Deoxyribonucleic acid hybridization and then hydroxyapatite chromatography was the technique used to assess relatedness. Strains of Enterobacter cloacae formed two separate hybridization groups that correlate with the presence or absence of yellow pigment. Pigmented E. cloacae were 75-100% related, but they were only 40-50% related to unpigmented strains. Conversely, unpigmented strains were 70% or more related but were only 40-50% related to the pigmented strains. Both pigmented and unpigmented E. cloacae were 40-45% related to Enterobacter aerogenes and klebsiellae, and 20-30% related to Serratia species and Enterobacter hafniae. Atypical erwiniae were highly related to E. cloacae. Serratia marcescens strains formed one closely related group. Serratia liquefaciens strains formed a single, more disperse, relatedness group, as did isolates of Serratia rubidaea. These species were related throughout a substantial portion of their genomes. A group of lysine-positive "Citrobacter-like" strains were 40-50% related to Serratia species. Only four E. hafniae strains were tested. Two of these were highly related, while the other two were only 50% related to the reference strain. Enterobacter hafniae was only 15-20% related to other Enterobacteriaceae.     

Measuring surgical decision-making with hypothetical cases

Hypothetical clinical cases were used to investigate surgical decision-making in relation to surgical rates across Ontario. Six procedures were studied (cholecystectomy, colectomy, inguinal herniorrhaphy, hysterectomy, cesarean section and tonsillectomy-adenoidectomy), and substantial differences of opinion regarding the choice of surgical or nonsurgical treatment were recorded. The decision to operate, however, was not made more frequently in Ontario counties with high operative rates, and none of the demographic variables studied were correlated with the decision to operate. Other variables that might have affected operative rates were not taken into account. There were also differences of opinion in referral decisions, but generally internists and pediatricians were less likely to refer the hypothetical cases to surgeons than were family physicians.     

Serotypes and biotypes and antibiotic susceptibility of Haemophilus influenzae encountered in a clinical laboratory in Taiwan.

Forty-four serologically and biochemically typable Haemophilus influenzae isolates from clinical specimens in Taiwan were subjected to analysis in their relationship with source of isolation and age distribution. It was found that all isolates from blood and cerebrospinal fluid were serotype b, biotype I, and all were in children less than 4 years of age. Serotypes b and e, biotypes I and III were encountered to have the highest incidence of infection caused by H. influenzae in this area. All H. influenzae isolates were further tested for susceptibility to several selected antibiotics. All strains of this organism were susceptible to erythromycin and chloramphenicol. All but two strains were susceptible to tetracycline, whereas more strains were resistant to carbenicillin, gentamycin, keflin, and penicillin. Thirty-four percent strains were found to be resistant to ampicillin and all were beta-lactamase producer. No direct correlation between ampicillin resistance and serotypes or biotypes was recognized.     

The use of cover and burrows by a population of rabbits (Mammalia: Oryctolagus cuniculus) in eastern Scotland

Adult rabbits were trapped in the spring on an area of grass and broom in the east of Scotland. They were ear-tagged and a sample of males and females were fitted with radio-collars. These were followed for two months to see whether they used burrows or ground cover for shelter during the day. Rabbits found on the surface were disturbed to see whether they bolted to burrows or stayed on the surface. The population was then re trapped to measure the population density, which was estimated to be 12.6 adults/ha in March, allowing for an apparent trapping bias against older females. One hundred and twelve burrow entrances/ha were counted from random quadrats. Males were more likely to be found on the surface than females, and rabbits that were more often on the surface were less likely to bolt to burrows when disturbed. Even when rabbits did bolt to burrows they frequently left them shortly afterwards and returned to the cover of the broom. Males that were most often found on the surface were lighter in weight than those found in burrows. This was not the case for females.     

THE TAXONOMY OF THE PSYCHROPHILIC MEAT-SPOILAGE BACTERIA: A REASSESSMENT

SUMMARY: A study was made of selected properties of 189 psychrophilic bacteria isolated from chilled beef and associated sources. Of these, 182 were Gram-negative and 7 were Gram-positive. Of the former, 128 were typical pseudomonads with polar flagella. They were resistant to penicillin and oxidized glucose to acid. There were 52 non-motile Gram-negative bacteria of which 42 were judged to be pseudomonads on the basis of penicillin resistance and the oxidation of glucose to acid. Flagellar characters were associated with the production of green pigment, with the production of acid from lactose and with resistance to several antibiotics.     

广西合浦儒艮国家级自然保护区及邻近水域鱼类种数及保护对策

2003年6月至2004年5月,通过底拖网作业收集鱼类标本对广西合浦儒艮国家级自然保护区及其邻近水域鱼类种数进行了调查,并走访当地鱼市进行实地调查.共记录到保护区及其邻近水域的鱼类14目41科57种,其中55种为硬骨鱼类,占总数的96.49%,另有2种软骨鱼类,占总数的3.51%.有41种为暖水性鱼类,占总数的71.93%.生态类型中底层鱼类共37种,占总数64.91%.区系特征以北太平洋和印度太平洋区系为主.掠夺性获取和开发以及环境污染是目前这一水域鱼类资源面临的最大威胁,针对以上威胁提出了相应的保护对策.     

Structural subunits of chondroitin sulfate isomers isolated from different aged human kidneys

Acidic glycosaminoglycans (AGAG) were extracted from whole human kidney tissues of different aged subjects and were purified by precipitation with cetylpyridinium chloride and by an ion exchange resin column chromatography. The prepared AGAG were individually digested with chondroitinase-AC and they were further digested with chondroitinase-ABC. The resulting unsaturated disaccharides and the undigested AGAG were identified by paper chromatography, electrophoresis, and other chemical analyses. The AGAG, which were resistant to chondroitinase-AC, were mainly heparan sulfates and their proportion to total AGAG appeared to decrease with the advance of age. Dermatan sulfate plus oversulfated dermatan sulfate were composed of one-fifth to one-third of the AGAG resistant to chondroitinase-AC, and their proportion tended to increase with the advance of age.     

Evaluation of gene, protein and neurotrophin expression in the brain of mice exposed to space environment for 91 days

Effects of 3-month exposure to microgravity environment on the expression of genes and proteins in mouse brain were studied. Moreover, responses of neurobiological parameters, nerve growth factor (NGF) and brain derived neurotrophic factor (BDNF), were also evaluated in the cerebellum, hippocampus, cortex, and adrenal glands. Spaceflight-related changes in gene and protein expression were observed. Biological processes of the up-regulated genes were related to the immune response, metabolic process, and/or inflammatory response. Changes of cellular components involving in microsome and vesicular fraction were also noted. Molecular function categories were related to various enzyme activities. The biological processes in the down-regulated genes were related to various metabolic and catabolic processes. Cellular components were related to cytoplasm and mitochondrion. The down-regulated molecular functions were related to catalytic and oxidoreductase activities. Up-regulation of 28 proteins was seen following spaceflight vs. those in ground control. These proteins were related to mitochondrial metabolism, synthesis and hydrolysis of ATP, calcium/calmodulin metabolism, nervous system, and transport of proteins and/or amino acids. Down-regulated proteins were related to mitochondrial metabolism. Expression of NGF in hippocampus, cortex, and adrenal gland of wild type animal tended to decrease following spaceflight. As for pleiotrophin transgenic mice, spaceflight-related reduction of NGF occurred only in adrenal gland. Consistent trends between various portions of brain and adrenal gland were not observed in the responses of BDNF to spaceflight. Although exposure to real microgravity influenced the expression of a number of genes and proteins in the brain that have been shown to be involved in a wide spectrum of biological function, it is still unclear how the functional properties of brain were influenced by 3-month exposure to microgravity.     

Investigation of venereal, transplacental, and contact transmission of the Lyme disease spirochete, Borrelia burgdorferi, in Syrian hamsters.

A hamster was inoculated with the SI-1 strain of Borrelia burgdorferi and subsequently served as a host to larval Ixodes scapularis Say. Approximately 68% of the nymphs resulting from the fed larvae were infected. Nymphs from this group were fed on uninfected hamsters, and 3 of 4 males and 6 of 6 females became infected. The infected hamsters were allowed to mate with uninfected partners to test for venereal transmission. Six infected females were mated with 6 uninfected males, whereas 3 infected males were mated with 6 uninfected females. None of the uninfected hamsters became infected after mating. Two protocols were used to determine if transplacental transmission of B. burgdorferi occurred. One group included 6 nonpregnant infected females that were subsequently mated and became pregnant. Three of the females were allowed to carry to full term, whereas the other 3 were killed prior to parturition. All fetuses and offspring were negative for B. burgdorferi based on cultures and monoclonal antibody assays. Another group of 6 females was infected via tick bite after becoming pregnant; those females were allowed to carry fetuses to birth and all were negative. Attempts at contact transmission of B. burgdorferi from 2 infected females to 2 uninfected male and 2 uninfected female hamsters and from 2 infected males to 2 uninfected male and uninfected female hamsters via urine or feces failed.     

树[鼠句]正常肠道细菌的培养分离鉴定及其药敏试验研究

目的了解人工饲养树[鼠句]肠道菌群感染情况及其各种细菌对药物的敏感性。方法通过肠道细菌采样、培养、分离和菌落生长特性观察,并经革兰氏染色、氧化酶试验、触酶试验、生化编码鉴定管试验和9种药敏试验分析,初步鉴定了107例人工饲养树[鼠句]肠道感染细菌的种类和这些细菌对药物的敏感程度。结果本次细菌培养共从树[鼠句]肠道中培养分离出5株细菌,其中革兰氏阳性菌2株,革兰氏阴性菌3株,以大肠杆菌和葡萄球菌最为多见。同时确定了菌株的药敏情况为：（1）大肠杆菌对头孢类药头孢哌酮最为敏感,对药物磺胺甲嚼唑／甲氧苄定、氧氟沙星、左氧氟沙星、呋喃妥因、诺氟沙星、氨苄西林高敏;（2）沙门氏菌对阿米卡星最为敏感,对药物头孢哌酮青霉素G高敏;（3）链球菌对试验药物氨苄西林、头孢哌酮、呋喃妥因显示为中敏;（4）葡萄球菌对头孢类药头孢哌酮、磺胺类磺胺甲晤唑／甲氧苄定、沙星类诺氟沙星、左氧氟沙星、氧氟沙星、呋喃妥因和氨苄西林最为敏感,对其它药物均为中敏;（5）假单胞菌对药物左氧氟沙星最为敏感,对大多数药物都显示高敏。结论大肠杆菌和葡萄球菌可能是树鼢肠道中正常寄生的主要菌群,同时其它菌群也有寄生。用药敏实验筛选出的药物可为临床用药和动物的生物净化提供指导依据。     

A survey of pesticide residues in pollen loads collected by honey bees in France

In 2002, a field survey was initiated on French apiaries to monitor weakness of honey bee, Apis mellifera L., colonies. Apiaries were evenly distributed in five sites located on continental France. Five colonies were randomly selected in each apiary, leading to a total of 125 studied honey bee colonies. For 3 yr (starting in autumn 2002), colonies were visited four times per year: after winter, before summer, during summer, and before winter. Pollen loads from traps were collected at each visit. Multiresidue analyses were performed in pollen to search residues of 36 different molecules. Specific analyses were conducted to search fipronil and metabolites and also imidacloprid and metabolites. Residues of 19 searched compounds were found in samples. Contamination by pesticides ranged from 50 to 0%. Coumaphos and tau-fluvalinate residues were the most concentrated of all residues (mean concentrations were 925.0 and 487.2 microg/kg, respectively). Fipronil and metabolite contents were superior to the limit of detection in 16 samples. Residues of fipronil were found in 10 samples. Nine samples contained the sulfone compound, and three samples contained the desulfinyl compound. Residues of imidacloprid and 6-chloronicotinic acid were found in 69% of samples. Imidacloprid contents were quantified in 11 samples with values ranging from 1.1 to 5.7 microg/kg. 6-Chloronicotinic acid content was superior to the limit of quantification in 28 samples with values ranging from 0.6 to 9.3 microg/kg. Statistical tests showed no difference between places of sampling with the exception of fipronil. Possible origins of these contaminations, concentration and toxicity of pesticides, and the possible consequences for bees are discussed.     

Selection of genotypes of Schistosoma mansoni and their maintenance by sporocyst transplantation

Schistosoma mansoni was isolated by hatching eggs obtained from a naturally infected Rat in Grand Etang, Guadeloupe; fifty Biomphalaria glabrata were exposed to five miracidia each. The resulting cercariae were used to infect laboratory mice which were later sacrificed to provide worms for enzyme analyses and eggs for further infections. Seven enzymes in extracts of individual worms were examined by isoelectric focusing in polyacrylamide gels: AcP, G6PDH, PGM, GPI and HK showed no variation, whereas MDH and LDH proved to be polymorphic. Two MDH loci were recognised, MDH-2 was invariant whereas two alleles were assumed at the MDH-1 locus. It was not possible to make a genetic interpretation of the complex banding pattern of LDH, although 4 types (LDH-A, -B, -C, -D) were observed. Of the snail infections, one batch of snails was exposed to 5 miracidia per snail in the normal way whereas other snails were each exposed to a single miracidium. The latter were sacrificed to provide sporocysts to transplant into further groups of recipient snails. Cercariae from the recipient snails were used to infect mice and the adult worms were analysed and compared with the normally passaged material. In this way, three lines, defined by the possession of particular MDH and LDH types, were selected from the originally polymorphic population; two were identical. The combination of single miracidium infections and enzyme typing has illustrated the possibility of selecting parasite lines of known genotype; transplantation of sporocysts from snail to snail has demonstrated that such lines can be maintained exclusively in the intermediate host.(ABSTRACT TRUNCATED AT 250 WORDS)     

The isolation and characterization of Campylobacter jejuni subsp. jejuni from domestic geese (Anser anser)

AIMS: The objectives of this study were to determine the presence of thermophilic Campylobacter spp. in free range domestic geese, and to characterize isolated strains using phenotyping criteria and SDS-PAGE of whole-cell proteins. METHODS AND RESULTS: Forty cloacal swabs from two different flocks of domestic geese were examined. All Camp. jejuni strains isolated from geese were biotyped using the Lior biotyping scheme. Twelve Camp. jejuni isolates were also tested for their susceptibility to 17 different antibacterial agents by a disc diffusion METHOD: Fourteen of the isolates were also subjected to SDS-PAGE. All of the geese examined were found to harbour Camp. jejuni. Six geese carried more than one species of Campylobacter. All strains examined were susceptible to various antibiotics but resistant to penicillin G and cephalothin. Eleven strains (92%) were resistant to sodium cefuroxime, and eight (67%) were resistant to cloxacillin, ampicillin and colistin sulphate. Three strains (25%) were resistant to tetracycline, and one strain was resistant to sulfamethoxazole/trimethoprim and kanamycin. Nine strains were subtyped as Camp. jejuni subsp. jejuni biotype II and the remaining ones as biotype I. There were 96% and 100% similarities between all the strains examined by SDS-PAGE. CONCLUSION: This study showed that Camp. jejuni were common in the intestinal tract of domestic geese. SIGNIFICANCE AND IMPACT OF THE STUDY: Geese should be considered as potential reservoirs for human and animal campylobacteriosis. The antibiotic resistance data from this study also showed that fluoroquinolone resistance, which appears to be a problem in poultry isolates in some countries, is not yet a problem in these geese.     

Effect of Hymenolepis nana infection on immunological responses of mice to sRBC

In an attempt to investigate the effect of Hymenolepis nana infection on immunological responses to sRBC in ICR strain of mice, cellular and humoral immune responses were chronologically monitored after sensitization with sRBC. Mice weighing about 20 g were allocated into artificial and natural infection groups. The shell-free eggs of H. nana were inoculated into mice on the day 0 (initial) and day 10 in the former group, and praziquantel (25 mg/kg/day) was administered for 3 days to the one half of the mice at the 15th day after the first inoculation and to all of the mice in natural infection group. In artificial infection group, the delayed-type hypersensitivity (DTH) to sRBC was considerably decreased on the day 10 after the first inoculation, and then elevated gradually to normal. Eosinophils in the peripheral blood increased slightly. The hemagglutinin (HA) and hemolysin (HE) titers during the early stage were shown to be more or less higher than those of control. Thereafter, the titers were returned to normal, followed by a transient decrease on the day 15 post-infection. The sRBC rosette and antibody-treated rosette-forming capacities on the day 15 post-infection were temporarily lowered but became higher thereafter. The mucosal mast cells (MMC) in the small intestine were gradually increased to make a peak on the day 10 post-infection and then maintained more or less at lower level. After praziquantel treatment, the DTH and the number of eosinophils were decreased slightly and the MMC number and sRBC rosette-forming capacity were considerably decreased. The titers of HA and HE and antibody-treated rosette-forming capacity, however, were elevated in general. In natural infection group, the DTH, the number of eosinophils, and MMC which were elevated due to H. nana infection were gradually returned to normal after praziquantel treatment. The titers of HA and HE which were decreased by parasite infection were increased to normal after the treatment. However, the capacities of sRBC rosette or antibody-treated rosette formation were maintained at low levels in spite of the treatment. These results revealed that the immune responses to sRBC were significantly activated during H. nana infection, although they were transiently decreased during the days 10-15 post-infection.     

Analysis of proteins synthesized by 9.5 day mouse embryos: determination of cardiac and noncardiac proteins.

To catalog polypeptides that were specific to developing hearts, we separated 35S-methionine-labeled 9.5 day mouse embryos into cardiac and noncardiac (carcass) components. Two-dimensional gels were then used to analyze the polypeptides synthesized in these two fractions. As a result, we were able to distinguish polypeptides that were specific to or increased in the heart as well as those polypeptides that were specific to or increased in the embryo minus the dissected heart. Using this analysis, there were two polypeptides that were cardiac-specific and 17 that were expressed at increased levels by at least twofold in the heart. The cardiac-specific polypeptides may be used in further studies to identify early cardiac tissue. Conversely, there were 26 polypeptides unique to noncardiac structures and an additional 15 that were increased in the carcass more than twofold relative to the heart. The noncardiac-specific polypeptides may be used to define contamination of putative cardiac tissue with noncardiac material. Two of the polypeptides expressed more abundantly in the carcass appeared to correspond to known proteins in the mouse fibroblast database, cyclin and tropomyosin 4. Thus the heart at 9.5 days of murine development can be distinguished readily from the remainder of the embryonic mouse both macroscopically and on two-dimensional gels.