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。     

Resistance patterns of non-O157 Shiga toxin-producing Escherichia coli (STEC) strains isolated from animals, food and asymptomatic human carriers in Switzerland

AIMS: The objective of the present study was to determine the resistance patterns of non-O157 Shiga toxin-producing Escherichia coli (STEC) strains isolated from different sources in Switzerland during the period 1997-99 as an epidemiological marker. METHODS AND RESULTS: The disk diffusion method was used to test 82 non-O157 STEC strains for susceptibility to 13 antibiotics. Ten strains were resistant to one and 20 strains to two and more antibiotics. The most frequent resistance types were streptomycin (14 strains), cephalothin (14 strains), sulfamethoxazole (14 strains) and tetracycline (14 strains). Three O100:H- STEC strains isolated from healthy slaughter pigs were resistant to eight antibiotics: streptomycin, sulfamethoxazole, trimethoprim, tetracycline, ampicillin, chloramphenicol, neomycin and gentamicin. CONCLUSION: Periodic surveillance of the antibiotic susceptibilities would be an important measure in detecting emergence and spread of resistance. SIGNIFICANCE AND IMPACT OF THE STUDY: Antibiotic susceptibility testing can be a useful tool for typing strains and should be used in combination with other phenotypic and genotypic methods.     

Hydrogen Sulfide-Producing Variants of Escherichia coli

Seventeen strains of H(2)S-producing variants of Escherichia coli were isolated from specimens submitted for microbiological study (ten from stool, five from urine, and two from postmortem material). Production of H(2)S was unstable in several strains; however, other than their production of H(2)S, all strains closely resembled typical E. coli in their biochemical reactions. In vitro susceptibilities of the H(2)S-producing variants to antimicrobics closely resembled those of typical E. coli in this laboratory.     

Heterogeneity of phenotypic and genotypic traits including organic-acid resistance in Escherichia coli O157 isolates

We undertook an epidemiologic study for the sensitivity of both Shiga-like toxin (Slt)-producing Escherichia coli (STEC) O157 and non-STEC O157 strains isolated from different patients with diarrhea to hydrochloric acid (HCl) and organic acids such as acetate, propionate, butyrate and lactate, and other pathogenic factors. The E. coli O157 isolates examined showed a wide variety of organic-acid susceptibility patterns. E. coli O157 isolates resistant to HCl or acetate were found more frequently than those resistant to other organic acids. These isolates also showed diverse pathogenicity patterns for the presence of the virulence genes, antibiotic susceptibility and plasmid profile.     

Antibiotic susceptibility and genotype patterns of Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa isolated from urinary tract infected patients

Thirty nine isolates of Escherichia coli, twenty two isolates of Klebsiella pneumoniae and sixteen isolates of Pseudomonas aeruginosa isolated from urinary tract infected patients were analyzed by antimicrobial susceptibility typing and random amplified polymorphic DNA (RAPD)-PCR. Antibiotic susceptibility testing was carried out by microdilution and E Test methods. From the antibiotic susceptibility, ten patterns were recorded (four for E. coli, three for K. pneumoniae and three for P. aeruginosa respectively). Furthermore, genotyping showed seventeen RAPD patterns (seven for E. coli, five for K. pneumoniae and five for P. aeruginosa respectively). In this study, differentiation of strains of E. coli, K. pneumoniae and P. aeruginosa from nosocomial infection was possible with the use of RAPD.     

从临床肺炎死亡树购中分离到致病性大肠埃希菌

目的对6例1月内因肺炎死亡的树鼢采样进行病原菌分离培养鉴定分析。方法解剖死亡树购,利用无菌刀片切开肺组织,用无菌接种环插入肺内采样接种于营养琼脂培养基,另取两份样品进行细菌涂片革兰氏染色和抗酸染色。培养出来的细菌进行进一步分离和菌落生长情况的观察,并经革兰氏染色、抗酸染色、氧化酶试验、生化编码鉴定和9种药敏试验,初步确定树鼢肺部感染的致病菌及其药敏情况。结果样本革兰氏染色见到大量阴性杆菌,抗酸染色结果显示为非结核分枝杆菌,大小约为0．2μm×2～6μm。营养琼脂培养6例样品中均仅见1株旺盛生长的细菌,进一步分离培养经革兰氏染色为阴性杆菌,抗酸染色为非结核分枝杆菌,大小和染色结果与样本涂片相同,经鉴定为致病性大肠埃希菌。药敏试验表明该菌对头孢哌酮,呋喃妥因,氨苄西林,阿米卡星,氧氟沙星,诺氟沙星,磺胺甲嗯唑／甲氧苄定高度敏感;对庆大霉素和青霉素G为低度敏感。结论6例树鼢死亡原因均为细菌性肺炎,病原菌初步鉴定为致病性大肠埃希菌。药敏实验筛选出的药物可为临床治疗树鼢该类病例用药提供指导。     

Comparison of stress susceptibility of in hospite and isolated zooxanthellae among five coral species

Coral species in a similar habitat often show different bleaching susceptibilities. It is not understood which partner of coral-zooxanthellae complexes is responsible for differential stress susceptibility. Stress susceptibilities of in hospite and isolated zooxanthellae from five species of corals collected from shallow water in Okinawa were compared. To estimate stress susceptibility, we measured the maximum quantum yields (F_v/F_m) of in hospite and isolated zooxanthellae after 3-h exposure to either 28 or 34 °C at various light intensities and their recovery after 12 h under dim light at 26 °C. Significant reduction in photochemical efficiency (F_v/F_m) of photosystem II (PSII) was observed in in hospite zooxanthellae exposed to high light intensity (1000 μmol quanta m⁻² s⁻¹), while PSII activity of isolated zooxanthellae decreased significantly even at a lower light intensity (70 μmol quanta m⁻² s⁻¹). The recovery of the PSII activity after 12 h was incomplete in both in hospite and isolated zooxanthellae, indicating the presence of chronic photoinhibition. The stress susceptibility of isolated zooxanthellae was more variable among species than in hospite zooxanthellae. The order of stress susceptibility among the five coral species was different between in hospite and isolated zooxanthellae. The present results suggest that the host plays a significant role in determining bleaching susceptibility of corals, though zooxanthellae from different host have different stress susceptibilities.     

粪便分离大肠埃希菌CRISPR系统在耐药及毒力中的作用

目的 探索粪便分离大肠埃希菌成簇规律间隔短回文重复序列(clustered regularly interspaced short palindromic repeats,CRISPR)在耐药及毒力中的作用。 方法 收集某院2018年8-12月分离自慢性腹泻患者及健康体检者粪便样本的大肠埃希菌。采用纸片扩散法检测其药物敏感性,PCR法检测并比较分析腹泻患者及健康体检者粪便样本分离大肠埃希菌的系统发育群、耐药基因及CRISPR系统。 结果 共收集到142株大肠埃希菌,源于63例慢性腹泻患者(疾病组)和79例健康体检者(健康组)。药敏结果显示,氨苄西林耐药率为48.0%,其余抗菌药物敏感率为73.1%～100.0%。63株源于慢性腹泻患者粪便样本分离大肠埃希菌中CRISPR系统的检出率显著低于79株源于健康体检者(3.2% vs 46.8%,χ2=33.538,P2=8.656,P=0.003)。 结论 粪便分离大肠埃希菌对常用抗菌药物仍保持较高敏感性。CRISPR系统可能在粪便分离大肠埃希菌毒力及耐药基因的传播方面发挥重要作用。     

The sensitivity of<Emphasis Type="Italic">Escherichia coli</Emphasis> strains with K1 surface antigen and rods without this antigen to the bactericidal effect of serum

The susceptibility of Escherichia coli strains with K1 surface antigen (K1+) and rods without this antigen (K1-) to the bactericidal action of normal bovine serum and human normal cord serum was determined. Seventy E. coli strains (35 K1+ and 35 K1-) were isolated from urine obtained from children with urinary tract infections. The strains investigated showed variable sensitivity to the bactericidal action of the sera. E. coli K1+ strains were characterized by lower sensitivity to bactericidal effect of the sera in comparison with K1- rods. The role of the particular mechanisms of complement activation in the process of killing of the E. coli strains was also determined.     

Susceptibilities of Candida albicans Mouth Isolates to Antifungal Agents, Essentials Oils and Mouth Rinses

Forty Candida albicans strains isolated from patient's mouth with fixed orthodontic appliances were analyzed to their susceptibilities to antifungal agents, mouth rinses and essential oils. Susceptibility to fluconazole, econazole, miconazole and ketoconazole, amphotericin B and nystatin was assessed by the disk diffusion (DD) method based on the Clinical and Laboratory Standards Institute M44-A protocol, and by Etest (fluconazole and amphotericin B). The susceptibilities to mouth rinses and essential oils were also determined by the DD technique. All isolates tested were susceptible (S) to amphotericin B, nystatin and fluconazole. The overall concordance between the DD and the Etest was 100% for amphotericin and fluconazole. One isolate was resistant to econazole (2.5%) and the other to ketoconazole (2.5%). Econazole and ketoconazole had the highest percentages of susceptible dose dependent (SDD), 55 and 95%, respectively. Regarding to the susceptibility isolates profile, seven phenotypes were detected, and the 3 more represented (90% of the isolates) of them were SDD to one, two or three azoles. The study of mouth rinses showed a high variability of efficacy against C. albicans. The results showed that the isolates susceptibility to essential oils differed (P < 0.05). The profile activity was: cinnamon > laurel > mint > eucalyptus > rosemary > lemon > myrrh > tangerine. The main finding was that the susceptibility to cinnamon and laurel varied among the three more representative antifungal phenotypes (P < 0.05). The susceptibility of econazole-SDD isolates to cinnamon and lemon was higher than those of the econazole-S yeasts (P < 0.05). In contrast, econazole-SDD isolates were less affected by laurel than econazole-S counterparts (P < 0.05).     

Free-range layer chickens as a source of <Emphasis Type="Italic">Campylobacter</Emphasis> bacteriophage

Bacteriophage specific for Campylobacter were isolated from chicken excreta collected from established free-range layer breed stock. Bacteriophage were either propagated on a Campylobacter jejuni host with broad susceptibility to bacteriophage (NCTC 12662) or on Campylobacter isolates from the same samples. Campylobacters were confirmed as being C. jejuni and or C. coli, using a combination of standard biochemical tests and PCR analysis with genus and species specific primers. The bacteriophage displayed differential patterns of susceptibility against reference NCTC strains and contemporary C. jejuni /C. coli isolates from chicken excreta. Electron microscopy demonstrated that the phage possessed icosahedral heads and rigid contractile tails. Pulsed-field gel electrophoresis revealed the bacteriophage genomes to be double stranded DNA in the range of 140 kb in size and the restriction enzyme patterns of the DNAs indicate they are genetically related members of the Myoviridae family. This study showed that Campylobacter bacteriophage could easily be isolated from free-range chickens and form part of their normal microbiological biota of environmentally exposed birds.     

Mechanism of increased susceptibility to 4-nitroquinoline-1-oxide in cultured skin fibroblasts from patients with familial polyposis coli

About 50% of the strains of cultured fibroblasts from patients with familial polyposis coli (FPC) exhibited increased susceptibility to cytotoxicity of 4-nitroquinoline-1-oxide (4NQO) compared with cells from normal individuals. The FPC cells that showed hyper-sensitivity to 4NQO were also hyper-sensitive to mitomycin C (MMC), but susceptibilities of these cells to UV radiation, methyl methanesulfonate (MMS) and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) were within the normal range. The extent of single-strand scission of DNA in the 4NQO-sensitive FPC cells was greater than in normal cells, and the amount of [14C]4NQO bound to DNA in the FPC cells was twice as high as in normal cells. The rate of release of [14C]4NQO from DNA by the post-culture was the same as in both FPC and normal cells. The 4NQO-sensitive FPC cells exhibited increased 4NQO-reductase activity; the level of this activity was consistent with the extent of the decrease in colony formation by 4NQO. These results suggest that the enhanced ability to activate 4NQO might be an important factor in the mechanism of susceptibility of FPC cells to 4NQO rather than the reduced ability to repair DNA.     

BPEX Pig Health Scheme: a useful monitoring system for respiratory disease control in pig farms?

Background

Both O157 and non-O157 Shiga toxin - producing Escherichia coli (STECs) cause serious human disease outbreaks through the consumption of contaminated foods. Cattle are considered the main reservoir but it is unclear how STECs affect mature animals. Neonatal calves are the susceptible age class for STEC infections causing severe enteritis. In an earlier study, we determined that mycotoxins and STECs were part of the disease complex for dairy cattle with Jejunal Hemorrhage Syndrome (JHS). For STECs to play a role in the development of JHS, we hypothesized that STEC colonization should also be evident in beef cattle with JHS. Aggressive medical and surgical therapies are effective for JHS, but rely on early recognition of clinical signs for optimal outcomes suggesting that novel approaches must be developed for managing this disease. The main objective of this study was to confirm that mouldy feeds, mycotoxins and STEC colonization were associated with the development of JHS in beef cattle.

Results

Beef cattle developed JHS after consuming feed containing several types of mycotoxigenic fungi including Fusarium poae, F. verticillioides, F. sporotrichioides, Penicillium roqueforti and Aspergillus fumigatus. Mixtures of STECs colonized the mucosa in the hemorrhaged tissues of the cattle and no other pathogen was identified. The STECs expressed Stx1 and Stx2, but more significantly, Stxs were also present in the blood collected from the lumen of the hemorrhaged jejunum. Feed extracts containing mycotoxins were toxic to enterocytes and 0.1% of a prebiotic, Celmanax Trademark, removed the cytotoxicity in vitro. The inclusion of a prebiotic in the care program for symptomatic beef calves was associated with 69% recovery.

Conclusions

The current study confirmed that STECs and mycotoxins are part of the disease complex for JHS in beef cattle. Mycotoxigenic fungi are only relevant in that they produce the mycotoxins deposited in the feed. A prebiotic, Celmanax Trademark, acted as a mycotoxin binder in vitro and interfered with the progression of disease.     

Antimicrobial susceptibilities of strains of Nocardia brasiliensis isolated from soil of Tucumán

The activity of antimicrobial agents against soil isolates of N. brasiliensis was studied by determination of the minimum inhibitory concentrations (MICs) and disk diffusion technique, according to the National Committee for Clinical Laboratory Standards (NCCLS). The objectives were: (a) to study the patterns of sensitivity among regional strains of N. brasiliensis isolated from natural sources (soil) of different zones of Tucumán province; (b) to correlate these results with those previously obtained with regional strains of N. brasiliensis isolated from human mycetomas, as a contribution in the evaluation of the importance of the natural reservoir area of the potentially pathogen strains. The results obtained by both methods identified strains of N. brasiliensis from soils with similar patterns of susceptibility to the strains N. brasiliensis isolated from human mycetomas. This showed strains sensitive and resistant to antibiotics. The majority of the isolates of N. brasiliensis from soils showed higher susceptibilities to antibiotics than the strains isolated from human mycetomas. Among the antibiotics studied, cefotaxime, ceftriaxone and gentamicin were the most effective against all the regional strains tested, and these results are correlated with those obtained with regional strains that cause human mycetomas. This revised version was published online in June 2006 with corrections to the Cover Date.     

Measurement of the susceptibility of paramagnetically labeled cells with paramagnetic solutions

A method of measuring the volumetric magnetic susceptibility, in which magnetically labeled cells or other particles are suspended in a paramagnetic solution of known susceptibility over the poles of a magnet, is presented. If the cells are more magnetic than the solution, they are attracted toward the poles; if they are less magnetic, they are repelled. If they have the same susceptibility as the solution, they do not move. Under this condition, the cells are said to be "isomagnetic" with the surrounding solution. Since the volumetric susceptibility of this solution is known, the susceptibility of the cells is obtained. Using the "isomagnetic" method, the volumetric susceptibilities of test metal powders were determined within +/- 8 X 10(-6) SI units. Yeast, colonic carcinoma, and liver cells, rendered magnetic with erbium chloride, had susceptibilities ranging from 13 to 20 X 10(-6). Particles of articular cartilage treated with erbium chloride were heterogeneous, with susceptibilities ranging between 50 and 125 X 10(-6), while particles of bone had a susceptibility of 560 to 580 X 10(-6). Eukaryotic cells labeled with ferritin attained susceptibilities of less than 1 X 10(-6).     

Subtilase cytotoxin-coding genes in verotoxin-producing Escherichia coli strains from sheep and goats differ from those from cattle

Subtilase cytotoxin (SubAB) from verotoxin (VT)-producing Escherichia coli (VTEC) strains was first described in the 98NK2 strain and has been associated with human disease. However, SubAB has recently been found in two VT-negative E. coli strains (ED 591 and ED 32). SubAB is encoded by two closely linked, cotranscribed genes (subA and subB). In this study, we investigated the presence of subAB genes in 52 VTEC strains isolated from cattle and 209 strains from small ruminants, using PCR. Most (91.9%) VTEC strains from sheep and goats and 25% of the strains from healthy cattle possessed subAB genes. The presence of subAB in a high percentage of the VTEC strains from small ruminants might increase the pathogenicity of these strains for human beings. Some differences in the results of PCRs and in the association with some virulence genes suggested the existence of different variants of subAB. We therefore sequenced the subA gene in 12 strains and showed that the subA gene in most of the subAB-positive VTEC strains from cattle was almost identical (about 99%) to that in the 98NK2 strain, while the subA gene in most of the subAB-positive VTEC strains from small ruminants was almost identical to that in the ED 591 strain. We propose the terms subAB1 to describe the SubAB-coding genes resembling that in the 98NK2 strain and subAB2 to describe those resembling that in the ED 591 strain.     

5-Methoxyindole-2-carboxylic acid is a potent inhibitor of respiration and potassium ion transport in the archaebacterium Haloferax volcanii

Abstract The chorioallantoic membrane (CAM) inoculated chick embryo model was used to study the effect of host lineage on the virulence of Campylobacter jejuni and Campylobacter coli . LD₅₀ values were used to compare the susceptibilities of chick embryos from eight inbred chicken lines to infection by four strains of C. jejuni and one strain of C. coli . Differences in susceptibility were found between inbred chicken lines. These were shown not to be due to maternal antibody status, not transfer of antibody to the developing embryo. Susceptibility to infection was also found to vary according to the Campylobacter strain used. These results indicate that both the bacterial strain and host lineage of the chicken line used affect resistance to infection in the CAM inoculated chick embryo model.     

Screening of benzalkonium chloride resistance in Listeria monocytogenes strains isolated during cold smoked fish production

AIMS: To determine the susceptibility to disinfectants and cross-resistance to antibiotics in Listeria monocytogenes strains isolated from fish products and the fish-processing environment. METHODS AND RESULTS: Minimal inhibitory concentration assessment, using the agar dilution method, showed 108 of 255 L. monocytogenes isolates with low susceptibility to benzalkonium chloride (BC), commonly used in food industries. Most of them are from raw products of farmed fish during processing, while the remaining resistant isolates were mainly from the environment and finished products irrespective of the fish species. Two BC-resistant isolates were resistant to ethidium bromide (EB). The conservation of resistance after plasmid curing suggested that the resistance genes are not plasmid associated. EB accumulation assays demonstrated that the two BC(R) EB(R) isolates used an efflux pump to expel these substrates whereas a different mechanism was probably used by the majority of the strains with BC(R) EB(S) pattern. No cross-resistance was found with antibiotics. CONCLUSIONS: This study highlights the difference in susceptibilities to BC for L. monocytogenes strains isolated from fish-processing plants and in resistance mechanisms to BC developed by these bacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: The presence of BC resistant L. monocytogenes strains could contribute to their adaptation and so explained their survival and persistence in the fish-processing environment.     

医院工作人员鼻腔葡萄球菌带菌状况年度推移的调查报告

本文报道1989年从202名医院工作人员鼻腔分离葡萄球菌的带菌状况和药敏性检测结果。并将此结果同作者等于1985年对200名同类人员检测的结果相比较,作了年度推移的调查分析发现1989年度的总带菌率(76.6％)比1985年度(84.5％)略有下降,但其中的金黄色葡萄球菌带菌率却从1985年的7.5％上升为10.4％。从1989年和1985两个年度的调查中,均发现临床科室人员金葡菌带菌率高于其它辅助科室人员,说明医务人员带菌率与接触病人成正相关关系。分离菌株对12种抗菌药物的耐药性检测结果显示,1989年分离菌株对其中9种的敏感性下降,并且从耐药谱显示出对5种抗菌药物耐药的多重耐药菌株明显增多。另从金葡菌的耐药情况,也看出1989年的耐药率高于1985年菌株。还在1989年分离的金葡菌中出现25％的耐甲氧西林菌株。     

Relationship between the susceptibility of various bacteria to active oxygen species and to intracellular killing by macrophages

The susceptibilities of six micro-organisms to active oxygen species generated in the xanthine oxidase-mediated bactericidal system were as follows: Escherichia coli 81 greater than or equal to Listeria monocytogenes EGD greater than or equal to Salmonella typhimurium HKB-1 greater than or equal to Staphylococcus aureus Smith much greater than Mycobacterium tuberculosis H37Rv approximately equal to Candida albicans NIH A207 (the last two organisms were essentially resistant to this system). The H2O2-Fe-mediated halogenation system exhibited a higher microbicidal activity. When the micro-organisms were compared for their sensitivity to bactericidal activity of resident mouse peritoneal macrophages (M phi s), C. albicans, Staph. aureus and E. coli were killed rapidly, whereas M. tuberculosis, L. monocytogenes and S. typhimurium were more resistant. In tests for the ability to trigger an oxidative burst in mouse peritoneal M phi s (as measured by chemiluminescence), Staph. aureus showed the highest activity followed by the other organisms in the following order: C. albicans greater than E. coli greater than L. monocytogenes congruent to M. tuberculosis. S. typhimurium exhibited no triggering activity. The high susceptibility of Staph. aureus and E. coli to M phi bactericidal activity, and the partial resistance of L. monocytogenes and M. tuberculosis, correlated with their susceptibility to active oxygen and the H2O2-Fe-mediated halogenation reaction.