R factors ofEscherichia coli strains causing urinary tract infections,their types of transfer factors and differences in their transmissibility toCitrobacter andSalmonella typhimurium recipient strains

A total of 107 R factors was demonstrated in 103Escherichia coli strains isolated from the urine of patients with urinary tract infections. Four of the strains were in a hetero-R state, i.e. each cell possessed two R factors with different types of transfer factors. Of the total number of R factors, 76.6% were fi⁺ and 23.4% fi⁻. The recipient strainCitrobacter O-7, 3b, 1c accepted all the given R factors, while the other,Salmonella typhimurium, accepted only 20%. Both the recipient strains accepted fi⁺ and fi⁻ factors. We presume that the transmissibility of R factors depends on their type of transfer factor, but in relation to criteria other than fi⁺ and fi⁻ and the recipient's affinity.     

Comparative genomics of Escherichia coli strains causing urinary tract infections

The virulence determinants of uropathogenic Escherichia coli have been studied extensively over the years, but relatively little is known about what differentiates isolates causing various types of urinary tract infections. In this study, we compared the genomic profiles of 45 strains from a range of different clinical backgrounds, i.e., urosepsis, pyelonephritis, cystitis, and asymptomatic bacteriuria (ABU), using comparative genomic hybridization analysis. A microarray based on 31 complete E. coli sequences was used. It emerged that there is little correlation between the genotypes of the strains and their disease categories but strong correlation between the genotype and the phylogenetic group association. Also, very few genetic differences may exist between isolates causing symptomatic and asymptomatic infections. Only relatively few genes that could potentially differentiate between the individual disease categories were identified. Among these were two genomic islands, namely, pathogenicity island (PAI)-CFT073-serU and PAI-CFT073-pheU, which were significantly more associated with the pyelonephritis and urosepsis isolates than with the ABU and cystitis isolates. These two islands harbor genes encoding virulence factors, such as P fimbriae (pyelonephritis-associated fimbriae) and an important immunomodulatory protein, TcpC. It seems that both urovirulence and growth fitness can be attributed to an assortment of genes rather than to a specific gene set. Taken together, urovirulence and fitness are the results of the interplay of a mixture of factors taken from a rich menu of genes.     

女性生殖道感染常见病原体及药敏研究进展

生殖道感染在妇科疾病中发病率较高,可造成不孕、异位妊娠、胎膜早破、早产等不良后果。引起女性生殖道感染的病原体种类较多,且由于临床不合理用药现象日趋严重,各种病原体对抗菌药物的耐药性逐年上升。本文对引起女性生殖道感染的常见病原体种类、病原体对女性生殖健康的影响及药敏试验研究进展进行了综述。了解各病原体特点,开展各种病原体对药物敏感性试验,可减少女性生殖道感染的复发率,提高治愈率,为改善女性生活质量与促进生殖健康提供帮助。     

Production of and sensitivity to colicins among serologically classified strains of Escherichia coli

A significant proportion of 242 serologically classified strains of Escherichia coli of human origin produced colicins (33%) or were inhibited by one or more of six standard colicins (57%). The most common colicins identified were E1, I, and B; colicins B and V had greatest range of activity. Generally, neither the production of, nor sensitivity to, individual colicins was restricted to strains of a single serogroup. The coexistence of strains of one serogroup that were sensitive to the action of a colicin produced by strains of another serogroup was encountered among 2 of 21 fecal specimens containing strains of multiple serogroups. The production of colicins was not a major determinant in the acquistion of, or subsequent changes in, strains of E. coli in the feces of 10 newborn infants.     

Fimbriation ofEscherichia coli in urinary tract infections. Comparisons between bacteria in the urine and subcultured bacterial isolates

Midstream urine samples from 37 patients with urinary tract infections were studied by electron microscopy, hemagglutination, and the salt aggregation test (SAT) to measure the hydrophobicity of the bacterial surface.Escherichia coli subcultured from these urine samples were tested in the same way. Fimbriae were visualized onE. coli in the urine of 31 specimens, and all these urines containedE. coli that expressed pronounced surface hydrophobicity and aggregated in ammonium sulfate of 0.1–1.6 M final concentration. Hemagglutination of human and/or guinea pig erythrocytes was expressed by 21E. coli in the urine. TheE. coli strains subcultured from these 31 urine samples were also fimbriated, but the number of fimbriae per bacterium as well as the percentage of fimbriated bacteria varied compared with the directly collected strains. The surface hydrophobicity and hemagglutination were similar to the results with the directly collected bacteria. However, after serial transfer in CFA-broth under static conditions, all non-hemagglutinating strains expressed mannose-sensitive hemagglutination of guinea pig erythrocytes, and three strains also expressed weak mannose-resistant hemagglutination of human erythrocytes. Following serial transfer, fimbriae were also visualized on the sixE. coli strains that appeared non-fimbriate in the urine. It is thus concluded thatE. coli causing urinary tract infection are often fimbriated and express surface hydrophobicity in the urine. Based on these findings, a rapid method to isolate hydrophobic, possibly fimbriated bacteria was tried in which the urine was mixed with a hydrophobic gel. Hydrophobic bacteria bound to the gel and could be eluted from the sedimented gel.     

Pathogenic characteristics of Escherichia coli strains in cases of asymptomatic bacteriuria and symptomatic urinary tract infections

The aim of this study was to examine if E. coli isolated from asymptomatic bacteriuria differed in pathogenic features from strains isolated from symptomatic infections of urinary tract. In this study 130 strains of E. coli isolated from women having asymptomatic bacteriuria and 112 strains isolated from patients with symptoms of urinary tract infection were examined. It was shown that E. coli isolated from patients with symptomatic urinary tract infection showed the more frequently ability to cause mannose-resistant haemagglutination of human erythrocytes, resistance to bactericidal activity of serum and haemolytic properties than those isolated from asymptomatic bacteriuria. These strains showed also the higher ability to adhere to Vero cells in tissue culture. Among E. coli strains isolated from persons with asymptomatic bacteriuria the pathogenic features were most frequently found in strains from healthy women and the most rarely in isolated from diabetic women.     

婴儿泌尿道感染的病原菌分布及耐药性分析

目的探讨婴儿泌尿道感染的病原菌构成及其耐药情况,以指导临床合理用药。方法对2012年5月至2013年7月某院门诊及住院婴儿送检的尿标本进行分离培养,用全自动微生物鉴定／药敏系统进行菌种鉴定和药敏试验,同时对大肠埃希菌和肺炎克雷伯菌进行超广谱β-内酰胺酶检测。结果婴儿泌尿道感染以大肠埃希菌检出率最高（46．24％）,其余依次是粪肠球菌（22．04％）、肺炎克雷伯菌（7．80％）、屎肠球菌（5．37％）、铜绿假单胞菌（4．30％）。大肠埃希菌和肺炎克雷伯菌超广谱β-内酰胺酶检出率分别为46．51％和58．62％。革兰阴性菌对亚胺培南、美罗培南的耐药率为0,对氨苄西林耐药率最高（〉80％）。革兰阳性菌对万古霉素耐药率为0,对苯唑西林、妥布霉素的耐药率100％。结论婴儿泌尿道感染病原菌以大肠埃希菌为主;大肠埃希菌、肺炎克雷伯菌超广谱β-内酰胺酶检出率高,应引起重视;临床医师要根据药敏结果指导用药,对危重病例和存在泌尿道畸形反复发作病例,革兰阴性菌可选用亚胺培南、美罗培南,革兰阳性菌可选用万古霉素。     

2014年泌尿道感染病原菌分布及药敏性分析

摘要：目的 分析并了解泌尿道感染病原菌的分布及药敏性,为临床合理有效的抗菌治疗提供参考依据。方法 收集宁波市医疗中心李惠利医院2014年住院及门诊部送检的中段尿标本分离的1 187株病原菌,对其菌群分布和药敏结果进行回顾性分析。结果 1 187株尿培养病原菌中,细菌占82.8%（983/1 187）,真菌占17.2%（204/1 187）。检出率前四位的细菌分别是大肠埃希菌（31.2%）、屎肠球菌（10.5%）、肺炎克雷伯菌（9.6%）和粪肠球菌（9.2%）,其中大肠埃希菌和肺炎克雷伯菌产超广谱β-内酰胺酶的阳性率分别是61.2%和26.9%,对头孢菌素类、青霉素类和单环酰胺类抗生素的敏感率普遍较低,对碳青霉烯类药物的敏感率>85%。屎肠球菌和粪肠球菌对抗菌药物的敏感性存在较大差异,且表现出较高的多药耐药性,屎肠球菌对万古霉素和利奈唑胺的敏感率分别为100.0%和95.1%,粪肠球菌对青霉素G和氨苄西林完全敏感。检出率前两位的真菌分别是白色假丝酵母菌（9.0%）和光滑假丝酵母菌（6.2%）,两者对5-氟胞嘧啶和两性霉素B近乎100.0%敏感。结论 本院引起泌尿道感染的病原菌种类繁多,对不同抗菌药物的敏感性差异较大,临床应根据药敏试验结果权衡利弊后合理使用抗菌药物,预防和控制耐药菌株的形成。     

Colicins G and H and their host strains.

Escherichia coli strains CA46(pColG) and CA58(pColH) each apparently synthesized two generally similar bactericidal colicin proteins whose molecular weights were approximately 5,500 and 100,000. These proteins were more resistant to trypsin than representative colicins A, D, E1, and V. The smooth wild-type strains harbouring plasmids pColG and pColH were serotyped O169:NM and O30:NM, respectively, being typically associated with nonpathogenic E. coli of human origin. Rough and semirough variants, which were selected using resistance to novobiocin, were intrinsically insensitive to almost as many colicins (10 tested) as their parents. For this reason the wild-type strains would not be useful for identifying colicins G and H on the basis of immunity. The O antigenic side chains of both wild-type strains shielded three of the six bacteriophage protein receptors tested.     

Characteristics ofPseudomonas aeruginosa strains isolated from urinary tract infections

Thirty-three uropathogenic strains ofPseudomonas aeruginosa were investigated for hemolytic activity in both bacterial broth culture filtrates and isolate lyzates, resistance to bactericidal activity of fresh human serum, resistance to six antibiotics and plasmid DNA profile. Twenty-four of the 33 (73%) bacterial filtrates showed lysis of rabbit erythrocytes, as did the three after guinea-pig erythrocyte treatment. Twelve of 33 isolate lysates showed in parallel lysis of both types of erythrocytes used. Serum resistance was found in 17 (52%) isolates, intermediate resistance in 15 (45%) isolates and only one isolate showed serum sensitivity. Resistance to antibiotics was detected as follows (in %): tetracycline 94, kanamycin 79, chloramphenicol 76, septrin 73, ampicillin 64, streptomycin 45, gentamicin 18. None of the isolates investigated showed resistance to colistine. With the exception of one isolate, plasmid DNA was detected in allP. aeruginosa strains.     

综合ICU危重症患者大肠埃希菌致尿路感染菌群特点及耐药性

目的分析综合ICU危重症患者大肠埃希菌致尿路感染病原菌的分布特点和耐药性。方法收集2012-2014年宁波市北仑区第二人民医院128例综合ICU危重症患者大肠埃希菌致尿路感染的清洁中段尿液培养标本,分别进行细菌鉴定、药敏试验及超广谱β-内酰胺酶(ESBLs)检测。结果 128例患者共分离出大肠埃希菌128株,2012-2014年每年留置尿管患者检出的产ESBLs菌株数均多于非留置尿管患者,但差异无统计学意义(均P0.05)。产ESBLs菌株对头孢唑林、头孢呋辛完全耐药,对头孢哌酮/舒巴坦、哌拉西林/他唑巴坦和头孢替坦较为敏感,对亚胺培南的敏感性最强。产ESBLs菌株对大部分抗菌药物的耐药性均高于非产ESBLs菌株,部分耐药性的差异具有统计学意义(P0.05)。结论大肠埃希菌产ESBLs菌株对多数抗菌药物存在较高的耐药性,但对头孢哌酮/舒巴坦、哌拉西林/他唑巴坦、头孢替坦、亚胺培南的耐药性较低,可作为治疗大肠埃希菌致尿路感染优先抗菌药物。     

Urinary tract infections of Escherichia coli strains of chaperone-usher system

Urinary tract infections are a very serious health and economic problem affecting millions of people each year worldwide. The most common etiologic agent of this type of bacterial infections, involving the upper and lower urinary tract, are E. coli strains representing approximately 80% of cases. Uropathogenic E. coli strains produce several urovirulence factors which can be divided into two main types, surface virulence factors and exported virulence factors. Surface-exposed structures include mainly extracellular adhesive organelles such as fimbriae/pili necessary in adhesion, invasion, biofilm formation and cytokine induction. Among the surface-exposed polymeric adhesive structures there are three most invasive groups, type 1 pili, type P pili and Dr family of adhesins which are bioassembled via the conserved, among Gram-negative bacteria, chaperone-usher secretion system. Type 1 and P-piliated E. coli cause cystitis and pyelonephritis. The Dr family of adhesins recognizing DAF receptor is responsible for cystitis, pyelonephritis (especially in pregnant women) and diarrhoea (in infants). In addition, Dr-positive E. coli strains carry the risk of recurrent urinary tract infections. Pyelonephritis in pregnant women leads to a series of complications such as bacteremia, urosepsis, acute respiratory distress syndrome and even death. In the era of increasing drug resistance of bacteria, the development of vaccines, drugs termed pilicides and inhibitors of adhesion may be a promising tool in the fight against urogenital infections.     

Proteomic analysis of Escherichia coli associated with urinary tract infections

Escherichia coli is a major cause of urinary tract infections (UTIs) where the initial infection arises from bacteria originating in the bowel. However, significant differences are observed between the genomes of intestinal and urinary E. coli strains with the latter possessing many adaptations that promote growth in the urinary tract. To define further the adaptation of urinary E. coli isolates, the cellular proteomes of 41 E. coli strains, collected from cases of UTIs or random faecal samples, were compared by 2-D gel electrophoresis and principal component analysis. The data indicated that individual patients carried relatively homogenous E. coli populations, as defined by their cellular proteomes, but the populations were distinct between patients. For one patient, E. coli, isolated during two recurrent infections 3 months apart, were indistinguishable, indicating that for this patient the infections were possibly caused by the same bacterial population. To understand the basis of the discrimination of the bacteria, selected protein spots were identified by peptide fragment fingerprinting. The identified proteins were involved in a variety of metabolic and structural roles. The data obtained for these E. coli strains provide a basis from which to target key bacterial proteins for further investigation into E. coli pathogenesis.     

Binding domains of colicins E1, E2 and E3 in the receptor protein btub ofEscherichia coli

Eight reagents specifically modifying amino acids were applied to cells of a standardEscherichia coli colicin indicator strain to followin vivo changes of its binding capacity for colicins E1–E3 and hence the binding domains (epitopes) for them in the outer membrane receptor protein BtuB. The effect of these reagents was also investigated in a mutant strain carrying an extensive BtuB deletion. The following differences of the binding epitopes could be ascertained.Colicin E1: Blockage of OH-groups, just as N-substitution of His and modification of Arg and Trp enhance binding of colicin E1. In the deleted receptor, also abolition of carboxylic anion bonds enhances its affinity for colicin E1. It follows that colicin E1 is bound, most of all, to the hydrophobic domain A (loops 1+2) of BtuB.Colicins E2 and E3: both exert rather analogous binding parameters. In contrast to E1, O-substitution of Ser and Thr dramatically decreases the E2 and E3 binding, similarly to modification of Lys. There is also a clear difference in the binding affinity of the domain for E2 and/or E3 and for E1 following modifications of their Arg and His. Colicins E2 and E3 are rather bound to the hydrophilic domain B (loops 5–7) of the receptor. In this respect, interactions of colicins E2 and E3 with deeper parts of A and B domains (Trp, several Arg, Lys and His residues) exhibited subtle differences. Acidic pH (4.5–6.0) shows a positive, while pH 7.0–8.5 a rather negative impact on the receptor-binding function for the colicins. It was clearly demonstrated that there is just a partial difference between the binding behavior of colicins E1, E2 and/or E3.