Physicochemical properties of the pKMR plasmids controlling antibiotic resistance and the capacity to produce colonization antigen

KMR plasmids controlling antibiotic resistance and the capacity for production of the colonization antigen were identified in wild strains of E. coli (026, 0126, 0124) and S. sonnei isolated from patients with acute intestinal diseases. The strains of E. coli 026 and E. coli 0126 carried p KMR207-1 plasmid determining resistance to chloramphenicol and tetracycline and the adhesive properties. The molecular weight of the plasmid is 98 mD. The strain of S. sonnei carried p KMR 208-1 plasmid responsible for resistance to streptomycin, chloramphenicol and tetracycline and the adhesive properties. The molecular weight of this plasmid is 98 mD. The resistance to streptomycin and tetracycline and the capacity for the synthesis of the colonization antigen in E. coli 0214 was controlled by p KMR209 plasmid with the molecular weight of 2.66 mD. The restriction analysis suggests that p KMR207a-1 and p KMR 207b-1 plasmids detected in E. coli of different serotypes were identical, since they could be broken with BamH1 endonuclease into equal numbers of fragments similar by their molecular weights. p KMR207-1 and p KMR208-1 plasmids differed in their sensitivity to BamH-1 endonuclease. However, they were broken into 6 fragments similar by their molecular weights. p KMR207-1 and p KMR208-1 plasmids are probably closely related but not identical.     

A comparative analysis of Stachybotrys chartarum strains isolated in Russia

This work deals with a comparative analysis of Stachybotrys chartarum strains isolated from various artificial cellulose-containing materials and natural substrates in the geographically distant regions of Russia. The analysis included the determination of the spore size, the strain toxicity to Paramecium caudatum, the strain resistance to the fungicides Benomil, Olilen, and Tilt, and the PCR study of the genome structure with the aid of a primer that was complementary to the core sequence of the SINE retrotransposon. It was found that some of the strains that were isolated from different areas and from different substrates differ in their toxicity, fungicide resistance, and genome structure. The PCR analysis showed the absence of any correlation between the genome structure, the strain properties, the geographic area, and the substrates from which the strains were isolated. The pheno- and genotypic diversity of the strains and their different vegetative compatibility suggest the existence of an intraspecies diversity of the S. chartarum strains that were isolated in different geographic areas. The absence of any correlation between the pheno- and genotypic properties of the strains and the substrates from which they were isolated implies that the colonization of artificial substrates by S. chartarum occurred occasionally from natural habitats. The S. chartarum populations that live on artificial substrates are unlikely to have their own evolutionary history.     

Comparative evaluation of biological properties of Salmonella typhimurium strains of different origin and genetic nature of resistance to antibiotics

The results obtained in the comparative study of the biological characteristics of Salmonella typhimurium strains of different origin are presented. The circulation of two biovariants differing in a number of biological characteristics, mainly in their susceptibility to antibiotics, has been shown. R-plasmids, mostly with the markers of resistance to tetracycline and with a molecular weight of 64 Md, have been isolated from "hospital" and "sporadic" strains possessing multiple antibiotic resistance.     

A Comparative Analysis of Stachybotrys chartarum Strains Isolated in Russia

This work deals with a comparative analysis of Stachybotrys chartarum strains isolated from various artificial cellulose-containing materials and natural substrates in geographically distant regions of Russia. The analysis included determination of the spore size; the strain toxicity to Paramecium caudatum; the strain resistance to the fungicides Benomil, Olilen, and Tilt; and the PCR study of the genome structure with the aid of a primer that was complementary to the core sequence of the SINE retrotransposon. It was found that some of the strains that were isolated from different areas and from different substrates differ in their toxicity, fungicide resistance, and genome structure. PCR analysis showed the absence of any correlation between the genome structure, the strain properties, the geographic area, and the substrates from which the strains were isolated. The pheno- and genotypic diversity of the strains and their different vegetative compatibility suggest the existence of an intraspecies diversity of the S. chartarum strains that were isolated in different geographic areas. The absence of any correlation between the pheno- and genotypic properties of the strains and the substrates from which they were isolated implies that the colonization of artificial substrates by S. chartarum occurred occasionally from natural habitats. The S. chartarum populations that live on artificial substrates are unlikely to have their own evolutionary history.     

Polyresistant Enterobacteriaceae strains and their plasmids in a hospital. Medical and theoretical aspects

The properties and origin of multiple resistant strains of Enterobacteriaceae found in the intestine and nasopharynx of infants admitted to the hospital for premature infants were studied. The strains of E. coli of different serovars isolated at various periods contained similar conjugative R plasmids with a molecular weight of 80 Md belonging to the O incompatibility group controlling resistance to kanamycin and physically independent small plasmids controlling resistance to ampicillin (7 Md) and streptomycin-sulfanilamides (4 Md). Multiple drug resistance in the strains of K. pneumoniae was controlled by single large (100-120 Md) plasmid cointegrates with 6-8 resistance markers. Such cointegrates consisted of several potentially independent plasmids, sometimes dividing on transformation of plasmid DNA of the recipient strains of E. coli K12. The small plasmids controlling resistance to ampicillin and streptomycin-sulfanilamides similar to the respective plasmids of E. coli were the constant components of the plasmids cointegrates. The multiple drug resistance in the above strains was combined with high capacity for colonization in premature infants. The medical staff and mothers were the sources of bacterial strains with single plasmids controlling definite types of resistance. It is suggested that the multiple resistant strains of Enterobacteriaceae are formed in hospital as a result of accumulation of the plasmids or plasmid markers and selection. One of the conditions for successive acquisition of new plasmid markers by definite bacterial strains was their high capacity for colonization in patients, which provided constant contacts and genetic exchange of such strains with a wide range of immigrant strains during colonization in the newly admitted patients.     

A comparative analysis of the properties of bacteria in the genus Salmonella isolated from children in Latvia]

Since social and economic changes in Latvia in 1991 the incidence of salmonellosis dramatically increased: more than 500 pediatric cases are registered every year. Specification of the properties of the Salmonella strains isolated in Latvia was undertaken. The study demonstrated that acute salmonellosis in pediatric inpatients was mainly due to S.typhimurium (78 per cent) and only in 22 per cent of the patients it was due to S.enteritidis. All the S.typhimurium isolates showed high antibiotic resistance defined by specific extended spectrum beta-lactamase (CTX-M-5).     

Effect of plasmids for multiple antibiotic resistance on the change in Salmonella typhimurium phagovar

The data on the influence of acquired plasmid resistance to antibiotics on S. typhimurium phagovar. Plasmid R was transferred from S. typhimurium strain, isolated from the focus of hospital salmonellosis and resistant to the lytic action of phages, to Escherichia coli K12 and then to antibiotic-sensitive S. typhimurium strains of different phagovars, isolated from patients with alimentary toxicoinfections. The influence of plasmid R on the phagovar of recipient strains, most pronounced in strains of phagovar I, was revealed. The transconjugates of this phagovar considerably changed sensitivity to phages and in some cases acquired resistance to the lytic action of typing phages, thus becoming identical in this feature to the donor of the plasmid.     

Molecular analysis confirms food source and simultaneous involvement of two distinct but related subgroups of Salmonella typhimurium bacteriophage type 10 in major interprovincial Salmonella outbreak

More than 2,000 confirmed cases of food poisoning occurred in the four Atlantic provinces of Canada and in Ontario during the second and third quarters of 1984. Salmonella typhimurium phage type 10 was identified as the etiologic agent, and cheddar cheese was implicated as the source of infection. Strains isolated from infected humans and from cheese were indistinguishable by biotyping, antibiotic resistance typing, and phage typing. Plasmid analysis confirmed cheese as the source of infection and revealed the presence of two molecular subgroups of bacteriophage type 10. Group I strains carried 57-, 22.3-, and 3.4-kilobase (kb) plasmids; group II strains carried 57-, 4.6-, and 3.4-kb plasmids. Digestion with endonucleases HaeIII, HpaII, and AvaIII indicated that the 3.4-kb plasmids were identical. This outbreak was, therefore, caused by a mixed infection with two distinct but related bacteria. Group I strains are fairly common among Canadian S. typhimurium phage type 10 isolates, whereas group II strains appeared to be unique to this outbreak.     

Molecular analysis confirms food source and simultaneous involvement of two distinct but related subgroups of Salmonella typhimurium bacteriophage type 10 in major interprovincial Salmonella outbreak.

More than 2,000 confirmed cases of food poisoning occurred in the four Atlantic provinces of Canada and in Ontario during the second and third quarters of 1984. Salmonella typhimurium phage type 10 was identified as the etiologic agent, and cheddar cheese was implicated as the source of infection. Strains isolated from infected humans and from cheese were indistinguishable by biotyping, antibiotic resistance typing, and phage typing. Plasmid analysis confirmed cheese as the source of infection and revealed the presence of two molecular subgroups of bacteriophage type 10. Group I strains carried 57-, 22.3-, and 3.4-kilobase (kb) plasmids; group II strains carried 57-, 4.6-, and 3.4-kb plasmids. Digestion with endonucleases HaeIII, HpaII, and AvaIII indicated that the 3.4-kb plasmids were identical. This outbreak was, therefore, caused by a mixed infection with two distinct but related bacteria. Group I strains are fairly common among Canadian S. typhimurium phage type 10 isolates, whereas group II strains appeared to be unique to this outbreak.     

Specific Distribution of R Factors in Serratia marcescens Strains Isolated from Hospital Infections

Serratia marcescens strains from three hospitals in the city of New York were tested for antibiotic susceptibility patterns and the presence of transmissible antibiotic resistance factors. There appears to be a pattern characteristic for each hospital with regard to the sensitivity to nalidixic acid, tetracycline, chloramphenicol, and sulfonamides, whereas the resistance to ampicillin, cephalothin, and streptomycin is similar in the strains isolated from all three hospitals. In one hospital, a single type of R factor was found which transfers resistance to streptomycin, kanamycin, ampicillin, and sulfonamides, whereas strains isolated from a second hospital transfer only ampicillin resistance. No R factors could be detected in multiply resistant Serratia strains isolated in a third hospital. The presence of a single type of R factor probably reflects the relative ecological isolation of S. marcescens and could be useful for epidemiological studies of hospital infections with Serratia.     

Transferable sodium arsenate resistance in enterobacteriaceae

The sodium arsenate and antibiotic resistance of a total of 750 strains of Enterobacteriaceae andPseudomonas aeruginosa isolated from hospital patients was determined. Resistance to sodium arsenate (minimal inhibitory concentration ≥25 mg/ml) was found in 61.4% of the isolates and was present both in antibiotic-susceptible and antibiotic-resistant strains. Ten enterobacterial isolates (3 sodium arsenate-resistant, antibiotic-susceptible strains and 7 sodium arsenate-resistant, antibiotic-resistant strains) could transfer sodium arsenate resistance to susceptible isolates and toEscherichia coli K-12 by conjugation. From sodium arsenate-and antibioticresistant strains, sodium arsenate and antibiotic resistances were transferred en bloc. Sodium arsenate resistance of antibiotic-susceptible strains was not self-transmissible, and transfer occurred only after R-plasmid mobilization.     

Typing of methicillin resistant strains of S. haemolyticus isolated from patients and from the hospital ward environment

Biotyping, antibiograms and fingerprinting were used to determine the relation of 16 methicillin-resistant S. haemolyticus isolated from drains in patients who underwent intraabdominal surgery to 9 methicillin-resistant strains of S. haemolyticus isolated at the same time from hospital environment. The comparison of biochemical properties of the examined strains showed a large variety of biochemical profiles as well as antibiotic patterns of susceptibility. The differences in sensitivity to the antibiotics used were not distinct. Biotyping and antibiograms did not permit determination of the relation of the investigated strains. Only the results of fingerprinting allowed for the division of the 25 examined strains into three genotypes demonstrating three main patterns of PCR products. 16 strains of 25 showed the same pattern of PCR products. This results suggests the presence of a source of infection on the clinical ward. A nurse may have been the source of infection because the same genotype of S. haemolyticus was isolated from her nasal anterior as from the majority of patients.     

Biological properties of plasmid-free strains of Salmonella typhimurium and S. dublin

The study of Salmonella virulent strains has revealed that the characteristic feature of such strains is the presence of plasmids with a molecular weight of 90.2-91.5 kb for S. typhimurium and 77.2-78.5 kb for S. dublin. From Salmonella strains harboring only a single plasmid, variants with no plasmid at all have been obtained. These variants possess lower virulence for mice infected through enteral and intraperitoneal routes; besides, they lose their capacity for penetration into epithelial cells of HeLa line. S. typhimurium and S. dublin have shown decreased multiplication rate in vivo in comparison with the parent strains, while the multiplication rates in vitro were similar. These results suggest that the products of plasmid genes are either responsible for the virulent properties of salmonellae, or they have regulatory functions, thus controlling the work of chromosomal genes.     

广州地区儿童血培养病原菌的分布及耐药性研究

目的探讨儿童血培养病原菌的分布特点及其耐药情况,为临床诊疗提供参考。方法对广州市儿童医院2005年至2006年临床各科室送检血液标本所分离病原菌的分布及药敏结果进行回顾性分析。结果共检出385株病原菌,其中革兰阳性菌208株,占54．0％,革兰阴性菌164株,占42．6％,真菌13株,占3．4％。分离率前6位的病原菌依次为凝固酶阴性葡萄球菌（CNS,35．8％）、肺炎克雷伯菌（8．8％）、不动杆菌（5．5％）、大肠埃希菌（4．9％）、铜绿假单胞菌（4、7％）、金黄色葡萄球菌（4．4％）。病原菌的病区分布特点：儿科重症监护病房以不动杆菌等非发酵菌为主要分离菌（占41．7％）,新生儿重症监护病房以CNS为主（40．5％）,血液病区以肠杆菌科细菌为主（35．7％）,新生儿病房及传染病房均以CNS为主要分离菌。CNS对青霉素、氨苄西林、红霉素耐药率均超过80％,但对万古霉素、替考拉宁和阿米卡星敏感,MRCNS检出率达72.5％。肠杆菌科细菌对哌拉西林、氨苄西林、头孢噻肟及头孢哌酮的耐药率为50％～100％,但对亚胺培南、阿米卡星和诺氟沙星耐药率较低。不动杆菌对广谱青霉素、第3代头孢菌素、氨曲南及庆大霉素的耐药率较高而对亚胺培南、头孢哌酮／舒巴坦较为敏感。结论凝固酶阴性葡萄球菌是广州地区儿童败血症最主要的病原菌。不同病区检出病原菌种类有较大差异。根据病原菌种类及药敏结果合理应用抗菌药是有效控制感染和减少耐药菌株产生的重要手段。     

Disappearance of differences in antibiotic resistance of Staphylococcus aureus strains isolated in hospitals and in general practice

There is general opinion that Staphylococcus aureus strains isolated in hospitals are more frequently resistant to antibiotics than community strains, however, the increasing resemblance between hospital and community strains has been recently reported. The aim of the study was to compare the antibiotic resistance and phage-type pattern of S. aureus strains isolated from patients treated either in hospitals or in general practice in northern part of Poland. The study was conducted on 771 S. aureus strains isolated from different specimens. Phage typing was performed according to the method of Blair and Williams. The drug susceptibility was determined by the disc-diffusion method. There were no significant differences in antibiotic resistance or phage-type pattern when hospital and community methicillin-sensitive S. aureus (MSSA) strains were compared. The most MSSA were resistant to penicillin (84.6% and 82.1% respectively) and doxycycline (49.3% and 50.4% respectively) whereas they were rarely resistant to other antibiotics. The predominance of phage group II was found in both hospitals (28.0%) and general practice (29.9%). Phage group III, usually associated with hospitals, occurred in small percentage (12.9% and 9.4% respectively) while to this group predominantly (76.6%) multiresistant methicillin resistant S. aureus (MRSA) isolated in hospitals belonged. These results suggest, that there is only slight difference in antibiotic resistance between hospital and community S. aureus strains. Antibiotic resistance pattern mainly results from frequency of appearance of MRSA, mostly occurring in hospitals.     

The use of a molecular hybridization method for studying the enterotoxigenic properties of Salmonella

The occurrence of the tox gene among 320 Salmonella strains of 23 serovars, differing in their origin, sensitivity to antibiotics, the presence of R-plasmids and a number of biochemical properties, has been studied by the method of DNA-DNA hybridization in situ. Essential differences in the occurrence of the tox gene have been detected both among S. typhimurium hospital strains and strains isolated in sporadic diseases, from the environment, from animals and among salmonellae belonging to different serovars. The direct correlation between the presence of the enterotoxigenicity gene and plasmids controlling resistance to antibiotics in Salmonella strains has been established. The expediency of using the method of gene probing for the study of the enterotoxigenic properties of salmonellae has been substantiated.     

Influence of plasmid pR50 controlling bacterial protease activity on Salmonella experimental infection

The comparative analysis of the infectious process and immunological parameters in (CBA x C57BL/6)F1 mice infected with S. typhimurium isogenic strains differing by the presence of plasmid pR50 determining protease activity, was carried out. A growth in the expression level of antilactoferrin, anticomplementary and anti-immunoglobulin activity in bacteria isolated from the spleen in the course of the infectious process was detected. In mice infected with S. typhimurium having plasmid pR50, in contrast to nonplasmid recipients, a higher level of contamination of organs, the suppression of spontaneous, stimulated production of interferon-gamma and the bactericidal properties of peritoneal macrophages were noted. The data obtained in this investigation suggested that the acquisition of R-plasmid of 50 MD, controlling protease activity and multiple medicinal resistance, contributed to the persistence of intracellular bacteria.     

Selection of methods of detecting lactose-fermenting Salmonella strains and evaluating their usefulness for diagnostic studies

Salmonella rods of subspecies I, lactose-fermenting were first isolated in Poland in 1980. They were isolated from a plus sample taken from a brain abscess of a child. Next strains were isolated from faeces of newborn and hospitalized children. Growth characteristic of colonies of lactose-fermenting Salmonella strains on selective-differentiating media (Mac Conkey's Levine, SS, So?tys) recommended for inoculation of clinical material resembled Escherichia coli. So far these type of colonies were omitted in diagnostic examinations. Lactose-fermenting variants showed on Bismuth sulfate agar "Difco" (WB) typical for Salmonella growth pattern. They grew on this medium after 48 hr of incubation in a form of black, medium sized colonies, with some metallic brilliance and characteristic blackening of the medium undercolonies. Precise knowledge of biochemical properties of lactose-fermenting Salmonella allows to supplement so far used diagnostic scheme with additional tests permitting differentiation of lactose-fermenting variants of Salmonella from the other members of Enterobacteriaceae family. Taking into consideration biochemical variants in diagnostic procedure i.e. lactose-fermenting Salmonella, allowedns to isolate in the years 1983-1985 lactose-positive strains in 1305 out of 2773 (47%) individuals positive for S. agona. In 1987, 246 persons (28.3%) out of 869 with lactose-fermenting Salmonella of various serotypes were simultaneously infected with lactose-negative variant. Lactose-fermenting strains of Salmonella belonged most frequently to the following genera: S. agona, S. enteritidis, S. oranienburg, S. typhimurium, and S. goldcoast. It was found that the modified diagnostic procedure makes possible the isolation and the identification of lactose-positive varians of Salmonella.     

广州儿童医院重症监护病房感染病原菌的分布及耐药性分析

目的探讨儿科重症监护病房（PICU）感染病原菌的分布及耐药情况,为临床合理选用抗菌药提供参考。方法对广州市儿童医院PICU病房2003年11月-2005年10月各类感染标本所分离的病原菌的分布及耐药性进行回顾性分析。结果共检出295株病原菌,其中革兰阴性杆菌213株（72．2％）,主要为铜绿假单胞菌、不动杆菌等非发酵菌;革兰阳性球菌58株（19．7％）,主要为葡萄球菌;真菌24株（8．1％）。药敏结果提示铜绿假单胞菌及不动杆菌对亚胺培南、头孢哌酮／舒巴坦、环丙沙星及阿米卡星较为敏感,铜绿假单胞菌对头孢噻肟耐药率较高,而不动杆菌对头孢哌酮、氨曲南、庆大霉素耐药严藿。肠杆菌科细菌对氨苄西林、氨苄西林／舒巴坦、哌拉西林及多种头孢菌素耐药率较高而对亚胺培南、头孢哌酮／舒巴坦、阿米卡星等较敏感。葡萄球菌对青霉素、红霉素严重耐药,但对万古霉素、替考拉宁及阿米卡星敏感性高。结论铜绿假单胞菌等非发酵菌已成为PICU病房感染的主要病原菌。根据病原菌种类及药敏结果合理应用抗菌药是有效控制危重病患儿感染和减少耐药菌株产生的重要手段。     

Genetic transfer of Pseudomonas aeruginosa R factors to plant pathogenic Erwinia species.

The R factors RP1, R68 and R91 were freely transmissible to and from Pseudomonas aeruginosa, Salmonella typhimurium, and various plant pathogenic Erwinia spp. The antibiotic resistance spectrum of R+ Erwinia recipients was similar to those of other bacteria harboring these R factors, but maximum resistance levels differed with each recipient. The sponstaneous elimination of these factors from the Erwinia strains and the ability to transfer multiple antibiotic resistance suggest that these exist as plasmids in these hosts. Several, but not all, RP1-carrying Erwinia strains were sensitive to the RP1 specific phage PRR1. The R factor R18-1 was also transferred from P. aeruginosa to Erwinia spp. R18-1 was unstable in all Erwinia strains. Stable strains were isolated in which R18-1 could not be eliminated by sodium dodecyl sulfate and could not be transferred to other strains.