Diversity of resistance phenotypes and plasmid analysis in multi-resistant 0:12 Pseudomonas aeruginosa

Antibiotic resistance phenotypes, plasmid content and ability of conjugal transfer of antibiotic resistance genes of 35 multi-resistant Pseudomonas aeruginosa strains were examined. The strains were isolated in 12 Greek hospitals and the majority of them (80%) belonged to serotype 0:12. The isolates were distributed to a variety of different antibiotic resistance phenotypes. Plasmid analysis showed that 10 isolates harboured plasmids ranging in size from 20 to 100 Mda. Among these strains, four carried plasmids of 100 Mda, two strains had 60 Mda plasmid each while in three strains the plasmids detected were 65, 25 and 20 Mda, respectively. One strain harboured two plasmids of 100 and 60 Mda. All strains containing plasmids belonged to 0:12 serotype, except the one harbouring the 25 Mda plasmid, which belonged to serotype 0:6. Using a P. aeruginosa recipient resistant to rifampicin and ciprofloxacin, conjugal transfer was achieved in two occasions. These plasmids, 100 Mda in size, encoded high-level resistance to both gentamicin and tobramycin whereas resistance to other drugs was not transferable. Interestingly, all 100 Mda plasmids, including the self-tansferable ones, were found to share a certain degree of homology as judged by restriction analysis. It is suggested that both resistance phenotypes and analysis of plasmid content might be useful in subdividing 0:12 multi-resistant P. aeruginosa.     

Plasmid analysis of 219 methicillin-resistant Staphylococcus aureus strains with uncommon profiles isolated in Lisbon

During the years 1986 and 1987, 219 methicillin-resistant Staphylococcus aureus (MRSA) strains were isolated in a Lisbon hospital. Antimicrobial susceptibilities and genetic analysis showed that resistance to penicillin, methicillin, erythromycin (inducible phenotype), tetracycline, gentamicin, tobramycin, kanamycin, streptomycin, neomycin and trimethoprim were chromosomally encoded. Plasmid DNA was absent from 38.8% of the isolates. Constitutive erythromycin resistance was coded by three plasmids of c. 2.3 Md, c. 2.0 Md and c. 1.6 Md. Chloramphenicol resistance was mediated by two plasmids of c. 2.9 Md and c. 1.8 Md. Small cryptic plasmids of c. 1.65 Md, c. 1.2 Md and c. 1.0 Md were also detected. The majority of the strains revealed antigen 17, were lysed by phages 75, 89 and/or 85, and were either devoid of plasmid DNA, or possessed a c. 1.6 Md plasmid coding for constitutive erythromycin resistance or a c. 1.0 Md cryptic plasmid. These observations cannot rule out that the MRSA Lisbon isolates are a homogeneous group of strains that might have a common origin, and seem to be different from MRSA recently isolated in other countries.     

院内感染肠球菌的克隆识别技术评价

为区分肠球菌的院内感染相关株与无关株,我们将质粒图谱分析技术与生化分型、血清学分型、耐药谱分型技术进行了比较。结果表明,生化分型和血清学分型技术极不敏感,2组菌株均以粪肠球菌为主,D—Ag携带率分别为86％和90％;相关菌株组的耐药性(72％)虽高于无关菌株组(55％),但其耐药谱并无明显规律可循;89％的相关菌株与对照菌株的质粒图谱不同,尤其是出现抗生素敏感菌株时,质粒图谱分析技术很容易将其识别为相关菌株或不相关菌株。     

Epidemiological,clinical and microbiological features of Yersinia enterocolitica infections in a community during a four-year period

Epidemiological and clinical features of 17 cases (13 children) of yersiniosis treated in a hospital over a four-year period, as well as factors associated with virulence, antibiotic resistance and plasmids in Yersinia enterocolitica strains from these patients were studied. The proportion of Y. enterocolitica was 3.57% of all fecal cultures positive for enteric pathogens, with 13 sporadic episodes and one outbreak. In 11 cases the infection was unimicrobial. The clinical presentation was: gastroenteritis (14 cases), pseudoappendicitis (1 case) and asymptomatic (2 cases). Eight cases needed hospital care, and 8 required antimicrobial treatment. None of the isolated bacterial strains produced pyrazinamidase, hemolysins, elastase, fibrinolysine, colicines or aerobactin. Eight strains showed calcium dependence, 7 of them exhibited autoagglutination, serum resistance, crystal violet binding and carried a 42 MDa plasmid related with virulence. Two strains carried a 3.3 MDa R-plasmid that encoded streptomycin-sulfadiazine resistance. The restriction analysis showed that the virulence plasmids constitute one variety and R-plasmids another.     

Diversity of plasmids in Staphylococcus saprophyticus isolated from urinary tract infections in women

A group of 150 Staphylococcus saprophyticus strains isolated from urinary tract infections in women were included in this study. Antimicrobial susceptibility tests showed that these isolates were sensitive to most antimicrobial agents. All strains were sensitive to penicillin, cephalothin, gentamicin, kanamycin, trimethoprim and nitrofurantoin. Resistance to tetracycline was present in 10.6% of the strains, to chloramphenicol in 4%, to erythromycin in 1.3% and to streptomycin in 1.3%. All strains were resistant to cadmium chloride as well as to novobiocin and nalidixic acid. Plasmid analysis showed that 82% of the strains harboured plasmids, some of them with complex plasmid profiles. Most plasmids were considered to be cryptic, although antibiotic resistance plasmids were identified in 18 isolates. Tetracycline resistance was encoded by a plasmid of c. 2.8 MDa, chloramphenicol resistance by a plasmid of c. 2.9 MDa and erythromycin resistance by a plasmid of c. 1.6 MDa. Streptomycin resistance could not be linked to the presence of any specific plasmid. Plasmid profiling seemed to be a good method for differentiating among S. saprophyticus strains.     

Plasmid deoxyribonucleic acid in throat and cerebrospinal fluid isolates of Neissepia meningitidis

Ten strains of Neisseria meningitides, isolated either from cerebrospinal fluid or from throat cultures, were typed and screened for the presence of plasmid DNA. Three group C strains, isolated in the same area, each harboured a plasmid of similar molecular weight (approx. 8.5 Md). No evidence of plasmid DNA was found in the other strains (whether of the same group but isolated in another area, or of other groups).Corresponding author.     

食品中多重耐药大肠埃希氏菌和沙门氏菌质粒图谱分析

目的：对自深圳市自由市场生肉类食品中分离得到的30株对3种和3种以上抗生素耐药的大肠埃希氏菌和31株对3种以上抗生素耐药的沙门氏菌进行质粒图谱分析，探讨质粒与耐药性的关系。方法：碱裂解法。结果：耐药谱不同的大肠埃希氏菌的质粒分子分型结果可以相同，31株多重耐药沙门氏菌有25种不同的分型结果。结论：细菌的耐药性与其携带的质粒的多少和大小没有直接的关系。     

Molecular characterization of trimethoprim resistance in Shigella sonnei in Sicily

During the 3-year period 1985-7, all strains of Shigella sonnei isolated in Catania, Sicily, showed a high level of resistance to trimethoprim (Tp) which was invariably associated with resistance to other antibiotics. Plasmid analysis showed 18 different electropherotypes: 35 of 37 strains harboured a plasmid of 70 Megadaltons (MDa), and 29 of 37 strains a plasmid of 130 MDa. Restriction endonuclease fingerprinting of purified 70 MDa plasmid DNA from different strains demonstrated that these plasmids were similar but not identical. In some strains with transferable Tp resistance, DNA hybridization analysis demonstrated the presence of gene coding for the production of dihydrofolate reductase (DHFR) type V. In contrast, there was no detectable hybridization with DNA probes specific for genes coding for DHFR types I, II and IV. This is the first report of the DHFR type V gene outside Sri Lanka.     

健康人群肠道耐药大肠埃希菌质粒图谱分析

目的：对深圳地区健康人肠道分离的150株大肠埃希菌进行质粒图谱分析,探讨质粒谱与耐药性的关系.方法：碱裂解法.结果：耐药谱不同的大肠埃希氏菌的质粒分子分型结果可以相同.结论：细菌的耐药性与其携带的质粒的多少和大小没有直接关系.     

Epidemiological characteristics ofPseudomonas aeruginosa strains causing infection in an Italian general hospital

During the 1989 calendar year,P. aeruginosa caused clinical infections in 0.46% of patients admitted to Ospedali Riuniti (a general hospital), Bergamo, Italy. Strains (n=267) ofP. aeruginosa were collected during this period, and epidemiological characteristics were studied. The mean prevalence ofP. aeruginosa infection in inpatients was 1.1% (range 0.06–7.3), whereas outpatients showed a significantly lower prevalence of infection (0.05%). Strains were recovered from inpatients of surgical wards (n=126; 47.2%), and outpatients (n=15; 5.6%). Males were more often affected than females (2.7:1). Infection of the urinary tract was the most common (34.1%).Pseudomonas aeruginosa was also involved in lower respiratory tract infections (18.7%) and septicaemia (17.6%). Four typing methods were performed, i.e. serotyping, antibiotyping, pyocin typing, and restriction endonuclease analysis (REA). Serotypes 0:11 and 0:6 were endemic in the hospital. Some serotypes correlated with specific clinical wards. Pyocin typing was an unreliable epidemiological tool. However, antibiotyping showed the presence of some epidemic clusters, probably related to the antibiotic consumption of the patients. REA suggested the circulation of endemicP. aeruginosa strains in both the obstetrics and neurosurgery wards.     

Plasmid profiles of legionella pneumophila strains isolated in Spain

An assay for plasmid DNA content was carried out in 100 strains of Legionella pneumophila of distinct serogroups and isolated from various sources (clinical, environment). The strains were isolated from different geographic regions in our country. The presence of plasmids was proved in one of the 11 clinical isolates and in 68 of the 89 isolated of environmental origin studied. In the strains belonging to serogroup 1 and isolated in our region (Cantabria), three plasmid profiles were observed, whereas in strains of the same serogroup from other geographic regions, two profiles were shown which exhibited differences compared to the former ones. Analysis by means of restriction endonucleases suggested that plasmids of similar size in serogroup 1 strains of different source, were related. The results obtained do not appear to reveal any correlation between plasmid profile and source of isolation or serogroup.Corresponding author.     

Epidemiology of Pseudomonas aeruginosa in a tertiary referral teaching hospital

A genotypically indistinguishable strain of Pseudomonas aeruginosa (Australian epidemic strain III: AES III) has previously been found in a proportion of adults with cystic fibrosis (CF) in Tasmania, Australia. The aim of this study was to identify a source of these infections within the major tertiary referral hospital for the State of Tasmania, and to determine if this strain could be isolated from settings other than the CF lung. A total of 120 isolates of P. aeruginosa were collected from clinical and environmental sources within the hospital and from environmental locations in the hospital vicinity. These isolates were genotyped by random amplification of polymorphic DNA (RAPD)–polymerase chain reaction (PCR) and antimicrobial susceptibility testing was performed using the Clinical and Laboratory Standards Institute method. Confirmation of similar genotypes identified by RAPD–PCR was performed using pulsed-field gel electrophoresis with restriction enzyme SpeI. AES III was not recovered from any source other than the respiratory secretions of CF patients. P. aeruginosa in the non-CF settings was found to be panmictic, and no cross-infection or acquisition of hospital environment strains by patients was observed.     

Molecular characterization of Vibrio cholerae O1 and non-O1 from human and environmental sources in Malaysia

A total of 31 strains of Vibrio cholerae O1 (10 from outbreak cases and 7 from surface water) and non-O1 (4 from clinical and 10 from surface water sources) isolated between 1993 and 1997 were examined with respect to presence of cholera enterotoxin (CT) gene by PCR-based assays, resistance to antibiotics, plasmid profiles and random amplified polymorphic DNA (RAPD) analysis. All were resistant to 9 or more of the 17 antibiotics tested. Identical antibiotic resistance patterns of the isolates may indicate that they share a common mode of developing antibiotic resistance. Furthermore, the multiple antibiotic resistance indexing showed that all strains tested originated from high risk contamination. Plasmid profile analysis by agarose gel electrophoresis showed the presence of small plasmids in 12 (7 non-O1 and 5 O1 serotypes) with sizes ranging 1.3-4.6 MDa. The CT gene was detected in all clinical isolates but was present in only 14 (6 O1 serotype and 8 non-O1 serotype) isolates from environmental waters. The genetic relatedness of the clinical and environmental Vibrio cholerae O1 and non-O1 strains was investigated by RAPD fingerprinting with four primers. The four primers generated polymorphisms in all 31 strains of Vibrio cholerae tested, producing bands ranging from < 250 to 4500 bp. The RAPD profiles revealed a wide variability and no correlation with the source of isolation. This study provides evidence that Vibrio cholerae O1 and non-O1 have significant public health implications.     

Plasmid content,serotypes, and antimicrobial susceptibility of Neisseria gonorrhoeae strains isolated in Munich in 1987–88

Eighty-four strains of Neisseria gonorrhoeae isolated in Munich between January 1987 and June 1988 were characterized in terms of their plasmid content, protein I serovar and susceptibility or resistance to four antimicrobial agents. Eighty two percent of the strains belonged to serogroup 1B, the three most prevalent serovars being 1B-1, 1B-2 and 1B-6. Among the serogroup 1A strains, 1A-2 was the commonest serovar. Fourteen strains (16.7%) lacked the 2.6 Md cryptic plasmid, although two of these strains contained the conjugative gonococcal plasmid. Although some degree of resistance to penicillin and tetracycline was noted, all the strains were sensitive to spectinomycin and cefotiam.     

Plasmid analysis as an epidemiological tool in neurosurgical infections with coagulase-negative staphylococci

Coagulase-negative staphylococci isolated from blood or spinal fluid during a period of 1 year in a department of neurosurgery, were analysed by biotyping, antibiotic resistance pattern and plasmid profiles. Altogether 41 isolates from 19 patients were studied. About 90% of the isolates were Staphylococcus epidermidis. The antibiotic resistance pattern seemed to be closely related to antibiotic usage in the unit. Most common was resistance to penicillin (63%), trimethoprim-sulphamethoxazole (49%) and cloxacillin (39%) while resistance to gentamicin was seen in only one strain. In several cases species and antibiograms were identical in isolates from different patients. Plasmid pattern analysis could then be used for identification of different strains. In one instance, plasmid pattern and restriction enzyme analysis confirmed that two patients probably were infected by the same strain.     

沙门氏菌食物中毒菌株的质粒图谱及耐药谱分析

本文对１９９１～１９９３年成都及南充地区食物中毒分离的５０株沙门氏菌进行了质粒图谱及耐药谱分析。质粒检出率为７０％，其中２８株鼠伤寒沙门氏菌的质粒检出率为９２．８％，可分为１４个质粒图谱型别，质粒分子量的变化范围在１．６～１８０．４６Ｍｄ。暴发流行菌株具有相同的质粒图谱，而散发菌株的质粒图谱型较为分散。所有菌株均是耐药菌株，且以多重耐药菌株为主，耐四种药的菌株占５４％，最多达耐１０种药。５０株菌对新霉素、卡那霉素、妥布霉素均敏感。未发现某种或某几种耐药性与某种质粒型别呈明显的一一对应关系。     

空肠/结肠弯曲菌的生物分型和质粒分析及其在流行病学中的初步应用

本文对来自成都地区的弯曲菌进行了生物分型和质粒分析,并结合血清学分型应用于弯曲菌肠炎病人家庭的调查。116株弯曲菌中,空肠弯曲菌生物1型、生物2型和结肠弯曲菌分别占58.6%、4.3%和37.1%;人源菌和鸡源菌均以空肠弯曲菌生物1型为主,猪源菌主要为结肠弯曲菌。弯曲菌质粒检出率为18.9%,检出的质粒株中,大多含2~3个质粒带,分子量﹤1.4~58×10⁶道尔顿;结肠弯曲菌的质粒检出率(34.21%)明显高于空肠弯曲菌(10.29%)。两个病家的调查结果说明:生物分型和质粒分析在追踪弯曲菌感染的传播中具有一定价值,可以作为弯曲菌感染流行病学调查的有用工具。     

产毒性大肠埃希氏菌质粒特征初步分析

本文对来自全军五个军区和第一军医大学附属珠江医院及广州远郊九佛农村检测的２０６株埃希氏菌阳性株进行了质粒特征的初步分析。发现质粒携带率为９０．８％，携带质粒数量１￣７个不等。最大质粒分子量为８２．９Ｍｄ，最小１．１Ｍｄ，以大分子量质粒居多且稳定。５３Ｍｄ和４５Ｍｄ质粒为优势质粒。不同地区和时期有相同质粒的流行株存在，环境流行株和人群流行株质粒特征不同。     

Plasmid typing of Shigella sonnei epidemic strains and molecular relationship of their R-plasmids

We conducted a surveillance program on epidemic and/or endemic Shigella strains in Asturias (Spain), their frequency and dispersion in our community, and their R-plasmids. We analyzed initial isolates of Shigella sonnei from two epidemic outbreaks using antibiotic resistance patterns and plasmid profile analysis as epidemiological markers. We found that the 2 outbreaks were caused by different S. sonnei strains, which respectively carried one and two R-plasmids together with other plasmids. The molecular relationship among these and three other R-plasmids from two S. sonnei strains isolated during a previous outbreak, were studied by restriction enzyme analysis and DNA-DNA hybridizations. We were able to establish different levels of relationship among the six R-plasmids.Corresponding author.     

血浆凝固酶阴性葡萄球菌鉴定及耐药谱分析

目的比较几种血浆固酶阳性葡萄球菌鉴定方法,探讨质粒谱与耐药谱之间的关系。方法生化、粘质、耐药谱及质粒谱分析对来自医院１８８株血浆凝固酶阴性葡萄球菌（ＣＮＳ）进行了鉴定。结果头部葡萄球菌（头葡）、表皮葡萄球菌（表葡）、木糖葡萄球菌（木葡）、人型葡萄球菌（人葡）为其主要生化型。５０％菌株产生粘质,耐药率高达９４％。对万古霉素（ＶＡＮ）、氟哌酸（ＮＯＲ）、丁胺卡那霉素（ＡＫＮ）敏感。质粒检出率７３．９％。３种质粒谱常见。结论手术伤口、患者鼻咽部、医护人员及空气标本中ＣＮＳ之间有同源性。８０％以上头葡和木葡只携带１个５４ｋｂ质粒。携带有２．２、１．６ｋｂ,１．６、１．４ｋｂ成对质粒的ＣＮＳ大多具有同一耐药谱