PubMed Health⌕ Search

Biomedical subjects

M E Kaufmann

Publications and source records attributed to M E Kaufmann.

At least 37 records · Page 2Linked to original sources
PubMed2000

Origins of Staphylococcus epidermidis and Streptococcus oralis causing bacteraemia in a bone marrow transplant patient.

Coagulase-negative staphylococcal bacteraemia in immunocompromised patients is often associated with the use of central venous catheters, while the proposed origin of viridans streptococci causing bacteraemia in this patient group is the oral cavity. This report describes an episode of polymicrobial bacteraemia caused by Staphylococcus epidermidis and Streptococcus oralis followed by several further episodes of S. epidermidis bacteraemia in a 15-year-old boy after bone marrow transplantation. Pulsed-field gel electrophoresis (PFGE) of SmaI chromosomal DNA digests was used to compare blood culture and oral isolates of S. epidermidis and Str. oralis. The results indicated that the mouth was the source of both S. epidermidis and Str. oralis causing the first episode of bacteraemia. PFGE further demonstrated that the central venous catheter was the origin of a second strain of S. epidermidis responsible for subsequent episodes of staphylococcal bacteraemia. Both the oral mucosa and central venous lines should be considered as potential sources of organisms, including coagulase-negative staphylococci, associated with bacteraemia in immunocompromised patients.

Adolescent↗
PubMed2000

Distribution of genes encoding putative transmissibility factors among epidemic and nonepidemic strains of Burkholderia cepacia from cystic fibrosis patients in the United Kingdom.

In the last 15 years, Burkholderia cepacia has emerged as a significant pathogen in cystic fibrosis (CF) patients, mainly due to the severity of infection observed in a subset of patients and the fear of transmission of the organism to noncolonized patients. Although patients who deteriorate rapidly cannot be predicted by microbiological characteristics, three genetic markers have been described for strains that spread between patients. These are the cblA gene, encoding giant cable pili; a hybrid of two insertion sequences, IS1356 and IS402; and a 1.4-kb open reading frame known as the B. cepacia epidemic strain marker (BCESM). The latter two are of unknown function. An epidemic strain lineage was previously identified among CF patients in the United Kingdom that apparently had spread from North America and that was characterized by a specific random amplified polymorphic DNA (RAPD) pattern. We searched for the described genetic markers using specific PCR assays with 117 patient isolates of B. cepacia from 40 United Kingdom hospitals. Isolates were grouped according to genomovar and epidemic strain lineage RAPD pattern with a 10-base primer, P272. A total of 41 isolates from patients in 12 hospitals were classified as the epidemic strain, and 40 of these were distributed in genomovars IIIa (11 isolates), IIIb (1 isolate), and IIIc (28 isolates). All isolates of the epidemic strain were positive for the cblA gene and BCESM, but two lacked the insertion sequence hybrid. None of the 76 sporadic isolates contained cblA or the insertion sequence hybrid, but 11 of them were positive for BCESM. Nonepidemic isolates were distributed among genomovars I or IV (9), II (49), IIIa (11), IIIb (3), and IIIc (4). There were three clusters of cross-infection (one involving two patients and two involving three patients) with isolates of genomovar II. We conclude that in the United Kingdom, a single clonal lineage has spread between and within some hospitals providing care for CF patients. The presence of the cblA gene is the most specific marker for the epidemic strain. We recommend that all isolates of B. cepacia from CF patients should be screened by PCR to influence segregation and infection control strategies.

Burkholderia Infections↗
PubMed1999

Evaluation of three oligonucleotide primer sets in PCR for the identification of Burkholderia cepacia and their differentiation from Burkholderia gladioli.

AIMS: To evaluate three oligonucleotide primer pairs--two specific for 16S and 23S rRNA sequences of Burkholderia cepacia, and the third specific for internal transcribed spacer region of 16S-23S sequences of B gladioli--for the identification and differentiation of reference and clinical strains of these and other species. METHODS: The three primers sets were applied in polymerase chain reaction (PCR) to a collection of 177 clinical isolates submitted for identification from diagnostic laboratories as presumed B cepacia. RESULTS: At an annealing temperature of 63 degrees C, all eight B cepacia and four B gladioli reference strains reacted with their specific primers. B vandii was the only other species that was positive with both B cepacia primers but five Burkholderia or Ralstonia species reacted with one of these primers. Seventy eight isolates were typical of B cepacia in biochemical tests and 75 of these reacted with specific primers; three, however, were positive with the B gladioli primers. Fifteen asaccharolytic isolates were confirmed as B cepacia by PCR but other non-fermenting Gram negative species were negative with each of the primers. CONCLUSIONS: PCR using 16S rRNA sequences is recommended for identification of B cepacia that give atypical results in biochemical tests.

Burkholderia↗
PubMed1998

Persistence of Pseudomonas aeruginosa strains in respiratory infection in AIDS patients.

OBJECTIVES: To establish the clinical pattern of Pseudomonas aeruginosa respiratory infections in HIV-seropositive patients and to determine whether repeated isolation of the organism represents reinfection or recurrence and to assess whether common source, nosocomial infection occurred. DESIGN AND METHODS: Evaluation of the clinical pattern of P. aeruginosa respiratory infections by case note review and epidemiological characterization of P. aeruginosa by serotype determination and Xbal DNA macrorestriction analysis. Serum sensitivity testing of strains was performed to further define phenotypic characteristics of the isolated organisms. RESULTS: Seventy-three per cent (29 out of 40) of individuals had P. aeruginosa isolated on two or more occasions in the setting of clinical respiratory infection. Overall, 85% had evidence of P. aeruginosa to within 2 months of study completion or death. Epidemiological characterization revealed persistence of unique single strains in 93% of individuals where multiple isolates were available for testing, whereas only two patients harboured a common strain. The serotype distribution of strains was similar to that reported from non-HIV-positive patients. CONCLUSIONS: Once established, eradication of P. aeruginosa from the respiratory tract of HIV-seropositive individuals with advanced immunosuppression is problematic and a chronic infective state appears common. There was no evidence of nosocomial transmission. Serotype loss and development of sensitivity to normal human serum were both observed and were highly correlated. This represents truncation of O-antigenic lipopolysaccharide on the cell surface of P. aeruginosa and may reflect progression to phenotypes commonly associated with chronic infection in other clinical settings such as cystic fibrosis.

Acquired Immunodeficiency Syndrome↗
PubMed1998

An outbreak of an unusual strain of Serratia marcescens in two Dublin hospitals.

We describe a serious outbreak of infection caused by a strain of Serratia marcescens in two Dublin hospitals which occurred over an 11 week period and affected a total of 15 patients. A contaminated bed-pan macerator in the Intensive Care Unit of one hospital was identified as the possible source of infection and spread of the organism probably occurred via hand transmission by hospital personnel and via patient transfer to a second hospital. All isolates of S. marcescens involved in the outbreak had the same antimicrobial susceptibility pattern, with reduced susceptibility to gentamicin, cefotaxime and ciprofloxacin. Epidemiological typing revealed that the strains of S. marcescens isolated in the outbreak were of an uncommon serotype, O21:K14, and using pulsed-field gel electrophoresis, XbaI DNA macrorestriction profiles clustered at 90% similarity. The DNA patterns of the outbreak strain were also highly similar to S. marcescens isolates of the same serotype recovered from a separate Dublin hospital during the same time period as the outbreak described here. In addition, the isolates clustered at 82% similarity with strains of the same serotype from a retrospective collection of S. marcescens isolates from various hospitals in the Dublin area, indicating that these may be genetic variants of the same strain. Although the outbreak was brought under control following implementation of infection control measures, a significant number of similar O:21 isolates of S. marcescens have since been identified in four Dublin hospitals. These results suggest the unique spread of a single strain of S. marcescens in Dublin hospitals.

Cross Infection↗
PubMed1998

Assessment of resolution and intercenter reproducibility of results of genotyping Staphylococcus aureus by pulsed-field gel electrophoresis of SmaI macrorestriction fragments: a multicenter study.

Twenty well-characterized isolates of methicillin-resistant Staphylococcus aureus were used to study the optimal resolution and interlaboratory reproducibility of pulsed-field gel electrophoresis (PFGE) of DNA macrorestriction fragments. Five identical isolates (one PFGE type), 5 isolates that produced related PFGE subtypes, and 10 isolates with unique PFGE patterns were analyzed blindly in 12 different laboratories by in-house protocols. In several laboratories a standardized PFGE protocol with a commercial kit was applied successfully as well. Eight of the centers correctly identified the genetic homogeneity of the identical isolates by both the in-house and standard protocols. Four of 12 laboratories failed to produce interpretable data by the standardized protocol, due to technical problems (primarily plug preparation). With the five related isolates, five of eight participants identified the same subtype interrelationships with both in-house and standard protocols. However, two participants identified multiple strain types in this group or classified some of the isolates as unrelated isolates rather than as subtypes. The remaining laboratory failed to distinguish differences between some of the related isolates by utilizing both the in-house and standardized protocols. There were large differences in the relative genome lengths of the isolates as calculated on the basis of the gel pictures. By visual inspection, the numbers of restriction fragments and overall banding pattern similarity in the three groups of isolates showed interlaboratory concordance, but centralized computer analysis of data from four laboratories yielded percent similarity values of only 85% for the group of identical isolates. The differences between the data sets obtained with in-house and standardized protocols could be the experimental parameters which differed with respect to the brand of equipment used, imaging software, running time (20 to 48 h), and pulsing conditions. In conclusion, it appears that the standardization of PFGE depends on controlling a variety of experimental intricacies, as is the case with other bacterial typing procedures.

Bacterial Typing Techniques↗
PubMed1997

A pseudo-outbreak of respiratory infection with Acinetobacter species.

We describe an apparent outbreak of respiratory infection with Acinetobacter species involving 14 patients over 8 days. Epidemiological investigation revealed two consecutive pseudo-outbreaks of infection caused by two consecutive, unrelated laboratory errors in the processing of sputum, nasopharyngeal, and endotracheal aspirates.

Acinetobacter↗
PubMed1997

Study of an outbreak of cefoxitin-resistant Klebsiella pneumoniae in a general hospital.

During a 3-month period, six Klebsiella pneumoniae isolates resistant to cefoxitin and penicillin-inhibitor combinations were derived from patients in the intensive care unit of a hospital in Athens, Greece. Enterobacterial repetitive intergenic consensus PCR and pulsed-field gel electrophoresis provided evidence of the clonal origin of the isolates. Conventional techniques and ribotyping were inadequate in proving that the isolates were related. Resistance was due to a plasmidic class C beta-lactamase.

Bacterial Typing Techniques↗
PubMed1996

Type characterisation and antibiotic susceptibility of Burkholderia (Pseudomonas) cepacia isolates from patients with cystic fibrosis in the United Kingdom and the Republic of Ireland.

The spread of Burkholderia cepacia among cystic fibrosis (CF) patients in the UK prompted an investigation into whether an epidemic strain was responsible. A total of 366 B. cepacia isolates from 178 CF patients in 17 centres was examined by ribotyping and pulsed-field gel electrophoresis (PFGE). Associations were also sought between antibiotic resistance and strain type. More than 50 ribotype patterns were found but one, termed ribotype 1, was identified from 68 patients in eight centres. One centre had a single patient with this type while, in others, most or all patients harboured this organism. Small clusters of apparent cross-colonisation within centres were also evident for some other ribotypes. PFGE confirmed that ribotype 1 isolates were genetically similar. Ribotype 1 isolates were not markedly more resistant to antimicrobial agents than were other isolates, and the MICs of individual antibiotics were no more tightly clustered for ribotype 1 isolates than for others. Most isolates were resistant to ciprofloxacin, amikacin, gentamicin, tobramycin, carbenicillin, cefuroxime, cefotaxime, imipenem, biapenem, chloramphenicol, tetracycline, trimethoprim and sulphamethoxazole, but > or = 77% were susceptible to ceftazidime, piperacillin, piperacillin/ tazobactam and meropenem. We conclude that numerous strains of B. cepacia colonise CF patients in the UK and Ireland but that one epidemic strain has spread in at least eight centres. Isolates of this strain appear homogenous in total genomic profile but very variable in antibiotic susceptibility.

Bacterial Typing Techniques↗
PubMed1996

Home-use nebulizers: a potential primary source of Burkholderia cepacia and other colistin-resistant, gram-negative bacteria in patients with cystic fibrosis.

Inhalation of aerosols contaminated with gram-negative bacteria generated from home-use nebulizers used by cystic fibrosis (CF) patients may be a primary route for bacterial colonization of the lung. Burkholderia cepacia was isolated from 3 of [corrected] 35 home-use nebulizers, and Stenotrophomonas maltophilia was isolated from 4 of 35 home-use nebulizers. Sputum cultures for two patients whose nebulizers were contaminated with B. cepacia did not yield the organism. However, DNA macrorestriction analysis by pulsed-field gel electrophoresis confirmed that one of two strains of B. cepacia recovered from the nebulizer of a third patient was also present in the sputum of that patient. Although Pseudomonas aeruginosa was isolated from 34 patients, none of the nebulizers were positive for the organism. Sixty-nine percent of nebulizers were contaminated, and up to 16 different environmental colistin-resistant, gram-negative species were identified. The heaviest contamination was found beneath the chamber atomizer. A questionnaire survey showed that the majority of patients (28 of 34) were receiving nebulized colistin and/or gentamicin. Patients who followed recommended instructions for good nebulizer hygienic practice and paid particular attention to drying had minimal or no contamination of their nebulizers.

Adult↗
PubMed1996

Comparison of outbreak and nonoutbreak Acinetobacter baumannii strains by genotypic and phenotypic methods.

Thirty-one Acinetobacter baumannii strains, comprising 14 strains from 14 outbreaks in different northwestern European cities and 17 sporadic strains, were compared by investigating various properties of the strains including biotype, antibiogram, cell envelope protein electrophoretic profile, ribotype pattern, and the band pattern generated by a novel genomic fingerprinting method, named AFLP, which is based on the selective amplification of restriction fragments. Results showed that 12 strains from unrelated outbreaks were linked together in two clusters according to their similarities by these typing methods, whereas sporadic strains were more heterogeneous. Outbreak strains appeared to be markedly more resistant to antibiotics than nonoutbreak strains. The uniformity of typing characters in two sets of outbreak strains suggests that strains in each cluster have a common clonal origin.

Acinetobacter↗
PubMed1994

Enterobacter cloacae in a neonatal intensive care unit: account of an outbreak and its relationship to use of third generation cephalosporins.

After uneventful use of cefotaxime and ceftazidime as first line therapy for three years in our neonatal intensive care unit we isolated cephalosporin-resistant Enterobacter cloacae (CREC) strains which caused clusters of cases or colonization and/or serious neonatal infection. By using two or more typing methods, at least five different strains with similar patterns of antimicrobial sensitivities were identified. The results of a case-control study did not support the notion that the use of third generation cephalosporins was associated with colonization and infection by CREC. The outbreak was brought under control by interrupting the transmission of the epidemic strain D, by measures such as cohort nursing, diligent handwashing before and after procedures, and thorough environmental cleaning as well as by decontamination with glutaraldehyde after dismantling of the blood gas analyser believed to have acted as a persistent reservoir. Our experience highlights the danger of inadequate supervision and maintenance of equipment used for near-patient testing and the need to monitor such equipment not only in terms of its calibration and analytical performance but also microbiologically.

Blood Gas Analysis↗
PubMed1994

Consecutive mutations leading to the emergence in vivo of imipenem resistance in a clinical strain of Enterobacter aerogenes.

Three consecutive isolates of Enterobacter aerogenes were obtained from the blood cultures of a hospitalised patient who was receiving antibiotic therapy. The initial isolate possessed an inducible cephalosporinase and was susceptible to third-generation cephalosporins. After ceftazidime treatment, a second isolate resistant to this antibiotic and characterised by stable overproduction of the chromosomal beta-lactamase was obtained, and therapy was altered to a new combination which included imipenem. During this course of treatment, a strain of E. aerogenes was isolated that was resistant to virtually all beta-lactam agents including imipenem. Comparison of biotypes and ribotyping profiles indicated that the three isolates were probably derived from a single strain which had undergone several mutations during antibiotic exposure. Examination of outer-membrane protein (OMP) preparations and lipopolysaccharide (LPS) profiles showed that the imipenem-resistant isolate lacked a major OMP and high molecular mass LPS. Furthermore, this isolate displayed reduced permeability to cephaloridine compared with the initial isolate. The introduction of a plasmid carrying a wild-type ampD allele prevented cephalosporinase production and restored beta-lactam susceptibility in the imipenem-resistant isolate. It was concluded that stable derepression of class-I beta-lactamase production and reduced permeability are both required for expression of imipenem resistance in E. aerogenes, and that previous exposure to cephalosporins may encourage the emergence of such strains.

Aged↗
PubMed1993

Biotyping, phage typing, and O-serotyping of clinical isolates of Enterobacter cloacae.

The purpose of this study was to make an independent evaluation of the methods of bio-, phage-, and O-serotyping which had been used only in the laboratory of origin, and to assess the extent of possible cross-infection of Enterobacter cloacae in a Danish university hospital. The material consisted of 237 clinical isolates of E. cloacae from the clinical microbiology laboratory at Hvidovre Hospital. The typability of bio-, phage-, and serotyping was 100%, 83%, and 85%, respectively. Reproducibility of serotyping was 90% and of phage typing 96% if two major differences were allowed to differentiate between patterns. O-serotyping had the highest discriminatory power and combination of all typing methods further increased discrimination. Outbreaks of E. cloacae were not evident in clinical departments, but cross-infections from one department to another could not be completely ruled out. We concluded that the combination of bio-, phage- and O-serotyping is sufficiently discriminating and will be satisfactory in the majority of clinical situations.

Bacteriophage Typing↗
PubMed1993

Epidemic of Pseudomonas cepacia in an adult cystic fibrosis unit: evidence of person-to-person transmission.

An epidemic of Pseudomonas cepacia occurred in an adult cystic fibrosis center in the United Kingdom, despite a policy of segregation of infected and noninfected patients within the hospital. Investigation of the outbreak by ribotyping and pulsed-field gel electrophoresis to characterize P. cepacia strain genomes together with inquiry into social contacts between patients revealed evidence of person-to-person transmission outside the hospital environment. Segregation policies aimed at reducing the spread of this infection in the cystic fibrosis community need to encompass patient contacts outside the hospital environment.

Adolescent↗