Biomedical subjects

I Kühn

Publications and source records attributed to I Kühn.

At least 55 records · Page 3Linked to original sources

PubMed1992

The use of biochemical fingerprinting, phage typing and antimicrobial-susceptibility testing in the detection of epidemic strains of Salmonella of serotype Typhimurium in Iran.

A collection of 86 strains of Salmonella of serotype Typhimurium isolated from children with gastroenteritis in Tehran, Iran was examined for biochemical phenotype, phage type and antibiotic-resistance pattern. Twenty-seven biochemical phenotypes (BPTs), 14 discrete phage types (PTs) and 18 resistotypes (RTs) were identified. Fifty-three strains (62%) belonged to two major and probably related BPTs, whereas the other 33 isolates belonged to less common BPTs. The two predominant BPTs contained 26 strains of the same PT and 23 strains of the same RT. Different PTs and RTs of strains with similar BPT were sometimes observed, possibly reflecting antibiotic pressures in Iran. These results suggest that two major "clones" of Typhimurium strains are particularly common in Iran and, although each method alone adequately detected these and other less common "clones", biochemical fingerprinting provided additional information about relationships among strains.

Bacterial Typing Techniques↗

PubMed1992

An outbreak of Klebsiella oxytoca septicemias associated with the use of invasive blood pressure monitoring equipment.

Seven cases of septicemia with piperacillin-resistant Klebsiella oxytoca (PRKO) occurred at 2-monthly intervals in a thoracic surgery intensive care unit. All PRKO isolates were serotyped, and phenotyped with a biochemical typing system. Only one patient in the unit was found to be colonized in stool or respiratory tract with PRKO, and this strain was different from the septicemia strains in phenotype though not in serotype. Environmental cultures, from humidifiers, oxygenators, pressure transducers, etc. were negative. PRKO of the epidemic phenotype was recovered from several non-patient transducer domes. The outbreak ended when transducer heads were disinfected and the use of non-patient domes was abolished.

Adult↗

PubMed1992

Biochemical fingerprinting of urinary Escherichia coli causing recurrent infections in women with pyelonephritic renal scarring.

A biochemical fingerprinting system, especially designed for subtyping of Escherichia coli and suitable for screening large number of bacterial strains was used in a long-term follow-up study of 19 women with non-obstructive pyelonephritic renal scarring and recurrent urinary infections in order to examine whether recurrent infections mostly are relapses or reinfections in this group of patients. Seventy-six recurrent infections occurred during a 47-month follow-up (0.09 infections per observation month). The majority of the recurrences were reinfections (58/76, 76%) and 18 (24%) were relapses caused by E. coli. Approximately 50% of relapses and reinfections caused by E. coli were symptomatic while the majority of reinfections caused by other bacteria were asymptomatic (23/30, 77%). In one patient a relapse of E. coli infection occurred more than two years (745 days) after the initial infection. Reinfections may occur early (7 days) after cessation of antimicrobial therapy in this group of patients. Two patients had an episode of symptomatic bacteriuria 51 and 56 days after asymptomatic bacteriuria with the same E. coli strain was detected. Biochemical fingerprinting of the E. coli isolates revealed that they belong to a wide variety of biochemical phenotypes which indicates that they are not members of widespread uropathogenic clones.

Adult↗

PubMed1992

Urinary Escherichia coli causing recurrent infections--a prospective follow-up of biochemical phenotypes.

Twenty-three women with non-obstructive acute pyelonephritis due to Escherichia coli were prospectively studied during 880 patient months, mean observation time 38 months. Each patient had between 1 and 4 new episodes of E. coli bacteriuria during the study period (altogether 49 recurrencies). All E. coli isolates were typed by biochemical fingerprinting. Twenty-six of the recurrencies were caused by an E. coli strain identical to one of those that had previously appeared. Sixteen of these infections were caused by a strain identical to the one that gave rise to the original acute pyelonephritis. Ten further recurrencies were due to an E. coli strain that had previously caused symptomatic or asymptomatic bacteriuria during the observation period. Despite appropriate treatment and repeated negative urine cultures post-treatment, infections caused by identical E. coli strains occurred up to 35 months after the initial episode of acute pyelonephritis. We suggest that the infecting E. coli strain may survive in the fecal flora or is harboured in the patient's surroundings, and after recolonizing the patient, these strains may give rise to further urinary tract infections.

Adult↗

PubMed1992

Nationwide spread of Klebsiella oxytoca K55 in Swedish neonatal special care wards.

In a nationwide survey of invasive bacterial infections in Swedish neonates, 36% of Klebsiella spp. were Klebsiella oxytoca serotype K55. This unexpectedly high proportion of K55 infections was due to clusters of infection in neonatal special care wards, and at first seemed attributable to nosocomial spread of a K. oxytoca strain of high virulence. Factors predisposing infants to infection were, however, found irrespective of whether the infecting strain was of serotype K55 or not. Additionally, the prevalence rates of a potential virulence factor, siderophore production, were similar among the two groups of strains. During the same period of time a K. oxytoca K55 with similar biochemical phenotype and drug resistance pattern was found to be spread among the neonates in 12 of 22 neonatal wards in Sweden. The increased proportion of invasive neonatal K. oxytoca K55 infections thus seemed to reflect a high rate of colonization rather than an increased virulence of the K55 strain.

Disease Outbreaks↗

PubMed1991

The use of the PhP-KE biochemical fingerprinting system in epidemiological studies of faecal Enterobacter cloacae strains from infants in Swedish neonatal wards.

The PhenePlate (PhP) biochemical fingerprinting system is an automated method for typing of bacteria, based on the evaluation of the kinetics of biochemical reactions, performed in microtitre plates. In the present study the PhP-Klebsiella/Enterobacter (KE) system was evaluated for typing of Enterobacter cloacae and employed to study the epidemiology of faecal E. cloacae strains isolated from infants in 22 Swedish neonatal wards. The PhP-KE system showed a high reproducibility and discrimination for E. cloacae isolates. Among 64 epidemiologically unrelated E. cloacae strains, 49 distinct phenotypes were found, and the diversity index was 0.985. E. cloacae was found as a part of the dominating Gram-negative aerobic bacterial flora in 83 out of 953 infants studied. The incidences of E. cloacae colonization varied between 0 and 35% in different wards, but in contrast to previous data for Klebsiella spp. and Escherichia coli, there was little evidence of spread of particular strains in the wards. We also discuss two different measures of nosocomial transmission of bacterial strains: transmissible strains and epidemic index.

Bacterial Typing Techniques↗

PubMed1991

Biochemical phenotypes of enteropathogenic Escherichia coli common to Iran and Sweden.

A collection of 143 strains of enteropathogenic Escherichia coli (EPEC) of 11 different serogroups isolated from children with diarrhoea, 71 in Sweden and 72 in Iran, was tested for similarity with a computerised biochemical fingerprinting method. From Sweden, there were 54 different phenotypes, 42 consisting of a single strain and 12 (common phenotypes) containing more than one isolate. From Iran, there were 48 different phenotypes, 38 with only one strain and 10 with more than one. Many of the strains which were biochemically similar, in both countries, also had similar virulence factors. Nine Swedish and 20 Iranian isolates showed biochemical identity to at least one of the strains of the other country, most of them belonging to serogroups O55, O119, O126, O127 and O128. The value of the biochemical fingerprinting method as an epidemiological tool and its ability to evaluate clonal relations among E. coli strains in different geographical areas is discussed.

Adhesins, Escherichia coli↗

PubMed1991

Biochemical fingerprinting of water coliform bacteria, a new method for measuring phenotypic diversity and for comparing different bacterial populations.

A simple, automated microplate system for biochemical characterization of water isolates can be used to obtain fingerprints of the bacterial flora from various water samples. Mathematical models for calculating the diversities and similarities between bacterial populations are described for such fingerprints. The diversity may give information on whether an indigenous or allochthonous flora is present, and the similarities between bacterial populations, as calculated by using a population similarity coefficient (Sp), may indicate contaminations between different water samples. The system was demonstrated on coliform bacterial populations from various water samples, with or without suspected intercontamination. For unrelated water samples, the Sps were close to 0, whereas repeated samples of the same source showed Sps of 0.64 to 0.74. The Sp values from several water samples were also clustered to form a dendrogram, thus indicating the relative similarities between the bacterial populations to confirm suspected common sources of pollution.

Bacterial Typing Techniques↗

PubMed1991

Characterization of Escherichia coli isolated in blood, urine and faeces from bacteraemic patients and possible spread of infection.

Blood, faecal and urine isolates from patients with culture-verified E. coli bacteraemia were investigated with respect to biochemical phenotype, O and K serotype and P. fimbriae. In 10/16 bacteraemic episodes, the blood isolates were identical to the corresponding faecal strains. In four of the remaining infections, antimicrobial therapy was initiated more than two days before faecal samples were taken. Urine cultures revealed growth of E. coli in 12/16 samples. However, only three had clinical signs of symptomatic urinary tract infections. Eight of these E. coli were saved. Further analysis revealed that five of eight strains were identical to the corresponding isolates from blood and stool samples, two were only identical to the faecal strain, while one was different to the corresponding E. coli in the blood and stool samples. The isolated E. coli strains belonged to varying and, among previously healthy persons, normally less common serotypes. No epidemiological relationship was observed between the studied strains. The high incidence of identical strains in the blood, stool and urine indicates a bacterial spread from the faecal flora directly to the urine and possibly also, via the blood, to the urine.

Bacteriuria↗

PubMed1991

Characterization of beta-lactam-resistant Klebsiella oxytoca isolated in a neonatal intensive care unit.

The occurrence of Klebsiella oxytoca resistant to ampicillin, piperacillin, aztreonam and cefuroxime in a neonatal intensive care unit, including two cases of septicemia, was shown to consist of a spread on three consecutive occasions caused by three different biochemical Klebsiella oxytoca phenotypes. All isolates, except six surface isolates from one infant belonging to phenotype 1, were sensitive to cefotaxime (MIC 0.5-4 mg/l) and ceftazidime (MIC 0.25-1 mg/l). Isolates of phenotypes 1 and 2 produced a beta-lactamase with an isoelectric point of 5.5 and isolates of phenotype 3, a beta-lactamase with an isoelectric point of 7.9. The beta-lactamases of all three phenotypes hydrolysed benzylpenicillin and more slowly cephalothin. All phenotype 1 isolates carried a 2.9 Md plasmid and most isolates also a 36 Md plasmid. All phenotype 2 isolates carried a 4.8 Md plasmid and one isolate also a 30 Md plasmid. The phenotype 3 isolates carried only one 85 Md plasmid.

Animals↗

PubMed1990

Drug-resistant coagulase-negative skin staphylococci. Evaluation of four marker systems and epidemiology in an orthopaedic ward.

Drug-resistant coagulase-negative staphylococci (DRCNS) in orthopaedic patients and ward staff were studied. A significant increase in the DRCNS carriage rate was observed among the 16 patients studied after 14 days of hospitalization with levels approaching that of the staff. Patients receiving dicloxacillin prophylaxis (n = 9) were more likely to be colonized with methicillin-resistant CNS, while patients receiving no antibiotics (n = 7) became to a larger extent colonized with multiple DRCNS. The combined data from species determination, biochemical, plasmid, and antibiogram typing revealed a considerable diversity among DRCNS; 64 types were distinguished among 112 DRCNS isolates selected for study after exclusion of apparently duplicate isolates. Plasmid plus antibiogram typing yielded almost as many types (61); whereas species determination plus antibiogram distinguished only 33 types. Although a novel computerized 96-reaction biotyping method alone enabled differentiation of 17 biotypes, most DRCNS isolates belonged to one of three major biotypes limiting the usefulness of this method. Ten of the 64 (16%) DRCNS types identified comprised 50 of the 112 (45%) isolates. These were isolated from staff and from patients on day 14, suggesting a nosocomial origin.

Adult↗

PubMed1990

Evaluation of numerical typing systems for Escherichia coli using the API 50 CH and the PhP-EC systems as models.

Reproducible and discriminating typing methods are required for epidemiological investigations. Numerical typing systems analyse patterns obtained in various ways by calculating similarity coefficients between isolates. In the present study, various measures of the efficiency of a numerical typing system are quantified. These include reproducibility, accuracy, and discrimination power. Three different numerical typing methods for Escherichia coli were compared using these measures: (a) Biotyping with API 50 CH system, (b) Biochemical fingerprinting with the API 50 CH system and (c) Biochemical fingerprinting with the PhP-EC system. Biotyping qualitatively measures the results of a set of biochemical reactions as + or -. Biochemical fingerprinting also uses biochemical reactions, but the tests are scored quantitatively by measuring the kinetics and intensity of each reaction. It was found that biotyping yielded poor reproducibility. When biochemical fingerprinting analysis was used with the API 50 CHE system the reproducibility and the discrimination was good. The PhP-EC system for biochemical fingerprinting showed equal reproducibility but was superior to the API 50 CH system with regard to discrimination power.

Bacterial Typing Techniques↗

PubMed1990

Escherichia coli populations from diabetic and non-diabetic patients with bacteraemia and faecal samples from healthy subjects--a comparative study.

Biochemical reactions, using the PhP-EC system of biochemical fingerprinting, were evaluated in order to group strains into different clusters and to investigate whether a biochemical typing system may be used to distinguish between randomly selected Escherichia coli strains obtained from bacteraemic patients and healthy controls. Fifty epidemiologically unrelated strains isolated from blood of non-diabetic patients and 46 faecal control strains were studied. Separately, 70 E. coli strains from 64 diabetic patients with bacteraemia were investigated. Diversity index was 0.977, 0.969 and 0.941 respectively. The strains were clustered at a similarity level of 0.95. The bacteraemic and control strains were subdivided into 14 different clusters with 2-12 strains each and 40 'outliers'. The largest cluster was dominated by bacteraemic strains (9/12, 75%). Two other clusters were dominated by control strains. In the remaining groups blood and faecal isolates were evenly distributed. No biochemical test was able to distinguish between bacteraemic and faecal control strains. Strains from patients with diabetes mellitus were grouped in 11 clusters containing 2-14 strains and 22 'outliers'. The low diversity index of bacteraemic strains obtained from diabetic patients as compared to other strains indicated a greater homogenicity. However, no correlation was observed between the examined host factors and the clusters.

Adult↗

PubMed1990

Evaluation of the stability of biochemical phenotypes of Escherichia coli upon subculturing and storage.

Stability of the biotypic characters of 72 enteropathogenic Escherichia coli (EPEC) and 21 faecal E. coli strains was evaluated after storage and after subculturing using a computerized biochemical fingerprinting method. Sixteen (22%) EPEC strains and nine (43%) faecal strains exhibited changes in their biochemical reactions after subculturing. In contrast, strains stored at -70 degrees C and 4 degrees C did not show any measurable changes. Of 23 biochemical markers tested, eight were subject to changes in at least one of these strains. Changes in lactulose fermentation was most frequent, occurring in 17 (18%) strains. A decrease or loss of activity in the fermentation of 5-ketogluconate, arbutin and methyl beta-D-glucoside in six strains (6%), and an increase in the ability to ferment sucrose, raffinose, melibiose and D-arabinose in 20 strains (22%) were observed. Mean similarity of the strains, when compared pairwise before and after subculturing, was slightly affected by these changes, but the overall biochemical phenotypes of the strains remained constant.

Biomarkers↗

PubMed1989

Cytotoxin activity on Vero cells among Escherichia coli strains associated with diarrhea in cats.

The role of Escherichia coli as a causative agent of diarrhea in cats was investigated. Isolates of E coli from healthy and diarrheic cats were serotyped and investigated for their biochemical characters, production of cytotoxin activity on Vero cells, heat-labile enterotoxin, heat-stable enterotoxin, and hemagglutination of erythrocytes from other animal species. None of 48 investigated strains produced heat-labile enterotoxin or heat-stable enterotoxin, nor did they agglutinate erythrocytes. Most strains were hemolytic and belonged to O-serotypes 2 and 6. Cytotoxin activity on Vero cells was significantly more common and produced in greater amounts among E coli strains isolated from diarrheic cats, and was neutralized by anti-Shiga-like toxin I serum.

Animals↗

PubMed1988

Influence of antibiotic therapy on faecal carriage of P-fimbriated Escherichia coli and other gram-negative bacteria in neonates.

The influence of previous antibiotic therapy on the aerobic faecal flora, including P-fimbriated Escherichia coli, was studied in 953 neonates at discharge from 22 neonatal wards in Sweden. Antibiotics, mainly ampicillin (with or without gentamicin) or cefuroxime, had been received by 37% of the infants. Treatment with ampicillin (with or without gentamicin) increased Klebsiella/Enterobacter and reduced Esch. coli colonization. Cephalosporin therapy (71% cefuroxime) reduced the frequency of colonization with both Esch. coli and Klebsiella/Enterobacter spp. but doubled the isolation rate of other Gram-negative bacteria (Citrobacter, Pseudomonas, Proteus and Acinetobacter spp.) and tripled the incidence of specimens yielding no aerobic Gram-negative growth. Gentamicin showed no significant ecological impact. The selection of Klebsiella/Enterobacter and P-negative Esch. coli strains by ampicillin was correlated with their resistance to this agent, while the association between P-fimbriated Esch. coli and cefuroxime therapy was not related to cefuroxime resistance.

Anti-Bacterial Agents↗

PubMed1988

Epidemiology of fecal strains of the family Enterobacteriaceae in 22 neonatal wards and influence of antibiotic policy.

The gram-negative fecal floras from 953 infants were studied upon discharge of the infants from 22 neonatal wards. More than 600 distinct phenotypes of Escherichia coli, Klebsiella spp., and Enterobacter spp. were distinguished by high-resolution biotyping. The colonization patterns observed showed considerable local and temporal variation. The major (M) strains (phenotypes), which colonized more than 10% and up to 78% of the infants in a ward (median, 23%), were Klebsiella oxytoca (15 strains), E. coli (4 strains), Klebsiella pneumoniae (1 strain), and Enterobacter cloacae (1 strain). Resistance to beta-lactam antibiotics was more pronounced among M strains than among strains of enteric bacteria colonizing few or single infants only. Local antibiotic policy influenced the colonization patterns. Despite the fact that M strains of Klebsiella spp. were usually resistant to ampicillin as well as to cephalexin and cefuroxime, their local dissemination was associated with the use of ampicillin with or without gentamicin but not with the use of cefuroxime. It thus appeared that in the neonatal setting, ampicillin posed a greater risk of local spread of certain drug-resistant bacterial clones than a newer cephalosporin, such as cefuroxime.

Anti-Bacterial Agents↗

PubMed1986

Fecal colonization with pyelonephritogenic Escherichia coli in neonates as a risk factor for pyelonephritis.

The aim of the study was to investigate the properties of fecal P-fimbriated Escherichia coli strains in neonates and to relate these characteristics to the later development of acute pyelonephritis. In a 2 1/2 year prospective study of the children admitted to a particular neonatal ward, 113 children were found to be fecally colonized with a P-fimbriated Escherichia coli strain. However, only one of these children developed pyelonephritis from this strain during the first year of life. The combined results of serotyping, biochemical phenotyping and determination of outer membrane protein pattern as clonal characterization suggested that only 26 of the P-fimbriated strains belonged to a pyelonephritogenic Escherichia coli clone. It is concluded that the risk of a child colonized with an Escherichia coli strain belonging to such a clone of developing pyelonephritis, as calculated in this study, is about 4%.

Acute Disease↗