Roland Möllby

OCCURRENCE OF P-FIMBRIATED ESCHERICHIA COLI IN URINARY TRACT INFECTIONS

The occurrence of Escherichia coli possessing P blood-group-specific adhesins (P-fimbriae) was examined in 97 children with urinary tract infections and 82 healthy controls. P-fimbriae were present in 91% (33/35) of the urinary strains causing acute pyelonephritis. Among strains causing cystitis and asymptomatic bacteriuria P-fimbriae were found in 19% and 14% of cases, respectively. Only 7% of faecal isolates from healthy controls carried P-fimbriae. The results were similar in three different studies. In most of the children with acute pyelonephritis the urinary pathogen was the predominant E. coli strain of the periurethral and faecal flora.

Vaccination with FimH Adhesin Protects Cynomolgus Monkeys from Colonization and Infection by Uropathogenic Eschevichia coli

Escherichia coli FimH adhesin mediates binding to the bladder mucosa. In mice, a FimH vaccine protects against bacterial challenge. In this study, 4 monkeys were inoculated with 100 microgram of FimCH adhesin-chaperone complex mixed with MF59 adjuvant, and 4 monkeys were given adjuvant only intramuscularly. After 2 doses (day 0 and week 4), a booster at 48 weeks elicited a strong IgG antibody response to FimH in the vaccinated monkeys. All 8 monkeys were challenged with 1 mL of 108 E. coli cystitis isolate NU14. Three of the 4 vaccinated monkeys were protected from bacteruria and pyuria; all control monkeys were infected. These findings suggest that a vaccine based on the FimH adhesin of E. coli type 1 pili may have utility in preventing cystitis in humans.

Clinical Pyelonephritis and Focal Renal Scarring: A Selected Review of Pathogenesis, Prevention, and Prognosis

This article considers the pathogenesis of acute pyelonephritis; determinants of focal renal scarring; prevention of renal damage by early recognition of urinary tract infection in childhood; and renal growth patterns in kidneys damaged during early childhood.

High prevalence of vancomycin-resistant enterococci in Swedish sewage

ABSTRACT In Europe the use of the growth promoter avoparcin is considered to have selected for vancomycin-resistant enterococci (VRE). Sweden ceased using avoparcin in 1986, and only occasional cases of VRE from hospitals have been reported since 1995. Within the framework of a European study, samples from urban raw sewage, treated sewage, surface water, and hospital sewage in Sweden (n = 118) were screened for VRE. Surprisingly, VRE were isolated from 21 of 35 untreated sewage samples (60%), from 5 of 14 hospital sewage samples (36%), from 6 of 32 treated sewage samples (19%), and from 1 of 37 surface water samples. Thirty-five isolates from 33 samples were further characterized by geno- and phenotyping, MIC determination, and PCR analysis. Most isolates (30 of 35) carried the vanA gene, and the majority (24 of 35) of the isolates were Enterococcus faecium. Most of the VRE were multiresistant. The typing revealed high diversity of the isolates. However, one major cluster with seven identical or similar isolates was found. These isolates came from three different sewage treatment plants and were collected at different occasions during 1 year. All VRE from hospital sewage originated from one of the two hospitals studied. That hospital also had vancomycin consumption that was 10-fold that of the other. We conclude that VRE were commonly found in sewage samples in Sweden. The origin might be both healthy individuals and individuals in hospitals. Possibly, antimicrobial drugs or chemicals released into the sewage system may sustain VRE in the system.

Comparison of enterococcal populations in animals, humans, and the environment - a European study

The objectives of the present study were to generate knowledge of enterococcal populations in the food chain, by studying the population structure (in measures of abundance and diversity) among enterococci in different geographical regions and in different parts of the food chain, as well as the similarities between different enterococcal populations. Altogether, 2868 samples were collected from humans (healthy and hospitalised individuals and clinical isolates), animals (slaughterhouse carcasses and farm animals), and the environment (pig farms, sewage, and surface water) in four European countries-Sweden, Denmark, UK, and Spain. The samples were characterised with regard to presence and numbers of enterococci, and eight (for faecal samples) or 24 (for environmental samples) isolates per sample were phenotyped and preliminarily identified with the PhP-RF system. In total, more than 20,000 isolates were typed. A majority of the samples (77%) showed the presence of presumed enterococci. The diversities of enterococci in environmental samples were generally high, and also faecal samples normally showed presence of more than one enterococcal strain. The most common species found were Enterococcus faecium (33%), E. faecalis (29%), and E. hirae (24%), but different enterococcal populations differed in their species distribution. Clinical isolates, hospitalised patients, and hospital sewage in Sweden showed a clear dominance of E. faecalis (80%, 57%, and 54%, respectively) whereas healthy individuals and urban sewage contained less E. faecalis (39% and 40%, respectively). The species distribution among isolates from slaughterhouses varied between animal species and also between countries, but E. faecalis seemed to be mainly associated with broiler, and E. hirae with cattle and pigs. The results from the study have indicated a simplified method to study the diversity of bacterial populations. Instead of collecting many samples and analysing one or a few isolates per sample, it is possible to collect fewer samples and analyse several isolates per sample. Both approaches yielded similar information on the diversity of the populations. Another useful information was that since samples from hospital sewage, urban sewage, and manure contained enterococcal populations that reflected those in faecal samples of hospitalised patients, healthy humans, and animals, respectively, such samples may be used as pooled faecal samples and may replace cumbersome samplings from many individuals.

Evaluation of redox indicators and the use of digital scanners and spectrophotometer for quantification of microbial growth in microplates

The growth indicators 2,3,5-triphenyltetrazolium chloride (TTC), 2-[4-iodophenyl]-3-[4-dinitrophenyl]-5-phenyltetrazolium chloride (INT), 2,3-bis[2-methoxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide inner salt (XTT), 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT), and resazurin were tested for their ability to indicate bacterial growth/growth inhibition. Two reading devices were evaluated and compared, a microplate spectrophotometer and a digital flatbed scanner. The bacteria used in the study were cultivated in 96-wells microplates and readings were made after 24 h. The scanned pictures were analysed with a software developed in-house to generate numerical values. It was found that resazurin was difficult to use since it shifts between three colours. MTT and TTC had a high correlation between the spectrophotometer data and the data from the scanned images. The reproducibility was similar for both reading devices. In no case was there a need to resuspend the pellets before reading. Both the XTT and INT showed lower correlations. It is concluded that bacterial growth/growth inhibition can be easily and reproducibly measured from microplate cultivations with a flatbed scanner or with a microplate spectrophotometer.

STRUCTURE OF CARBOHYDRATE PART OF RECEPTOR ON HUMAN UROEPITHELIAL CELLS FOR PYELONEPHRITOGENIC ESCHERICHIA COLI

The binding of pyelonephritogenic Escherichia coli strains to human uroepithelial cells from patients with and without P blood group antigens was investigated. Uroepithelial cells from p phenotypes bound pyelonephritogenic e. coli to a significantly lesser extent than did cells from P1 and P2 phenotypes. The binding of pyelonephritogenic E. coli to urinary epithelial cells of P1 phenotypes was blocked by the synthetic disaccharide alpha-D-Galp-(1 leads to 4)-beta-D-Galp whose structures is related to that of the P blood group antigens. Coating of P1 cells with a synthetic disaccharide derivative increased the binding of bacteria. None of 30 individuals of p phenotype had had urinary tract infection. The findings show that the disaccharide alpha-D-Galp-(1 leads to 4)-beta-D-Galp, previously shown to be the erythrocyte receptor for the fimbriae of pyelonephritongenic E. coli, is also the receptor structure on uroepithelial cells.

The effect of zinc oxide supplementation on the stability of the intestinal flora with special reference to composition of coliforms in weaned pigs

The effect of a dietary supplementation of zinc oxide (ZnO) on the stability of the intestinal flora and on the composition of coliforms in weaned pigs was investigated. Faecal floras were characterized by their metabolic activities and fermentative capacity (FC) using the Phene Plate generalized microplate. Coliforms were characterized by conventional enumeration and by the Phene Plate‐RS plates. The latter measured FC, phenotypic diversity, persistence of each coliform strain in piglets, and similarity among the coliform populations within groups. From weaning onwards, the control pigs (n = 5) were fed a basal diet ad libitum, while experimental pigs (n = 5) were given the same food supplemented with 2500 ppm ZnO. Metabolic fingerprinting of faecal floras indicated marked differences between the composition of floras of treated and control pigs during the first 2 weeks post‐weaning. The FC of faecal flora in both groups decreased as pigs aged, but it was significantly (P≤ 0·0001) lower in control pigs during the first 2 weeks post‐weaning. Neither the number of coliforms, nor their FC‐values, differed between the groups. However, during the first 2 weeks post‐weaning, there was a significant increase in both variety (P = 0·019) and diversity (P≤ 0·001) of coliforms in control pigs compared with the ZnO treated group. Homogeneity between coliform populations of piglets was high during the suckling period, indicating the presence of many identical strains among piglets. This, however, decreased in control pigs during the first 2 weeks post‐weaning. Several coliform strains that colonized the gut at the early stage of the pigs’ life were found to be resident in animals of both groups. It is concluded that supplementation of ZnO to weaned pigs helped to maintain the stability of the intestinal microflora and the diversity of coliforms during the first 2 weeks post‐weaning, but not later, and that ZnO supplementation to creep feed should be restricted to the first 2 weeks post‐weaning in veterinary practice.

Occurrence and Relatedness of Vancomycin-Resistant Enterococci in Animals, Humans, and the Environment in Different European Regions

ABSTRACT Vancomycin-resistant enterococcci (VRE) in Europe are thought to have emerged partly due to the use of the glycopeptide avoparcin in animal husbandry. We compared the occurrence of VRE in geographical regions of Europe in which until 1997 large amounts of avoparcin were used (Spain, United Kingdom, and Denmark) with the occurrence of VRE in Sweden, where avoparcin was banned in 1986. We also studied the relatedness between VRE strains from different regions and habitats. In total, 2,580 samples were collected from humans, animals, and the environment (soil, sewage, recipient water). VRE resistant to 20 μg/ml vancomycin were identified in 8.2% of the samples and were found most frequently in raw and treated urban sewage samples (means, 71% and 36% of the samples, respectively), pig manure (17%), and hospital sewage (16%). The proportions of VRE-positive sewage samples were similar in Sweden, Spain, and the United Kingdom, whereas pig feces and manure were more often positive in Spain than in Sweden (30% versus 1%). Most VRE were Enterococcus faecium carrying vanA, and computerized biochemical phenotyping of the isolates of different ecological origins showed a high degree of polyclonality. In conclusion, it seems that animal-associated VRE probably reflect the former use of avoparcin in animal production, whereas VRE in human-associated samples may be a result of antibiotic use in hospitals. Since there seems to be a reservoir of the resistance genes in all countries studied, precautions must be taken to limit the use of antibiotics and antibiotic-like feed additives.

Serum antibody response to clostridium difficile toxins in patients with clostridium difficile diarrhoea

SummaryConsecutive serum samples from 61 patients withClostridium difficile diarrhoea were investigated for antibody response toC. difficile toxins A and B in an indirect enzyme immunoassay (ELISA) and in a neutralization assay againstC. difficile cytotoxin. Sera from 64 blood donors, elderly healthy females and patients with other known intestinal enteropathogens served as controls. An immune response was detected by ELISA in approximately half of the patients withC. difficile diarrhoea. The specificity of the ELISA was 94% or 97%, depending on the control material used. Furthermore, a correlation was found between clinical recovery without relapse ofC. difficile diarrhoea and high IgG titers to toxin B in the ELISA, and/or appearance of neutralizing antibodies. It is concluded that the ELISA for detection of serum antibodies toC. difficile toxins may be of diagnostic value in combination with the conventional tissue culture assay for cytotoxin in stool. High ELISA IgG titres to toxin B and/or the appearance of neutralizing antibodies may also be a positive prognostic sign in patients withC. difficile diarrhoea.ZusammenfassungVon 61 Patienten mitClostridium difficile-Diarrhoe wurden konsekutive Serumproben mit einem indirekten Enzymimmunassay (ELISA) und einem Neutralisationstest fürC. difficile Cytotoxin auf die Antikörperantwort gegen die Toxine A und B vonC. difficile untersucht. Als Kontrollen wurden Seren von 64 Blutspendern, älteren gesunden Frauen und Patienten, die an Krankheiten durch andere bekannte enteropathogene Erreger litten, verwendet. Bei annähernd der Hälfte der Patienten mitC. difficile-Diarrhoe wurde mittels ELISA eine Immunantwort entdeckt. In Abhängigkeit vom Kontrollmaterial ergab sich für den ELISA-Test eine Spezifität von 94% oder 97%. Bei Patienten, die sich ohne Rezidiv von derC. difficile-Diarrhoe erholten, bestand eine Korrelation zu hohen IgG-Titern gegen Toxin B im ELISA-Test und/oder Auftreten von neutralisierenden Antikörpern. Daraus läßt sich schließen, daß die Bestimmung der Antikörper gegenC. difficile-Toxine im Serum mit ELISA in Kombination mit dem herkömmlichen Gewebekultur-Test auf Cytotoxin von diagnostischem Wert ist. Hohe ELISA IgG-Titer gegen Toxin B und/oder das Auftreten neutralisierender Antikörper im Serum können bei Patienten mitC. difficile-Diarrhoe als positives prognostisches Zeichen gewertet werden.