ABSTRACT
We investigated the influence of assay choice on the results in a two-tier testing algorithm for the detection of anti-Borrelia antibodies. Eighty-nine serum samples from clinically well-defined patients were tested in eight different enzyme-linked immunosorbent assay (ELISA) systems based on whole-cell antigens, whole-cell antigens supplemented with VlsE and assays using exclusively recombinant proteins. A subset of samples was tested in five immunoblots: one whole-cell blot, one whole-cell blot supplemented with VlsE and three recombinant blots. The number of IgM- and/or IgG-positive ELISA results in the group of patients suspected of Borrelia infection ranged from 34 to 59%. The percentage of positives in cross-reactivity controls ranged from 0 to 38%. Comparison of immunoblots yielded large differences in inter-test agreement and showed, at best, a moderate agreement between tests. Remarkably, some immunoblots gave positive results in samples that had been tested negative by all eight ELISAs. The percentage of positive blots following a positive ELISA result depended heavily on the choice of ELISA-immunoblot combination. We conclude that the assays used to detect anti-Borrelia antibodies have widely divergent sensitivity and specificity. The choice of ELISA-immunoblot combination severely influences the number of positive results, making the exchange of test results between laboratories with different methodologies hazardous.
Subject(s)
Antibodies, Bacterial/blood , Borrelia/immunology , Clinical Laboratory Techniques/methods , Immunoblotting/methods , Lyme Disease/diagnosis , Antigens, Bacterial/immunology , Enzyme-Linked Immunosorbent Assay/methods , Humans , Immunoglobulin G/blood , Immunoglobulin M/blood , Recombinant Proteins/immunology , Sensitivity and SpecificityABSTRACT
An open-label randomised clinical trial was designed to compare the efficacy and tolerance of levofloxacin and ciprofloxacin plus phenethicillin for the prevention of bacterial infections in patients with high-risk neutropenia, and to monitor the emergence of antimicrobial resistance. Adult patients (n = 242) scheduled to receive intensive treatment for haematological malignancies were assigned randomly to receive oral prophylaxis with either levofloxacin 500 mg once-daily (n = 122), or ciprofloxacin 500 mg twice-daily plus phenethicillin 250 mg four-times-daily (n = 120). The primary endpoint was failure of prophylaxis, defined as the first occurrence of either the need to change the prophylactic regimen or the initiation of intravenous broad-spectrum antibiotics. This endpoint was observed in 89 (73.0%) of 122 levofloxacin recipients and in 85 (70.8%) of 120 ciprofloxacin plus phenethicillin recipients (RR 1.03, 95% CI 0.88-1.21, p 0.71). No differences were noted between the two groups with respect to secondary outcome measures, including time to endpoint, occurrence of fever, type and number of microbiologically documented infections, and administration of intravenous antibiotics. A questionnaire revealed that levofloxacin was tolerated significantly better than ciprofloxacin plus phenethicillin. Surveillance cultures indicated the emergence of viridans group (VG) streptococci resistant to levofloxacin in 17 (14%) of 122 levofloxacin recipients; in these cases, the prophylactic regimen was adjusted. No bacteraemia with VG streptococci occurred. It was concluded that levofloxacin and ciprofloxacin plus phenethicillin are equally effective in the prevention of bacterial infections in neutropenic patients, but that levofloxacin is tolerated better. Emergence of levofloxacin-resistant VG streptococci is of concern, but appears to be a manageable problem.
Subject(s)
Anti-Bacterial Agents/therapeutic use , Antibiotic Prophylaxis/methods , Ciprofloxacin/therapeutic use , Cross Infection/prevention & control , Hematologic Neoplasms/microbiology , Levofloxacin , Ofloxacin/therapeutic use , Penicillin V/analogs & derivatives , Adolescent , Adult , Aged , Antibiotic Prophylaxis/adverse effects , Drug Resistance, Bacterial/drug effects , Drug Therapy, Combination , Female , Fever/microbiology , Humans , Male , Middle Aged , Neutropenia/microbiology , Penicillin V/therapeutic use , Treatment Outcome , Viridans Streptococci/drug effectsABSTRACT
Herpes simplex virus type 1 (HSV-1) has been associated with pulmonary disease, mostly in severely immunocompromised patients. After reactivation and shedding in the oropharynx, the virus may reach the lower respiratory tract by aspiration or by contiguous spread. HSV-1 can be detected in clinical specimens by virus culture or quantitatively by nucleic acid amplification techniques. With these techniques, HSV-1 is often detected in the respiratory secretions of critically-ill patients. However, a clear diagnosis of HSV-1 pneumonia is difficult to establish because clinical criteria, radiological features and laboratory findings all lack specificity. Lower respiratory tract HSV-1 infections have not been associated with specific risk-factors. There is also an absence of consistent data concerning the effect of antiviral treatment on the outcome of critically-ill patients. Further studies are needed to better define the pathogenic role of HSV-1 in the lower respiratory tract of these patients, to improve the diagnosis, and, especially, to assess the need for antiviral treatment in the individual patient.
Subject(s)
Herpesvirus 1, Human , Pneumonia, Viral , Antiviral Agents/therapeutic use , Bronchoscopy , Carrier State/virology , Critical Illness , DNA, Viral/analysis , DNA, Viral/genetics , Herpesvirus 1, Human/isolation & purification , Herpesvirus 1, Human/physiology , Humans , Immunocompromised Host , Incidence , Nucleic Acid Amplification Techniques , Pneumonia, Viral/diagnosis , Pneumonia, Viral/drug therapy , Pneumonia, Viral/epidemiology , Pneumonia, Viral/virology , Risk Factors , Virus ActivationABSTRACT
The most common complication of continuous subcutaneous insulin infusion (CSII) is inflammation at the infusion site. To determine possible risk factors to these infections, we studied several factors in the management of CSII and compared the pyogenic skin inflammation rate, the carriage rate of Staphylococcus aureus, and the HbA1 level among 50 CSII-treated diabetic patients, 50 diabetic patients on insulin injections, 48 diabetic patients on oral medication, and 40 healthy volunteers. There was no increased carriage rate of S. aureus among CSII-treated patients (42%) as compared with the other groups. An unexpected inverse relationship existed between HbA1 level and carriage rate in the CSII-treated group (HbA1 5-8%, n = 16, 69%; HbA1 8-10% n = 15, 40%; HbA1 greater than 10, n = 19, 21% P = .02). Pyogenic skin inflammations were reported by 24 (48%) CSII-treated patients, of which 18 had infected infusion sites, 6 (12%) insulin injecting patients, 2 (4%) patients on oral medication, and 3 (8%) healthy volunteers (P less than .01). The occurrence of inflamed infusion sites was not associated with carriage of S. aureus, the indwelling time of the needle, or the insulin dosage per day. There was an association, however, with the type of insulin preparation classified according to the added preservative: m-cresol-containing insulin (n = 24, 54%); methyl p-hydroxybenzoate-containing insulin (n = 26, 19%, P = .02). We concluded that the carriage of S. aureus is not increased among diabetic patients on CSII treatment and is not a risk factor in the occurrence of inflammation at the infusion site.(ABSTRACT TRUNCATED AT 250 WORDS)
Subject(s)
Insulin Infusion Systems/adverse effects , Staphylococcal Infections/etiology , Staphylococcus aureus/isolation & purification , Carrier State , Diabetes Mellitus, Type 1/complications , Diabetes Mellitus, Type 1/drug therapy , Diabetes Mellitus, Type 2/complications , Diabetes Mellitus, Type 2/drug therapy , Female , Humans , Hypoglycemic Agents/therapeutic use , Inflammation , MaleABSTRACT
Gram-positive breakthrough infections pose a major drawback to the use of quinolones for antibacterial prophylaxis in neutropenic patients. Levofloxacin offers the advantage of an augmented Gram-positive spectrum and may potentially overcome this problem. In an open-label, clinical pilot study, we investigated the effects on throat and bowel microflora and pharmacokinetics of a once-daily oral dose of 500 mg levofloxacin, during neutropenia in 20 patients with haematological malignancies. Gram-negative bowel flora and Staphylococcus aureus were successfully eradicated. No Gram-negative infections occurred. Minimal inhibitory concentration values for viridans group (VG) streptococci tended to increase, in four patients over 8 mg/l, indicating resistance to levofloxacin. Four patients developed blood-stream infections with levofloxacin-resistant Gram-positive cocci. No significant changes in numbers of anaerobic microorganisms were observed. Pharmacokinetic parameters of levofloxacin, including the maximum serum concentration (C(max)), time to C(max) (T(max)), area under the concentration-time curve (AUC), volume of distribution at steady state (V(ss)/F) and clearance (CL/F) were not statistically different at first dose and during neutropenia. In conclusion, levofloxacin eradicates Gram-negative microorganisms and S. aureus and spares the anaerobic flora. Its pharmacokinetic profile is unaltered during neutropenia. However, prolonged administration of levofloxacin as antibacterial prophylaxis may be hampered by the emergence of levofloxacin-resistant VG streptococci.
Subject(s)
Anti-Infective Agents/administration & dosage , Anti-Infective Agents/pharmacokinetics , Digestive System/microbiology , Hematologic Neoplasms/drug therapy , Levofloxacin , Neutropenia/drug therapy , Neutropenia/microbiology , Ofloxacin/administration & dosage , Ofloxacin/pharmacokinetics , Pharynx/microbiology , Administration, Oral , Adult , Aged , Drug Resistance, Bacterial , Female , Gram-Negative Bacteria/drug effects , Gram-Positive Bacterial Infections/prevention & control , Gram-Positive Cocci/drug effects , Hematologic Neoplasms/metabolism , Hematologic Neoplasms/microbiology , Hematologic Neoplasms/therapy , Hematopoietic Stem Cell Transplantation , Humans , Male , Middle Aged , Staphylococcus aureus/drug effectsABSTRACT
We conducted an open label, randomised clinical trial to compare amphotericin B colloidal dispersion (ABCD, Amphocil) 2 mg/kg/day intravenously with fluconazole 200 mg/day orally, for the prevention of fungal disease in neutropenic patients with haematological malignancies. In the event of unresolved fever after 4 days of empirical antibacterial therapy, patients in both treatment groups were to receive ABCD, 4 mg/kg/day. However, the study had to be stopped in an early phase, due to severe side-effects of ABCD. A total of 24 patients were enrolled, 12 patients were randomly assigned to receive prophylactic ABCD, which was administered for a mean of 13.9 days. Fluconazole prophylaxis was given to 12 patients for a mean of 21.2 days. Therapeutic ABCD, 4 mg/kg, was initiated in four patients because of suspected fungal infection, all of whom had initially received fluconazole. A high rate of infusion-related toxicity of ABCD was observed. Chills occurred in 15/16 ABCD recipients (94%), accompanied by a temperature rise of >/=2 degrees C in 4/16 patients and of >/=1 degrees C but <2 degrees C in 10/16 patients. Other ABCD-related adverse events were hypotension (4/16), nausea with vomiting (5/16), tachycardia (7/16), headache (3/16) and dyspnoea (3/16). For premedication patients received: antihistamines (12/16), hydrocortisone (9/16) and/or morphine (6/16). ABCD was discontinued in 8/16 patients (50%) due to side-effects, which ultimately dictated early termination of the study. We conclude that ABCD is not suitable for antifungal prophylaxis in neutropenic patients due to severe infusion-related side-effects. Subject numbers were too low for conclusions on variables of antifungal efficacy.
Subject(s)
Amphotericin B/toxicity , Fluconazole/administration & dosage , Hematologic Neoplasms/complications , Mycoses/drug therapy , Mycoses/prevention & control , Neutropenia/complications , Adolescent , Adult , Aged , Amphotericin B/administration & dosage , Bilirubin/blood , Consumer Product Safety , Contraindications , Female , Fluconazole/toxicity , Hematologic Neoplasms/drug therapy , Hematopoietic Stem Cell Transplantation/adverse effects , Humans , Infusions, Intravenous/adverse effects , Male , Middle Aged , Morphine/therapeutic use , Mycoses/etiology , Neutropenia/drug therapy , Respiratory Tract Diseases/chemically induced , Shivering , Survival , Time Factors , Transaminases/bloodABSTRACT
AIMS: To compare the sensitivity and specificity of two semiautomated systems against a conventional (MIC 2000) test system for the identification and antibiotic susceptibility of Gram negative bacteria. METHODS: Clinical isolates of Gram negative bacilli (188 urinary and 229 non-urinary strains) were identified and tested for antibiotic susceptibility in the Cobas Micro and MIC 2000 systems. Of these, 359 strains were then tested in the Vitek and MIC 2000 systems. Two hundred and forty three strains were tested in all three systems immediately after isolation. Forty three were also tested only in the Vitek and MIC 2000 systems immediately after isolation. The remaining 174 strains were tested after storage at -20 degrees C for several months. RESULTS: The Cobas Micro and MIC 2000 systems agreed on the identification of 310 of the 417 (74.3%) strains; the Vitek and MIC 2000 systems agreed on 338 of the 359 (94.2%) strains. The Cobas Micro system correctly identified 86.8% of strains tested after storage and 65.4% of those immediately after isolation. Organism-antibiotic combinations (non-urinary isolates) were tested in the Cobas Micro and MIC 2000 systems (n = 2335), in the Vitek and MIC 2000 systems (n = 999). Essential correlation (complete agreement plus minor errors) was observed in 98% (with 90% complete agreement) in the former and in 97% (with 86% complete agreement) in the latter. For the urinary isolates, 1949 organism-antibiotic combinations were analysed in the Cobas Micro and MIC 2000 systems where complete agreement was observed in 92% (with 3% very major discrepancies), for 1382 urinary organism-antibiotic combinations tested in the Vitek and MIC 2000 systems, the figures were 95% and 2%, respectively. CONCLUSIONS: The Vitek system is highly accurate in the identification and antibiotic susceptibility testing of Gram negative bacteria. The Cobas Micro system has many shortcomings in its identification of Gram negative rods, especially freshly isolated strains, but it is comparable with the Vitek system in antibiotic susceptibility testing.
Subject(s)
Gram-Negative Bacteria/classification , Gram-Negative Bacteria/drug effects , Anti-Bacterial Agents/pharmacology , Bacteriological Techniques , Humans , Microbial Sensitivity Tests/methods , Pseudomonas/drug effects , Sensitivity and Specificity , Urinary Tract/microbiologyABSTRACT
AIMS: To compare the efficacy of and tolerance to oral fluconazole and intraconazole in preventing fungal infection in neutropenic patients with haematological malignancies. PATIENTS: 213 consecutive, afebrile adult patients treated with or without autologous stem cell transplantation for haematological malignancies. METHODS: A randomised, double blind, single centre study. Patients were randomly assigned to receive fluconazole 50 mg or itraconazole 100 mg, both twice daily in identical capsules. An intention to treat analysis was performed on 202 patients, 101 in each group. RESULTS: Microbiologically documented systemic fungal infections occurred in four patients in each group. Clinical fungal infection was thought to be present in seven recipients of fluconazole and four of itraconazole. In all 202 patients, 29 proceeded to intravenous amphotericin (amphotericin B), 16 in the fluconazole group and 13 in the itraconazole group. Superficial fungal infection was seen only in three non-compliant patients in the fluconazole group. All these infections were oral. No major differences were noted in the isolates of fungi in mouth washes and fecal samples. Overall mortality was 8.9% (18 deaths; seven in the fluconazole group, 11 in the itraconazole group). Mortality from microbiologically and clinically documented fungal infection was 4.5% (nine deaths; three in the fluconazole group, six in the itraconazole group). Median time to suspected or proven fungal infection was 16 days in both groups. None of these comparisons reached statistical significance (p < 0.05). No major clinical toxicity was noted and compliance was excellent. CONCLUSIONS: In neutropenic patients treated for haematological malignancies with or without autologous stem cell transplantation, fluconazole and itraconazole in low doses result in a similar low frequency of fungal disease. Fluconazole may be the preferable drug because of the smaller number of capsules and lack of need for timing relative to meals.
Subject(s)
Antifungal Agents/therapeutic use , Fluconazole/therapeutic use , Itraconazole/therapeutic use , Mycoses/prevention & control , Opportunistic Infections/prevention & control , Adult , Aged , Double-Blind Method , Female , Hematologic Neoplasms/therapy , Hematopoietic Stem Cell Transplantation , Humans , Male , Middle Aged , Mycoses/complications , Neutropenia/complications , Opportunistic Infections/complications , Patient Compliance , Survival RateABSTRACT
Chemiluminescence (CL) of human polymorphonuclear leukocytes was determined after stimulation with 89 clinical isolates of Klebsiella which differed in serotype and in their virulence for mice. With K1, K2, K4 and K5 strains, a significantly lower CL response was observed than with K3, K6 and K greater than 6 strains. These results correlated well with virulence: greater virulence could be explained by greater resistance to phagocytosis.
Subject(s)
Klebsiella/immunology , Neutrophils/immunology , Phagocytosis , Animals , Humans , Klebsiella/classification , Klebsiella/pathogenicity , Luminescent Measurements , Luminol , Mice , Serotyping , Virulence , ZymosanABSTRACT
The importance of K antigen of Klebsiella as a virulence factor was studied in nine pairs of K+ and K- strains, each pair isogenic apart from the presence of K antigen. Loss of K antigen by nine K+ strains resulted in the reduced virulence of their K- variants in a mouse-skin model. This reduced virulence of K- strains for mice may be explained in all strains by a higher degree of phagocytosis as measured by chemiluminescence response of human polymorphonuclear leukocytes (PMNL) and in most strains by enhanced killing by either human PMNL or human serum or both. Although the protective role of the K antigen in serum-induced killing and killing by PMNL was generally evident, our results also suggested that other virulence factors were sometimes involved.
Subject(s)
Antigens, Bacterial , Antigens, Surface , Klebsiella pneumoniae/pathogenicity , Animals , Blood Bactericidal Activity , Klebsiella pneumoniae/genetics , Klebsiella pneumoniae/growth & development , Klebsiella pneumoniae/immunology , Luminescent Measurements , Mice , Mutation , Neutrophils/immunology , Neutrophils/metabolism , Phagocytosis , VirulenceABSTRACT
The virulence of 93 clinical isolates of Klebsiella was compared in a mouse model by subcutaneous injection. Skin pathogenicity was measured by estimating the number of viable bacteria in the lesions 24 h after infection with a dose of 10(7) bacteria. Strains of serotypes K1-6 were compared with strains of serotypes higher than K6. All K1 and K5, and some K2 and K4 strains were more virulent for mice than strains with a serotype higher than K6. The K3 strains were significantly less virulent than the strains with a serotype higher than K6. The bacteriological findings were confirmed by histological examination with some strains. No differences in virulence were observed between strains of the same serotype isolated from patients with cystitis or from those with pyelonephritis, nor between strains of the same serotype isolated from the blood of patients with septicaemia or from other sites. The mouse model has been found satisfactory for observing differences in virulence between Klebsiella isolates.
Subject(s)
Klebsiella Infections/microbiology , Skin Diseases, Infectious/microbiology , Animals , Female , Klebsiella/classification , Klebsiella Infections/pathology , Klebsiella pneumoniae/classification , Lethal Dose 50 , Mice , Serotyping , Skin Diseases, Infectious/pathology , Time Factors , VirulenceABSTRACT
We report on a 64-year-old man who developed pneumonia after a laryngectomy. Legionella pneumophila serogroup Leiden-I was isolated from his sputum. Investigation revealed that infection followed exposure to an aerosol from a mechanical humidifier.
Subject(s)
Cross Infection/transmission , Legionnaires' Disease/transmission , Cross Infection/microbiology , Hot Temperature , Humans , Humidity , Legionella/classification , Legionella/isolation & purification , Legionnaires' Disease/microbiology , Male , Middle Aged , Respiratory Therapy , Serotyping , Water Microbiology , Water Supply/standardsABSTRACT
Two patients, a 34-year old man-to-woman transsexual and a 32-year-old man, with aids presented with pulmonary symptoms, fever, serious weight loss and an oral ulcer. A third patient, a 16-year-old boy, had signs of transverse myelitis and meningitis without immunodeficiency. All were South American citizens and had disseminated histoplasmosis. After antifungal treatment they recovered, although the third patient remained a wheelchair user. If pulmonary or miliary tuberculosis is suspected in a patient originating from South America, histoplasmosis should be considered. Oral ulcers and skin lesions can be diagnostic clues. Specific stainings of direct preparations and longer-lasting cultures of various materials, especially of biopsy samples, then provide the diagnosis.
Subject(s)
Histoplasmosis/complications , Histoplasmosis/diagnosis , AIDS-Related Opportunistic Infections/microbiology , Adolescent , Adult , Antifungal Agents/therapeutic use , Diagnosis, Differential , Female , Histoplasmosis/drug therapy , Histoplasmosis/ethnology , Humans , Male , Meningitis/microbiology , Myelitis, Transverse/microbiology , Pneumonia/microbiology , South America/ethnology , Stomatitis, Aphthous/microbiology , Treatment Outcome , Tuberculosis/diagnosisABSTRACT
The prescription of antibiotics in the dental office should be balanced against the possible side effects. For prophylactic use in selected cases, advice is given with regard to the choice of the antibiotics, the oral dosage and the time period.
Subject(s)
Anti-Bacterial Agents/adverse effects , Anti-Bacterial Agents/therapeutic use , Dental Care/methods , Antibiotic Prophylaxis/adverse effects , Drug Resistance, Microbial , HumansSubject(s)
Encephalitis/etiology , Mycoplasma Infections , Adult , Antibodies/administration & dosage , Antibodies, Bacterial/isolation & purification , Drug Therapy, Combination , Encephalitis/drug therapy , Humans , Male , Mycoplasma Infections/drug therapy , Mycoplasma Infections/immunology , Mycoplasma pneumoniae/immunologyABSTRACT
The case of a 73-year-old man with chronic cystitis due to Corynebacterium urealyticum was complicated by hematuria and urinary stone formation. The diagnosis was based on an amplification product obtained using polymerase chain reaction for mycobacterial species on urine and a bladder biopsy specimen. A specific 212 bp amplification fragment that did not hybridize with a Mycobacterium-specific probe was recognized. Sequence analysis of the fragment revealed Corynebacterium urealyticum. Routine urine cultures were negative, but prolonged culture on sheep blood agar led to the isolation and identification of Corynebacterium urealyticum. Identification was confirmed by polymerase chain reaction on the colonies. The patient was treated successfully with vancomycin. Integration of molecular laboratory diagnostics with conventional microbiology and pathology was synergistic for the diagnosis.
Subject(s)
Corynebacterium Infections/microbiology , Corynebacterium/isolation & purification , Cystitis/diagnosis , Cystitis/microbiology , Polymerase Chain Reaction/methods , Aged , Chronic Disease , Corynebacterium/classification , Corynebacterium/genetics , Corynebacterium Infections/diagnosis , DNA, Bacterial/analysis , Humans , Male , Urine/microbiologyABSTRACT
A series of 925 clinical isolates of klebsiella was examined by serological and biochemical typing. To perform serological typing (capsular swelling) 77 capsular antisera were prepared, tested against the type strains and grouped in 13 pools. With this serotyping method 80% of the cultures were typable and 63 distinct types could be recognized. All strains were typable biochemically by means of the numerical coding system of the API-20E system supplemented by digits derived from 15 additional conventional biochemical tests. With the API-20E system 24 different biotypes could be distinguished whereas the combination of API-20E and the 15 additional tests produced 93 biotypes. Maximum discrimination of strains was achieved by the combination of serological and biochemical typing (256 bioserotypes). The reproducibility, typability and discriminating power of the biotyping system was not inferior to serotyping. For epidemiological purposes biotyping can replace serotyping of Klebsiella species, especially in laboratories less well equipped.
Subject(s)
Klebsiella Infections/microbiology , Klebsiella/classification , Antibodies, Bacterial/immunology , Antigens, Bacterial/immunology , Biochemical Phenomena , Biochemistry , Klebsiella/isolation & purification , Klebsiella/metabolism , Polysaccharides, Bacterial/immunology , SerotypingABSTRACT
An analysis of the serological and biochemical typing results of 925 clinical isolates of klebsiella revealed that biotyping and serotyping of klebsiella could replace each other for epidemiological purposes. The combination of both typing methods provided even more epidemiological information in analysing clusters of particular serotypes and biotypes in time. Clustering serotypes, mainly of neonatal origin, were nearly uniformly more resistant to the antibiotics in common use than other serotypes. Biotyping as well as serotyping of klebsiella isolates recovered from environmental surveys in the neonatal ward showed that epidemic and non-epidemic klebsiella isolates could occasionally be cultured from the environment and from the staff.
Subject(s)
Klebsiella/classification , Cross Infection , Disease Outbreaks , Drug Resistance, Microbial , Epidemiologic Methods , Humans , Infant, Newborn , Klebsiella/drug effects , Klebsiella/isolation & purification , Seasons , SerotypingABSTRACT
In a study of the role of virulence factors in the outcome of Escherichia coli bacteraemia, blood isolates from 30 hospitalised patients were characterised with regard to O and K antigens, P and type 1 fimbriae, haemolysin production, cytonecrotising factor 1 production, serum resistance, ability to activate neutrophils and resistance to killing. Patients were analysed to identify host factors contributing to morbidity and mortality. In univariate analyses the presence of a K antigen, type 1 fimbriae, absence of haemolysin production, serum resistance and resistance to killing were associated with morbidity and mortality. In multivariate analyses only the absence of haemolysin production was associated with morbidity and mortality, after taking host factors into account. These preliminary findings suggest that host factors override bacterial virulence factors in determining the course of Escherichia coli bacteraemia. The negative association between haemolysin production and clinical deterioration during Escherichia coli bacteraemia might indicate predominance of less virulent strains in patients with other risk factors for morbidity and mortality or inactivation of neutrophil products needed for host defence.