Bo Svenungsson

Enteropathogens in Adult Patients with Diarrhea and Healthy Control Subjects: A 1-Year Prospective Study in a Swedish Clinic for Infectious Diseases

A 1-year prospective study was conducted to identify enteropathogens in adults with diarrhea (n=851) and in healthy control subjects (n=203) by use of conventional laboratory methods. Virulence factor genes for diarrheagenic Escherichia coli were detected by polymerase chain reaction. Enteropathogens were identified in 56% of patients and 16% of control subjects. The isolation rate was 65% for patients with symptoms for <1 week and for travelers; >1 pathogen was found in 11% of patients. The most frequent enteropathogens were Campylobacter (13% of patients), Clostridium difficile (13%), enterotoxigenic Escherichia coli (8%), Salmonella (7%), Shigella (4%), Blastocystis hominis (4%), calicivirus (3%), rotavirus (3%), enteroaggregative E. coli (2%), Aeromonas (2%), Giardia intestinalis (2%), Cryptosporidium (2%), and astrovirus (2%). Less frequently isolated (< or =1% of patients) were verotoxigenic E. coli, enteropathogenic E. coli, enteroinvasive E. coli, Entamoeba histolytica/Entamoeba dispar, microsporidia, and adenovirus. Fifty percent of the patients were hospitalized, and 43% needed intravenous fluids. The median duration of diarrhea was 14 days. Clinical features were not helpful for predicting the etiology of diarrhea.

Increased Sporulation Rate of Epidemic Clostridium difficile Type 027/NAP1

ABSTRACT Clostridium difficile PCR ribotype 027 comprised 0.2% of a collection of Swedish isolates in 1997-2001 (3 of 1,325 isolates). These isolates had lower moxifloxacin MICs than the epidemic type 027 isolates, but they had the same tcdC sequence and toxin yield. Type 027 produced 3- to 13-fold more toxin than did major Swedish types. One epidemic strain (027/NAP1a) sporulated more than did other type 027 isolates, a feature that should contribute to its survival and spread.

Correlation of Disease Severity with Fecal Toxin Levels in Patients with Clostridium difficile-Associated Diarrhea and Distribution of PCR Ribotypes and Toxin Yields In Vitro of Corresponding Isolates

ABSTRACT We investigated in vivo and in vitro yields of toxins A and B from and PCR ribotypes of Clostridium difficile isolates from 164 patients with differing severities of C. difficile-associated diarrhea (CDAD) (patients were grouped as follows: <3 loose stools per day, n = 45; 3 to 10 per day, n = 97; >10 per day, n = 22). The median fecal toxin levels in each group were 0.5, 6.8, and 149 U/g feces (P < 0.001), respectively. Patients with severe diarrhea also had more-frequent occurrence of blood in stool and vomiting, but there was no association with fecal toxin levels per se. There was no correlation between fecal toxin level and toxin yield in vitro for the corresponding C. difficile isolate or between its PCR ribotype and disease severity. A broad range of toxin yields among isolates belonging to major PCR ribotypes indicated a presence of many subtypes. We hypothesize that bacterial and host factors that affect C. difficile toxin levels in feces are important determinants of symptoms in CDAD patients. An inverse correlation between toxin yield and spore count (r = 0.66) in stationary-phase cultures supported the notion that toxin production and sporulation represent opposite alternative survival strategies for C. difficile cells facing nutrient shortage.

Clinical Manifestations and Diagnosis of Neuroborreliosis

Lyme borreliosis has in a few years turned out to be a health problem not only in the United States, but also in many European countries. When it affects the nervous system, Lyme borreliosis acts as the great disease imitator. Because of this characteristic it is often difficult to diagnose on clinical grounds. Patients with neuroborreliosis might appear within all medical disciplines. Clinical markers, such as preceding tick bite and/or ECM, are important clues to the diagnosis. Mononuclear pleocytosis and elevated CSF protein are present in most patients with neuroborreliosis. Final evidence for the diagnosis is the demonstration of specific antibodies in serum and/or CSF. Measurement of antibody titers should be carried out in both serum and CSF, since these methods are complementary when trying to obtain a serological diagnosis of neuroborreliosis.

Molecular epidemiology and clinical manifestations of human cryptosporidiosis in Sweden.

This study describes the epidemiology and symptoms in 271 cryptosporidiosis patients in Stockholm County, Sweden. Species/genotypes were determined by polymerase chain reaction-restriction fragment-length polymorphism (PCR-RFLP) of the Cryptosporidium oocyst wall protein (COWP) and 18S rRNA genes. Species were C. parvum (n=111), C. hominis (n=65), C. meleagridis (n=11), C. felis (n=2), Cryptosporidium chipmunk genotype 1 (n=2), and a recently described species, C. viatorum (n=2). Analysis of the Gp60 gene revealed five C. hominis allele families (Ia, Ib, Id, Ie, If), and four C. parvum allele families (IIa, IIc, IId, IIe). Most C. parvum cases (51%) were infected in Sweden, as opposed to C. hominis cases (26%). Clinical manifestations differed slightly by species. Diarrhoea lasted longer in C. parvum cases compared to C. hominis and C. meleagridis cases. At follow-up 25-36 months after disease onset, 15% of the patients still reported intermittent diarrhoea. In four outbreaks and 13 family clusters, a single subtype was identified, indicating a common infection source, which emphasizes the value of genotyping for epidemiological investigations.

Prevalence of Tick-borne Encephalitis and Lyme Borreliosis in a Defined Swedish Population

Sera from 346 individuals living on Lisö, an area south of Stockholm, endemic for tick-borne encephalitis (TBE) and Lyme borreliosis, were tested for antibody activity to TBE-virus (TBEV) and Borrelia burgdorferi, using a sonicate antigen, by haemagglutination-inhibition and ELISA, respectively. 10/346 (3%) individuals had a history of previous serologically confirmed TBE with encephalitic symptoms, and 33/346 (10%) had a history of previous erythema chronicum migrans (ECM). Four individuals (1%) had been treated for neuroborreliosis and another 4 (1%) for acrodermatitis chronica atrophicans (ACA). Antibodies to TBEV and B. burgdorferi were detected in 40/346 (12%) and 89/346 (26%) individuals, respectively. The seroprevalence of Lyme borreliosis increased with age, time spent on Lisö, and number of reported tick-bites. For TBE there was a correlation between seropositivity and time spent on Lisö only. In sera from 50 healthy blood-donors, living in a non-endemic area, no antibody activity to TBEV could be detected and only 1/50 (2%) had antibodies to borrelia. In sera from 150 age and sex matched control individuals, living in the city of Stockholm, antibody activity to TBEV and borrelia was found in 8/150 (5%) and 13/150 (9%), respectively.

Two-year survey of the incidence of lyme borreliosis and tick-borne encephalitis in a high-risk population in Sweden

A survey was made over a two-year period (September 1987 to August 1989) of a population living in an area endemic for Lyme borreliosis and tick-borne encephalitis in Sweden. For each patient a blood sample was collected and a questionnaire completed annually. All sera were tested for an antibody response toBorrelia burgdorferi in an EIA using sonicated antigen and for an antibody response to the tick-borne encephalitis virus using an EIA and a haemagglutination inhibition test. Antibodies toBorrelia burgdorferi and tick-borne encephalitis virus were detected in 89 (25.7 %) and 40 (11.6 %) respectively of 346 samples collected in August 1987. In the first year of the study 14 of 303 subjects (4.6 %) developed Lyme borreliosis and in the second year 9 of 277 subjects (3.2 %). A significant increase in the antibody titre forBorrelia burgdorferi was seen in 14 of 303 (4.6 %) subjects in the first year and 8 of 277 (2.9 %) subjects in the second year. An earlier episode of Lyme borreliosis or an elevated antibody titre did not seem to protect against reinfection. One case of tick-borne encephalitis was seen each year. Seroconversion for tick-borne encephalitis virus was found in 3 of 258 (1.2 %) subjects in the first year and 5 of 211 (2.4 %) in the second year, excluding subjects who had undergone successful immunisation or had earlier been hospitalised for tick-borne encephalitis. The study thus demonstrated a high yearly incidence of tick-borne infections in a population at risk.

Prevalence of Enterotoxigenic Bacteroides fragilis in Adult Patients with Diarrhea and Healthy Controls

Enterotoxigenic strains of Bacteroides fragilis (ETBF) have been associated with diarrheal diseases in animals and humans. The enterotoxin of ETBF induces fluid changes in ligated intestinal segments and a cytotoxic response in HT29/C1 cells. An assay based on immunomagnetic-beads separation in combination with PCR was used to detect ETBF in fecal samples from patients with diarrhea and healthy Swedish adults. A total of 922 fecal samples were analyzed in this study, including 728 samples from patients with diarrhea and 194 samples from controls. ETBF was detected in 195 of 728 patients (26.8%) and 24 of 194 healthy controls (12.4%). The difference between the two groups was statistically significant (P<.01). ETBF was the only potential diarrheal agent in 91 (12.5%) of 728 patients. All ETBF-positive samples from patients and controls were also positive in the HT29/C1 assay. The data show high carriage of ETBF in Swedish adults, which might be associated with diarrheal disease.

Incidence and genetic diversity of group C rotavirus among adults.

Fecal samples from a 1-year prospective study were investigated to establish the role of group C rotavirus infections in acute diarrhea in Swedish adults (>15 years old). Rotaviruses were found in samples from 3% of the patients, and, in 35% of these, group C rotavirus was detected. Clinical symptoms of group C rotavirus infection were generally milder than those of group A rotavirus infection. Gene 8 (vp7) from 12 group C isolates, including strains from the prospective study, a military outbreak, and a sporadic case, was sequenced. The gene was found to be extremely conserved, with identities of 99.1%-100% at the amino acid level. This study has systematically investigated the prevalence and genetic diversity of group C rotavirus in adults. The data confirm the extreme sequence conservation within human group C rotavirus strains and suggest that symptomatic group C rotavirus infections occur more frequently in adults than has been previously recognized.

Antimicrobial Susceptibility Pattern of Clostridium difficile and Its Relation to PCR Ribotypes in a Swedish University Hospital

ABSTRACT All 238 Clostridium difficile isolates were susceptible to metronidazole and vancomycin, whereas 84% and 1% were resistant to clindamycin and fusidic acid. Etest MICs for metronidazole were lower than agar dilution MICs (P < 0.01) but without difference in susceptible-intermediate-resistant categorization. No particular PCR ribotype was associated with clindamycin or fusidic acid resistance.