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Biomedical subjects

L Engstrand

Publications and source records attributed to L Engstrand.

At least 73 records · Page 4Linked to original sources
PubMed1997

Intracellular reservoir of Streptococcus pyogenes in vivo: a possible explanation for recurrent pharyngotonsillitis.

Numerous theories have been presented that attempt to explain the frequent recurrences of pharyngotonsillitis caused by Streptococcus pyogenes; these recurrences occur after seemingly adequate antibiotic treatment. We previously have demonstrated that Spyogenes can survive for up to 7 days intracellularly in immortalized human respiratory epithelial cells grown in an antibiotic supplemented medium. Viable S pyogenes were externalized and established an extracellular infection, whenever the extracellular antibiotic was removed. We have investigated the presence of intracellular S pyogenes in two in vivo studies using respiratory epithelial cells collected from patients with tonsillitis and the tonsils of asymptomatic carriers. Electron microscopy and immunohistochemistry demonstrated intracellular S pyogenes in pharyngeal epithelial cells in 13 of 14 patients with tonsillitis (93%). Furthermore, intracellular S pyogenes were found in macrophage-like cells in eight (73%) and in epithelial cells in four (36%) tonsils from 11 asymptomatic S pyogenes carriers. These in vivo data strongly support the hypothesis that intracellular S pyogenes can constitute a reservoir of bacteria with the potential to cause reinfections.

Adolescent↗
PubMed1997

Combination treatment with ranitidine is highly efficient against Helicobacter pylori despite negative impact of macrolide resistance.

BACKGROUND: This double-blind, randomized study evaluated the efficacy of dual and triple therapies including ranitidine for treatment of Helicobacter pylori infection. MATERIALS AND METHODS: Dyspeptic patients (n = 105) with a positive rapid urease test formed the intention-to-treat population (ITT). All patients were assigned to 14 days treatment with ranitidine 300 mg b.i.d and clarithromycin 750 mg b.i.d. Group A (n = 53) also received a placebo twice daily, while group B (n = 52) received lymecycline 300 mg b.i.d. Treatment with ranitidine, 150 mg b.i.d, was continued for an additional 30 days. H. pylori infection was verified by culture. Twelve weeks after antibiotic treatment, H. pylori status was investigated by culture and 14C-urea breath test (UBT). The per-protocol (PP) group consisted of 73 patients (A, n = 38; B, n = 35). RESULTS: Cure rates were 87% (95% C.I. = 72% to 94%) vs. 72% (95% C.I. = 58% to 83%) in the ITT-group and 89% (95% C.I. = 73% to 97%) vs. 87% (95% C.I. = 72% to 96%) in the PP-population (culture and UBT) when triple and dual therapies were compared. In all patients who were not cured, clarithromycin resistance of H. pylori was acquired. Side effects were experienced by 54% of patients. CONCLUSIONS: The difference in efficacy between the two treatment regimens was not significant. However, the cure rates in this study are comparable to combination treatments with omeprazole. Treatment failures were due to acquired clarithromycin resistance.

Adult↗
PubMed1997

Macrolide resistance in Helicobacter pylori: mechanism and stability in strains from clarithromycin-treated patients.

Helicobacter pylori strains from seven patients treated with clarithromycin were investigated for development, mechanism, and stability of resistance. Genetic relatedness between pre- and posttreatment isolates was shown by arbitrary primed PCR. Clarithromycin resistance was associated with A-to-G transitions at either position 2143 or 2144 or at both positions 2116 and 2142. In four cases, the mutations were homozygous. The Cla(r) phenotype was stable after 50 subcultivations in vitro. No erythromycin-modifying enzymes or rRNA methylases were found by biological assays, PCR and sequencing, or cloning methods.

Anti-Bacterial Agents↗
PubMed1997

Diagnostic accuracy of a rapid whole-blood test for detection of Helicobacter pylori.

In this study, we evaluated a rapid whole-blood test, BM-test Helicobacter pylori, for detection of H. pylori infection in 144 and 48 patients with other gastrointestinal symptoms and with gastric cancer, respectively. The sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of the test correlated well with the standards used for the calculation, i.e., serology by enzyme-linked immunosorbent assay or culture and histology.

Adult↗
PubMed1997

An intracellular sanctuary for Streptococcus pyogenes in human tonsillar epithelium--studies of asymptomatic carriers and in vitro cultured biopsies.

A novel method for the in vitro culture of tissue biopsies is presented. Infected tonsillar biopsies were successfully cultured by means of the continuous flow of media without the addition of antibiotics. Histological and immunohistological examinations were carried out on sections of Streptococcus pyogenes-infected cultured tonsillar biopsies and sections from the surgically removed tonsils of asymptomatic S. pyogenes carriers. Low numbers of intracellular S. pyogenes were detected inside epithelial cells in eight out of 12 (67%) S. pyogenes-infected biopsies, and in four out of 11 (36%) tonsils of asymptomatic carriers. Our findings support the hypothesis that the sanctuary where S. pyogenes avoids antibacterial treatment is intracellular, which may provide a possible explanation of recurrent tonsillitis.

Adolescent↗
PubMed1997

Susceptibility of Chlamydia pneumoniae to azithromycin and doxycycline: methodological aspects on the determination of minimal inhibitory and minimal bactericidal concentrations.

An in vitro assay for measuring and comparing the efficacy of different antimicrobial agents against Chlamydia pneumoniae was developed. Azithromycin, a representative of the new azalide group of antibiotics, and doxycycline were evaluated with respect to their antibacterial effect and capacity for intracellular killing under different experimental conditions. For both study drugs, the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) values increased significantly with longer bacterial preincubation time. The effect of different exposure times of antibiotics on the bacteria was also studied.

Anti-Bacterial Agents↗
PubMed1997

The diagnostic value of enzyme immunoassay and immunoblot in monitoring eradication of Helicobacter pylori.

55 patients with severe ulcer disease and H. pylori infection, successfully treated with antimicrobials, were followed-up with repeated blood samples for up to 32 months. Sera were analysed by enzyme immunoassay (EIA) for IgG and IgA antibodies and by IgG immunoblot. The EIA for IgG antibodies showed a high sensitivity (100%), while IgA antibodies above the cut-off level were found in 55% of the patients. At a median of 77 days after onset of treatment, approximately 50% of the patients showed a significant decrease (> or = 50%) of IgG or had titres below the cut-off level. All patients but 1 had a significant decrease of IgG after 6-12 months. The decrease was slower for IgA. The H. pylori-specific 116 kDa and 19.5 kDa bands were found in all pre-treatment samples, but the decrease in median intensity of the bands was slower than for the IgG EIA. In the 32-months post-treatment samples, both bonds had an intensity still above 50% of the pre-treatment value. The study showed that the IgG EIA is a useful method for monitoring eradication of H. pylori. Immunoblot can detect previous H. pylori infection in EIA negative Individuals.

Enzyme-Linked Immunosorbent Assay↗
PubMed1997

Detection of Mycobacterium avium complex in cerebrospinal fluid of a sarcoid patient by specific polymerase chain reaction assays.

The etiology of sarcoidosis is unknown, but it has long been suspected to be mycobacterial. In the present study, we used 4 mycobacterial species-specific polymerase chain reaction assays on cerebrospinal fluid obtained from a patient with neurosarcoidosis. Positive hybridization was observed with both the Mycobacterium avium complex probe and the insertion element IS900-specific probe that has been found in M. paratuberculosis species. There was no hybridization with M. tuberculosis or M. avium woodpigeon strain-specific probes. This case report demonstrates that M. paratuberculosis or some closely related M. avium spp which perhaps also carry IS900, or contain closely related DNA sequences, are associated with at least some cases of sarcoidosis disease.

Adult↗
PubMed1997

Assay of antibiotic susceptibility of Chlamydia pneumoniae.

It is well known that treatment of Chlamydia pneumoniae infections is difficult. High doses and prolonged treatment is often needed to achieve clinical cure despite good in vitro effect of the drugs used. We here discuss different methodological problems in the determination of MIC and MBC values of C. pneumoniae. The length of the preincubation time and the lack of fluctuation of the antibiotic concentrations may affect the outcome of the currently used assay.

Anti-Bacterial Agents↗
PubMed1997

Rapid detection of Helicobacter pylori infection in serum and whole-blood samples.

The aims of this study were to evaluate the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and diagnostic accuracy of a rapid serum and whole-blood test, Quick Vue One-Step H. pylori test (Quidel Corporation) for detection of Helicobacter pylori infection. We tested 79 patients with gastrointestinal symptoms, including 8 gastric cancer patients. In total, 116 rapid tests were performed: both serum and whole-blood samples were tested in 37 patients (74 tests) and serum only was tested in a further 42 patients (42 tests). Serology by ELISA, bacterial culture and histology were also carried out on samples from these patients and used as standards for determining H. pylori infection. Diagnostic accuracy of the tests was 0.76 for both sera and whole-blood when culture and histology was used as the standard in the calculations. However, using serology by ELISA as the standard raised the diagnostic accuracy to 0.08 in serum samples and to 0.89 in whole-blood samples. Overall, the H. pylori status observed when using the rapid tests correlated well with serology, bacterial culture and histology in this study.

Adult↗
PubMed1996

Helicobacter pylori in the drinking water in Peru.

BACKGROUND & AIMS: An association between water sources and the prevalence of Helicobacter pylori infection in Peruvian children was shown previously. The aim of this study was to confirm the presence of H. pylori in drinking water in the same community. METHODS: Forty-eight drinking water samples from different locations in pueblo jovenes (new towns) near Lima were collected. Samples were frozen until technology advanced to the point to the point at which H. pylori might be reliably detected. Immunomagnetic beads coated with anti-H. pylori immunoglobulin Gs were used to concentrate H. pylori, and two polymerase chain reaction assays based on different H. pylori genes were used. One was a polymerase chain reaction for the detection of the H. pylori adhesin subunit encoding gene, and the second was a previously validated H. pylori 16S ribosomal RNA reverse transcriptase-polymerase chain reaction. RESULTS: The expected 375-base pair fragment from the adhesin gene was amplified from 24 water samples. The expected 500-base pair fragment of the 16S ribosomal RNA and the 375-base pair fragment of the adhesin gene were amplified from 11 of the samples. CONCLUSIONS: These results confirm the presence of H. pylori in drinking water in Peru and are consistent with conclusions from a previous epidemiological study of the same population. This provides additional evidence for waterborne transmission of H. pylori in some environments.

Adhesins, Bacterial↗
PubMed1996

In-vitro activity of azithromycin in against intracellular Helicobacter pylori.

We studied the effect in vitro of azithromycin on the clinical strain Helicobacter pylori H:72 growing intracellularly in monolayers of HEp-2 epithelial cells. After using gentamicin to eradicate extracellular bacteria, different concentrations of azithromycin were added to the infected cells and samples were taken after 0, 4, 8 and 24 h. Infected cells not exposed to antibiotic were included as controls. The MIC of azithromycin to the H. pylori was 0.25 mg/L and the MBC 0.5 mg/L in a broth dilution plate count method. A bactericidal effect was observed on intracellular H. pylori, with inhibition increasing with increasing azithromycin concentrations. However, extracellular concentrations of 200 x MBC were necessary to achieve intracellular killing. Our results show that azithromycin is active against intracellular H. pylori suggesting that it might be possible to exploit this activity when treating infections due to the organism.

Anti-Bacterial Agents↗
PubMed1996

An increase in sudden unexpected cardiac deaths among young Swedish orienteers during 1979-1992.

BACKGROUND: Sixteen cases of sudden unexpected cardiac death, 15 males and one female, are known to have occurred among young Swedish orienteers from 1979 to 1992, of which seven cases occurred between 1989 and 1992. This is considered to be indicative of an increased death rate. RESULTS: Histopathological evaluation showed myocarditis in a higher than expected proportion of cases. In one such case, which we studied before the sudden unexpected death occurred, the victim had suffered a Chlamydia pneumoniae infection verified by serology, and a nucleotide sequence was found in the heart and lung by means of the polymerase chain reaction (PCR) that hybridized with a probe specific for that organism. Male Swedish orienteers do not, however, seem to have an increased rate of exposure to this agent. No further sudden unexpected deaths among young orienteers have occurred over the past 3.5 years. At the beginning of that period, attempts were made to modify training habits and attitudes.

Adolescent↗
PubMed1996

Egg passage of rodshaped and coccoid forms of Helicobacter pylori: preliminary studies.

BACKGROUND: We used egg passage of bacteria stored in water to evaluate the culturability of the coccoid form of Helicobacter pylori, as a complement to the results obtained from various animal models. Egg passage was performed, as it is a simple, rapid, and well-characterized old method by which to culture and evaluate culturability of bacteria compared to experiments in animal models. Egg passage has been used in such experiments since 1938 for isolation and growth of, for example, Rickettsiae sp. and Chlamydia sp. MATERIALS AND METHODS: The rod-shaped form of H. pylori was produced by plate cultures for 4 and 7 days. The coccoid form of H. pylori was produced by culture on agar plates for 10 days, followed by storage in water. These preparations then were inoculated into the yolk sac of differently aged fertilized eggs. RESULTS: Positive culture was obtained from 14 of 17 eggs (82%) inoculated with rod-shaped H. pylori compared to 0 of 22 eggs (0%) inoculated with the coccoid form. CONCLUSION: Culturability of H. pylori is reduced when it converts into the coccoid form produced by starvation and age followed by storage in water for several weeks at room temperature. Egg passage did not raise the culturability of the coccoid form of H. pylori. Our study demonstrates some clear differences between fresh rods and stored cocci forms of H. pylori in terms of culturability when passed through eggs.

Animals↗
PubMed1996

New pharmacokinetic in vitro model for studies of antibiotic activity against intracellular microorganisms.

The capacity for intracellular growth is an important survival strategy for a large group of common pathogens. Helicobacter pylori, the etiological agent for gastritis and duodenal ulcer, has been shown by both in vivo and in vitro studies to have the capacity to invade epithelial cells. In vitro models are used to study the effect of antibiotics on microoganisms. Most investigations are performed in broth culture or on agar plates, but kinetic models for bacteria in broth have been described. We present a new, kinetic model adapted for intracellular pathogens. A glass chamber, with a metal rack fitting Falcon cell culture inserts, was connected to a pump by rubber tubes. Different tube diameters and pump speeds were evaluated, and the assay was designed to mimic the half-lives of the antibiotics in vivo, i.e., 11.5 h for azithromycin, 5 h for clarithromycin, and 1 h for amoxicillin. Monolayers of HEp-2 cells were grown in the inserts for 2 days, after which H. pylori (clinical strain 88-23), was added to the system. Internalization was allowed for 12 h, and extracellular H. pylori cells were eradicated with gentamicin. The inserts were moved to the glass chamber, containing medium with 12.5 mg of either amoxicillin or azithromycin per liter or 2.4 mg of clarithromycin per liter. This represents 12.5, 50, and 80 times the extracellular minimum bactericidal concentration value, respectively. Samples were taken at 0, 2, 4, 6, 8, and 24 h. The HEp-2 cells were lysed, and intracellular bacteria were counted by plating. Inserts with infected cells grown in drug-free medium were included as controls for each time interval. A 3-log10 reduction of H. pylori was achieved in the experiments with azithromycin, and a 4-log10 reduction was achieved in the clarithromycin experiments, while no intracellular effect was seen when amoxicillin was used. The antibiotic concentrations at the sampling intervals were 12.5, 3.1, 0.8, 0.2, 0.05, and 0 mg/liter for amoxicillin; 12.5, 11.5, 10, 9, 8, and 3 mg/liter for azithromycin; and 2.4, 1.8, 1.4, 1, 0.8, and 0 mg/liter for clarithromycin. This new model for pharmacokinetic studies provides a useful tool, with applications for a broad range of microorganisms.

Amoxicillin↗
PubMed1996

Prevalence of Helicobacter pylori infection among sewage workers.

OBJECTIVES: An increased risk for gastric cancer among sewage workers has been described in several studies. During the last decade the bacterium Helicobacter pylori has emerged as one important risk factor for gastric cancer and is now considered a class I carcinogen by the International Agency for Research on Cancer. The route of transmission for this bacterium remains unclear, but fecal-oral transmission has been proposed. If true, this might entail a yet undescribed risk for sewage workers. METHOD: The prevalence of immunoglobulin G (IgG) antibodies against H pylori was studied with a cross-sectional study design in a group of 289 municipal workers. Samples of serum from 151 sewage workers at 11 sewage plants in Sweden and of serum from 138 referents were analyzed. The referents were group matched for age and socioeconomic status. RESULTS: The prevalence of IgG antibodies against H pylori among sewage workers did not differ from that of the referents. The adjusted odds ratio (adjOR) was calculated from a logistic model with age and residence as confounding variables (adjOR 0.90, 95% confidence interval 0.53-1.5). The previously described increase in the prevalence of IgG antibodies against H pylori with increasing age was observed. Geographic differences were also observed in the prevalence of H pylori in Sweden. CONCLUSIONS: The exposures in sewage work in Sweden do not cause an increased risk of infection with H pylori.

Adult↗
PubMed1995

Prevalence of Helicobacter pylori infection in subtypes of gastric cancer.

BACKGROUND & AIMS: Although Helicobacter pylori has already been declared a human carcinogen, the exact nature of the association with gastric cancer remains to be explored. The aim of this study was to determine if the association is confined to specific types of gastric cancer. METHODS: The prevalence of H. pylori immunoglobulin G antibodies (HM-CAP immunoassay; Enteric Products Inc., Westbury, NY) was determined in prospectively collected sera from 279 patients with gastric cancer. RESULTS: The overall prevalence of H. pylori seropositivity was 77%. The prevalence of H. pylori infection was significantly lower among patients with tumors of the gastric cardia compared with those with other gastric locations. Age-adjusted H. pylori seroprevalence among patients with the intestinal type of gastric cancer tended to be higher than among those with the diffuse type according to Laurén (P > 0.05). In both histological types, the seroprevalence decreased with increasing age. Multivariate logistic regression analysis showed that high age and proximal tumor location were independent predictors of absence of H. pylori. CONCLUSIONS: The association with H. pylori infection is similar regardless of the histological features of the tumor, whereas it is stronger for noncardiac gastric cancer than for cardiac cancer. The apparent loss of H. pylori seropositivity among patients with gastric cancer is determined by age rather than tumor stage.

Age Factors↗