Biomedical subjects

Mikael Sörberg

Publications and source records attributed to Mikael Sörberg.

9 recordsLinked to original sources

PubMed2006

Epidemiological MIC cut-off values for tigecycline calculated from Etest MIC values using normalized resistance interpretation.

OBJECTIVES: To apply the normalized resistance interpretation (NRI) method to Etest MIC results which have higher precision than conventional log2 dilution MIC tests due to the inclusion of intermediate values. If successful, NRI might provide an objective tool for the definition of epidemiological MIC cut-off values. METHODS: MICs of tigecycline and other antimicrobial agents were determined for 4771 clinical isolates comprising five Gram-positive and 13 Gram-negative species or species groups using the Etest. Histograms of MIC values were constructed for each species and NRI calculations were applied to them. An upper MIC limit of 2.5 SD above the theoretical mean of the normalized distribution was used for setting the epidemiological cut-off values. RESULTS: Calculated cut-off values for wild-type strains were between 0.11 and 0.96 mg/L for Gram-positive species, and between 0.44 and 8.3 mg/L for Gram-negative species, except for Pseudomonas aeruginosa, which had a cut-off value of 450 mg/L, consistent with earlier reports on the lack of activity of tigecycline against this species. CONCLUSIONS: NRI offers an objective method for the analysis of MICs produced using Etests and the determination of epidemiological MIC cut-off values.

Anti-Bacterial Agents↗

PubMed2005

Immunogenicity and tolerability of a heptavalent pneumococcal conjugate vaccine administered at 3, 5 and 12 months of age.

BACKGROUND: The recommended vaccination schedule for the pneumococcal conjugate vaccine (PCV) includes 4 immunizations, according to the national programs in the United States and some European countries. Other countries use a national schedule for routine vaccinations in early childhood that includes only 3 doses. AIMS: The goals were to assess the immunogenicity and tolerability of PCV with a vaccination schedule that included 3 doses during the first 1 year of life (a 2+1 dose schedule) and to determine the immune responses to concomitantly administered Haemophilus influenzae type b (Hib) vaccine. METHODS: A total of 101 healthy Swedish infants were enrolled in an open, nonrandomized, multicenter study. PCV was administered concomitantly with (at separate sites) a diphtheria-tetanus toxoids-acellular pertussis vaccine, inactivated polio vaccine and Hib conjugate vaccine combination at 3, 5 and 12 months of age. IgG antibody concentrations for the 7 serotypes included in the PCV and the Hib capsular polysaccharide in serum samples taken at 3, 6, 12 and 13 months were determined with enzyme immunoassays. Local and systemic reactions were monitored for 3 days after each immunization, and serious adverse reactions were monitored for the whole study period. RESULTS: Two doses of PCV induced satisfactory antibody responses, with the exception of serotypes 6B and 23F. The third dose evoked strong responses for all serotypes, which suggests good immunologic priming with the primary series of 2 doses. The mean anti-Hib antibody concentrations were similar to those noted in earlier studies among Swedish children. The PCV was well tolerated. CONCLUSION: The pneumococcal antibody concentrations at 13 months were comparable with those noted previously with the 4-dose schedule. The results suggest that the implementation of a 2+1 dose schedule for PCV should be considered.

Antibodies, Bacterial↗

PubMed2005

Seroprevalence of Helicobacter pylori infection in urban and rural Vietnam.

Helicobacter pylori-associated diseases, such as peptic ulcer and gastric cancer, are common in Vietnam, but the prevalence of the infection is largely unknown. A validated enzyme-linked immunosorbent assay was used for seroepidemiology with 971 samples from the general population, ages 0 to 88 years, with 546 samples from an urban population (Hanoi), and with 425 samples from a poor, rural province (Hatay). The overall seroprevalence of the infection was 746 per 1,000, with a prevalence of 788 per 1,000 in Hanoi and 692 per 1,000 in Hatay (P=0.0007). The risk for infection in the rural area of Hatay was 40% lower than in the urban population of Hanoi, with the odds ratio being 0.59 (95% confidence interval, 0.43 to 0.81). The study shows that the prevalence of H. pylori infection is high in Vietnam and especially high in a large urban area, such as the city of Hanoi.

Adolescent↗

PubMed2004

Enzyme-linked immunosorbent assay for Helicobacter pylori needs adjustment for the population investigated.

Helicobacter pylori infection and peptic ulcer disease are common in developing countries, e.g., Vietnam. An enzyme-linked immunosorbent assay (ELISA) for screening of patients and for seroepidemiology is a useful tool but needs to be validated in the population studied. We used in-house ELISA with sonicated Swedish and Vietnamese strains as antigens to measure immunoglobulin G antibodies after absorption with sonicated Campylobacter jejuni in sera from 270 H. pylori culture-confirmed peptic ulcer patients, 128 Swedish urea-breath test and immunoblot-positive healthy controls, and 432 Vietnamese immunoblot-positive population controls. Sonicated whole-cell antigen based on the local strains showed a significantly better performance. Immunoblot-positive peptic ulcer patients had significantly higher antibody concentrations than immunoblot-positive population controls, necessitating a lower cutoff level if serology is used for screening or epidemiological purposes. The study shows that the parameters of ELISA for H. pylori need to be adjusted for the population being investigated.

Adolescent↗

PubMed2003

Capsular types and antibiotic susceptibility of invasive Streptococcus pneumoniae among children in Sweden.

To investigate the serotype distribution and antibiotic susceptibility patterns 204 isolates of Streptococcus pneumoniae obtained from blood or cerebrospinal fluid (CSF) of children < or = 18 y of age were collected from 19 clinical microbiological laboratories in Sweden during the years 1998-2001. 166 isolates were from blood only, and 38 isolates were from CSF. The most common serotypes found were 6B, 1, 7F, 14, 18C, 19F, 6A, 4, 23F, 9V and 19A, in descending order of frequency. During the study period serotype 6B increased in frequency from 14.3% in 1998 to 28.3% in 2001 and serotype 1 decreased simultaneously from 20.4% to 9.4%. Serotype 1 was the most common serotype among children > or = 2 y of age or older, but was not found among children < 2 y of age. The potential coverage rate for the heptavalent pneumococcal conjugate vaccine varied between 53 and 68% during the studied years, and was higher for children < 2 y of age (74%) than for older children (51%). The majority of isolates were susceptible to penicillin and other antibiotics tested.

Age Factors↗

PubMed2003

Concordance of Helicobacter pylori strains within families.

Helicobacter pylori infection is typically acquired in early childhood, and a predominantly intrafamilial transmission has been postulated. To what extent family members share the same strains is poorly documented. Our aim was to explore patterns of shared strains within families by using molecular typing. Family members of H. pylori-infected 10- to 12-year-old index children identified in a school survey were invited to undergo gastroscopy. Bacterial isolates were typed with random amplified polymorphic DNA and PCR-restriction fragment length polymorphism of the genes ureA-B, glmM, or flaA. The presence or absence of the cag pathogenicity island, a bacterial virulence factor, was determined by PCR. GelCompar II software, supplemented with visual inspection, was used in the cluster analysis. In 39 families, 104 individuals contributed 208 bacterial isolates from the antrum and corpus. A large proportion, 29 of 36 (81%) of the offspring in a sibship, harbored the same strain as at least one sibling. Mother-offspring strain concordance was detected in 10 of 18 (56%) of the families. Of 17 investigated father-offspring relations in eight families, none were strain concordant. Spouses were infected with the same strains in 5 of 23 (22%) of the couples. Different strains in the antrum and corpus were found in 8 of 104 (8%) of the subjects. Our family-based fingerprinting study demonstrates a high proportion of shared strains among siblings. Transmission between spouses seems to be appreciable. The data support mother-child and sib-sib transmission as the primary transmission pathways of H. pylori.

Child↗

PubMed2002

Antibiotic use and Escherichia coli resistance trends for quinolones and cotrimoxazole in Sweden.

Resistance rates among Escherichia coli isolates for quinolones and cotrimoxazole were analysed at 12 Swedish hospitals, and compared with antibiotic use. Resistance figures for E. coli were retrieved from the diagnostic microbiology service databases for the period 1989-99, and antibiotic sales figures were obtained from the National Corporation of Swedish Pharmacies. At the 2 university teaching hospitals included, norfloxacin resistance of E. coli increased significantly (p < 0.001) from 0% to 2.7% and 2.5%, respectively. Ciprofloxacin resistance increased (p < 0.001) in parallel. Quinolone use increased until 1992; subsequently, sales have remained at a stable level. The increase in norfloxacin and ciprofloxacin resistance started relatively simultaneously in all hospitals, around 1991. Cotrimoxazole resistance has also been increasing significantly in most hospitals, in spite of decreasing sales of cotrimoxazole and trimethoprim. Similar trends could be seen in blood isolates from the same hospitals for the period 1991-98. Clinical laboratory data are subject to bias but surveillance over longer periods of time provides a useful method for detecting trends in increasing resistance and therefore functions as a resistance warning system.

Anti-Infective Agents↗

PubMed2002

Long-term antibiotic resistance surveillance of gram-negative pathogens suggests that temporal trends can be used as a resistance warning system.

Antibiotic resistance among Gram-negative bacteria and antibiotic consumption were investigated at the Karolinska Hospital, Stockholm, Sweden over a 12-y period. The investigation showed an increase in ciprofloxacin resistance of Escherichia coli from 0% in 1991 to 7% in 1997 and to 11% in 1999. Resistance among Pseudomonas aeruginosa isolates to ciprofloxacin increased from 2.5% in 1991 to 9.0% in 1997 and to 13% in 1999. Resistance levels for norfloxacin showed the same high statistical significance in terms of the temporal trend. A more detailed analysis showed higher resistance against norfloxacin in specific wards. Relationships between antibiotic use and antibiotic susceptibility showed different patterns. The increased ciprofloxacin resistance of E. coli and P. aeruginosa during the study period was paralleled by an increased consumption of quinolones. During the 12-y study period the total use of cephalosporins increased 2.5-fold, while the levels of E. coli resistance to cefuroxime and cefotaxime remained stable. A third pattern was seen with trimethoprim-sulfamethoxazole, namely increasing resistance of E. coli as the use of trimethoprim-sulfamethoxazole declined. The analysis of resistance levels and antibiotic consumption in the present study suggests different mechanisms for the increased resistance. The significant trend of increased resistance to antibiotics over time constitutes an important warning system.

Anti-Bacterial Agents↗

PubMed2002

Pharmacodynamic effects of nitroimidazoles alone and in combination with clarithromycin on Helicobacter pylori.

Pharmacodynamic studies of Helicobacter pylori exposed to metronidazole and tinidazole alone and in combination with clarithromycin were performed by bioluminescence assay of intracellular ATP. The pharmacodynamic parameter control-related effective regrowth time (CERT) was used. CERT is defined as the time required for the resumption of logarithmic growth and a return of the level of growth to the preexposure inoculum in the test culture minus the corresponding time in the control culture. CERT measures the combined effects of the initial level of killing and postantibiotic effect. The incubation times and drug concentrations were chosen according to their half-lives and their clinically achievable concentrations. The study shows that the parameter CERT is useful for the testing of antibiotic combinations. The CERTs induced by clarithromycin, metronidazole, and tinidazole alone and in the combinations tested were concentration dependent, with no maximum response, indicating that the use of high doses may be preferable. The combinations with the highest concentrations induced synergistic effects and prevented regrowth. The use of tinidazole in combination with clarithromycin proved to give the longest CERTs, indicating that this is the most effective combination.

Clarithromycin↗