Prevailing effectiveness of the 2009 influenza A(H1N1)pdm09 vaccine during the 2010/11 season in Sweden.

Sixty per cent of the Swedish population received the monovalent AS03-adjuvanted pandemic influenza vaccine in the autumn of 2009. We assessed the age-specific effectiveness of this pandemic vaccine against hospitalisation with laboratory-confirmed influenza A(H1N1)pdm09 during the season 2010/11, in the age group from six months to 64 years in Sweden. The screening method was applied to available surveillance data. Our results suggest a prevailing effectiveness of 72% (95% confidence interval (CI): 63­80%) with the highest effectiveness among children, six months to nine years-old (92%, 95%CI: 80­97%). However, there were limitations in data quality and study design due to the lack of systematic recording of administered vaccinations, which underline the importance of preparing for an evaluation when planning for large public health actions. Despite these limitations, we believe the results reflect true, high prevailing vaccine effectiveness. Indeed, there were fewer deaths caused by influenza and the impact of influenza on intensive care units was less severe during the 2010/11 season in Sweden than in countries with lower pandemic vaccination coverage. The association between the pandemic vaccine and narcolepsy has increased the importance of assessing the risks and benefits of the vaccination; studies on the effectiveness and the duration of protection are needed for this.

Decrease in number of genital chlamydia cases in Norrbotten, Sweden, October - November 2009: an indirect effect of pandemic influenza A(H1N1)?

A sudden reduction in the number of reported genital chlamydia cases was observed in Norrbotten County, Sweden, during October to November 2009. After exploring other possibilities, such as a reduction in the number of chlamydia tests analysed or a new Chlamydia trachomatis variant that had been undetected in standard laboratory tests, it was found likely that the decrease was an indirect effect of the 2009 influenza A(H1N1) pandemic due to reduced social interactions among young adults.

Improved contact tracing for Chlamydia trachomatis with experienced tracers, tracing for one year back in time and interviewing by phone in remote areas.

OBJECTIVES: To evaluate the Swedish model for contact tracing and especially the "Västerbotten model" with centralised, extended contact interview periods, sometimes by telephone. METHODS: Using questionnaires, the contact tracing and interview procedure was evaluated during 2002, followed by an evaluation of contact interviewing by phone in 2005-6. RESULTS: Patients with diagnosed Chlamydia trachomatis infection reported on average 2.5 sexual contacts, 3.0 contacts when contact interviewing was performed at the clinic, and 2.3 contacts when performed by phone. 65% of the sexual contacts with a known test result were infected. CONCLUSION: Centralised contact tracing, exploring the sexual history for at least 12 months back in time, shows good results. Combined with screening of certain risk groups it is probably one effective way of preventing C trachomatis infections. Preventing C trachomatis by primary prevention such as information and counselling is, however, still of great importance.

Epidemiological observations on Streptococcus pyogenes serotype T1 in Uppsala county, Sweden 1989-1995.

During the period 1989-1995, the T-type distribution pattern of Streptococcus pyogenes pharyngeal isolates was compared with the annual incidence of culture-verified S. pyogenes bacteremias in Uppsala county, Sweden. An exceptional increase in the number of S. pyogenes bacteremias was seen in 1994. During the study period, the annual number of blood culture isolates was shown to correlate with the proportion of S. pyogenes serotype T1 among pharyngeal isolates.

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.

Biological strategies expressed by different Streptococcus pyogenes strains: an explanation of the epidemiology.

The numerous reports in the last ten years on the serious diseases caused by Streptococcus pyogenes indicate the continued significance of this pathogen. Furthermore, clinical studies and modern techniques have yielded new information on S. pyogenes and its pathogenic mechanisms. Although much still remains to be discovered about the biology of S. pyogenes, two different strategies--the 'epidemic' and the 'endemic' strategy--can be seen in the interaction of different S. pyogenes strains with the human host. The challenges posed by these two groups of bacteria are also outlined.

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.

Intracellular penetration and survival of Streptococcus pyogenes in respiratory epithelial cells in vitro.

Recurrence of pharyngotonsillitis caused by S. pyogenes after seemingly adequate antibiotic treatment has puzzled scientists for many years. We investigated the ability of S. pyogenes to invade HEp-2 cells and survive intracellularly. Five strains were tested, of which two were isolated from patients with recurrent pharyngotonsillitis, two without recurrent infection, while one was a reference strain. All five strains were found capable of penetrating the cells and surviving intracellularly for between 4 and 7 days. In this manner, an intracellular reservoir of bacteria was created, with the potential to cause recurrent infections.

Outbreak of Salmonella typhimurium in cats and humans associated with infection in wild birds.

An outbreak of Salmonella typhimurium infection in cats and humans in Sweden in 1999, associated with wild birds, is described. In the county of Värmland, 62 sick cats were examined. All were anorectic and lethargic, 57 per cent had vomiting and 31 per cent had diarrhoea. It was considered likely that salmonellosis was transmitted from cats to humans, but there were only a few such cases.

[Fluoroquinolone resistance of human pathogenic bacteria. Resistant E coli now appearing in Sweden]. / Fluorokinolonresistens hos humanpatogena bakterier. Nu resistensutveckling hos E coli även i Sverige.

Fluoroquinolone-resistance is a growing international problem. Warnings have earlier been issued concerning the risk of resistance development due to excessive fluoroquinolone prescription. The development of resistance among E. coli strains isolated from primary care patients with UTI is now apparent in Sweden. So far the majority of these strains manifest only low-level resistance. However, in view of the risk of high-level resistance developing among these strains further exposed to fluoroquinolones, it is important to think twice before prescribing these drugs.

Prevalence trends in Sweden for the new variant of Chlamydia trachomatis.

In 2006, a new variant of Chlamydia trachomatis (nvCT) was discovered in Sweden that was not detectable with Abbott m2000 (Abbott) and Amplicor/COBAS Amplicor/TaqMan48 (Roche). The proportion of nvCT was 20-64% of the detected Chlamydia cases in counties using Abbott/Roche test systems. Although the ProbeTec system from Becton Dickinson (BD) could detect nvCT, the proportion of nvCT in counties using BD was 7-19%. The objective of the current study was to follow the nvCT proportions from 2007 to 2009 in two counties that used Roche and had introduced test systems able to detect nvCT in late 2006. The nvCT was also followed in two counties that used BD, and in all four counties the effect of nvCT on the serotype distribution of C. trachomatis wild-type strains was analysed. A total of 2576 specimens positive for C. trachomatis were collected in the four counties at three time points, and analysed for nvCT and serotype E. The proportion of nvCT declined significantly in the two counties using Roche, from 65% and 48% in 2007 to 24% for both counties in 2009 (p <0.001). The nvCT proportion increased in Norrbotten county, which used BD, from 9% in 2007 to 19% in 2009 (p 0.03). In Uppsala county, which also used BD but was surrounded by counties using detection systems from Roche, the proportion of nvCT declined from 24% in 2007 to 18% in 2009 (p <0.03). No major difference in the level of serotype E was seen. The proportion of nvCT seems to rapidly converge in the Swedish counties after the selective diagnostic advantage for nvCT has been lost in the Abbott/Roche counties.

More than one variant of Listeria monocytogenes isolated from each of two human cases of invasive listeriosis.

Two variants of Listeria monocytogenes were isolated from blood cultures from each of two patients with listeriosis. Each variant displayed a two-band difference in DNA profile from the other by pulsed-field gel electrophoresis. Although this difference in profile is insufficient to distinguish clearly between the variants, the possibility of co-infection with different strains of L. monocytogenes needs to be considered. We suggest that more than one colony should be selected for molecular typing to aid interpretation during investigation of the sources and routes of Listeria infection.

Staphylococcus aureus resistant to fusidic acid among Swedish children: a follow-up study.

We previously described the epidemic spread of a fusidic acid resistant clone of Staphylococcus aureus among children with bullous impetigo throughout Sweden 1. In this follow-up study we present data showing that Swedish clinicians in 2002 drastically reduced prescriptions of fusidic acid ointments, probably in response to the epidemic. Furthermore, we show that the fusidic acid resistant clone which dominated in 2001 is still the most prevalent fusidic acid resistant S. aureus in the population. The epidemic which reached its peak in 2002 is now clearly declining.

Diversity among 2481 Escherichia coli from women with community-acquired lower urinary tract infections in 17 countries.

OBJECTIVES: In the recently published ECO.SENS survey, the antimicrobial susceptibility of Escherichia coli from urinary tract infections in women in 16 European countries and Canada was investigated. This study reports the diversity among these E. coli. METHODS: The 2481 E. coli, typed with the PhenePlate (PhP) System utilizing the dynamics and end result of 11 biochemical reactions in a microplate system, were clustered and the Simpson's index of diversity calculated. RESULTS: Seventy-four Common PhP Types (CT) comprising 2067 isolates and 414 Single Types (Si) were identified. Of these, 916 isolates (37%) belonged to one of the four most frequent CT (arbitrarily numbered CT48, 10, 26 and 20). CT48 with 400 isolates and 11 different susceptibility patterns, was widely disseminated across Europe and Canada and was the most frequent type in 13 countries and the second most frequent in the remaining four countries. Sixty-four per cent of the E. coli were susceptible to all eight investigated antimicrobials (CT48: 73%, CT10: 77%, CT26: 62% and CT20: 37%). Forty-six different susceptibility patterns were seen, the three most common being isolated resistance to ampicillin, resistance to ampicillin and trimethoprim, and isolated resistance to trimethoprim. Multiresistance, here defined as resistance to four or more of the investigated antibiotics, was distributed among E. coli belonging to several PhP types. CONCLUSIONS: There was no obvious correlation between the phenotypes identified with the PhP System and the susceptibility pattern. The data did not indicate clonal dissemination within or between countries as a major reason for differences in antimicrobial resistance rates.

Are penicillin treatment failures in Arcanobacterium haemolyticum pharyngotonsillitis caused by intracellularly residing bacteria?

Arcanobacterium haemolyticum is an infrequent agent of pharyngotonsillitis in children and young adults. Despite the fact that A. haemolyticum is fully sensitive to penicillin in vitro, penicillin treatment failures are frequent. The ability of A. haemolyticum to invade HEp-2 cells and survive intracellulary was investigated. All 12 strains tested, of which 10 were isolated from patients with pharyngotonsillitis, and 2 were reference strains, were internalized by the HEp-2 cells. Four strains tested further, one of the reference strains and 3 of the clinical isolates, proved able to survive intracellularly for 4 days, thus creating intracellular reservoirs of bacteria. It was also shown that erythromycin, an antibiotic known to penetrate well intracellularly, efficiently killed these bacteria.

Wound infection caused by Staphylococcus hyicus subspecies hyicus after a donkey bite.

Staphylococcus hyicus subspecies hyicus has not previously been reported to cause human infections, but is a well known cause of diseases in a variety of animals. We report a wound infection following a donkey bite.