Wild and domestic bird faeces likely source of psittacosis transmission-A case-control study in Sweden, 2014-2016.

Psittacosis is a zoonotic disease transmitted by birds. In Sweden, where psittacosis is notifiable, an average of eight cases per year were reported between 2002 and 2012. In 2013, an unusual increase in cases in southern Sweden was associated with exposure to wild birds. To further explore specific risk factors connected to wild birds and identify other risk factors for sporadic psittacosis, we conducted a case-control study including all domestically acquired psittacosis cases reported between December 2014 and April 2016 in Sweden. Cases were age-, sex- and geo-matched to controls randomly selected from a population register. Cases and controls completed a questionnaire investigating detailed exposures to wild and domestic birds. We compared cases to controls, calculating adjusted matched odds ratios (amOR) using conditional logistic regression. Thirty-one cases were notified: all cases lived in southern Sweden and 26 were ill during winter season. Two risk factors were independently associated with psittacosis infection: cleaning a wild bird feeder (amOR = 18.95; 95% CI: 2.11-170.03) and owning domestic birds (amOR = 5.55, 95% CI: 1.16-26.61). Our results suggest that exposure to bird faeces, for example when cleaning a wild bird feeder, was the main route of transmission. Following this study, the Public Health Agency of Sweden published recommendations on good practices when cleaning surfaces contaminated with bird faeces and recommended use of bird feeders with a design limiting faeces accumulation.

A nationwide outbreak of listeriosis associated with cold-cuts, Sweden 2013-2014.

In January 2014, the Public Health Agency of Sweden noticed an increase in listeriosis cases. Isolates from 10 cases had identical pulsed field gel electrophoresis (PFGE) profiles, suggesting a common source. We investigated the outbreak to identify the source and stop transmission. We looked for cases in 2013-2014 and also compared cases notified after February 2014 to randomly selected controls. We surveyed food items consumed two weeks prior to symptom onset. Listeria monocytogenes isolates found by food producers were PFGE-typed. Patient and food isolates with the outbreak PFGE profile were whole-genome sequenced and 51 cases with identical PFGE profile were identified; 12/20 cases and 108/186 controls responded to the survey. All cases were exposed to cold-cuts, compared with 72% of controls (p = 0.034). Five isolates of L. monocytogenes with the outbreak PFGE profile were found in cold-cuts from a food producer which stopped production in February 2014, but cases appeared until October 2014. Whole-genome sequencing showed that cold-cut and patient isolates differed by eight single nucleotide polymorphisms. Three patient isolates differed more and were probably not part of the outbreak. Epidemiological and microbiological results indicated cold-cuts as a possible source of the outbreak.

Prevalence of penicillin-non-susceptible Streptococcus pneumoniae in children in day-care centres subjected to an intervention to prevent dispersion.

BACKGROUND: The aim of this study was to evaluate the day-care interventions implemented in southern Sweden to restrict the dispersion of penicillin-non-susceptible pneumococci with a minimum inhibitory concentration of penicillin G of at least 0.5 mg/l (PNSP0.5). METHODS: A retrospective epidemiological study was performed and data from 109 day-care centre interventions from 2000 to 2010 were analysed, including screening results from 7157 individuals. RESULTS: It was found that 42% of the children were carriers of pneumococci and 5% of the screened children were PNSP0.5 carriers. Very few personnel were PNSP0.5 carriers and they were carriers for only a short time. Significantly more contact cases with the same serogroup as the index case were found in the first screening and in the same department as the index case, but a substantial number of contact cases were found in adjacent departments. CONCLUSIONS: Screening of personnel is not worth the effort. Based on our results, procedures to restrict dispersion of PNSP0.5 in day-care centres could be improved. To find the majority of contact cases with PNSP0.5 an early screening including adjacent departments seems to be the best approach.

Risk factors for pneumococcal carriage in day care centers: a retrospective study during a 10-year period.

In this retrospective epidemiologic study, we present pneumococcal carriage data from 109 Swedish day care centers over a period of 10 years. Aspects of season, age, personnel and group size were studied. We found a significant seasonal variation in pneumococcal carriage. Group size was a significant risk factor for pneumococcal carriage. Pneumococcal carriage was 4.5 % in personnel.

Eradication of nasopharyngeal carriage of penicillin-non-susceptible Streptococcus pneumoniae--is it possible?

BACKGROUND: The South Swedish Pneumococcal Intervention Project (SSPIP) was started in 1995 with the aim of limiting the spread of penicillin-non-susceptible pneumococci (PNSP) in Skåne County, Sweden. As part of the SSPIP, eradication therapy with rifampicin in combination with 1 more antibiotic was considered on a social indication after prolonged carriage of 2-3 months. METHODS: In this retrospective study, 125 medical records were analyzed. Children aged 0-10 y referred for eradication therapy in Malmö and Lund, due to a prolonged nasopharyngeal carriage of PNSP with a penicillin G minimum inhibitory concentration of ≥ 0.5 mg/l, between the y 1997 and 2011 were included. Two consecutive negative cultures, with the second one no shorter than 7 days after treatment completion, were required for the carriage to be considered eradicated. RESULTS: Out of 125 children, 71 received treatment with rifampicin in combination with amoxicillin (n = 44), erythromycin (n = 22), or clindamycin (n = 5) for 7 days. Eradication treatment was successful in 91.5% of the children. Six children (8.5%) had treatment failure with amoxicillin and rifampicin; 3 were found by late follow-up. There was a trend towards a better outcome with erythromycin and clindamycin combinations in comparison to amoxicillin. CONCLUSIONS: Eradication therapy was successful, but a proper follow-up is essential.

Duration of methicillin-resistant Staphylococcus aureus colonization after diagnosis: a four-year experience from southern Sweden.

BACKGROUND: The duration of colonization with methicillin-resistant Staphylococcus aureus (MRSA) is not well known and there is debate as to whether a patient colonized with MRSA ever can be defined as 'MRSA-negative'. METHODS: Since 2003 all notified MRSA cases have been systematically followed in Skåne County, southern Sweden. Cultures are taken from the nares, throat, perineum and possible skin lesions. Contact tracing is conducted. The screening program continues as long as cultures are positive and then until 1 y of consecutive negative cultures for MRSA is completed. RESULTS: Of the 578 MRSA cases during 2003-2006, 535 were included in this retrospective study. The median duration of colonization with MRSA was 5.9 months. Having household contacts with MRSA, young age, spa-type t002 and colonization in 2 or more locations, were significantly associated with a longer duration of colonization. Having a clinical infection treated with antibiotics (compared to clinical infection with no antibiotic treatment or asymptomatic carriage) was significantly associated with a shorter carriage time. Eradication treatment was associated with a shorter carriage time. CONCLUSION: These results may have implications for the management of patients with MRSA carriage. The study indicates that MRSA carriage can be defined as 'negative' in a follow-up program and shows the importance of performing contact tracing among household members.

Imported methicillin-resistant Staphylococcus aureus, Sweden.

Countries such as Sweden that have a low prevalence of methicillin-resistant Staphylococcus aureus (MRSA) offer the opportunity to discern and study transmission of imported cases of MRSA. We analyzed 444 imported cases of MRSA acquisition reported in Sweden during 2000-2003. Risk for MRSA in returning travelers ranged from 0.1 (95% confidence interval [CI] 0.01-0.4) per 1 million travelers to Nordic countries to 59.4 (95% CI 44.5-79.3) per 1 million travelers to North Africa and the Middle East. Most imported cases (246, 55%) were healthcare acquired, but regions with the highest risk for MRSA in travelers showed a correlation with community acquisition (r = 0.81, p = 0.001). Characteristic differences in MRSA strains acquired were dependent on the region from which they originated and whether they were community or healthcare acquired. Knowledge of differences in transmission of MRSA may improve control measures against imported cases.

Characterization of human invasive isolates of Listeria monocytogenes in Sweden 1986-2007.

Since 1986, 68% of the Listeria monocytogenes isolates from human cases of invasive listeriosis in Sweden are available for retrospective studies. The aim of the present study was to characterize 601 human invasive isolates of L. monocytogenes in Sweden from 1986 to 2007 by using serotyping and pulsed-field gel electrophoresis. Since 1996, serovar 4b was permanently reduced to the second or third most common serovar in human cases in Sweden. During the latter period, 2000-2007, only 13% belonged to serovar 4b and 71% to 1/2a. The dendrogram, based on pulsovars, reveals two clusters with different serovars. Cluster 1 exhibits serovars 4b and 1/2b, whereas cluster 2 consists of serovar 1/2a. Serovar 1/2a seems to be more heterogeneous than serovar 4b.

High prevalence of MRSA in household contacts.

In a 6-y period, 114 household contacts connected to newly diagnosed MRSA patients screened for MRSA in the southern part of Sweden. In 22 of 51 (43%) families, 1 to 4 household contact(s) connected to a MRSA patient were positive for MRSA. In the 22 families, 42 of 60 (70%) household contacts were positive for MRSA and transmission of MRSA occurred between adult couples, parents and children, grandparent and children and between siblings. Within a family, MRSA-positive family members had in all but 1 instance identical MRSA strain genotypes (spa types) making intrafamilial spread of MRSA highly probable. MRSA transmission among household contacts may contribute to the prevalence of MRSA in the community and failure to identify MRSA in household contacts may maintain MRSA colonization in an already known MRSA patient. MRSA screening of family members living in the same household as a known MRSA patient should therefore be considered.

Age- and serogroup-related differences in observed durations of nasopharyngeal carriage of penicillin-resistant pneumococci.

Using data from an ongoing Swedish intervention project, the observed durations of nasopharyngeal carriage of penicillin-nonsusceptible Streptococcus pneumoniae (PNSP) (MIC of penicillin G of >or=0.5 microg/ml) stratified by both pneumococcal serogroup and age of the carrier were compared. The means and 95% confidence intervals (CIs) were estimated by fitting a gamma distribution to the observed duration of carriage for each age and serogroup stratum. The mean observed duration of carriage for all cases was 37 days (95% CI, 35 to 38 days). Children below the age of 5 years carried PNSP for significantly longer periods (43 days; 95% CI, 41 to 45 days) compared with older individuals (25 days; 95% CI, 24 to 27 days). There were also differences within the group of cases below the age of 5 years, as the duration of carriage became significantly shorter for each increasing age step: <1, 1 to 2, and 3 to 4 years. In addition, patients <5 years of age carried serogroups 9 and 14 for significantly shorter periods than groups 6 and 23. Serogroup 9 was also carried for significantly shorter periods than group 19. For patients aged 5 years or older, no significant difference in carriage duration for different ages or serogroups could be noted. As young children have the longest duration of PNSP carriage, interventions aiming to reduce the prevalence in this group are of great importance. The results highlight the importance of taking both serogroup and age of the carriers into account when studying the dynamics of pneumococcal transmission in young children.

The throat: an important site for MRSA colonization.

In order to evaluate the value of bacterial cultures taken from the throat, 266 patients with MRSA were retrospectively assessed. At the time when MRSA was first detected in the patient, the most frequent sites positive for MRSA were a skin lesion (110 patients, 41%), the anterior nares (109 patients, 41%), and the throat (102 patients, 38%). In 26%, 17%, and 17% of the patients, a skin lesion, the anterior nares, and the throat, respectively, were the only site where MRSA was seen. In 123 patients cultured for MRSA because of a close contact with an already known MRSA patient, 65 patients (53%) were positive for MRSA in their throat and in 40 patients (33%), throat was the only sample site with MRSA at the time when the patient was found to be MRSA positive. 146 of the 266 patients (55%) were colonized with MRSA in the throat any time throughout the period they were MRSA positive. We conclude that throat is an important reservoir for MRSA and that samples taken from the throat should be included in screening patients for MRSA.

Penicillin-resistant pneumococci in Sweden 1997-2003: increased multiresistance despite stable prevalence and decreased antibiotic use.

Antimicrobial resistance patterns and capsular groups of penicillin-resistant Streptococcus pneumoniae (PRP; MIC penicillin G > or = 0.5 mg/ml) in Sweden between 1997 and 2003 were described, and trends in resistance and antibiotic sales during the same period were compared. The most common serogroups were in descending order 9, 19, 14, 23, and 6. Despite a low and stable annual PRP rate (proportion of PRP out of all pneumococci) of around 2% during the study period, the proportion of PRP resistant to other antibiotics increased. Of all tested PRP isolates, 82% were also resistant to trimethoprim/sulfamethoxazole, 32% had additional resistance to tetracycline, and 26% to erythromycin. Antibiotic sales figures for all studied antibiotic subgroups decreased during the same period. Little correlation was found between antibiotic sales and PRP resistance rates, indicating that there are still other poorly defined factors contributing to the reported resistance levels in the population. However, although PRP strains in Sweden are becoming more commonly resistant to antibiotics other than beta-lactams, the low and further reduced antibiotic sales still might have delayed the development and rapid spread of PRP in the population.

Epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) in Sweden 2000-2003, increasing incidence and regional differences.

BACKGROUND: The occurrence of methicillin-resistant Staphylococcus aureus (MRSA) has gradually become more frequent in most countries of the world. Sweden has remained one of few exceptions to the high occurrence of MRSA in many other countries. During the late 1990s, Sweden experienced a large health-care associated outbreak which with resolute efforts was overcome. Subsequently, MRSA was made a notifiable diagnosis in Sweden in 2000. METHODS: From the start of being a notifiable disease in January 2000, the Swedish Institute for Infectious Disease Control (SMI) initiated an active surveillance of MRSA. RESULTS: The number of reported MRSA-cases in Sweden increased from 325 cases in 2000 to 544 in 2003, corresponding to an overall increase in incidence from 3.7 to 6.1 per 100,000 inhabitants. Twenty five per cent of the cases were infected abroad. The domestic cases were predominantly found through cultures taken on clinical indication and the cases infected abroad through screening. There were considerable regional differences in MRSA-incidence and age-distribution of cases. CONCLUSION: The MRSA incidence in Sweden increased over the years 2000-2003. Sweden now poises on the rim of the same development that was seen in the United Kingdom some ten years ago. A quarter of the cases were infected abroad, reflecting that international transmission is now increasingly important in a low-endemic setting. To remain in this favourable situation, stepped up measures will be needed, to identify imported cases, to control domestic outbreaks and to prevent transmission within the health-care sector.

The impact of active intervention on the spread of penicillin-resistant Streptococcus pneumoniae in Swedish day-care centres.

Policies for handling cases of penicillin-non-susceptible Streptococcus pneumoniae (PNSP) in day-care groups vary between different counties in Sweden. The aim of this study was to evaluate the epidemiological effect of excluding PNSP-carriers from children's day-care centres (DCC). We followed the incidence in 14 DCC groups with ongoing PNSP-spread, by repeated group screens until no further cases could be identified. All identified carriers were excluded from DCC attendance in study area A (Skåne region) while they remained in the group in study area B (Göteborg and örebro), according to local policies. The intervention effect was evaluated by comparing the number of additional cases after the baseline screen (start of the intervention period) between the 2 study areas. All PNSP-isolates were characterized by resistance pattern, serotype and pulse-field gel electrophoresis. The relative risk for children in DCCs without active intervention was 6.4 (95% CI: 2.0-20.7). Each prevented case in area A can be estimated to have demanded the exclusion of 2 other children from day care for approximately 4 weeks each. The total cost-benefit outcome of this action has to be seen in the light of the local situation with regard to the population prevalence and the distribution of other risk factors.

Limited spread of penicillin-nonsusceptible pneumococci, Skåne County, Sweden.

In response to increasing frequencies of penicillin-nonsusceptible pneumococci (PNSP), for which the MIC of penicillin was >0.12 mg/L, in Skåne County, southern Sweden, national recommendations were initiated in 1995 to limit the spread of pneumococci with high MICs (> or =0.5 mg/L) of penicillin (PRP), especially among children of preschool age. Traditional communicable disease control measures were combined with actions against inappropriate antimicrobial drug use. During the first 6 years that these recommendations were applied in Skåne County, the average frequency of penicillin-resistant pneumococci has been stable at =2.6%, as has the average PNSP frequency (7.4%). However, PNSP have been unevenly distributed in the county, with the highest frequencies in the southwest. Simultaneously, the rate of antimicrobial drug use for children <6 years of age was reduced by 20%. Thus the spread of PNSP between and within the municipalities in the county has been limited.