Human isolates of Listeria monocytogenes in Sweden during half a century (1958-2010).

Isolates of Listeria monocytogenes (n = 932) isolated in Sweden during 1958-2010 from human patients with invasive listeriosis were characterized by serotyping and pulsed-field gel electrophoresis (PFGE) (AscI). Of the 932 isolates, 183 different PFGE types were identified, of which 83 were each represented by only one isolate. In all, 483 serovar 1/2a isolates were distributed over 114 PFGE types; 90 serovar 1/2b isolates gave 32 PFGE types; 21 serovar 1/2c isolates gave nine PFGE types; three serovar 3b isolates gave one PFGE type; and, 335 serovar 4b isolates gave 31 PFGE types. During the 1980s in Sweden, several serovar 4b cases were associated with the consumption of European raw soft cheese. However, as cheese-production hygiene has improved, the number of 4b cases has decreased. Since 1996, serovar 1/2a has been the dominant L. monocytogenes serovar in human listeriosis in Sweden. Therefore, based on current serovars and PFGE types, an association between human cases of listeriosis and the consumption of vacuum-packed gravad and cold-smoked salmon is suggested.

Unusual increase of psittacosis in southern Sweden linked to wild bird exposure, January to April 2013.

Free-living wild birds worldwide act as reservoir for Chlamydia psittaci, but the risk of transmission to humans through contact with wild birds has not been widely documented. From 12 January to April 9 2013, a total of 25 cases of psittacosis were detected in southern Sweden, about a threefold increase compared with the mean of the previous 10 years. A matched case-control study investigating both domestic and wild bird exposure showed that cases were more likely than controls to have cleaned wild bird feeders or been exposed to wild bird droppings in other ways (OR: 10.1; 95% CI: 2.1-47.9). We recommend precautionary measures such as wetting bird feeders before cleaning them, to reduce the risk of transmission of C. psittaci when in contact with bird droppings. Furthermore, C. psittaci should be considered for inclusion in laboratory diagnostic routines when analysing samples from patients with atypical pneumonia, since our findings suggest that psittacosis is underdiagnosed.

Validity of routine surveillance data: a case study on Swedish notifications of methicillin-resistant Staphylococcus aureus.

Surveillance of communicable diseases is a public health corner stone. Routine notification data on communicable diseases are used as a basis for public health action as well as for policy making. While there are agreed standards for evaluating the performance of surveillance systems, it is rarely possible to analyse the validity of the data entered into these systems. In this study we compared data on all Swedish cases of methicillin-resistant Staphylococcus aureus (MRSA) routinely notified between 2000 and 2003 with follow-up information collected for each of these cases as part of a public health project. The variables Reason for testing (clinical sample, contact tracing, screening of risk group), Clinical presentation (disease, colonisation), Transmission setting (healthcare-acquired, community-acquired), Country of acquisition (Sweden, abroad) and Risk-occupation (yes, no) were analysed for sensitivity, positive predictive value and completeness of answers. The sensitivity varied between 23% and 83%, the positive predictive values were generally higher (55% to 97%), while missing answers varied from 11% to 59%. The proportion of community-acquired cases was markedly higher when excluding either cases of MRSA colonisation or cases found through public health-initiated activities (contact tracing or screening of risk groups). We conclude that the quality of routine surveillance data may be inadequate for in-depth epidemiological analyses. This should be taken into account when interpreting routine surveillance figures. Whether or not the case definition includes cases of MRSA colonisation may have a significant impact on population-wide estimates of MRSA occurrence.

MRSA in children from foreign countries adopted to Swedish families.

AIM: To determine if children adopted to Swedish families from countries with a high carrier rate of methicillin-resistant Staphylococcus aureus (MRSA) are infected or colonized with MRSA. METHODS: From January 2000 to May 2005, 23 adopted children from 6 countries were examined for MRSA at the University hospital in Lund after their arrival in Sweden. RESULTS: Thirteen of the 23 children (57%) were MRSA positive with a median age of the children at the time MRSA was detected of 6 (range 3-16) months. All MRSA positive children had a history of hospitalization in their native country before arriving in Sweden. The throat was the most frequent and persistent site where MRSA was seen while in sites such as the anterior nares and perineum, MRSA was found more intermittently. The MRSA-positive children were adopted into 13 Swedish families and in 3 families, 6 of 10 family members became MRSA positive. CONCLUSION: Children adopted from foreign countries to Swedish families and with a history of hospitalization in their native country were commonly colonized with MRSA. The throat was the most frequent site colonized and transmission of MRSA from adopted children to other family members occurred.

Metastatic complications of Staphylococcus aureus septicemia. To seek is to find.

Improvement in the high mortality from Staphylococcus aureus septicemia must address the individualized treatment (surgery and/or prolonged antibiotic treatment) of metastatic complications. The aim of this study was to evaluate the results of a comprehensive diagnostic monitoring for metastatic complications in S. aureus septicemia. 68 consecutive patients with S. aureus septicemia were prospectively followed. The performance rate and results of chest X-ray, echocardiography, bone scintigraphy and leukocyte scintigraphy are described. Metastatic complications were found in 53% of the 68 patients, endocarditis in 26%. Positive findings resulted in surgical intervention in 23 patients. The total mortality defined as all deaths within 12 weeks was 24%; 81% of the deceased were > or = 60 years of age. Non-endocarditis patients with peripheral septic metastases had good prognosis. An active monitoring for metastatic complications in S. aureus septicemia is a necessary prerequisite for optimizing treatment and to improve survival rate.

Bacteriologic evidence of infection caused by coagulase-negative staphylococci in total hip replacement.

Coagulase-negative staphylococci are important agents of infected hip arthroplasties, but sample contamination from the skin flora may confuse the diagnosis. Recovery of multiple identical strains has been regarded as indication of true infection. We have evaluated 29 total hip replacement operations with cultures positive for coagulase-negative staphylococci in a prospective study, 16 with > or = 3 isolates available for strain identity analysis. In 26 episodes, > or = 3 cultures were positive for coagulase-negative staphylococci, but only 19 of them had strong or intermediate clinical evidence of infection. Negative clinical evidence of infection coincided with the absence of a predominating strain according to plasmid profile analysis. A reliable identity analysis may help to rule out infection when multiple cultures are positive in patients who lack clinical evidence of infection.

Prediction of creatinine clearance by several methods in patients with severe infections.

Since almost all urinary creatinine is derived from the muscle mass, the amount of creatinine in the urine will be proportional to muscle mass, and it will show an almost constant decrease with age. A simple equation for estimating creatinine clearance has been derived. For women the creatinine clearance (ml.min-1) was [150-(years)].body weight (kg)/serum creatinine (mumol.l-1). For men less than 70 years it was [170-age (years)].body weight (kg)/serum creatinine (mumol/l) and for men greater than or equal to 70 years it was [160-age (years)].body weight (kg)/serum creatinine (mumol/l). The prediction was quite simple when laboratory results were given in SI units. A simple nomogram was devised for easy estimation of the creatinine clearance in individual patients according to the age, sex and weight. Predicted values according to our equations were compared with those derived from other formulae in 54 patients with severe infections treated with aminoglycosides. No major differences were found, but the new method seemed more convenient.

Evaluation of coagulase-negative staphylococci in blood cultures. A prospective clinical and microbiological study.

Coagulase-negative staphylococci (CNS) are the commonest microorganisms in blood cultures, and sorting out patients with CNS septicemia from sample contamination a persistent problem. We prospectively evaluated 73 patients with CNS-positive blood cultures during 1 year and analysed the corresponding 122 isolates in order to determine the rate of septicemia and define the role of microbiological markers of identity such as plasmid profile for that purpose. Three patients had true septicemia, all of them with implanted foreign devices. The plasmid analysis, being the most reliable identity marker, had its greatest implication in reducing the intermediate group of patients clinically suspected of septicemia from 12 to 4. Strict clinical criteria and serial blood cultures are most important in sorting out patients with CNS septicemia from cases of sample contamination. In high risk patients--critically ill with implanted foreign devices--plasmid analysis or other reliable markers of identity are of great additional value.

Does administration of an aminoglycoside in a single daily dose affect its efficacy and toxicity?

Treatment efficacy, oto- and nephrotoxicity, and aminoglycoside pharmacokinetics were evaluated in a prospective, comparative, randomized clinical study of aminoglycosides given once a day or three times a day for severe infections. Sixty patients were treated with netilmicin or gentamicin 4.5 mg/kg bodyweight/day, either once a day or divided into three doses a day. The patients were allocated randomly to the different groups. The clinical effect was difficult to compare in the different groups, because of the small numbers of patients. Therapeutic failures were seen in seven patients (three after one and four after three doses per day). Two patients, one with Staphylococcus aureus endocarditis and one with streptococcal endocarditis, on netilmicin once daily and conventional high-dose therapy with a penicillin had positive blood cultures after five and seven days of treatment, respectively. Vestibular function and hearing acuity were examined by serial audiograms and electronystagmograms. In spite of extensive diagnostic evaluation, only two cases of ototoxicity were detected. One patient treated with gentamicin three times a day developed vertigo and a severe abnormality of her electronystagmogram. One young patient treated with gentamicin once daily had a slight bilateral reduction of hearing. Nephrotoxicity was mild and did not differ in the four treatment groups. This was the first investigation of a once-daily dosing regimen conducted in seriously ill patients with systemic infections. We could not demonstrate any evidence that aminoglycoside treatment once daily has greater oto- or nephrotoxicity than the traditional three times daily regimen.