Source attribution of community-acquired cases of Legionnaires' disease-results from the German LeTriWa study; Berlin, 2016-2019.

INTRODUCTION: Sources of infection of most cases of community-acquired Legionnaires' disease (CALD) are unknown. OBJECTIVE: Identification of sources of infection of CALD. SETTING: Berlin; December 2016-May 2019. PARTICIPANTS: Adult cases of CALD reported to district health authorities and consenting to the study; age and hospital matched controls. MAIN OUTCOME MEASURE: Percentage of cases of CALD with attributed source of infection. METHODS: Analysis of secondary patient samples for monoclonal antibody (MAb) type (and sequence type); questionnaire-based interviews, analysis of standard household water samples for Legionella concentration followed by MAb (and sequence) typing of Legionella pneumophila serogroup 1 (Lp1) isolates; among cases taking of additional water samples to identify the infectious source as appropriate; recruitment of control persons for comparison of exposure history and Legionella in standard household water samples. For each case an appraisal matrix was filled in to attribute any of three source types (external (non-residence) source, residential non-drinking water (RnDW) source (not directly from drinking water outlet), residential drinking water (RDW) as source) using three evidence types (microbiological results, cluster evidence, analytical-comparative evidence (using added information from controls)). RESULTS: Inclusion of 111 study cases and 202 controls. Median age of cases was 67 years (range 25-93 years), 74 (67%) were male. Among 65 patients with urine typable for MAb type we found a MAb 3/1-positive strain in all of them. Compared to controls being a case was not associated with a higher Legionella concentration in standard household water samples, however, the presence of a MAb 3/1-positive strain was significantly associated (odds ratio (OR) = 4.9, 95% confidence interval (CI) 1.7 to 11). Thus, a source was attributed by microbiological evidence if it contained a MAb 3/1-positive strain. A source was attributed by cluster evidence if at least two cases were exposed to the same source. Statistically significant general source types were attributed by calculating the population attributable risk (analytical-comparative evidence). We identified an external source in 16 (14%) cases, and RDW as source in 28 (25%). Wearing inadequately disinfected dentures was the only RnDW source significantly associated with cases (OR = 3.2, 95% CI 1.3 to 7.8) and led to an additional 8% of cases with source attribution, for a total of 48% of cases attributed. CONCLUSION: Using the appraisal matrix we attributed almost half of all cases of CALD to an infectious source, predominantly RDW. Risk for LD seems to be conferred primarily by the type of Legionella rather than the amount. Dentures as a new infectious source needs further, in particular, integrated microbiological, molecular and epidemiological confirmation.

Ten years of KISS: the most important requirements for success.

Ten years ago, in January 1997, data collection for the German national nosocomial infection surveillance system was established, which is known by the acronym KISS (Krankenhaus-Infektions-Surveillance-System). Meanwhile KISS was able to demonstrate a beneficial effect from ongoing surveillance activities and appropriate feedback to the users in combination with reference data for ventilator associated pneumonia, primary bloodstream infections and surgical site infections. Significant reductions of infection rates between 20-30% over 3 years periods in the components for intensive care units, operative departments and neonatal intensive care units were demonstrated. Due to our experience the following requirements have to be fulfilled to keep a surveillance system successful over longer periods: close contact between the participating institutions, consideration of new developments, timely regular data feedback and constant reevaluation of the way of data presentation, data validity and demonstration of its contribution to the reduction of healthcare associated infections (HAI). The article describes in more detail how KISS tries to fulfill these requirements.

Outbreaks in neonatal intensive care units - they are not like others.

BACKGROUND: Outbreaks of health care-associated infections in neonatal intensive care units (NICUs) are frequent and have received more attention in medical literature than outbreaks from other types of intensive care units (ICUs). The objective of this systematic review was to identify differences between outbreaks of health care-associated infections in NICUs and other ICUs as reported to date in the medical literature. METHODS: Screening the outbreak database (http://www.outbreak-database.com), a systematic comparison of outbreaks was performed with the following categories: causing pathogen, type of infection, sources identified, and measures taken to stop the outbreak. RESULTS: Two hundred and seventy-six outbreaks were reported from NICUs and 453 from other ICU types. Enterobacteriaceae were significantly more often responsible for NICU outbreaks, whereas nonfermenting bacteria are more frequently identified in other ICU types. On average, 23.9 patients and 1.8 health care workers were involved in NICU outbreaks. Average mortality in NICU outbreak was 6.4% (1.5 newborns on average). In 48.6% of NICU outbreaks the authors were unable to identify the sources compared with 38.0% in other ICU outbreaks. The most important infection control measures were significantly more often implemented in NICUs than in other ICUs. CONCLUSIONS: Systematic outbreak analysis is essential for gaining insights into the control of NICU outbreaks.

Pyoderma outbreak among kindergarten families: Association with a Panton-Valentine leukocidin (PVL)-producing S. aureus strain.

OBJECTIVES: We report on an outbreak of skin and soft tissue infections (SSTI) among kindergarten families. We analyzed the transmission route and aimed to control the outbreak. METHODS: The transmission route was investigated by nasal screening for Panton-Valentine leukocidin (PVL)-producing Staphylococcus aureus (PVL-SA), subsequent microbiological investigation including whole genome sequencing and a questionnaire-based analysis of epidemiological information. The control measures included distribution of outbreak information to all individuals at risk and implementation of a Staphylococcus aureus decontamination protocol. RESULTS: Individuals from 7 of 19 families were either colonized or showed signs of SSTI such as massive abscesses or eye lid infections. We found 10 PVL-SA isolates in 9 individuals. In the WGS-analysis all isolates were found identical with a maximum of 17 allele difference. The clones were methicillin-susceptible but cotrimoxazole resistant. In comparison to PVL-SAs from an international strain collection, the outbreak clone showed close genetical relatedness to PVL-SAs from a non-European country. The questionnaire results showed frequent travels of one family to this area. The results also demonstrated likely transmission via direct contact between families. After initiation of Staphylococcus aureus decontamination no further case was detected. CONCLUSIONS: Our outbreak investigation showed the introduction of a PVL-SA strain into a kindergarten likely as a result of international travel and further transmission by direct contact. The implementation of a Staphylococcus aureus decontamination protocol was able to control the outbreak.

How often do asymptomatic healthcare workers cause methicillin-resistant Staphylococcus aureus outbreaks? A systematic evaluation.

A systematic search was performed to identify outbreaks of methicillin-resistant Staphylococcus aureus infection and colonization caused by healthcare workers (HCWs). Of 191 outbreaks identified, 11 had strong epidemiological evidence that HCWs were the source. In 3 of these outbreaks, asymptomatic carriers were the cause. The frequent practice of screening asymptomatic HCWs should be reconsidered.

Where should one search when confronted with outbreaks of nosocomial infection?

The outbreak database (http://www.outbreak-database.com), containing 1561 records of nosocomial outbreaks published in the medical literature in a systematic format, was used to identify the most frequent outbreak sources for the entire database as well as for specific outbreak pathogens. Overall, in 37.1%, no source was identified. The main sources identified were index patients (40.3%), followed by equipment and devices (21.1%), environment (19.8%), and personnel (15.8%).

How outbreaks can contribute to prevention of nosocomial infection: analysis of 1,022 outbreaks.

OBJECTIVE: To describe the epidemiology of nosocomial outbreaks published in the scientific literature. DESIGN: Descriptive information was obtained from a sample of 1,022 published nosocomial outbreaks from 1966 to 2002. METHODS: Published nosocomial outbreaks of the most important nosocomial pathogens were included in the database. A structured questionnaire was devised to extract information in a systematic manner on nosocomial outbreaks published in the literature. The following items were used: the reference, type of study (case reports or studies applying epidemiologic or fingerprinting methods), type of microorganism, setting, patients and personnel involved, type of infection, source of infection, mode of transmission, risk factors identified, and preventive measures applied. RESULTS: Bloodstream infection was the most frequently identified type of infection (37.0%), followed by gastrointestinal infection (28.5%) and pneumonia (22.9%). In 37% of the outbreaks, the authors were not able to identify the sources. The most frequent sources were patients (25.7%), followed by medical equipment or devices (11.9%), the environment (11.6%), and the staff (10.9%). The mode of transmission remained unclear in 28.3% of the outbreaks. Transmission was by contact in 45.3%, by invasive technique in 16.1%, and through the air in 15.0%. The percentage of outbreaks investigated by case-control studies or cohort studies over the years was small (21% and 9%, respectively, for the whole time period). CONCLUSION: Outbreak reports in the literature are a valuable resource and should be used for educational purposes as well as for preparing outbreak investigations.

Reducing central venous catheter-associated primary bloodstream infections in intensive care units is possible: data from the German nosocomial infection surveillance system.

BACKGROUND AND OBJECTIVE: The German Nosocomial Infection Surveillance System (KISS) began in 1997 as a nationwide surveillance project for voluntary registration of nosocomial infections in intensive care units (ICUs). This study investigates trends in the rates of central venous catheter (CVC)-associated primary bloodstream infections (BSIs) in ICUs since participation in KISS. METHODS: Eighty-four ICUs that had participated in KISS for at least 24 months were considered for more detailed analysis. Monthly rates of primary BSI for the 84 ICUs were pooled for the 24 months. The best model for describing the curve of reduction was sought. Additionally, incidence densities were compared using the z test. RESULTS: For the 212 ICUs participating, a relative 25.7% decrease (from 2.1 to 1.6 primary BSIs per 1,000 CVC-days) was observed from January 1997 to June 2001. The 84 ICUs that participated in KISS for a minimum of 24 months accumulated 552,359 patient-days and 404,897 CVC-days during their 24 months. A linear regression model was selected to explain the curve of primary BSI reduction in the 84 ICUs. It showed a decrease from 2.1 to 1.5 primary BSIs per 1,000 CVC-days, meaning an overall relative reduction of 28.6% during the 2-year observation period. These results were significant (Student's t test for the monthly reduction coefficient; P = .04). The reduction of primary BSIs was shown for both clinical sepsis and laboratory-confirmed, CVC-associated primary BSIs. CONCLUSION: Performing surveillance with KISS was associated with a reduction of the rates of CVC-associated primary BSIs in ICU patients.

The relationship between methodological trial quality and the effects of impregnated central venous catheters.

OBJECTIVE: We assessed the methodological trial quality of individual randomized controlled studies on chlorhexidine silver sulfadiazine impregnated catheters and the effect on catheter-related infection (CRI). DESIGN: Only the studies identified in the Medline database from 1966 to December 2001 were considered, abstracts being excluded. The outcome of this investigation centered on bloodstream CRI. The trial quality of the 11 studies identified and published (total 3,131 catheters) was assessed using a scoring system based on allocation, patient selection, patient characteristics, blinding of the intervention and the diagnosis of CRI (range 0-2 points, 10 points maximum). RESULTS: The mean methodological quality score was 7.1 (range 5-9). The relative risk reduction for bloodstream CRI ranged from -0.14 to 1.0. No association between trial quality and the impact of chlorhexidine silver sulfadiazine impregnated catheters on CRI was found. The summary odds ratio for CRI was 0.69 (95% CI 0.46-1.03). Taking only those studies with 2 points for diagnosis of CRI a summary odds ratio of 0.87 (95% CI 0.44-1.72) resulted, whereas studies with a diagnosis score of only 1 point led to a summary odds ratio of 0.60 (95% CI 0.35-1.02). CONCLUSIONS: The quality of the studies seems to have had no influence on the outcome, according to the results of this investigation, but the use of only a single quality score may not be sufficient to investigate the prevention effect of impregnated catheters.

Representativeness of the surveillance data in the intensive care unit component of the German nosocomial infections surveillance system.

OBJECTIVE: To assess the representativeness of the data in the Krankenhaus Infektions Surveillance System (KISS), which is a nosocomial infections surveillance system for intensive care units (ICUs) in Germany. DESIGN: Prospective and retrospective surveillance study. SETTING: Medical-surgical ICUs in Germany. METHODS: A sample of medical-surgical ICUs from all over Germany, stratified according to hospital size, was randomly selected. Surveillance personnel from the hospitals were trained in surveillance of nosocomial infections, and they subsequently conducted a 2-month surveillance in their ICUs. Data were compared with KISS data for medical-surgical ICUs. RESULTS: During the period from 2004 through 2005, a total of 50 medical-surgical ICUs agreed to participate in our study: 21,832 patient-days were surveyed, and 262 cases of nosocomial infection were registered, 176 of which were cases of device-associated nosocomial infection (100 cases of lower respiratory tract infection, 47 cases of urinary tract infection, and 29 cases of bloodstream infection). The overall incidence density of all types of nosocomial infections was estimated to be 10.65 cases per 1,000 patient-days. Device utilization rates in the study ICUs and in the KISS medical-surgical ICUs were similar. The pooled mean device-associated infection rates were higher in the study ICUs than in the KISS medical-surgical ICUs (10.2 vs 5.1 cases of pneumonia; 2.0 vs 1.2 cases of bloodstream infection; and 2.7 vs 1.2 cases of urinary tract infection), but the pooled mean device-associated infection rates in the study ICUs were comparable to those of the KISS ICUs during their first year of participation in KISS. The incidence density for nosocomial infections in the study ICUs varied according hospital size, with ICUs in larger hospitals having a higher incidence density than those in smaller hospitals. CONCLUSIONS: KISS ICUs started with nosocomial infection rates comparable to those found in our study ICUs. Over the years of participation, however, a decrease in nosocomial infections is seen. Thus, rates of nosocomial infection from KISS should be used as benchmarks, but estimations for Germany that are based on KISS data may underestimate the real burden of nosocomial infections.

Incidence rate of nontuberculous mycobacterial disease in immunocompetent children: a prospective nationwide surveillance study in Germany.

An increasing incidence in disease caused by nontuberculous mycobacteria is being reported. We investigated the burden of disease in immunocompetent German children in a prospective nationwide study from April 2003 to September 2005. Ninety-seven percent of children presented with lymphadenitis; median age was 2.5 years. Using the capture-recapture method, we estimated a cumulative incidence rate of 3.1/100000 children.