Is there an association between nosocomial infection rates and bacterial cross transmissions?

OBJECTIVE: Surveillance data of nosocomial infection rates are increasingly used for public reporting and interhospital comparisons. Approximately 15% of nosocomial infections on intensive care units are the result of patient-to-patient transmissions of the causative organisms. These exogenous infections could be prevented by adherence to basic infection control measures. The association between bacterial cross transmissions and nosocomial infection rates was analyzed. DESIGN: Prospective cohort study during 24 months. SETTING: Eleven intensive care units from two university hospitals. PATIENTS: All inpatients. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Primary isolates of six indicator organisms (Acinetobacter baumannii, Enterococcus faecalis and E. faecium, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus) cultured from clinical samples or methicillin-resistant S. aureus surveillance testing of all inpatients were genotyped. Indistinguishable isolates in > or =2 patients defined potential episodes of transmissions. Surveillance of nosocomial infection rates was performed according to the German nosocomial infection surveillance system, Krankenhaus Infektions Surveillance System. Transmission events and nosocomial infection rates were pooled by intensive care unit to calculate Spearman's rank-correlation test. During 100,781 patient days, 100,829 microbiological specimens from 24,362 patients were sampled (average investigation density: 1.0 sample per patient and day) and 3419 primary indicator organisms were cultured. Altogether, 462 transmissions (incidence density of 4.6 transmissions per 1000 patient days; range, 1.4-8.4 days) and 1216 nosocomial infections (incidence density of 12.1 per 1000 patient days; range, 6.2-16.6 days) were discerned. Correlation analysis was unable to reveal any association between the incidence of cross transmissions and nosocomial infections, duration of hospitalization, or device use. CONCLUSIONS: Differences in nosocomial infection rates between study intensive care units are not explained solely by cross transmissions. Other factors, like the severity of the patient's underlying diseases, the patient's endogenous flora, or invasive procedures, likely have a dominant effect on the magnitude of nosocomial infection rates.

Mortality attributable to hospital acquired infections with multidrug-resistant bacteria in a large group of German hospitals.

BACKGROUND: According to extrapolations, around 35,000 patients in Germany develop hospital acquired infections (HAI) with a multidrug-resistant organism (MDRO) every year, and about 1500 of them die. Previous estimations were based on laboratory data and prevalence studies. Aim of this study was to establish the incidences of hospital acquired MDRO infections and the resulting deaths by expert review. METHODS: Data on patients suffering from a hospital acquired MDRO infection were collected from 32 hospitals from all care levels. Records of patients with MDRO infection who died in the year 2016 underwent an onsite review by two experts to determine the impact of the infection, if any, on the cause of death. RESULTS: A total of 714,108 in-patients were treated in 32 hospitals participating in the study. Of these patients, 1136 suffered a hospital acquired MDRO infection (1.59 per 1000 patients). 215 patients with an MDRO infection died [0.301 per 1000, (95% CI 0,261-0,341)], but only in 78 cases this was estimated as the cause of death [0.109 per 1000 patients (95% CI 0.085-0.133)]. CONCLUSION: By putting the above rates in relation to the total number of in-patients in Germany, it can be rated that around 31,052 patients per year suffer a hospital acquired MDRO infection, and 2132 patients die from it. These results from our reviewer investigation confirm earlier extrapolations.

Early- and late-onset pneumonia: is this still a useful classification?

The choice of empirical treatment of nosocomial pneumonia in the intensive-care unit (ICU) used to rely on the interval after the start of mechanical ventilation. Nowadays, however, the question of whether in fact there is a difference in the distribution of causative pathogens is under debate. Data from 308 ICUs from the German National Nosocomial Infection Surveillance System, including information on relevant pathogens isolated in 11,285 cases of nosocomial pneumonia from 1997 to 2004, were used for our evaluation. Each individual pneumonia case was allocated either to early- or to late-onset pneumonia, with three differentiation criteria: onset on the 4th day, the 5th day, or the 7th day in the ICU. The frequency of pathogens was evaluated according to these categories. A total of 5,066 additional cases of pneumonia were reported from 2005 to 2006, after the CDC criteria had been modified. From 1997 to 2004, the most frequent microorganisms were Staphylococcus aureus (2,718 cases, including 720 with methicillin [meticillin]-resistant S. aureus), followed by Pseudomonas aeruginosa (1,837 cases), Klebsiella pneumoniae (1,305 cases), Escherichia coli (1,137 cases), Enterobacter spp. (937 cases), streptococci (671 cases), Haemophilus influenzae (509 cases), Acinetobacter spp. (493 cases), and Stenotrophomonas maltophilia (308 cases). The order of the four most frequent pathogens (accounting for 53.7% of all pathogens) was the same in both groups and was independent of the cutoff categories applied: S. aureus was first, followed by P. aeruginosa, K. pneumoniae, and E. coli. Thus, the predictabilities of the occurrence of pathogens were similar for the earlier (1997-to-2004) and later (2005-to-2006) time frames. This classification is no longer helpful for empirical antibiotic therapy, since the pathogens are the same for both groups.

Operating room ventilation with laminar airflow shows no protective effect on the surgical site infection rate in orthopedic and abdominal surgery.

OBJECTIVE: To evaluate whether operating room (OR) ventilation with (vertical) laminar airflow impacts on surgical site infection (SSI) rates. DESIGN: Retrospective cohort-study based on routine surveillance data. PATIENTS AND METHODS: Sixty-three surgical departments participating voluntarily in the German national nosocomial infections surveillance system "KISS" were included (a total of 99,230 operations). Active SSI surveillance was performed according to the methods and definitions given by the US National Nosocomial Infection Surveillance system. Surgical departments were stratified according to type of OR ventilation used: (1) turbulent ventilation with high-efficiency particulate air-filtered air, and (2) HEPA-filtered (vertical) laminar airflow ventilation. Multivariate analyses were performed by the generalized estimating equations method to control for the following variables as possible confounders: (a) Patient-based: wound contamination class, ASA score, operation duration, patients' age and gender, endoscopic operation; (b) Hospital-based: the number of beds in the hospital, its academic status, operation frequency, and long-term participation in KISS. RESULTS: The risk for severe SSI after hip prosthesis implantation was significantly higher using laminar airflow OR ventilation (1.63 < 1.06; 2.52>), as compared with turbulent ventilation. The adjusted odds ratios for the other operative procedures analyzed were: knee prosthesis 1.76 < 0.80, 3.85>; appendectomy 1.52 < 0.91, 2.53>; cholecystectomy 1.37 < 0.63, 2.97>; colon surgery 0.85 < 0.49, 1.49>; and herniorrhaphy 1.48 < 0.67; 3.25>. CONCLUSIONS: Unexpectedly, in this analysis, which controlled for many patient and hospital-based confounders, OR ventilation with laminar airflow showed no benefit and was even associated with a significantly higher risk for severe SSI after hip prosthesis.

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.

Risk factors for the development of nosocomial pneumonia and mortality on intensive care units: application of competing risks models.

INTRODUCTION: Pneumonia is a very common nosocomial infection in intensive care units (ICUs). Many studies have investigated risk factors for the development of infection and its consequences. However, the evaluation in most of theses studies disregards the fact that there are additional competing events, such as discharge or death. METHODS: A prospective cohort study was conducted over 18 months in five intensive care units at one university hospital. All patients that were admitted for at least 2 days were included, and surveillance of nosocomial pneumonia was conducted. Various potential risk factors (baseline- and time-dependent) were evaluated in two competing risks models: the acquisition of nosocomial pneumonia and discharge (dead or alive; model 1) and for the risk of death in the ICU and discharge alive (model 2). RESULTS: Patients from 1,876 admissions were included. A total of 158 patients developed nosocomial pneumonia. The main risk factors for nosocomial pneumonia in the multivariate analysis in model 1 were: elective surgery (cause-specific hazard ratio = 1.95; 95% CI 1.33 to 2.85) or emergency surgery (1.59; 95% CI 1.10 to 2.28) prior to ICU admission, usage of a nasogastric tube (3.04; 95% CI 1.25 to 7.37) and mechanical ventilation (5.90; 95% CI 2.47 to 14.09). Nosocomial pneumonia prolonged the length of ICU stay but was not directly associated with a fatal outcome (p = 0.55). CONCLUSION: More studies using competing risk models, which provide more accurate data compared to naive survival curves or logistic models, should be carried out to verify the impact of risk factors and patient characteristics for the acquisition of nosocomial infections and infection-associated mortality.

Development of a surveillance system for methicillin-resistant Staphylococcus aureus in German hospitals.

OBJECTIVE: To determine the appropriate method to calculate the rate of methicillin-resistant Staphylococcus aureus (MRSA) infection and colonization (hereafter, MRSA rates) for interhospital comparisons, such that the large number of patients who are already MRSA positive on admission is taken into account. DESIGN: A prospective, multicenter, hospital-based surveillance of MRSA-positive case patients from January through December 2004. SETTING: Data from 31 hospitals participating in the German national nosocomial infections surveillance system (KISS) were recorded during routine surveillance by the infection control team at each hospital. RESULTS: Data for 4,215 MRSA-positive case patients were evaluated. From this data, the following values were calculated. The median incidence density was 0.71 MRSA-positive case patients per 1,000 patient-days, and the median nosocomial incidence density was 0.27 patients with nosocomial MRSA infection or colonization per 1,000 patient-days (95% CI, 0.18-0.34). The median average daily MRSA burden was 1.13 MRSA patient-days per 100 patient-days (95% CI, 0.86-1.51), with the average daily MRSA burden defined as the total number of MRSA patient-days divided by the total number of patient-days times 100. The median MRSA-days-associated nosocomial MRSA infection and colonization rate, which describes the MRSA infection risk for other patients in hospitals housing large numbers of MRSA-positive patients and/or many patients who were MRSA positive on admission, was 23.1 cases of nosocomial MRSA infection and colonization per 1,000 MRSA patient-days (95% CI, 17.4-28.6). The values were also calculated for various MRSA screening levels. CONCLUSIONS: The MRSA-days-associated nosocomial MRSA rate allows investigators to assess the extent of MRSA colonization and infection at each hospital, taking into account cases that have been imported from other hospitals, as well as from the community. This information provides an appropriate incentive for hospitals to introduce further infection control measures.

Usefulness of severity-of-illness scores based on admission data only in nosocomial infection surveillance systems.

BACKGROUND: Surveillance of nosocomial infection (NI) and the use of reference data for comparison is recommended to improve the quality of patient care. In addition to standardization according to device use, another stratification of reference data according to patients' severity-of-illness scores is often required for benchmarking in intensive care units (ICUs). OBJECTIVE: To determine whether severity-of-illness scores on admission to the ICU are sufficient data for predicting the development of NI. METHODS: This study was performed in an interdisciplinary ICU at a teaching hospital. Two scores were studied: the Acute Physiology and Chronic Health Evaluation (APACHE) II scoring system and the Therapeutic Intervention Scoring System (TISS). The patient's clinical condition was evaluated on admission and reevaluated daily during the period before the development of NI. In addition, we recorded the number of intubations for every patient-day, the age and sex of the patients, and their history of operations. The Fisher exact test and the stepwise multiple logistic regression model were applied to identify significant predictors of NI. RESULTS: During a 12-month period, 270 patients with ICU stays of more than 24 hours were included in the study. Sixty-nine NIs were identified (incidence, 25.6 cases per 100 patients [95% confidence interval, 19.9-32.3]). A mean APACHE II score and a mean TISS score above the median for these scores, duration of ventilation above the median in the period before the development of NI, and patient age were significantly associated with the development of NI; the score data on admission provided a clearly poorer prediction. CONCLUSION: The APACHE II and TISS scores on admission are not useful predictors for NI in ICUs.

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.

Compliance with antiseptic hand rub use in intensive care units: the Hawthorne effect.

OBJECTIVE: To determine the influence the Hawthorne effect has on compliance with antiseptic hand rub (AHR) use among healthcare personnel. DESIGN: Observational study. SETTING: Five intensive care units of a university hospital in Berlin, Germany. PARTICIPANTS: Medical personnel were monitored in 2 periods regarding compliance with AHR use when there were indications for AHR use. In the first period, the personnel had no knowledge of being observed. The second observation period was announced to the staff of the intensive care units in advance and information about what the observer would be monitoring was provided. Potential confounders of compliance with AHR use included occupational groups (nurses, physicians, and other healthcare workers), intensive care units, and indications for AHR use before or after any procedure. RESULTS: Data were collected from 2,808 indications for AHR use. The overall rate of compliance was 29% (95% confidence interval, 26%-32%) in the first period and 45% (95% confidence interval, 43%-47%) in the second period. A logistic regression analysis with potential confounders revealed a significant odds ratio for the comparison between period 2 and period 1. The differences in compliance with AHR use were statistically significant (P<.001) between the occupational groups (nurses had the highest compliance and physicians had middle compliance) and between indication for AHR use before procedures and indication for AHR use after procedures. CONCLUSIONS: The Hawthorne effect has a marked influence on compliance with AHR use, with a 55% increase of compliance with overt observation. This result is consistent throughout subgroups. The rate of compliance with AHR use may in fact be lower than we thought because of results from studies that did not take the Hawthorne effect into account. The results of this study underline the necessity for infection control teams to be on wards as often as possible.

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%).

Evaluation of six agglutination tests for Staphylococcus aureus identification depending upon local prevalence of meticillin-resistant S. aureus (MRSA).

Most routine laboratory detection of Staphylococcus aureus isolates is based on rapid agglutination test systems. Failure of agglutination assays to identify meticillin-resistant S. aureus strains (MRSA) has been demonstrated. The aim of this study was to evaluate six commercially available agglutination tests for the detection of meticillin-sensitive S. aureus (MSSA) and mecA-positive MRSA strains. The Dry Spot Staphytect Plus test (Oxoid), the Pastorex Staph Plus test (Bio-Rad), the Slidex Staph-Kit and Slidex Staph Plus test (bioMérieux), the Staphaurex Plus test (Remel) and the Staphylase Test (Oxoid) were used. As determined by pulsed field gel electrophoresis, 52 distinct MRSA strains from five countries, 83 MSSA strains and 150 coagulase-negative staphylococci were included. Species identification and determination of susceptibility patterns were performed using colony morphology, Gram stain, catalase testing, tube coagulase testing, DNase testing, mannitol fermentation, susceptibility testing towards oxacillin by Etest, coagulase gene PCR, fibrinogen receptor gene PCR and PCR of the mecA gene. Sensitivity of the agglutination tests ranged from 82.7 to 100.0 % for MRSA strains and 92.8 to 100.0 % for MSSA strains, respectively. Specificity of the test systems ranged from 91.3 to 99.1 %. None of the six agglutination assays produced correct reactions for all staphylococci tested. Only the Dry Spot Staphytect Plus test correctly identified all 52 MRSA strains. For the other tests kits, sensitivity of MRSA detection was lower than for MSSA isolates. Depending upon the local MRSA prevalence and the parameter of interest (sensitivity or specificity), these test systems may be useful for routine diagnostic purposes.

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.

AMBU-KISS: quality control in ambulatory surgery.

BACKGROUND: Cost-containment measures have led to a constant increase in the number of patients cared for as outpatients. Several studies have demonstrated that surgical site infections result in considerable morbidity and excess health care costs from extended duration of hospitalization and antibiotic use. OBJECTIVE: AMBU-KISS is a protocol designed to create a reference database on surgical site infections for institutions involved in ambulatory surgery. METHODS: This study was carried out using a physician questionnaire. We compared surgical site infection rates for 3 indicator procedures in the ambulatory setting to those observed in the inpatient setting. The 3 indicator procedures chosen for the protocol were arthroscopic knee surgery and inguinal hernia and vein-stripping procedures. RESULTS: The arithmetic mean values of surgical site infection rates in arthroscopic surgery of the knee are 0.09% in the ambulatory setting and 0.11% in the hospital setting. For inguinal hernias, the respective rates are 0.65% and 0.78%. These differences, however, did not reach statistical significance (arthroscopic surgery, P = .8323 and inguinal herniotomies, P = .4895). A marked difference was observed for vein-stripping procedures, with surgical site infection rates of 0.38% in the ambulatory setting and 0.64% in the hospital setting. However, this difference was also not statistically significant, P = .1556. CONCLUSION: The AMBU-KISS protocol appears to be suitable for assessing and defining the magnitude of surgical site infections in ambulatory surgery. The preliminary results of our study show no significant differences for the 3 indicator procedures.

The burden of MRSA in four German university hospitals.

In the last few years, a dramatic increase of Methicillin-resistant Staphylococcus aureus (MRSA) detection in German hospitals can be recognized. Under this enormous pressure it is very important for infection control teams to assess the epidemiologic situation correctly. Therefore, a prospective multicenter hospital-based surveillance of MRSA cases was executed in four university hospitals with 1017-1333 beds in Germany. Routine surveillance data were recorded of all patients with MRSA isolates from clinical samples or screening cultures. Patients had been colonized or infected with MRSA during their hospital stay. In 2002 between 183 and 291 MRSA cases were treated in the respective hospitals (between 0.53 and 0.96 MRSA cases per 1000 patient days). Of these, 44.4% were MRSA infections. The most frequent type of MRSA infections were wound infections (56.9%) followed by pneumonia (21.0%) and bloodstream infections (15.1%). Of the infected patients 51.5% were already infected at admission. The median duration of isolation of MRSA patients in private rooms was between 11 and 16 days. Altogether 21,665 isolation days were observed in four hospitals; this means 1.52% of all patient days. On average, 9.0% of roommates were identified as MRSA carriers. Due to the high percentage of imported cases, the four university hospitals introduced a general screening for MRSA at admission in all ICUs and some further departments as well as an automatic alert system for readmitted patient with MRSA during their last hospital stay.

To isolate or not to isolate? Analysis of data from the German Nosocomial Infection Surveillance System regarding the placement of patients with methicillin-resistant Staphylococcus aureus in private rooms in intensive care units.

OBJECTIVE: To investigate whether isolating patients with MRSA in private rooms in ICUs (or cohorting) is a protective factor for nosocomial MRSA infection. DESIGN: Association between nosocomial MRSA infection rates and ICU structure and process parameters in the German Nosocomial Infection Surveillance System (KISS). SETTING: Two hundred twelve ICUs participating in KISS in 2001. METHODS: In June 2001, a structured questionnaire was sent to the participating ICUs regarding their preventive measures, their type and size, their patient-to-personnel ratios, and routine cultures. Univariate and multivariate analyses were conducted to identify risk factors for nosocomial MRSA infection. RESULTS: The questionnaire was completed by 164 (77.4%) of the ICUs. These ICUs had 325 nosocomial MRSA infections in a 5-year period (1997 to 2001). The mean incidence density of nosocomial MRSA infections was 0.3/1,000 patient-days. Ninety-one ICUs (55.5%) did not register any nosocomial MRSA infections during the observation period. Forty-two ICUs had an incidence density of at least 0.3/1,000 patient-days (75th percentile). Surgical ICUs were found to be a risk factor for a nosocomial MRSA infection rate above this threshold. Multivariate analysis found surgical ICUs to be an independent predictor and isolation in private rooms (or cohorts) to be a protective factor (OR, 0.36; CI95, 0.17-0.79). CONCLUSION: Many (34.4%) of the German ICUs have not isolated MRSA patients in private rooms or cohorts, a procedure associated with lower MRSA infection rates in this study.

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.

How many nosocomial infections are associated with cross-transmission? A prospective cohort study in a surgical intensive care unit.

OBJECTIVE: To determine the percentage of cross-transmissions in an intensive care unit (ICU) with high nosocomial infection (NI) rates according to the data of the German Nosocomial Infection Surveillance System. SETTING: A 14-bed surgical ICU of a 1,300-bed, tertiary-care teaching hospital. METHOD: Prospective surveillance of NIs during a period of 9 months. If an NI was present, the isolates of the following indicator pathogens were stored and typed by species: Staphylococcus aureus, Enterococcus species, Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumannii, and Enterobacter species. Pulsed-field gel electrophoresis was performed for typing of S. aureus strains and arbitrarily primed polymerase chain reaction was applied for the other pathogens. The presence of two indistinguishable strains in two patients was considered as one episode of cross-transmission. RESULTS: Two hundred sixty-two patients were observed during a period of 2,444 patient-days; 96 NIs were identified in 59 patients and the overall incidence density of NI was 39.3 per 1,000 patient-days. For 104 isolates, it was possible to consider typing results. Altogether, 36 cross-transmissions have lead to NIs in other patients. That means at least 37.5% of all NIs identified were due to cross-transmissions. CONCLUSION: Because of the method of this study, the percentage of NIs due to cross-transmission identified for this ICU is an "at least number." In reality, the number of cross-transmissions, and thus the number of avoidable infections, may have been even higher. However, it is difficult to assess whether the percentage of NIs due to cross-transmission determined for this ICU may be the crucial explanation for the relatively high infection rate in comparison to other surgical ICUs.

A quality management project in 8 selected hospitals to reduce nosocomial infections: a prospective, controlled study.

OBJECTIVE: To reduce the number of nosocomial infections (NIs) in surgical patients by a quality management approach. DESIGN: Prospective, controlled study in 8 medium-sized hospitals during a 26-month period. SETTING: Four study hospitals and 4 control hospitals. METHODS: In two 10-month intervention periods, 4 external physicians introduced quality circles and ongoing surveillance in the 4 study hospitals. There were three 8-week observation periods in all 8 hospitals with the same physicians before, during, and after the intervention periods. RESULTS: During the first observation period, almost identical overall incidence densities were found for the study hospitals and the control hospitals. During the course of the study, the overall incidence density decreased significantly in the study hospitals (risk ratio [RR], 0.74; 95% confidence interval [CI 95], 0.59 to 0.94) and nonsignificantly in the control hospitals (RR, 0.90; CI 95 0.70 to 1.16). With the use of a Cox regression model to evaluate the impact of the intervention periods while taking into account the distribution of risk factors for NI in both groups, a significant risk reduction (RR, 0.75; CI 95, 0.58 to 0.97) was observed after the first intervention period when comparing study and control hospitals. At the end of the study (ie, after the second intervention period), the difference between the study hospitals and the control hospitals was not significant (RR, 0.78; CI 95, 0.60 to 1.01). This was due to no further improvement at the end of the study in the study hospitals and a decrease in the control hospitals. CONCLUSION: This study demonstrates that NI rates can be significantly reduced by appropriate intervention methods in hospitals that are interested in quality management activities. However, continuous intense efforts are necessary to maintain these improvements.