Comparative efficacy of alternative hand-washing agents in reducing nosocomial infections in intensive care units

Nosocomial Serratia marcescens infections associated with extrinsic contamination of a liquid nonmedicated soap

OBJECTIVE

To determine the role of nonmedicated soap as a source of Serratia marcescens nosocomial infections (NIs) in hospital units with endemic S marcescens NI and to examine the mechanisms of soap colonization.

SETTING

University-affiliated tertiary-care hospitals.

METHODS

A prospective case-control study and an environmental investigation were performed to assess the relationship between S marcescens NIs in hospital units and S marcescens-contaminated soap. Soap-bottle use and handwashing practices were reviewed. Cultures of healthcare workers' (HCWs) hands were obtained before and after hand washing with soap.

RESULTS

5 of 7 hospital units with S marcescens NIs had soap bottles contaminated with S marcescens, compared to 1 of 14 other units (P=.006). After hand washing with an S marcescens-contaminated soap pump, HCWs' hands were 54 times more likely to be contaminated with S marcescens (P<.001).

CONCLUSIONS

Extrinsic contamination of a non-medicated liquid soap by S marcescens resulted in handborne transmission of S marcescens NIs by HCWs in our setting. This finding led to the application of strict guidelines for nonmedicated soap use and to the reinforcement of alcoholic hand disinfection.

Skin hygiene and infection prevention: more of the same or different approaches?

The purpose of this article is to review research indicating a link between hand hygiene and nosocomial infections and the effects of hand care practices on skin integrity and to make recommendations for potential changes in clinical practice and for further research regarding hand hygiene practices. Despite some methodological flaws and data gaps, evidence for a causal relationship between hand hygiene and reduced transmission of infections is convincing, but frequent handwashing causes skin damage, with resultant changes in microbial flora, increased skin shedding, and risk of transmission of microorganisms, suggesting that some traditional hand hygiene practices warrant reexamination. Some recommended changes in practice include use of waterless alcohol-based products rather than detergent-based antiseptics, modifications in lengthy surgical scrub protocols, and incorporation of moisturizers into skin care regimens of health care professionals.

Methicillin-Resistant Staphylococcus aureus Infections

Methicillin-resistant Staphylococcus aureus (MRSA) has continued to spread and cause serious nosocomial infections. Failure to control MRSA may result in higher rates of use of glycopeptides, which may, in turn, lead to higher rates of glycopeptide resistance. Resistance to glycopeptides has recently begun to appear in S. aureus. Transfer of glycopeptide-resistance genes from enterococci to S. aureus has been documented in laboratory experiments but has not yet been found in clinical isolates. Over time, MRSA is becoming more common in various subsets of the general population. Some studies claim that many MRSA-colonized outpatients and their close contacts have had no health care contacts, but these studies have usually not considered contacts in outpatient clinics. Several other recent studies have found that all or a vast majority of patients with MRSA have had frequent contact with health care providers. Failure to wash hands and disinfect equipment between patients, which has been commonly seen in studies of health care worker compliance with infection control measures, may explain much of the continuing spread. The source of spread of antibiotic-resistant microbes can be likened to an iceberg, with clinically obvious infections representing the tip of the iceberg and most of the spread coming from clinically inapparent colonized patients who represent most of the reservoir for transmission. Surveillance cultures to identify this reservoir are important to the control of spread with effective barrier precautions. Such precautions have been shown to reduce the spread of MRSA 15.6-fold compared with standard precautions.

Epidemiology and risk factors for nosocomial pneumonia. Emphasis on prevention

VAP is a complex nosocomial infection, the disease expression and resulting patient outcome of which is dependent on host factors, the causative organism, the timing and adequacy of treatment, and the presence of intrinsic or inducible antibiotic resistance. Significant improvements have been achieved in our ability to reduce the occurrence of VAP in the hospital setting. Clinicians caring for mechanically ventilated patients should strive to develop focused programs for the prevention of VAP, other nosocomial infections, and the occurrence of antibiotic-resistant infections at their institutions. The benefits of such programs are well demonstrated. The components of a PDSA (Plan-Do-STUDY-Act) model that can be simply employed to develop a VAP prevention program are as follows: Stages Plan: 1. Identify potentially modifiable risk factors for VAP at the institutional level. 2. Develop a strategy to modify or prevent the occurrence of these risk factors. [figure: see text] Do: 1. Carry out the planned intervention strategy. 2. Identify problems in the implementation of the designed intervention. 3. Update the intervention with solutions for the identified problems. 4. Collect basic data (e.g., VAP rates, severity of illness).

STUDY

1. Analyze data. 2. Summarize the results. Act: 1. Determine the overall success or failure of the intervention. 2. Identify potential modifications to improve the intervention strategy. 3. Prepare for next PDSA cycle. Inherent in the development and application of such programs is the concept that they are continuous processes striving to improve clinical performance over time (Fig. 3). At any given institution, the most likely approach to the prevention of NP and VAP will be a multifaceted one, employing interventions aimed at reducing the occurrence of aerodigestive tract colonization with pathogenic bacteria and aspiration. To be successful, such quality improvement programs must be embraced at the institutional level. Only in this way can hospitals hope to successfully reduce their rates of VAP and sustain or improve upon those efforts over time.

Patient education model for increasing handwashing compliance

BACKGROUND

A review of the literature on handwashing has documented the absence of research on the education of the patient as an intervention model for changing staff behavior regarding handwashing compliance. The primary objective of this project was to conduct a prospective control study of the effect of patient handwashing education on staff compliance with handwashing.

METHOD

A prospective, controlled, 6-week intervention/control study was performed in 4 community hospitals in South Jersey. Each hospital served as its own control. Patients were educated within 24 hours of admission about the importance of asking their health care workers to wash their hands. Soap usage and handwashing was calculated by bed-days. Patient follow-up was conducted through telephone interviews 2 weeks after discharge.

RESULTS

The patient handwashing education model increased soap usage by health care workers an average of 34% (P =.021); this increase was consistent across hospitals regardless of the initial soap usage rates. Of the patients interviewed, 81% read the materials provided, 57% asked health care workers whether they had washed their hands, and 81% of this 57% said they received positive responses.

CONCLUSIONS

For the first time, our findings document that education of patients regarding their role in monitoring handwashing compliance among health care workers can increase soap usage and handwashing and provide sustainable reinforcement of handwashing principles for health care workers.

A close look at alcohol gel as an antimicrobial sanitizing agent

BACKGROUND

Hand transmission of microbes by health care workers is a primary cause of nosocomial infections in both long-term and acute care facilities. Compliance with effective handwashing and hand sanitization regimens can break this cycle.

METHODS

We investigated the antimicrobial efficacy and irritation potential of 5 handwash product regimens: a nonantimicrobial lotion soap, an antimicrobial lotion soap, an alcohol gel sanitizer, a nonantimicrobial lotion soap with an alcohol gel sanitizer, and an antimicrobial lotion soap with an alcohol gel sanitizer. The regimens were evaluated by using a Healthcare Personnel Handwash procedure, and irritation was assessed by using expert hand evaluation after 25 consecutive washes.

RESULTS

The Healthcare Personnel Handwash data showed that the mean log reductions from baseline were greatest for the lotion soaps with alcohol gel sanitizer, less for the alcohol and the antimicrobial soap alone, and least for the bland soap. All of the product regimens showed a low potential for skin irritation.

CONCLUSION

In terms of both microorganism reduction and skin irritation, the most effective product regimens were the use of alcohol gel sanitizer in combination with either an antimicrobial or a plain lotion soap.

Vancomycin-resistant enterococci in intensive-care hospital settings: transmission dynamics, persistence, and the impact of infection control programs

Vancomycin-resistant enterococci (VRE) recently have emerged as a nosocomial pathogen especially in intensive-care units (ICUs) worldwide. Transmission via the hands of health-care workers is an important determinant of spread and persistence in a VRE-endemic ICU. We describe the transmission of nosocomial pathogens by using a micro-epidemiological framework based on the transmission dynamics of vector-borne diseases. By using the concept of a basic reproductive number, R0, defined as the average number of secondary cases generated by one primary case, we show quantitatively how infection control measures such as hand washing, cohorting, and antibiotic restriction affect nosocomial cross-transmission. By using detailed molecular epidemiological surveillance and compliance monitoring, we found that the estimated basic reproductive number for VRE during a study at the Cook County Hospital, Chicago, was approximately 3-4 without infection control and 0.7 when infection control measures were included. The impact of infection control was to reduce the prevalence from a predicted 79% to an observed 36%. Hand washing and staff cohorting are the most powerful control measures although their efficacy depends on the magnitude of R0. Under the circumstances tested, endemicity of VRE was stabilized despite infection control measures, by the constant introduction of colonized patients. Multiple stochastic simulations of the model revealed excellent agreement with observed pattern. In conjunction with detailed microbiological surveillance, a mathematical framework provides a precise template to describe the colonization dynamics of VRE in ICUs and impact of infection control measures. Our analyses suggest that compliance for hand washing significantly in excess of reported levels, or the cohorting of nursing staff, are needed to prevent nosocomial transmission of VRE in endemic settings.

Antimicrobial resistance in intensive care units

The unique nature of the intensive care unit (ICU) environment makes this part of the hospital a focus for the emergence and spread of many antimicrobial-resistant pathogens. There are ample opportunities for the cross-transmission of resistant bacteria from patient to patient, and patients are commonly exposed to broad-spectrum antimicrobial agents. Rates of resistance have increased for most pathogens associated with nosocomial infections among ICU patients, and rates are almost universally higher among ICU patients compared with non-ICU patients. There are many opportunities, however, to prevent the emergence and spread of these resistant pathogens through improved use of established infection control measures (i.e., patient isolation, hand washing, glove use, and appropriate gown use), and implementation of a systematic review of antimicrobial use.

Handwashing with soap or alcoholic solutions? A randomized clinical trial of its effectiveness

BACKGROUND

The effectiveness of an alcoholic solution compared with the standard hygienic handwashing procedure during regular work in clinical wards and intensive care units of a large public university hospital in Barcelona was assessed.

METHODS

A prospective, randomized clinical trial with crossover design, paired data, and blind evaluation was done. Eligible health care workers (HCWs) included permanent and temporary HCWs of wards and intensive care units. From each category, a random sample of persons was selected. HCWs were randomly assigned to regular handwashing (liquid soap and water) or handwashing with the alcoholic solution by using a crossover design. The number of colony-forming units on agar plates from hands printing in 3 different samples was counted.

RESULTS

A total of 47 HCWs were included. The average reduction in the number of colony-forming units from samples before handwashing to samples after handwashing was 49.6% for soap and water and 88.2% for the alcoholic solution. When both methods were compared, the average number of colony-forming units recovered after the procedure showed a statistically significant difference in favor of the alcoholic solution (P <.001). The alcoholic solution was well tolerated by HCWs. Overall acceptance rate was classified as "good" by 72% of HCWs after 2 weeks use. Of all HCWs included, 9.3% stated that the use of the alcoholic solution worsened minor pre-existing skin conditions.

CONCLUSIONS

Although the regular use of hygienic soap and water handwashing procedures is the gold standard, the use of alcoholic solutions is effective and safe and deserves more attention, especially in situations in which the handwashing compliance rate is hampered by architectural problems (lack of sinks) or nursing work overload.

Methicillin-resistant Staphylococcus aureus outbreak in a veterinary teaching hospital: potential human-to-animal transmission

During a 13-month period, 11 equine patients visiting a veterinary teaching hospital for various diagnostic and surgical procedures developed postprocedural infections from which methicillin (oxacillin)-resistant Staphylococcus aureus (MRSA) strains were isolated. The S. aureus isolates were identified by conventional methods that included Gram staining, tests for colonial morphology, tests for clumping factor, and tests for coagulase and urease activities and were also tested with the API STAPH IDENT system. Antimicrobial susceptibility tests were performed by the disk diffusion method. The biochemical profile and antibiogram of each isolate suggested that the isolates may have come from a common source. Because MRSA strains are very uncommon animal isolates but are rather common human isolates, a nasal swab specimen for culture was collected voluntarily from five persons associated with equine surgery and recovery in an attempt to identify a possible source of the organisms. MRSA strains were isolated from three of the five people, with one person found to be colonized with two biotypes of MRSA. The MRSA isolates from the people appeared to be identical to the isolates from horses. Further study of the isolates included SmaI and EagI macrorestriction analysis by pulsed-field gel electrophoresis conducted in two different laboratories. The results indicated that both the equine and human isolates were members of a very closely related group which appear to have originated from a common source. On the basis of the pattern associated with the infection, it is speculated that the members of the Veterinary Teaching Hospital staff were the primary source of the infection, although the specific mode of transmission is unclear.

Studies of antibiotic resistance within the patient, hospitals and the community using simple mathematical models

The emergence of antibiotic resistance in a wide variety of important pathogens of humans presents a worldwide threat to public health. This paper describes recent work on the use of mathematical models of the emergence and spread of resistance bacteria, on scales ranging from within the patient, in hospitals and within communities of people. Model development starts within the treated patient, and pharmacokinetic and pharmacodynamic principles are melded within a framework that mirrors the interaction between bacterial population growth, drug treatment and the immunological responses targeted at the pathogen. The model helps identify areas in which more precise information is needed, particularly in the context of how drugs influence pathogen birth and death rates (pharmacodynamics). The next area addressed is the spread of multiply drug-resistant bacteria in hospital settings. Models of the transmission dynamics of the pathogen provide a framework for assessing the relative merits of different forms of intervention, and provide criteria for control or eradication. The model is applied to the spread of vancomycin-resistant enterococci in an intensive care setting. This model framework is generalized to consider the spread of resistant organisms between hospitals. The model framework allows for heterogeneity in hospital size and highlights the importance of large hospitals in the maintenance of resistant organisms within a defined country. The spread of methicillin resistant Staphylococcus aureus (MRSA) in England and Wales provides a template for model construction and analysis. The final section addresses the emergence and spread of resistant organisms in communities of people and the dependence on the intensity of selection as measured by the volume or rate of drug use. Model output is fitted to data for Finland and Iceland and conclusions drawn concerning the key factors determining the rate of spread and decay once drug pressure is relaxed.

Drug resistance in intensive care units

Intensive care units (ICUs) are generally considered epicenters of antibiotic resistance and the principal sources of outbreaks of multi-resistant bacteria. The most important risk factors are obvious, such as excessive consumption of antibiotics exerting selective pressure on bacteria, the frequent use of invasive devices and relative density of a susceptible patient population with severe underlying diseases. Infections due to antibiotic-resistant bacteria have a major impact on morbidity and health-care costs. Increased mortality is not uniformly shown for all of these organisms: Methicillin-resistant Staphylococcus aureus (MRSA) seems to cause significantly higher mortality, in contrast to vancomycin-resistant enterococci (VRE). Therefore it is essential to diminish these potential risk factors, especially by providing locally adapted guidelines for the prudent use of antibiotic therapy. A quality control of antimicrobial therapy within a hospital, and especially within the ICU, might help to minimize the selection of multidrug-resistant bacteria. The restricted use of antimicrobial agents in prophylaxis and therapy has also been shown to have at least temporal effects on local resistance patterns. New approaches to the problem of drug resistance in ICUs are badly needed.

Outbreak of extended spectrum beta lactamase producing Klebsiella pneumoniae in a neonatal unit

An outbreak of extended spectrum beta lactamase producing Klebsiella pneumoniae (ESBLKp) in a neonatal unit was controlled using simple measures. Normally, the control of such infections can be time consuming and expensive. Seven cases of septicaemia resulted in two deaths. ESBLKp isolates were subtyped by pulsed field gel electrophoresis, and four of the five isolates typed were identical. Control of the outbreak was achieved by altered empiric antibiotic treatment for late onset sepsis and prevention of cross infection by strict attention to hand washing. Widespread colonisation of babies in the unit was presumed, so initial surveillance cultures were not performed. No further episodes of sepsis occurred.

Risk reduction in the intensive care unit

Many potentially preventable complications occur in patients who receive intensive care. We have reviewed the epidemiology of three important complications (venous thromboembolism, stress-related upper gastrointestinal bleeding, and vascular catheter-related infection) and evaluated common preventive treatments to provide evidence-based recommendations for prevention. We used English language articles located by MEDLINE or cross-citation, giving preference to articles published in the last 10 years, meta-analyses, and clinical trials that were randomized, double-blinded, and used intention-to-treat analysis. We recommend prophylaxis against venous thromboembolism in most patients, whereas those without respiratory failure or coagulopathy may not require prophylaxis against stress-related upper gastrointestinal hemorrhage. Chlorhexidine gluconate is the preferred antiseptic for disinfecting the skin prior to and during intravascular catheterization. Central venous catheters impregnated with antibacterial or antiseptic agents should be considered in patients at high risk for vascular catheter-related infection. Finally, central venous, pulmonary arterial, and systemic arterial catheters should be changed only when clinically indicated.

Vancomycin-resistant enterococci in intensive care hospital settings

Vancomycin-resistant enterococci (VRE) have recently emerged as a nosocomial pathogen and present an increasing threat to the treatment of severely ill patients in intensive-care hospital settings. We outline results of a study of the epidemiology of VRE transmission in ICUs and define a reproductive number R0; the number of secondary colonization cases induced by a single VRE-colonized patient in a VRE-free ICU, for VRE transmission. For VRE to become endemic requires R0 > 1. We estimate that in the absence of infection control measures R0 lies in the range 3-4 in defined ICU settings. Once infection control measures are included R0 = 0.6, suggesting that admission of VRE-colonized patients can stabilize endemic VRE.

Multiresistant bacteria as a hospital epidemic problem

Since the introduction of antibiotics into clinical use, bacteria have protected themselves by developing antibiotic resistance mechanisms. Currently, there are increasing problems worldwide with multiresistant bacteria. These problems are especially evident within hospitals, where they frequently present as nosocomial epidemics. Currently, the most important nosocomial resistance problems on a global scale are caused by methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci and Enterobacteriaceae with plasmid-encoded extended-spectrum beta-lactamases. In this review we describe the characteristics of nosocomial epidemics of these three groups of multiresistant nosocomial pathogens. Despite the differences in bacterial species, the differences in mechanisms of resistance, the different ecological niches and the different infections caused by these pathogens, there are striking similarities in the variables determining nosocomial spread. The existence of each of these multiresistant micro-organisms and their concurrent spread seem to result from extensive antibiotic use and lapses in compliance with infection control measures. Problems with these bacteria became evident as monoclonal outbreaks, soon followed by establishment of endemicity especially in intensive care units. Finally, endemicity seems to be established on general hospital wards and in chronic care facilities and nursing homes, creating a continuous influx of colonized patients into special care wards. High compliance with infection control measures and a prudent and more restrictive use of antibiotics are the key measures to prevent these epidemics.

Urosepsis in the critical care unit

Critical care unit patients show a higher risk of developing a bloodstream infection than ward patients. The urinary tract is the main source of hospital-acquired secondary bloodstream infection. Nosocomial urinary tract infection is promoted by bladder catheterization in the vast majority of cases. Aerobic gram-negative bacilli are the prevalent agents of bloodstream infection secondary to a nosocomial urinary tract infection. Sepsis and septic shock are severe complications of these infections in the critical care patient. Management of patients with a septic process of urinary source calls for the combination of adequate life-supporting care, an appropriate antibiotic therapy, and innovative adjunctive measures. Accurate catheter care is the best measure to adopt for the prevention of urosepsis.

Handwashing patterns in primary pediatric community clinics

Handwashing is acknowledged as a critical factor in the prevention of nosocomial infection. Nonetheless, health care personnel often wash their hands inadequately. The purpose of this study was to examine the flora of hands and the frequency of handwashing of physicians working in primary care pediatric community clinics. The fingers of the dominant hand of 55 physicians working in 12 clinics were sampled for bacterial cultures. Only 354/720 (49%) of the expected handwashings by 17 board-certified pediatricians were recorded as having been performed. None of them washed their hands after each contact with an examined child. All physicians' hands were found to be contaminated with microorganisms. Staphylococcus species were isolated from 47 (85.4%) of the physicians' hands. Methicillin-resistant Staphylococcus aureus was found on the hands of 9.1% of the physicians. Such contaminated hands may serve as a potential vector of community-acquired infection with highly resistant organisms. Compliance with handwashing recommendations among these physicians was low. An active educational infection control program must be introduced in ambulatory pediatric community clinics.

Magnitude and prevention of nosocomial infections in the intensive care unit

Nosocomial infections among intensive care unit (ICU) patients usually are related to the use of invasive devices (e.g., mechanical ventilators, urinary catheters, or central venous catheters). This article discusses the impact of these devices and other risk factors for nosocomial infection in ICU patients. Data on etiologic pathogens and device-related infection rates from the National Nosocomial Infection Surveillance System are presented, general infection control guidelines for ICUs are reviewed, and special infection control problems encountered in ICUs are discussed.

Vancomycin-resistant enterococcus. Detection, epidemiology, and control measures

VRE have spread rapidly since their initial description in 1988. Although much has been learned about the epidemiology of VRE, further studies are needed to establish the reservoirs of the organism and the relative importance of various modes of transmission. There is considerable anecdotal evidence that nosocomial transmission of VRE can be thwarted by using measures such as those recommended by HICPAC, especially if they are implemented promptly after VRE have been introduced into hospitals.

Candidemia in intensive care unit patients: risk factors for mortality

Aim of this study was to evaluate whether risk factors which predict the development of candidemia may also predict death in ICU patients with candidemia. During an 8-year-period all ICU patients whose blood cultures yielded Candida species (n = 40) were retrospectively evaluated in a case-control fashion. The average incidence of Candida bloodstream infections was 5.5 per 10,000 patient days, ranging from 2.4 in 1990 to 7.4 in 1994. C. albicans was the most common pathogen in candidemic patients, but the proportion of non-C. albicans strains showed an increasing trend during 1989-1993, with a major shift towards non-C. albicans species in 1994. The overall mortality of patients with candidemia was 58%. Mortality was highest in the group of patients with multi-organ dysfunction syndrome, especially among those in need of hemodialysis. Risk factors for the development of candidemia, such as age, malignancy, steroid use, i.v. catheterization, and the use of broad-spectrum antibiotics were not correlated with mortality in the ICU patients studied.

Fever in the neutropenic host

Fever in the neutropenic patient following myelosuppressive chemotherapy is a medical emergency. Appropriate antimicrobial therapy can dramatically reduce infection-related morbidity and mortality. This article reviews the rationale and methodology of treatment as well as its applicability to other neutropenic states. The utility of adjunct therapy with granulocyte- stimulating compounds is also discussed.

Infectious risks associated with the use of propofol

BACKGROUND

Investigations of the Centers for Disease Control into postoperative infections have implicated extrinsically contaminated propofol.

METHODS

To evaluate the infectious risk associated with intravenous anaesthetic agents, we surveyed the literature from 1971 to 1995 using the Medline database. Papers covering infections related to intravenous anaesthetic agents were included.

RESULTS

The review of the literature on infections associated with propofol and other intravenous anaesthetics shows that this infectious risk is minimal and often caused by breakdowns in aseptic techniques.

CONCLUSIONS

We conclude that, if standard hygienic precautions are taken, the risk of in-use contamination of intravenous anaesthetics is low. If strict hygienic guidelines are followed in handling propofol, this agent can be safely administered to patients.

New modalities for treating neonatal infection

While the overall incidence of infection has remained constant at approximately 7/1000 livebirths, the last decade has witnessed a reduction in early onset infections and a relative increase in nosocomial sepsis, chiefly with coagulase-negative staphylococci. Immaturity of host defence mechanisms contributes to an increasing susceptibility to infection with decreasing gestational age and birth weight. In the past, efforts to enhance host defence have included the use of granulocyte infusions, fresh frozen plasma, exchange blood transfusions and immunoglobulin therapy. Current trials are investigating the use of agents which enhance endogenous defence mechanisms, such as, recombinant human granulocyte colony-stimulating factant and recombinant human granulocyte-macrophage colony-stimulating factor and of pentoxifylline. In the meantime strict attention to handwashing and aseptic technique remain the best methods of preventing nosocomial sepsis.

Reported blood exposure rates and staff nurse satisfaction with a closed surgical drainage system

BACKGROUND

The purposes of this investigation were (1) to describe performance characteristics, incidence of exposure, and staff satisfaction with a closed drainage system, the Kendall Tru-Close, and (2) to compare performance, incidence of exposure, and satisfaction between the closed drainage system and a currently used surgical drainage system (the Hemovac).

METHODS

Subjects were 40 adult male and female patients who had undergone selective orthopedic joint surgery. Twenty patients received the Hemovac drainage system, and 20 patients received the Tru-Close drainage system. Data collection instruments included a patient demographic data form, a daily assessment form, a nurses' bedside survey (self-report), and a satisfaction questionnaire.

RESULTS

There were significantly fewer exposures with the closed drainage system when compared with the Hemovac system. An odds ratio of 5.09 indicated that the odds of exposure to fluids with the Hemovac system were five times greater than for the closed system. Nursing satisfaction scores were higher for the Tru-Close system than the Hemovac system for items that related to protection from exposure to self or environment. However, overall nursing satisfaction with the new device was mixed.

CONCLUSIONS

Although nurses liked the increased protection from exposure afforded by the Tru-Close drainage system, other patient management issues emerged related to the increased weight of the reservoir bag.

Outbreak of severe Pseudomonas aeruginosa respiratory infections due to contaminated nebulizers

During the six months from January-June 1994, 10 cases of severe and 11 of less severe pulmonary infection caused by Pseudomonas aeruginosa were diagnosed in patients with chronic obstructive airways disease. Possible sources were evaluated. P. aeruginosa was isolated from four of the 22 nebulizers tested. The relationship of isolates from the patients and nebulizers was confirmed by sero- and phage-typing, and by arbitrarily-primed polymerase chain reaction (AP-PCR). Three types were identified and the distribution of types in patients with severe infection was as follows (one patient had a multiple infection). Type I was isolated from two nebulizers and from sputa, and/or blood and/or bronchial protected specimen brush samples or bronchial lavage fluid from four patients. Type II came from the sputa of three patients and a third nebulizer; and type III from sputa and/or blood of four further patients and another nebulizer. The data provided evidence for the relation between P. aeruginosa as a cause of infection and the contamination of the nebulizers. When nebulizer mouthpieces were changed every 24 h and sterilized between patients, no more contamination occurred, and the outbreak ceased.

Quantitative Epidemiology

We provide guidance for new practitioners in the vocabulary of modern epidemiology and the application of quantitative methods. Most hospital epidemiology involves surveillance (observational) data that were not part of a planned experiment, so the rubric and logic of controlled experimental studies cannot be applied. Forms of incidence and prevalence often are confused. The names “cohort study” and “case-control study” are unfortunate, as cohort studies rarely involve cohorts and case-control studies allow no active control by the investigator. Either type of study can be prospective or retrospective. Results of studies with discrete outcomes (infected or not, lived or died) often are represented best by a form of the risk ratio with 95% confidence intervals. The potential distorting effects of selection bias, misclassification, and confounding need to be considered.

Treatment and Control of Colonization in the Prevention of Nosocomial Infections

Patients frequently develop nosocomial infections that are caused by normal flora colonizing the patient at the time of admission, or by exogenous pathogens that are acquired and subsequently colonize the patient after admission to the hospital. To prevent nosocomial infections, a variety of strategies have been used either to prevent colonization from occurring, to eradicate colonizing organisms, or to prevent the progression from colonization to infection. These strategies include implementation of infection control measures designed to prevent acquisition of exogenous pathogens, eradication of exogenous pathogens from patients or personnel who have become colonized, suppression of normal flora, prevention of colonizing flora from entering sterile body sites during invasive procedures, microbial interference therapy, immunization of high-risk patients, and modification of antibiotic utilization practices. Because strategies that require widespread use of antimicrobial agents to suppress or eradicate colonizing organisms tend to promote emergence of multidrug-resistant pathogens, greater emphasis should be given to those strategies that prevent colonization from occurring or employ techniques other than administration of prophylactic antibiotics to eradicate colonization. Restricting inappropriate use of antibiotics should reduce the frequency with which patients become colonized and infected with multidrug-resistant organisms.