Hospital-Acquired Infections in Intensive Care Unit Patients An Overview with Emphasis on Epidemics

Surveillance activities for the detection of nosocomial infections at the University of Virginia Hospital (Charlottesville, Virginia) and at hospitals participating in the Virginia Statewide Infection Control Program have focused on outbreaks and device-related infections which are potentially preventable. Eleven outbreaks of nosocomial infections were identified at the University of Virginia Hospital between January 1, 1978 and December 31, 1982 (9.8 outbreaks/100,000 admissions). Ten of the 11 were centered in critical care units. The 269 patients involved in the epidemics represented 0.2% of all hospital admissions and 3.7% of all patients who developed nosocomial infections. Eight of the 11 outbreaks involved infection of the bloodstream, and the 90 patients who developed a bloodstream infection as part of an epidemic represented 8% of all patients with nosocomial bloodstream infections identified during the five-year study period. The reservoir of the 11 outbreaks involved devices (5), contaminated cocaine (1), probable blood products (1), other patients (3), and nursing personnel (1). Forty-one percent of all nosocomial bloodstream infections and 41% of all nosocomial pneumonias occurred in intensive care units (ICUs).

In 38 hospitals in the state of Virginia with ICUs and practitioners who voluntarily reported surveillance data between June 1,1980 and May 31,1982, there were 264,757 patients admitted and a crude infection rate of 3%. Of note is that 1,867 of the 7,407 nosocomial infections (25%) occurred in the ICU patients. Several factors point to a compelling argument that the highest priority in infection control resources be assigned to the prevention and control of ICU infections: ICU patients often have serious device-related infections and may be identified as high risk prior to infection. Furthermore, they are at risk of being infected as part of a major outbreak. Such characteristics define a population of hospitalized patients, many of whose infections are preventable.

Disseminated toxoplasmosis presenting as septic shock five weeks after renal transplantation

We discuss a case of acute disseminated toxoplasmosis in a renal transplant recipient presenting with septic shock. Our literature review of disseminated toxoplasmosis presenting as septic shock reveals a disease process that is rapid and almost uniformly fatal. This unusual presentation warrants a high index of suspicion in transplant recipients with immediate administration of appropriate empiric antimicrobials.

Inflammatory response and clinical course of adult patients with nosocomial bloodstream infections caused by Candida spp

Candida spp. are an important cause of nosocomial bloodstream infection (nBSI) and are associated with significant morbidity and mortality. An historical cohort study was performed to evaluate the clinical course of 60 randomly selected adult patients with nBSIs caused by Candida spp. Patients with BSI caused by Candida albicans (n = 38) and non-albicans spp. (n = 22) were compared with 80 patients with Staphylococcus aureus BSI by serial systemic inflammatory response syndrome (SIRS) and APACHE II scores. The patients had a mean age of 52 years, the length of hospital stay before BSI averaged 21 days, and 57% of patients required care in an intensive care unit before BSI. The mean APACHE II score was 17 on the day of BSI, and 63% of BSIs were caused by C. albicans. Antifungal therapy within the first 24 h of onset of BSI was appropriate in 52% of patients. Septic shock occurred in 27% of patients, and severe sepsis in an additional 8%. Overall mortality was 42%, and the 7-day mortality rate was 27%. The inflammatory response and clinical course were similar for patients with BSI caused by C. albicans and non-albicans spp. In univariate analysis, progression to septic shock was correlated with high overall mortality, as was an APACHE II score >25 at the onset of BSI. In multivariate analysis, the APACHE II score at the onset of BSI and a systemic inflammatory response independently predicted overall mortality, but the 7-day mortality rate was only predicted independently by the APACHE II score. Clinical course and mortality in patients with Candida BSI were predicted by systemic inflammatory response and APACHE II score, but not by the infecting species.

Antibiotic-Resistant Bloodstream Infections in Hospitalized Patients: Specific Risk Factors in a High–Risk Population?

BACKGROUND

The aim of this study was to explore characteristics that are associated with bloodstream infections due to specific multiresistant microorganisms (methicillinresitant Staphylococcus aureus, MRSA; vancomycin-resistant enterococci, VRE; third-generation cephalosporin-resistant Enterobacteriaceae) or Candida spp. in hospitalized patients.

PATIENTS AND METHODS

All patients who experienced a bloodstream infection with one of the aforementioned pathogens between September 1999 and October 2001 were included into a statistical analysis of independent risk factors. The possible impact of previous antibiotic and antifungal therapies was evaluated.

RESULTS

Of the study population, 22% had two or more episodes with different pathogens. In the 314 patients with a single bloodstream infection MRSA was isolated in 189 patients, VRE in 31, Enterobacteriaceae in 13, and Candida spp. in 80 patients. Crude mortality was high in the study population (overall 40%) and varied between 33% (MRSA bacteremia only) and 58% (VRE bacteremia only). Patients who yielded more than one of the pathogens under surveillance had crude mortalities ranging from 41% to 83% (all four pathogens). In this group of high-risk patients, the following factors were independently associated with the individual pathogen: prior chemotherapy (OR 4.88 CI(95) 1.50-15.87) and bronchoscopy (OR 3.17 CI(95) 1.05-9.52) for VRE patients; burns (OR 4.50 CI(95) 0.90-22.73), presence of a tracheostomy (OR 4.22 CI(95) 1.15-15.38) and acute dialysis (OR 3.62 CI(95) 0.99-13.16) for patients with Enterobacteriaceae; and an underlying malignant disease (OR 1.98 CI95 0.99-3.97), performance of a bowel endoscopy (OR 2.80 CI(95) 1.27-6.13) and presence of a central venous catheter (CVC) (OR 12.34 CI(95) 1.63-90.91) for patients with candidemia.

CONCLUSION

Patients with bacteremia due to VRE, Enterobacteriaceae or Candida spp. had more severe risk factors associated with the respective pathogen than patients with MRSA bacteremia.

Clonal spread of methicillin-resistant Staphylococcus aureus in a large geographic area of the United States

Methicillin resistance in Staphylococcus aureus has rapidly increased over the last two decades. This increase is paralleled by the emergence of unique multi-resistant MRSA clones. In Brazil, Argentina, Uruguay, Portugal and Czech Republic a specific MRSA clone is widely spread, the so-called Brazilian epidemic clone. Another epidemic clone, the Iberian clone, is disseminated in Spain, Portugal, Belgium, Scotland, Italy, Germany and New York. Thus, a large number of hospital-acquired infections have been caused by specific MRSA clones. Using different molecular techniques for MRSA typing, we verified that two unique epidemic clones are spread over large geographic area in the US. In addition, we showed that a previously described MRSA clone type, the New York clone (I::A:A), is widely spread beyond the New York frontiers.

Racial bias in using USMLE step 1 scores to grant internal medicine residency interviews

PURPOSE

To determine whether the United States Medical Licensing Examination (USMLE) Step 1 score, commonly used in screening residency applicants for interviews, eliminates a greater proportion of African-American applicants from the interview process at an internal medicine residency program.

METHOD

A survey of internal medicine residency programs was performed to determine the prevalence of using USMLE Step 1 scores to grant interviews. A cohort of applicants was analyzed by constructing a database of USMLE Step 1 scores from the Electronic Residency Application Service (ERAS) database of applications from U.S., Canadian, and osteopathic medical schools to one residency program in 2000. Each applicant was classified as African American or non-African American. Rejection rates were then calculated for each five-point increment from a hypothetical threshold rejection score of <180 to <215.

RESULTS

Responses were received from 259 residency programs (69%), and 92% used the USMLE Step 1 score in deciding which applicants to interview. A cohort of 626 non-African-American and 47 African-American applicants was analyzed. The proportion of applicants below each incremental threshold score was significantly higher for African-American applicants (p <.05 at each level). Depending on the threshold score used, an African-American applicant was three to six times less likely to be offered an interview.

CONCLUSIONS

When USMLE Step 1 scores are used to screen applicants for a residency interview, a significantly greater proportion of African-American students will be refused an interview.

Risk factors for Candida species colonization of neonatal intensive care unit patients

BACKGROUND

Candida spp. are increasingly important pathogens in neonatal intensive care units (NICU). Prior colonization is a major risk factor for candidemia, but few studies have focused on risk factors for colonization, particularly in NICU patients.

METHODS

A prospective, multicenter cohort study was performed in six NICUs to determine risk factors for Candida colonization. Infant gastrointestinal tracts were cultured on admission and weekly until NICU discharge and health care worker hands were cultured monthly for Candida spp.

RESULTS

The prevalence of Candida spp. colonization was 23% (486 of 2157 infants); 299 (14%), 151 (7%) and 74 (3%) were colonized with Candida albicans, Candida parapsilosis and other Candida spp., respectively. Multiple logistic regression analysis adjusting for length of stay, birth weight < or = 1000 g and gestational age < 32 weeks revealed that use of third generation cephalosporins was associated with either C. albicans (155 incident cases) or C. parapsilosis (104 incident cases) colonization. Use of central venous catheters or intravenous lipids were risk factors for C. albicans, whereas delivery by cesarean section was protective. Use of H2 blockers was an independent risk factor for C. parapsilosis. Of 2989 cultures from health care workers' hands, 150 (5%) were positive for C. albicans and 575 (19%) for C. parapsilosis, but carriage rates did not correlate with NICU site-specific rates for infant colonization.

CONCLUSIONS

We speculate that NICU patients acquire Candida spp., particularly C. parapsilosis, from the hands of health care workers. H2 blockers, third generation cephalosporins and delayed enteral feedings alter gastrointestinal tract ecology, thereby facilitating colonization.

Effective suppression of vancomycin-resistant Enterococcus species in asymptomatic gastrointestinal carriers by a novel glycolipodepsipeptide, ramoplanin

Nosocomial bloodstream infections due to vancomycin-resistant enterococci (VRE) are associated with increased morbidity rates, mortality rates, and hospitalization costs. Gastrointestinal carriage of VRE is an important risk factor for subsequent infections. This 3-arm, phase II, double-blinded, randomized, multicenter, placebo-controlled study evaluated the safety and efficacy of oral ramoplanin (a novel, nonabsorbed glycolipodepsipeptide) versus placebo for suppression of gastrointestinal VRE colonization. Sixty-eight patients who were colonized with VRE were enrolled and received 2 daily doses of ramoplanin (100 mg or 400 mg) or placebo orally for 7 days. The primary end point was the proportion of persons per group from whom VRE were not recovered (VRE-free) on days 7, 14, and 21 after screening. After treatment, VRE-free status was as follows: day 7, none of the 20 patients in the placebo group, and 17 of 21 (P<.001) and 18 of 20 (P<.001) in the 100-mg and 400-mg ramoplanin groups, respectively; on day 14, 2 of 20 patients in the placebo group, and 6 of 21 (P=.134) and 7 of 17 (P=.028), in the 100-mg and 400-mg ramoplanin groups, respectively. By day 21, there were no differences between treatment groups. Adverse events were similar for all treatment groups. Ramoplanin was safe and effective in temporarily suppressing gastrointestinal VRE carriage.

Systemic inflammatory response syndrome in adult patients with nosocomial bloodstream infection due to Staphylococcus aureus

To determine the impact of methicillin resistance on clinical course and outcome, we evaluated nosocomial bloodstream infections (BSIs) due to Staphylococcus aureus that were diagnosed in 82 adult patients at the Medical College of Virginia Hospitals from December 1995 through May 1997. Patients with BSI due to methicillin-resistant S. aureus were compared with patients with BSI due to methicillin-susceptible S. aureus; the groups did not differ with regard to inflammatory response or outcome. Mortality was predicted by systemic inflammatory response and Acute Physiology and Chronic Health Evaluation II score but did not correlate with bacterial resistance to methicillin.

Risk factors for candidal bloodstream infections in surgical intensive care unit patients: the NEMIS prospective multicenter study. The National Epidemiology of Mycosis Survey

To assess risk factors for development of candidal blood stream infections (CBSIs), a prospective cohort study was performed at 6 sites that involved all patients admitted to the surgical intensive care unit (SICU) for >48 h over a 2-year period. Among 4276 such patients, 42 CBSIs occurred (9.82 CBSIs per 1000 admissions). The overall incidence was 0.98 CBSIs per 1000 patient days and 1.42 per 1000 SICU days with a central venous catheter in place. In multivariate analysis, factors independently associated with increased risk of CBSI included prior surgery (relative risk [RR], 7.3), acute renal failure (RR, 4.2), receipt of parenteral nutrition (RR, 3.6), and, for patients who had undergone surgery, presence of a triple lumen catheter (RR, 5.4). Receipt of an antifungal agent was associated with decreased risk (RR, 0.3). Prospective clinical studies are needed to identify which antifungal agents are most protective and which high-risk patients will benefit from antifungal prophylaxis.

Antifungal antibiotics and breakthrough bacteremias

Patients with fever and neutropenia are at high risk for infection ( approximately 50%) and bacteremia ( approximately 20%). As a result, most are treated with antibacterial prophylaxis until their absolute neutrophil count exceeds 500 cells/mm(3) and their temperature returns to normal. The 1997 guidelines of the Infectious Diseases Society of America suggested 1 of 3 regimens: vancomycin plus ceftazidime, monotherapy with ceftazidime or imipenem (possibly cefepime or meropenem), or dual therapy with an aminoglycoside plus an antipseudomonal beta-lactam.

The impact of hospital-acquired bloodstream infections

Nosocomial bloodstream infections are a leading cause of death in the United States. If we assume a nosocomial infection rate of 5%, of which 10% are bloodstream infections, and an attributable mortality rate of 15%, bloodstream infections would represent the eighth leading cause of death in the United States. Because most risk factors for dying after bacteremia or fungemia may not be changeable, prevention efforts must focus on new infection-control technology and techniques.

Nosocomial bloodstream infections caused by Acinetobacter species in United States hospitals: clinical features, molecular epidemiology, and antimicrobial susceptibility

We examined the clinical and epidemiological features of nosocomial bloodstream infections (BSIs) caused by Acinetobacter species and observed from 1 March 1995 through 28 February 1998 at 49 United States hospitals (SCOPE National Surveillance Program). Acinetobacter species were found in 24 hospitals (49%) and accounted for 1.5% of all nosocomial BSIs reported. One hundred twenty-nine isolates were identified either as A. baumannii (n=111) or other Acinetobacter species (n=18). Patients with A. baumannii BSI, compared with patients with nosocomial BSI caused by other gram-negative pathogens, were more frequently observed in the intensive care unit (69% vs. 47%, respectively; P<.001; odds ratio [OR] 2.4; 95% confidence interval [CI] 1.6-3.7) and were more frequently receiving mechanical ventilation (58% vs. 30%, respectively; P<.001; OR 3.2; 95% CI 2.1-4.8). Crude mortality in patients with A. baumannii BSI was 32%. Molecular relatedness of strains was studied by use of polymerase chain reaction-based fingerprinting. Clonal spread of a single strain occurred in 5 hospitals. Interhospital spread of epidemic A. baumannii strains was not observed. The most active antimicrobial agents against A. baumannii (90% minimum inhibitory concentration values) were imipenem (1 mg/L; 100% of isolates susceptible), amikacin (8 mg/L; 96%), tobramycin (4 mg/L; 92%), and doxycycline (4 mg/L; 91%). Thirty percent of isolates were resistant to > or =4 classes of antimicrobials and were considered to be multidrug resistant.

Epidemiology of bacteriuria caused by vancomycin-resistant enterococci--a retrospective study

BACKGROUND

The epidemiology of vancomycin-resistant enterococcal (VRE) bacteriuria has not been previously described. Our objectives are to describe the frequency of VRE bacteriuria, to use strict definitions to distinguish symptomatic urinary tract infection (UTI) versus urine colonization without pyuria versus asymptomatic bacteriuria with pyuria, and to describe the outcomes of each group.

METHODS

We used a retrospective analysis of patients with VRE bacteriuria in an academic medical center.

RESULTS

During the 18-month study period, 98 of the 107 patients (92%) with urine cultures positive for VRE (23/10,000 admissions), had charts that were available for review. In 94 of 98 patients, the organism was Enterococcus faecium, and in only 4 was Enterococcus faecalis recovered. Thirty-seven patients were colonized with VRE; 21 patients had asymptomatic bacteriuria, and the status of 27 patients was not ascertainable. Thirteen patients had VRE UTIs with two associated bacteremias and one death. Patients with UTI versus patients without UTI were more likely to have an underlying malignancy (39% vs 9%, P =.014).

CONCLUSION

The majority of urine cultures yielding VRE do not represent true infection, rather colonization or asymptomatic bacteriuria.

Handwashing compliance by health care workers: The impact of introducing an accessible, alcohol-based hand antiseptic

CONTEXT

Under routine hospital conditions handwashing compliance of health care workers including nurses, physicians, and others (eg, physical therapists and radiologic technicians) is unacceptably low.

OBJECTIVES

To investigate the efficacy of an education/ feedback intervention and patient awareness program (cognitive approach) on handwashing compliance of health care workers; and to compare the acceptance of a new and increasingly accessible alcohol-based waterless hand disinfectant (technical approach) with the standard sink/soap combination.

DESIGN

A 6-month, prospective, observational study.

SETTING

One medical intensive care unit (ICU), 1 cardiac surgery ICU, and 1 general medical ward located in a 728-bed, tertiary care, teaching facility.

PARTICIPANTS

Medical caregivers in each of the above settings.

INTERVENTIONS

Implementation of an education/ feedback intervention program (6 in-service sessions per each ICU) and patient awareness program, followed by a new, increasingly accessible, alcohol-based, waterless hand antiseptic agent, initially available at a ratio of 1 dispenser for every 4 patients and subsequently 1 for each patient.

MAIN OUTCOME MEASURE

Direct observation of hand-washing for 1575 potential opportunities monitored over 120 hours randomized for both time of day and bed locations.

RESULTS

Baseline handwashing compliance before and after defined events was 9% and 22% for health care workers in the medical ICU and 3% and 13% for health care workers in the cardiac surgery ICU, respectively. After the education/feedback intervention program, handwashing compliance changed little (medical ICU, 14% [before] and 25% [after]; cardiac surgery ICU, 6% [before] and 13% [after]). Observations after introduction of the new, increasingly accessible, alcohol-based, waterless hand antiseptic revealed significantly higher handwashing rates (P<.05), and handwashing compliance improved as accessibility was enhanced-before 19% and after 41% with 1 dispenser per 4 beds; and before 23% and after 48% with 1 dispenser for each bed.

CONCLUSIONS

Education/feedback intervention and patient awareness programs failed to improve handwashing compliance. However, introduction of easily accessible dispensers with an alcohol-based waterless handwashing antiseptic led to significantly higher handwashing rates among health care workers.

Risk factors for candidemia in Neonatal Intensive Care Unit patients. The National Epidemiology of Mycosis Survey study group

BACKGROUND

Candida species are important nosocomial pathogens in neonatal intensive care unit (NICU) patients.

METHODS

A prospective cohort study was performed in six geographically diverse NICUs from 1993 to 1995 to determine the incidence of and risk factors for candidemia, including the role of gastrointestinal (GI) tract colonization. Study procedures included rectal swabs to detect fungal colonization and active surveillance to identify risk factors for candidemia. Candida strains obtained from the GI tract and blood were analyzed by pulsed field gel electrophoresis to determine whether colonizing strains caused candidemia.

RESULTS

In all, 2,847 infants were enrolled and 35 (1.2%) developed candidemia (12.3 cases per 1,000 patient discharges or 0.63 case per 1,000 catheter days) including 23 of 421 (5.5%) babies < or =1,000 g. After adjusting for birth weight and abdominal surgery, forward multivariate logistic regression analysis demonstrated significant risk factors, including gestational age <32 weeks, 5-min Apgar <5; shock, disseminated intravascular coagulopathy, prior use of intralipid, parenteral nutrition, central venous catheters, H2 blockers, intubation or length of stay > 7 days before candidemia (P < 0.05). Catheters, steroids and GI tract colonization were not independent risk factors, but GI tract colonization preceded candidemia in 15 of 35 (43%) case patients.

CONCLUSIONS

Candida spp. are an important cause of late onset sepsis in NICU patients. The incidence of candidemia might be decreased by the judicious use of treatments identified as risk factors and avoiding H2 blockers.

Does the Centers for Disease Control's NNIS system risk index stratify patients undergoing cardiothoracic operations by their risk of surgical-site infection?

BACKGROUND

In 1991, the Centers for Disease Control and Prevention devised the National Nosocomial Infection Surveillance (NNIS) System risk index to stratify populations of surgical patients by the risk of acquiring surgical-site infections (SSIs).

OBJECTIVE

To determine whether the NNIS risk index adequately stratifies a population of cardiothoracic surgery patients by the risk of developing SSI.

DESIGN

Case-control study.

SETTING

The University of Iowa Hospitals and Clinics, a 900-bed, midwestern, tertiary-care hospital.

PATIENTS

201 patients with SSIs identified by prospective infection control surveillance and 398 controls matched by age, gender, type of procedure, and date of procedure. All patients underwent cardiothoracic operative procedures between November 1990 and January 1994.

RESULTS

The SSI rate was 7.8%. Seventy-four percent of cases and 80% of controls had a NNIS risk index score of 1; 24% of cases and 16% of controls had a score of 2 (P=.05). Patients with a NNIS risk score > or =2 were 1.8 times more likely to develop an SSI than those with a NNIS score <2 (odds ratio, 1.83; 95% confidence interval, 1.14-2.94, P=.01). The duration of the procedure was the only component of the index that stratified the population by risk of SSI.

CONCLUSIONS

The risk of SSI after cardiothoracic operations increases as the NNIS risk index score increases. However, this index only dichotomized the patient population on the basis of the procedure duration. More research is needed to develop a risk index that adequately stratifies the risk of SSI after cardiothoracic operations.

Does infection control control infections?

Compelling data exist for the return on investment of infection control activities. Such information is important in the era of managed care where cost containment and accountability are mandated.

Molecular epidemiology of vancomycin-resistant Enterococcus faecium in a large urban hospital over a 5-year period

To investigate the dissemination of vancomycin-resistant Enterococcus faecium (VREF) in a 728-bed tertiary-care hospital, all clinical VREF isolates recovered from June 1992 to June 1997 were typed by pulsed-field gel electrophoresis, and the transfer histories of the patients were documented. A total of 413 VREF isolates from urine (52%), wounds (16%), blood (11%), catheter tips (6%), and other sites (15%) were studied. VREF specimens mostly came from patients on wards (66%) but 34% came from patients in an intensive care unit. The number of VREF isolates progressively increased over time, with higher rates of isolation during the winter months and lower rates in the late summer months. Four distinct banding patterns were detected by pulsed-field gel electrophoresis among 316 samples (76%). Strain A (122 samples; 30%) appeared in June 1992 as the first VREF strain and was found until December 1994 throughout the entire hospital. Type B (92 samples; 22%) was initially detected in January 1994 and disappeared in November 1996. Strain C (10 samples; 2%) was limited to late 1996 and early 1997. Strain D (92 samples; 22%) showed two major peaks during March 1996 to August 1996 and January 1997 to February 1997. Unrelated strains (97 samples; 24%) appeared 1 year after the appearance of the first VREF isolate, and the numbers increased slightly over the years. Nosocomial acquisition (i.e., no known detection prior to admission and first isolation from cultures performed with samples retrieved >/=2 days after hospitalization) was found for 316 (91%) of 347 patients. Despite the implementation of Centers for Disease Control and Prevention guidelines, the proportion of related strains and high number of nosocomial cases of infection indicate a high transmission rate inside the hospital. The results imply an urgent need for stringent enforcement of more effective infection control measures.

Seeking vancomycin resistant Staphylococcus aureus among patients with vancomycin-resistant enterococci

Clinical isolates of Staphylococcus aureus displaying intermediate resistance to vancomycin (VISA) have been identified. The objective of our study was to identify VISA colonization among patients known to be colonized or infected with vancomycin-resistant enterococci (VRE). Eight weekly point prevalence screening surveys for VRE and S. aureus were conducted on 5 hospital units. Of the 243 patients screened, 31 (12.8%) were colonized with VRE. In addition, 18 inpatients were already known to be VRE-positive. Fourteen (28.6%) of the 49 VRE-positive patients were co-colonized with S. aureus. All 30 S. aureus isolates from these 14 patients were methicillin-resistant (MRSA) but remained vancomycin-susceptible (minimal inhibitory concentration [MIC] range, 0.75-2 microg/mL). Population analysis profiling demonstrated no evidence of heteroresistant subpopulations that could grow on agar containing 3 microg/mL vancomycin for any of the MRSA isolates. Although 23 (77%) of 30 staphylococcal isolates had vancomycin MICs of 1.5 or 2 microg/mL, no VISA strains (MICs, 8-16 microg/mL) were recovered.

Persistence of Legionella pneumophila in a hospital's water system: a 13-year survey

OBJECTIVE

To describe the molecular epidemiology of Legionella pneumophila infections in the University of Iowa Hospitals and Clinics (UIHC).

DESIGN

Molecular epidemiological study using pulsed-field gel electrophoresis (PFGE).

SETTING

A large university teaching hospital. ISOLATES: All surviving isolates obtained from culture-proven nosocomial L. pneumophila infections and all surviving isolates obtained from the University of Iowa Hospital and Clinics' water supply between 1981 and 1993.

RESULTS

Thirty-three isolates from culture-proven nosocomial cases of L. pneumophila pneumonia were available for typing. PFGE of genomic DNA from the clinical isolates identified six different strains. However, only strain C (16 cases) and strain D (13 cases) caused more than 1 case. Strain C caused clusters of nosocomial infection in 1981, 1986, and 1993 and also caused 4 sporadic cases. Strain D caused a cluster in 1987 and 1988 plus 4 sporadic cases. Of the six strains causing clinical infections, only strains C and D were identified in water samples. PFGE identified three strains in the water supply, of which strains C and D caused clinical disease and also persisted in the water supply during most of the study period.

CONCLUSION

Specific strains of L. pneumophila can colonize hospital water supplies and cause nosocomial infections over long periods of time.

Elucidating the origins of nosocomial infections with Candida albicans by DNA fingerprinting with the complex probe Ca3

Computer-assisted DNA fingerprinting with the complex probe Ca3 has been used to analyze the relatedness of isolates collected from individuals with nosocomial bloodstream infections (BSIs) and hospital care workers (HCWs) in the surgical and neonatal intensive care units (ICUs) of four hospitals. The results demonstrate that for the majority of patients (90%), isolates collected from commensal sites before and after collection of a BSI isolate were highly similar or identical to the BSI isolate. In addition, the average similarity coefficient for BSI isolates was similar to that for unrelated control isolates. However, the cluster characteristics of BSI isolates in dendrograms generated for each hospital compared to those of unrelated control isolates in a dendrogram demonstrated a higher degree of clustering of the former. In addition, a higher degree of clustering was observed in mixed dendrograms for HCV isolates and BSI isolates for each of the four test hospitals. In most cases, HCW isolates from an ICU were collected after the related BSI isolate, but in a few cases, the reverse was true. Although the results demonstrate that single, dominant endemic strains are not responsible for nosocomial BSIs in neonatal ICUs and surgical ICUs, they suggest that multiple endemic strains may be responsible for a significant number of cases. The results also suggest that cross-contamination occurs between patients and HCWs and between HCWs in the same ICU and in different ICUs. The temporal sequence of isolation also suggests that in the majority of cases HCWs are contaminated by isolates from colonized patients, but in a significant minority, the reverse is true. The results of this study provide the framework for a strategy for more definitive testing of the origins of Candida albicans strains responsible for nosocomial infections.

Nosocomial bloodstream infections in United States hospitals: a three-year analysis

Nosocomial bloodstream infections are important causes of morbidity and mortality. In this study, concurrent surveillance for nosocomial bloodstream infections at 49 hospitals over a 3-year period detected >10,000 infections. Gram-positive organisms accounted for 64% of cases, gram-negative organisms accounted for 27%, and 8% were caused by fungi. The most common organisms were coagulase-negative staphylococci (32%), Staphylococcus aureus (16%), and enterococci (11%). Enterobacter, Serratia, coagulase-negative staphylococci, and Candida were more likely to cause infections in patients in critical care units. In patients with neutropenia, viridans streptococci were significantly more common. Coagulase-negative staphylococci were the most common pathogens on all clinical services except obstetrics, where Escherichia coli was most common. Methicillin resistance was detected in 29% of S. aureus isolates and 80% of coagulase-negative staphylococci. Vancomycin resistance in enterococci was species-dependent--3% of Enterococcus faecalis strains and 50% of Enterococcus faecium isolates displayed resistance. These data may allow clinicians to better target empirical therapy for hospital-acquired cases of bacteremia.

National epidemiology of mycoses survey (NEMIS): variations in rates of bloodstream infections due to Candida species in seven surgical intensive care units and six neonatal intensive care units

Candida species are the fourth most frequent cause of nosocomial bloodstream infections, and 25%-50% occur in critical care units. During an 18-month prospective study period, all patients admitted for > or = 72 hours to the surgical (SICUs) or neonatal intensive care units (NICUs) at each of the participant institutions were followed daily. Among 4,276 patients admitted to the seven SICUs in six centers, there were 42 nosocomial bloodstream infections due to Candida species (9.8/1,000 admissions; 0.99/1,000 patient-days). Of 2,847 babies admitted to the six NICUs, 35 acquired a nosocomial bloodstream infection due to Candida species (12.3/1,000 admissions; 0.64/1,000 patient-days). The following were the most commonly isolated Candida species causing bloodstream infections in the SICU: Candida albicans, 48%; Candida glabrata, 24%; Candida tropicalis, 19%; Candida parapsilosis, 7%; Candida species not otherwise specified, 2%. In the NICU the distribution was as follows: C. albicans, 63%; C. glabrata, 6%; C. parapsilosis, 29%; other, 3%. Of the patients, 30%-50% developed incidental stool colonization, 23% of SICU patients developed incidental urine colonization, and one-third of SICU health care workers' hands were positive for Candida species.

Electronic medical record systems at academic health centers: advantages and implementation issues

The growth of managed care has fueled expectations for a more coordinated delivery of clinical services and a reduction of unnecessary utilization. Among the most important issues that constrain these expectations is the transfer of medical information. Electronic medical record (EMR) systems appear to offer substantive advantages over paper records for both containing costs and improving the quality of care. However, incorporation of EMR systems into practice settings has languished. Among the barriers to implementation are software problems of codification and entry of data, security issues, a dearth of integrated delivery systems, reluctant providers, and prohibitive costs. The training programs of academic health centers (AHCs) are optimal environments for testing and implementing EMR systems. AHCs have the expertise to resolve remaining software issues, the components necessary for integrated delivery, a culture for innovation in clinical practice, and a generation of future providers that can be acclimated to the requisites for computerized records. The authors critically review these and other issues of implementing EMR systems at AHCs and propose four necessary steps for financing their implementation.

Molecular epidemiology of gram-negative bacteremia

We did pulsed field gel electrophoresis (PFGE) and antibiotic susceptibility testing on 202 gram-negative isolates obtained from blood cultures between 1 January 1989 and 31 December 1993. Seventy-eight patients had at least two gram-negative isolates of the same species recovered from blood drawn one or more days apart and met the other study criteria. Twenty patients had only 1 bloodstream infection, 48 patients had 1 recurrence of bacteremia, and 10 patients had > 1 recurrence of bacteremia. Of 80 recurrences of bacteremia, 52 (65%) were relapses and 28 (35%) were reinfections. Seventy-eight percent of the episodes of bacteremia occurring < or = 300 days apart were relapses, and 100% occurring > 300 days apart were reinfections (P < .001). Organisms causing recurrent bacteremia were not more resistant than those causing initial episodes. In conclusion, most episodes of recurrent gram-negative bacteremia were relapses. Relapses and reinfections could not be distinguished only by the length of time between episodes or by antimicrobial susceptibility patterns.

Recurrent gram-negative bacteremia: incidence and clinical patterns

Fifty-eight patients who had at least two episodes of gram-negative bacteremia were evaluated to define the epidemiology of recurrent bacteremia caused by these organisms. Thirty-two patients (55%) had single relapses, 16 (28%) had one reinfection, and 10 (17%) had more than one recurrence of bacteremia. Intravenous catheters were the most common probable source of bacteremia. Relapses occurred earlier after the initial episode than did reinfections (58 days vs. 292 days; P = .002). The duration of antibiotic therapy for the first episode was shorter for patients with relapses than for those with reinfections (13.9 days vs. 17.5 days; P = .046). Microorganisms causing recurrent bacteremic episodes were not unusually resistant to antimicrobial agents. Reinfections may be difficult to prevent because they are associated with the severity of the underlying illness, which may not improve. The frequency of relapses might be reduced by increasing the duration of antibiotic therapy and eliminating foci of infection.

Costs of providing primary care: comparison of an academic general medicine practice with an MGMA benchmark

Market-based healthcare reform has placed great financial pressures on academic departments of internal medicine. The current emphasis and increased recruiting for primary care have not been accompanied by a financially supportive institutional culture or favorable third-party reimbursement system for the generalist practitioners. In one department's analysis, there was a large difference in revenue (-$130,000) compared to a Medical Group Management Association (MGMA) standard, yet a reduced level of compensation for primary-care physicians, $61,000 less per full-time equivalent (FTE). Total overhead per FTE in our department was $80,000 greater than comparable practices of the MGMA standard. We have estimated the institutional strategic costs of having primary-care clinics in three separate locations in the city of Richmond ($74,000/FTE). No viable cost-cutting options placed the primary-care program in positive balance, but the analysis contributed to a creative institutional approach for a solution.

Vancomycin-resistant Staphylococcus aureus: infection control considerations

The lessons of the antibiotic era are crystal clear: in the footrace between humans and microbes, the organisms' genetic repertoire and efficient response to environmental changes will win the day. New antibiotics are essential, but their shelf life will be enhanced only if used wisely and sparingly. The antibiotic era is continually threatened by inappropriate decisions regarding use, inappropriate choices, and unnecessary durations of treatment. In concert with improved prescribing habits, efforts to identify and isolate resistant organisms introduced from outside institutions are essential. Last, continual energy is needed to influence the behavior of health care professionals and to maintain optimal infection control policies and procedures. We remain optimistic about the ability of infectious diseases physicians to respond appropriately to continued microbial challenges with research, education, and wise practice.

An epidemic of presumed Acanthamoeba keratitis that followed regional flooding. Results of a case-control investigation

OBJECTIVES

To investigate an outbreak of presumed Acanthamoeba keratitis (AK), to identify risk factors associated with its development, and to characterize the changing epidemiology of AK.

METHODS

We performed a pairwise-matched case-control study involving 31 patients who were diagnosed as having AK between July 1993 and December 1994. Risk factors were identified using conditional logistic regression analysis. To investigate the impact of regional flooding, we stratified counties within Iowa by whether their water facilities were affected and then calculated population-based estimates of the incidence of AK.

RESULTS

During the study, 43 presumed incident cases of AK were diagnosed; 31 were included in the case-control study. Cases were diagnosed based on the clinical presentation of keratitis, positive tandem scanning confocal microscopy examination results, and confirmatory cytopathologic findings. There were no positive culture specimens. On average, cases had symptoms for 8 weeks before diagnosis, most notably photophobia (94%), red eyes (94%), and pain (80%). Contact lens use (odds ratio [OR] = 44.16; P = .02) and fishing (OR = 22.62; P = .04) were independent predictors of the development of AK. The presence of a humidifier in the home (OR = 0.08; P = .03) and having household water that originated from a private well instead of the municipal water supply (OR = 0.12; P = .08) were protective. Twenty-nine of 30 cases resided in counties in which the water supplies were affected by flooding as determined by the Department of Natural Resources, Des Moines, Iowa. The incidence of AK in these counties was more than 10 times higher than that in the unaffected counties (relative risk = 10.83, 95% confidence interval, 1.48-79.49; P < .003).

CONCLUSIONS

We describe an epidemic of keratitis that, based on clinicopathologic and epidemiological evidence, is consistent with AK. As in previous outbreaks of culture-proven AK, contact lens use was the major risk factor. Both the results of the case-control study and the population-based incidence estimates suggest that the recent outbreak may be caused, in part, by the effects of regional flooding. However, because the outbreak also coincided with a change in diagnostic techniques, we cannot eliminate recognition bias as the reason for the apparently changing epidemiology.

The dynamics of disease progression in sepsis: Markov modeling describing the natural history and the likely impact of effective antisepsis agents

We conducted a 9-month prospective cohort study of 2,527 patients with systemic inflammatory response syndrome in three intensive care units and three general wards in a tertiary health care institution. Markov models were developed to predict the probability of movement to and from more severe stages--sepsis, severe sepsis, or septic shock--at 1, 3, and 7 days. For patients with sepsis, severe sepsis, and septic shock, the probabilities of remaining in the same category after 1 day were .65, .68, and .61, respectively. The probability for progression after 1 day was .09 for sepsis to severe sepsis and .026 for severe sepsis to shock. The probability of patients with sepsis, severe sepsis, and septic shock dying after 1 day was .005, .009, and .079, respectively. The model can be used to predict the reduction in end organ dysfunction and mortality with use of increasingly effective antisepsis agents.

Hospital specificity, region specificity, and fluconazole resistance of Candida albicans bloodstream isolates

In a survey of bloodstream infection (BSI) isolates across the continental United States, 162 Candida albicans isolates were fingerprinted with the species-specific probe Ca3 and the patterns were analyzed for relatedness with a computer-assisted system. The results demonstrate that particular BSI strains are more highly concentrated in particular geographic locales and that established BSI strains are endemic in some, but not all, hospitals in the study and undergo microevolution in hospital settings. The results, however, indicate no close genetic relationship among fluconazole-resistant BSI isolates in the collection, either from the same geographic locale or the same hospital. This study represents the first of three fingerprinting studies designed to analyze the origin, genetic relatedness, and drug resistance of Candida isolates responsible for BSI.

Septic shock: an analysis of outcomes for patients with onset on hospital wards versus intensive care units

OBJECTIVE

To determine if early interventions for septic shock were associated with reduced mortality.

DESIGN

Retrospective cohort study.

SETTING

University hospital intensive care unit (ICU) and general wards.

PATIENTS

Forty-one consecutive patients prospectively identified with positive blood cultures and septic shock. Although all patients were eventually treated in an ICU, ten (24%) patients were on a general ward at the onset of septic shock, and 31 (76%) were in an ICU setting.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Over a period of 9 mos, a cohort of 41 patients who had positive blood cultures and septic shock was prospectively identified. The 28-day crude mortality was 46% (19 deaths). We compared the management of septic shock and outcome for patients on a general ward vs. those patients in an ICU setting. Of the ten patients on the ward at time of shock onset (median age 55.5 yrs; median Acute Physiology and Chronic Health Evaluation [APACHE] II score of 18.5), seven (70%) died. In contrast, the 31 patients receiving intensive care when shock developed were older and more ill (median age 66 yrs; median APACHE II 24), yet had a mortality of 39% (12 deaths). The odds ratio (OR) for death for ward patients compared with ICU patients was 3.57 (p=.17). In a multivariate logistic regression analysis, two risk factors for mortality were important: APACHE II score (p=.015) and ward status (p=.08). Candida species in the bloodstream is known to have a high attributable mortality. When type of bloodstream pathogen (Candida species vs. bacteria) was added to the model, APACHE II (OR 2.64 for 10-unit increase) remained significant (p=.014), but ward status (OR 3.97) became statistically nonsignificant (p=.222). The patients who were on a general ward when their shock developed had a median delay of 67 mins before transfer to an ICU setting. Ward patients received an intravenous fluid bolus after a median delay of 27 mins, whereas those in the ICU who received a fluid bolus did so after a median of 15 mins (p=.48). Ward patients also had a median delay of 310 mins to receive inotropic support compared with a median 22.5 mins (p=.037) for the patients in an ICU setting when shock started.

CONCLUSIONS

The data suggest that for patients with septic shock on wards, there were clinically important delays in transfer of patients to the ICU, receipt of intravenous fluid boluses, and receipt of inotropic agents. However, the most powerful predictors of mortality were APACHE II scores and bloodstream infection with Candida species.

National epidemiology of mycoses survey: a multicenter study of strain variation and antifungal susceptibility among isolates of Candida species

The National Epidemiology of Mycoses Survey (NEMIS) involves six academic centers studying fungal infections in surgical and neonatal intensive care unit (ICU) patients. We studied variation in species and strain distribution and anti-fungal susceptibility of 408 isolates of Candida spp. Candida spp. were isolated from blood, other normally sterile site cultures, abscesses, wounds, catheters, and tissue biopsies of 141 patients hospitalized in the surgical (107 patients) and neonatal (34 patients) ICUs of medical centers located in Oregon, Iowa, California, Texas, Georgia, and New York. Isolates were also obtained from selected colonized patients (16 patients) and the hands of health care workers (27 individuals). DNA typing was performed using pulsed field gel electrophoresis, and antifungal susceptibility to amphotericin B, 5-fluorocytosine, fluconazole, and itraconazole was determined using National Committee for Clinical Laboratory Standards (NCCLS) methods. Important variation in susceptibility to itraconazole and fluconazole was noted: MICs of itraconazole ranged from 0.25 microgram/mL (MIC90) in Texas to 2.0 micrograms/mL (MIC90) in New York. Similarly, the MIC90 for fluconazole was higher for isolates from New York (64 micrograms/mL) compared to the other sites (8-16 micrograms/mL). In general, DNA typing revealed patient-unique strains; however, there were 13 instances of possible cross-infection noted in 5 of the medical centers. Notably, 9 of the 13 clusters involved species of Candida other than C. albicans. Potential transmission from patient-to-patient (C. albicans, C. glabrata, C. tropicalis, C. parapsilosis) and health care worker-to-patient (C. albicans, C. parapsilosis, C. krusei) was noted in both surgical ICU and neonatal ICU settings. These data provide further insight into the epidemiology of nosocomial candidiasis in the ICU setting.

National surveillance of nosocomial blood stream infection due to Candida albicans: frequency of occurrence and antifungal susceptibility in the SCOPE Program

Surveillance of nosocomial blood stream infections (BSI) in the USA between April 1995 and June 1996 revealed that Candida was the fourth leading cause of nosocomial BSI, accounting for 8% of all infections. Fifty-two percent of 379 episodes of candidemia were due to Candida albicans. In vitro susceptibility studies using the 1997 National Committee for Clinical Laboratory Standards reference method demonstrated that 92% of C. albicans isolates were susceptible to 5-fluorocytosine and 90% were susceptible to fluconazole and itraconazole. Geographic variation in susceptibility of fluconazole and itraconazole was observed. Isolates from the Northwest and Southeast regions were more frequently resistant to fluconazole (13.3-15.5%) and to itraconazole (17.2-20.0%) than those from the Northeast and Southwest regions (2.9-5.5% resistant to fluconazole and itraconazole). Continued surveillance for infections caused by C. albicans and other species of Candida among hospitalized patients is recommended.

Methicillin-resistant Staphylococcus aureus outbreak: a consensus panel's definition and management guidelines

OBJECTIVE

To provide medical personnel with a definition of an outbreak of methicillin-resistant Staphylococcus aureus (MRSA) and guidelines for managing potential outbreaks.

PARTICIPANTS

Eighteen panel members were chosen from different specialties, types of institutions, and geographic regions. Representatives from the American Society of Consultant Pharmacists, the American Society of Health-Systems Pharmacists, the Society for Healthcare Epidemiology of America, and the National Association of Directors of Nursing Administration participated.

CONSENSUS PROCESS

In preparation for the conference, panel members reviewed the literature and wrote abstracts outlining their personal opinions on the core issues, which were circulated to all participants. During a weekend conference, the panel summarized the reviewed literature, defined an MRSA outbreak, and developed management guidelines.

EVIDENCE

Published literature, clinical experience, and expert opinion concerning the emergence and subsequent management of MRSA cases in health care institutions.

RESULTS

An outbreak of MRSA was defined as either an increase in the rate of MRSA cases or a clustering of new cases due to the transmission of a single microbial strain in the health care institution. An increased rate of cases can be defined statistically or experientially and includes both infected and colonized patients. A potential outbreak should trigger stepwise, multidisciplinary actions consisting of basic epidemiologic procedures (phase I) to form an initial epidemiologic hypothesis of an outbreak (phase II) followed by a standard epidemiologic workup (phase III) and microbiologic studies (phase IV) to confirm the hypothesis. Mupirocin calcium treatments should be considered to decolonize health care workers during the fourth phase, even before typing is completed.

CONCLUSIONS

Until studies can be conducted to delineate the effectiveness of different recommendations, the proposed guidelines may provide a useful starting point that can be adapted to meet an individual institution's specific needs.