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This study evaluated whether antibiotic cycling programmes using broad-spectrum agents including carbapenems were associated with increased rates of colonization or infection by Stenotrophomonas maltophilia. Retrospective analyses of colonization or infection by S. maltophilia from 1992 to 2002 were conducted using University of Virginia Hospital clinical microbiology records of patients with any culture positive for S. maltophilia and hospital epidemiology records of nosocomial S. maltophilia infections. Incidence rates were calculated and compared for cycling and non-cycling periods. No significant differences were found in incidence rates of S. maltophilia isolates between cycling and non-cycling periods, but there was a significant secular increase in the hospital-wide rate of infections caused by S. maltophilia (P=0.01728). Antibiotic cycling protocols were not associated with a significantly increased rate of colonization of S. maltophilia as determined by the frequency of patients having at least one positive routine clinical culture in this hospital.

The incidence of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE) infections continues to rise in National Nosocomial Infections Surveillance system hospitals, and these pathogens are reportedly causing more than 100,000 infections and many deaths each year in US healthcare facilities. This has led some to insist that control measures are now urgently needed, but several recent articles have suggested that isolation of patients does not work, is not needed, or is unsafe, or that a single cluster-randomized trial could be used to decide such matters. At least 101 studies have reported controlling MRSA infection and 38 have reported controlling VRE infection by means of active detection by surveillance culture and use of isolation for all colonized patients in healthcare settings where the pathogens are epidemic or endemic, in academic and nonacademic hospitals, and in acute care, intensive care, and long-term care settings. MRSA colonization and infection have been controlled to exceedingly low levels in multiple nations and in the state of Western Australia for decades by use of active detection and isolation. Studies suggesting problems with using such data to control MRSA colonization and infection have their own problems, which are discussed. Randomized trials are epidemiologic tools that can sometimes provide erroneous results, and they have not been considered necessary for studying isolation before it is used to control other important infections, such as tuberculosis, smallpox, and severe acute respiratory syndrome. No single epidemiologic study should be considered definitive. One should always weigh all available evidence. Infection with antibiotic-resistant pathogens such as MRSA and VRE is controllable to a low level by active detection and isolation of colonized and infected patients. Effective measures should be used to minimize the morbidity and mortality attributable to these largely preventable infections.

Cognitive function was assessed in 191 Bangladeshi children 6-9 years of age using verbal and nonverbal tests. These scores were added to a health surveillance database that was compiled over the four previous years that includes incidence of diarrhea and Entamoeba histolytica infection and nutritional status. The associations of diarrhea, malnutrition, and social factors with cognitive scores were analyzed statistically, and associations between diarrhea and test scores were controlled for the influence of social factors. Cognitive scores were negatively associated with stunting during school age, as well as the height-for-age and weight-for-age scores at study enrollment. Incidence of diarrhea was associated with nonverbal test scores before, but not after, controlling for socioeconomic factors. Generally E. histolytica infection was not found to independently influence scores, except that E. histolytica-associated dysentery was associated with lower test scores while dysentery of any etiology was not. Thus, malnutrition during the school age years, but not diarrhea or E. histolytica infection, was associated with a lower level of cognitive functioning. This suggested that intervention during school age years may be able to mitigate the cognitive deficiencies associated with malnutrition.

Background: Most hospitals in the United States do not perform active surveillance cultures and, thus, rely on clinical microbiological cultures (CMCs) to identify patients colonized with methicillin-resistant Staphylococcus aureus (MRSA). We sought to determine what proportion of patients who are colonized with MRSA at admission are identified by CMCs during hospitalization., Methods: From February 1998 through November 2002, patients found to be colonized with MRSA at admission by use of active surveillance cultures were identified. The proportion of colonized patients who had a CMC that was positive for MRSA, the number of CMCs performed and their type (ie, according to the anatomical site from which specimens were obtained for culture), and the number and type of CMCs that were positive for MRSA were calculated., Results: Four hundred thirty-seven patients were found to be colonized with MRSA at admission, and 98 of 1,238 CMCs (7.9%; 95% confidence interval, 6.5%-9.6%) performed for 66 of these patients (15%; 95% confidence interval, 11.9%-18.8%) were positive for MRSA. The number of nonisolated days that would have occurred by relying on CMCs to identify MRSA-colonized patients was 3,247 (mean, 7.4 days per patient). Among the anatomical sites from which specimens were obtained for CMC, wounds demonstrated the highest sensitivity (30.2%) for identifying MRSA-colonized patients., Conclusions: CMCs failed to identify 85% of MRSA-colonized patients, because, in part, CMCs identified only a small proportion of colonized patients. Because many studies have shown a decrease in the transmission of MRSA from colonized patients for whom contact precautions, rather than standard precautions, are used, the findings of this study suggest that failure to identify colonized patients and to use contact precautions may be an important reason for the increasing rate of nosocomial MRSA infection in hospitals in the United States.

The contribution of amebiasis to the burden of diarrheal disease in children and the degree to which immunity is acquired from natural infection were assessed in a 4-year prospective observational study of 289 preschool children in an urban slum in Dhaka, Bangladesh. Entamoeba histolytica infection was detected at least once in 80%, and repeat infection in 53%, of the children who completed 4 years of observation. Annually there were 0.09 episodes/child of E. histolytica-associated diarrhea and 0.03 episodes/child of E. histolytica-associated dysentery. Fecal immunoglobulin A (IgA) anti-parasite Gal/GalNAc lectin carbohydrate recognition domain (anti-CRD) was detected in 91% (183/202) of the children at least once and was associated with a lower incidence of infection and disease. We concluded that amebiasis was a substantial burden on the overall health of the cohort children. Protection from amebiasis was associated with a stool anti-CRD IgA response. The challenge of producing an effective vaccine will be to improve upon naturally acquired immunity, which does not provide absolute protection from reinfection.

Objectives: To assess the effects of interventions to prevent transmission of influenza and to increase employee compliance with influenza vaccination., Design: The change in the proportion of hospitalized patients with laboratory-confirmed nosocomial influenza was observed over time and assessed using chi-square for trend analysis. The association between nosocomial influenza in patients and healthcare worker (HCW) compliance with vaccine was assessed by logistic regression., Setting: A 600-bed, tertiary-care academic hospital., Methods: After an outbreak of influenza A at this hospital in 1988, a mobile cart program was instituted with increased efforts to motivate employees to be vaccinated and furloughed when ill as well as new measures to prevent nosocomial spread., Results: HCW vaccination rates increased from 4% in 1987-1988 to 67% in 1999-2000 (P < .0001). Proportions of nosocomially acquired influenza cases among employees or patients both declined significantly (P < .0001). Logistic regression analysis revealed a significant inverse association between HCW compliance with vaccination and the rate of nosocomial influenza among patients (P < .001)., Conclusion: A mobile cart vaccination program and an increased emphasis on HCWs to receive the vaccine were associated with a significant increase in vaccine acceptance and a significant decrease in the rate of nosocomial influenza among patients.

Purpose of Review: This article reviews many recent publications relevant to the prevention and control of nosocomial methicillin-resistant Staphylococcus aureus (MRSA) infection., Recent Findings: Higher risk-adjusted costs and mortality have been found for MRSA infections than for methicillin-susceptible S. aureus infections confirming their epidemiologic importance. Staphylococcal cassette chromosome mec, the genetic basis for MRSA, does not develop in methicillin-susceptible S. aureus exposed to antimicrobials. Instead virtually all patients acquire MRSA via spread. Nevertheless, antibiotic therapy provides a selective advantage for such spread, especially within healthcare settings where antimicrobial therapy is most frequent. Several studies have suggested better control of MRSA through antibiotic control, but far more studies have reported control using surveillance cultures and contact precautions for preventing spread (rather than just using standard precautions). More rapid detection of MRSA (within 6 h) has been reported using polymerase chain reaction, but studies using this method to reduce spread have not yet been published. A structured survey of research methods used regarding MRSA control noted that many studies had methodologic shortcomings (for example, none was a randomized trial), but nevertheless concluded that active detection and isolation work should be used. A Society for Healthcare Epidemiology of America guideline emphasized the same approach noting that scores of studies on multiple continents had reported success with this approach, with best results in several northern-European countries where all facilities used it routinely., Summary: Improved MRSA control is possible by detecting and isolating colonized patients.

Antibiotic-resistant bacteria are an increasingly common problem in intensive care units (ICUs), and they are capable of impacting on patient outcome, the ICU's budget and bed availability. This issue, coupled with recent outbreaks of illnesses that pose a direct risk to ICU staff (such as SARS [severe acute respiratory syndrome]), has led to renewed emphasis on infection control measures and practitioners in the ICU. Infection control measures frequently cause clinicians to practice in a more time consuming way. As a result it is not surprising that ensuring compliance with these measures is not always easy, particularly when their benefit is not immediately obvious. In this issue of Critical Care, two experts face off over the need to isolate patients infected with methicillin-resistant Staphylococcus aureus.

Objective: Oral vancomycin therapy has been a risk factor for turning culture positive for vancomycin-resistant Enterococcus (VRE). VRE colonization status was reviewed for all patients who received oral vancomycin and underwent prospective cultures., Methods: Data were extracted from the medical records of all patients receiving oral vancomycin between August 1995 and February 2001 regarding history, hospital course, and perirectal VRE cultures. Hospital policy required contact isolation for patients receiving oral vancomycin until colonization with VRE was excluded., Results: Twenty-six courses of oral vancomycin were given to 22 patients. VRE colonization status after completion of therapy was evaluated for 23 courses in 20 (91%) of these patients. None of these patients became VRE culture positive during a median follow-up of 18 days (range, 9 to 39 days), with a median duration of treatment of 10 days (range, 3 to 58 days), and with a median total dose of 6,500 mg (range, 1,250 to 29,000 mg). All patients received other antibiotics within 30 days prior to therapy with oral vancomycin, during therapy with oral vancomycin, or both; 95% had received anti-anaerobic therapy and 35% had received parenteral vancomycin., Conclusions: Even when other risk factors were present, no patient receiving oral vancomycin at our facility subsequently became culture positive for VRE. This suggests that oral vancomycin therapy or other antibiotic use, including anti-anaerobic therapy, may not be a significant independent risk factor for turning culture positive for VRE among patients not previously exposed to the microbe.

Background: The association of antibody responses with both innate and acquired immunity to amebiasis indicate that CD4+ T cells play a role in protection against Entamoeba histolytica infection. To test this hypothesis, we compared the genotype frequencies of human leukocyte antigen (HLA) class II alleles in a cohort of Bangladeshi children intensively monitored for E. histolytica infection for a 3-year period., Methods: Using logistic regression, we calculated the odds of disease by genotype and by haplotype., Results: The DQB1*0601 heterozygous and homozygous genotypes were found in 55% of E. histolytica-negative children but in only 34% of E. histolytica-positive children (overall odds ratio, 2.39; 95% confidence interval [CI], 1.26-4.54). Children who were heterozygous for the DQB1*0601/DRB1*1501 haplotype were 10.1 times (95% CI, 2.02-50.6) more likely to be both E. histolytica negative and serum anti-lectin immunoglobulin G negative at baseline. Other DQB1 and DRB1 alleles (DQB1*0202, DQB1*0301, and DRB1*0701) were not associated with any of the clinical outcomes related to amebiasis., Conclusion: A potential protective association was observed with the HLA class II allele DQB1*0601 and the heterozygous haplotype DQB1*0601/DRB1*1501. This association may explain why amebiasis does not occur in some children who are exposed to the parasite and implicates HLA class II-restricted immune responses in protection against E. histolytica infection.

The epidemiology, clinical features, nutritional status, and causative agents of diarrhea were studied in 289 Bangladeshi children (147 boys and 142 girls) 2-5 years old. The use of improved diagnostic tests for amebiasis enabled for the first time analysis of the contribution of Entamoeba histolytica to total diarrheal illness in this community setting. The average incidence rate of diarrhea was 1.8/child-year, and the average number of diarrheal days was 3.7 days/child-year over an average observation period of 2.8 years/child. Seventy-five percent of the diarrheal episodes were < or = 2 days in duration. Persistent diarrhea was relatively uncommon (0.2% of the children) and chronic diarrhea was observed in only one episode. Compared with malnourished and/or stunted children, better-nourished children experienced significantly fewer diarrheal episodes. The diarrheal incidence rate for children with blood group A was significantly less that that of the children with blood groups O and AB. The most frequent bacterial enteropathogens isolated from diarrheal stool specimens were enterotoxigenic Escherichia coli (9%) and Aeromonas species (9%), followed by Plesimonas shigelloides (4%) and Shigella flexneri (3.8%). Rotavirus was the most common viral agent isolated from diarrheal stool samples (5%). Giardia lamblia, Cryptosporidium parvum, and E. histolytica were identified in 11%, 8.4%, and 8%, respectively, of the diarrheal stool specimens. Dysentery was observed in 7.7% of all diarrheal episodes. The most common pathogens isolated from dysenteric stool were S. flexneri (11.6%), Aeromonas sp. (10%), E. histolytica (8.7%), Campylobacter jejunii (5.8%), P. shigelloides (4.3%), and A. caviae (4.3%). The overall incidence rate of E. histolytica-associated diarrhea was 0.08/child-year. Visible blood and hemoccult test-detected blood loss was found in 7% and 25%, respectively, of cases of E. histolytica-associated diarrhea. Children who had recovered from a diarrheal episode with E. histolytica, but not E. dispar, had half the chance of developing subsequent E. histolytica-associated diarrhea, consistent with the development of species-specific acquired immunity. In conclusion, the use of modern diagnostic tests demonstrated that E. histolytica contributed to overall morbidity from diarrheal illness. Understanding the etiology, frequency, and consequences of acute diarrhea in children from a developing country should aid in the design of interventions to improve child health.

An abrupt and persistent 30% increase in the rate of nosocomial infections was detected at a university teaching hospital after a prolonged period with a relatively constant nosocomial infection rate. Demographic data, risk factors for nosocomial infection, features of reported cases of nosocomial infection, and policy and procedure changes were evaluated for the periods of 1 January 1997 to 30 April 1998 (endemic period) and 1 May to 31 December 1998 (epidemic period). An extensive outbreak investigation revealed no evidence of a true outbreak of nosocomial infection. The apparent outbreak involved all four major body sites, began during the same month that an antibiotic management programme was started, involved the same adult medical and surgical units where antibiotics were being controlled, and occurred months before any significant change in antibiotic usage. A greater proportion of nosocomial infection during the epidemic period was reported by the nosocomial infection surveillance nurses, based on a treating physician's diagnosis rather than on specific clinical criteria. In an attempt to justify existing antibiotic prescribing practices after the implementation of an antibiotic management programme, clinicians altered the threshold at which they documented the presence of nosocomial infection. This change in documentation produced a large pseudo-outbreak of nosocomial infection.

Background: Because patients with vancomycin-resistant Enterococcus bacteremia (VREB) usually have a higher severity of illness, it has been unclear whether VREB is worse than vancomycin-susceptible Enterococcus bacteremia (VSEB)., Methods: Data on morbidity and case fatality rates and costs were pooled from studies comparing VREB and VSEB, identified by Medline January 1986 to April 2002) and meeting abstracts. Heterogeneity across studies was assessed with contingency table chi-square. Multivariate analyses (MVAs) controlling for other predictors were evaluated., Results: Thirteen studies compared case-fatality rates of VREB and VSEB. VREB case fatality was significantly higher (48.9% vs 19%; RR, 2.57; CI95, 2.27 to 2.91; attributable mortality = 30%). Five studies compared VREB with VSEB when bacteremia was the direct cause of death; VREB case fatality was significantly higher (39.1% vs 21.8%; RR, 1.79; CI95, 1.28 to 2.5; attributable mortality = 17%). Four MVAs found significant increases in case-fatality rates (OR, 2.10 to 4.0), 3 showed trends toward increase (OR, 1.74 to 3.34 with wide confidence intervals), and 3 with low statistical power found no difference. VREB recurred in 16.9% versus 3.7% with VSEB (P < .0001). Three studies reported significant increases in LOS, costs, or both with VREB., Conclusion: Most studies have had inadequate sample size, inadequate adjustment for other predictors of adverse outcomes, or both, but available data suggest that VREB is associated with higher recurrence, mortality, and excess costs than VSEB including multiple studies adjusting for severity of illness.

We sought to determine the ability of surveillance cultures and isolation of vancomycin-resistant Enterococcus (VRE)-colonized patients to control nosocomial VRE infection and colonization during a 5-year period (November 1994 through October 1999). During this period, VRE colonization was limited to 0.82% of admissions. The incidence of VRE infection was 0.12 cases per 1000 patient-days (attack rate, 0.07%). Colonized patients were first identified by surveillance (95%) or routine clinical cultures (5%); 14% of colonized patients had a positive clinical culture a median of 15 days after a positive surveillance culture. Ten percent of colonized patients were identified by surveillance at the time of transfer from another health care facility. Identification of these colonized patients was associated with reduction from a peak incidence rate of 2.07% to a rate of 1.25% and stabilization at this lower level. The use of surveillance cultures to identify and isolate patients with asymptomatic colonization can provide sustained control of the spread of VRE within a health care facility.

Background and Objective: CDC has estimated that 23% of Legionella infections are nosocomial. When a new hospital was being constructed and a substantial increase in transplantation was anticipated, an ultraviolet light apparatus was installed in the water main of the new building because 27% of water samples from taps in the old hospital contained Legionella. This study reports the rate of nosocomial Legionella infection and water contamination since opening the new hospital., Methods: Charts of all patients with positive Legionella cultures, direct immunofluorescent antibody (DFA), or urine antigen between April 1989 and November 2001 were reviewed. Frequencies of DFAs and urine antigens were obtained from the laboratory., Results: None of the 930 cultures of hospital water have been positive since moving into the new building. Fifty-three (0.02%) of 219,521 patients had a positive Legionella test; 41 had pneumonia (40 community acquired). One definite L. pneumophila pneumonia confirmed by culture and DFA in August 1994 was nosocomial (0.0005%) by dates. This patient was transferred after prolonged hospitalization in another country, was transplanted 11 days after admission, and developed symptoms 5 days after liver transplant. However, tap water from the patient's room did not grow Legionella. Seventeen (2.5%) of 670 urine antigens were positive for Legionella (none nosocomial). Thirty-three (1.2%) of 2,671 DFAs were positive, including 7 patients (21%) without evidence of pneumonia and 6 (18%) who had an alternative diagnosis., Conclusion: Ultraviolet light usage was associated with negative water cultures and lack of clearly documented nosocomial Legionella infection for 13 years at this hospital.

Objective: To determine the frequency with which methicillin-resistant Staphylococcus aureus (MRSA) is spread from colonized or infected patients to their household and community contacts., Design: Retrospective cohort study., Setting: University hospital., Participants: Household and community contacts of MRSA-colonized or -infected patients for whom MRSA screening cultures were performed., Results: MRSA was isolated from 25 (14.5%) of 172 individuals. Among the contacts of index patients who had at least one MRSA-colonized contact, those with close contact to the index patient were 7.5 times more likely to be colonized (53% vs 7%; 95% confidence interval, 1.1 to 50.3; P = .002). An analysis of antimicrobial susceptibility and DNA fingerprint patterns suggested person-to-person spread., Conclusions: MRSA colonization occurs frequently among household and community contacts of patients with nosocomially acquired MRSA, suggesting that transmission of nosocomially acquired MRSA outside of the healthcare setting may be a substantial source of MRSA colonization and infection in the community.