Susan M. Ray

Multistate Point-Prevalence Survey of Health Care–Associated Infections

BACKGROUND Currently, no single U.S. surveillance system can provide estimates of the burden of all types of health care-associated infections across acute care patient populations. We conducted a prevalence survey in 10 geographically diverse states to determine the prevalence of health care-associated infections in acute care hospitals and generate updated estimates of the national burden of such infections. METHODS We defined health care-associated infections with the use of National Healthcare Safety Network criteria. One-day surveys of randomly selected inpatients were performed in participating hospitals. Hospital personnel collected demographic and limited clinical data. Trained data collectors reviewed medical records retrospectively to identify health care-associated infections active at the time of the survey. Survey data and 2010 Nationwide Inpatient Sample data, stratified according to patient age and length of hospital stay, were used to estimate the total numbers of health care-associated infections and of inpatients with such infections in U.S. acute care hospitals in 2011. RESULTS Surveys were conducted in 183 hospitals. Of 11,282 patients, 452 had 1 or more health care-associated infections (4.0%; 95% confidence interval, 3.7 to 4.4). Of 504 such infections, the most common types were pneumonia (21.8%), surgical-site infections (21.8%), and gastrointestinal infections (17.1%). Clostridium difficile was the most commonly reported pathogen (causing 12.1% of health care-associated infections). Device-associated infections (i.e., central-catheter-associated bloodstream infection, catheter-associated urinary tract infection, and ventilator-associated pneumonia), which have traditionally been the focus of programs to prevent health care-associated infections, accounted for 25.6% of such infections. We estimated that there were 648,000 patients with 721,800 health care-associated infections in U.S. acute care hospitals in 2011. CONCLUSIONS Results of this multistate prevalence survey of health care-associated infections indicate that public health surveillance and prevention activities should continue to address C. difficile infections. As device- and procedure-associated infections decrease, consideration should be given to expanding surveillance and prevention activities to include other health care-associated infections.

Emergence of Community-Acquired Methicillin-Resistant Staphylococcus aureus USA 300 Clone as the Predominant Cause of Skin and Soft-Tissue Infections

Context In community outbreaks of methicillin-resistant Staphylococcus aureus (MRSA), 2 clones predominate in the United States: USA 300 and USA 400. Little is known about these infections in the nonoutbreak setting. Contribution This study evaluated nonoutbreak community-acquired S. aureus skin and soft-tissue infections in patients in a large urban setting. Almost three quarters of the soft-tissue infections were caused by MRSA, and these were predominantly the USA 300 type. No MRSA USA 300 isolate was resistant to trimethoprimsulfamethoxazole or vancomycin, while most were resistant to erythromycin in addition to -lactams. Implications Antibiotic choice for serious nonoutbreak community-acquired skin and soft-tissue infection should consider high rates of MRSA in some communities. The Editors Methicillin-resistant Staphylococcus aureus (MRSA) infections have usually been associated with exposure to health care settings, but they have recently been recognized in persons without traditional risk factors. These infections have been called community-acquired or community-associated MRSA (1). Most cases have been associated with skin and soft-tissue infection and have been reported among selected populations, including correctional facility inmates, homosexual men, and sports teams (2-5). Molecular typing studies in the United States and Australia have demonstrated that most community-acquired MRSA infections are caused by one of several clones or pulsed-field types (6, 7). In the United States, 2 clones, designated as USA 300 and USA 400 by the Centers for Disease Control and Prevention (CDC), have been identified as the primary types that cause community-acquired MRSA infections (6). The outbreaks of MRSA skin and soft-tissue infections observed in correctional facilities and among athletes have been associated with the USA 300 pulsed-field type, while outbreaks associated with severe and fatal disease in children, as well as skin and soft-tissue infections in Native American populations, have been associated with the USA 400 pulsed-field type (6). The community-acquired MRSA clones have frequently been associated with the PantonValentine leukocidin virulence factor and the presence of staphylococcal chromosome cassette mec (SCCmec) type IV allele (1, 6-9). In contrast, hospital-acquired or health careassociated MRSA strains usually lack genes for PantonValentine leukocidin and are associated with other SCCmec alleles (for example, SCCmec type II) (1, 6, 7). In addition to PantonValentine leukocidin and SCCmec type IV, the community-acquired MRSA USA 300 and USA 400 genotypes have usually demonstrated resistance to -lactams and erythromycin while retaining susceptibility to clindamycin, trimethoprimsulfamethoxazole, and fluoroquinolones, whereas health careassociated genotypes are often multidrug-resistant (1, 6). Although increasingly reported as a cause of outbreaks of skin and soft-tissue infection, the proportion of S. aureus skin and soft-tissue infections caused by community-acquired MRSA in nonoutbreak settings remains poorly defined. We sought to determine the proportion of infections caused by community-acquired MRSA, the clinical characteristics associated with community-acquired MRSA, and the molecular epidemiology of community-acquired MRSA among persons with community-onset S. aureus skin and soft-tissue infection who were receiving care at a large hospital and its affiliated clinics in urban Atlanta, Georgia. Methods Laboratory Surveillance for Community-Onset S. aureus Skin and Soft-Tissue Infection We conducted active, prospective laboratory surveillance from 1 August 2003 to 15 November 2003 to identify S. aureus isolates of patients with skin and soft-tissue infections at the Grady Health System. The Grady Health System includes Grady Memorial Hospital, a 1000-bed public inner-city hospital, and its affiliated outpatient clinics. We limited surveillance to S. aureus isolates that were obtained from patients with a community-onset skin and soft-tissue infection (isolates designated either as an exudate or a body fluid culture). We defined community-onset S. aureus by positive test results from cultures that were obtained within 72 hours of admission or at an outpatient visit. An investigator classified community-onset S. aureus before we performed molecular typing studies or before we reviewed antimicrobial susceptibility results other than methicillin susceptibility. We identified S. aureus and tested antimicrobial susceptibility for all isolates in the Grady Memorial Hospital Clinical Microbiology Laboratory in accordance with the National Committee for Clinical Laboratory Standards (10). Study Sample and Data Collection The Emory University Institutional Review Board and the Grady Research Oversight Committee approved the study. Grady Memorial Hospital provides medical care for a primarily medically indigent inner-city population, approximately 80% of whom are African American, residing within inner-city Atlanta (Fulton County and DeKalb County). The hospital serves as a teaching hospital for both Emory University School of Medicine and Morehouse School of Medicine. The referral pattern for the hospital and its affiliated clinics is primarily patient self-referral on the basis of place of residence (that is, residence within DeKalb or Fulton Counties) or indigent status, with some patients referred for tertiary academic medical care. We retrospectively reviewed computerized medical and laboratory records to document patient demographic characteristics, HIV status, presence of end-stage renal disease, hospitalization within the previous 12 months, and any history of MRSA infection or colonization. The reviewer completed the abstraction process blinded to the molecular typing results of MRSA isolates. We documented the need for hospitalization for managing the S. aureus skin and soft-tissue infection. We obtained S. aureus antimicrobial susceptibility profiles from the hospitals microbiology laboratory, and we categorized infections as due to either methicillin-susceptible S. aureus (MSSA) or MRSA. We reviewed computerized pharmacy records to document the antimicrobial agent therapy that was used to treat the patients skin and soft-tissue infection. We considered antimicrobial agent therapy to be adequate if the prescribed antimicrobial agent had in vitro activity against the isolated S. aureus strain. Molecular Typing and Genetic Analyses We performed pulsed-field gel electrophoresis (PFGE) using SmaI as a restriction endonuclease on all available MRSA isolates, as described by Bannerman and colleagues (11). We digitized gels and saved them as an image for analysis with BioNumerics software (Applied Maths, Sint-Martens-Latem, Belgium). We performed cluster analysis by using the unweighted pair-group method based on Dice coefficients. We defined pulsed-field type clusters by using a similarity coefficient of at least 80% and the criteria of Tenover and colleagues (12). By using the nomenclature outlined by McDougal and colleagues (6), we categorized MRSA isolates into 1 of 8 lineages: USA 100 through USA 800. For some isolates, we determined SCCmec type by using polymerase chain reaction (PCR)typing of the mec gene complex as described by Okuma and colleagues (7). Similarly, we assessed the presence of PantonValentine leukocidin genes in selected MRSA isolates by using PCR as previously described by Lina and colleagues (13). Classification of Community-Onset S. aureus Skin and Soft-Tissue Infections We classified community-onset S. aureus skin and soft-tissue infections into 3 groups on the basis of either molecular typing results (pulsed-field type) of MRSA isolates or antimicrobial susceptibility pattern in cases in which the MRSA isolate was not available for PFGE. The 3 groups were 1) the community-acquired MRSA USA 300/USA 400 group, 2) the other MRSA group, and 3) the MSSA group. The community-acquired MRSA USA 300/USA 400 group was defined by MRSA skin and soft-tissue infections caused by a MRSA isolate that either demonstrated a USA 300 or USA 400 pulsed-field type (6) or had an antimicrobial susceptibility profile demonstrating resistance only to -lactams and erythromycin while retaining susceptibility to clindamycin, levofloxacin, trimethoprimsulfamethoxazole, and vancomycin. The other MRSA group was defined by MRSA skin and soft-tissue infections caused by a MRSA isolate that either demonstrated a pulsed-field type other than USA 300 or USA 400 (for example, USA 100, USA 500, or USA 800 [which have all been described as health careassociated pulsed-field types]) or had an antimicrobial susceptibility profile demonstrating resistance to -lactams, erythromycin, and at least 1 additional antibiotic. We defined the MSSA group by skin and soft-tissue infections caused by MSSA. Statistical Analysis We performed data management and statistical analyses by using Microsoft Excel 2000 software (Microsoft Corp., Redmond, Washington) and SAS software, version 8.2 (SAS Institute, Cary, North Carolina). We assessed risk factors for community-acquired MRSA skin and soft-tissue infection in 2 separate analyses. Our first analysis compared the community-acquired MRSA USA 300/USA 400 group with the MSSA group, and our second analysis compared the community-acquired MRSA USA 300/USA 400 group with the other MRSA group. In addition, we repeated each analysis using data that were limited to those skin and soft-tissue infections in which a MRSA isolate was available for PFGE to account for any potential misclassification bias introduced when skin and soft-tissue infections were classified according to antimicrobial susceptibility profile. We initially identified potential risk factors for community-acquired MRSA skin and soft-tissue infection by univariate analysis. We calculated prevalence ratios and the corresponding 95% CIs. Multivariable log-binomial regression models included variables that were

Emergence of Community-Associated Methicillin-Resistant Staphylococcus aureus USA300 Genotype as a Major Cause of Health Care—Associated Blood Stream Infections

BACKGROUND Whether community-associated methicillin-resistant Staphylococcus aureus (MRSA) genotypes (e.g., USA300) are a major cause of bloodstream infections (BSIs) and health care-associated infections has been poorly defined. METHODS Consecutive MRSA isolates recovered from patients with BSIs were prospectively collected at an urban public hospital. Molecular typing studies were performed. Prevalence and risk factors for the MRSA USA300 genotype were assessed. RESULTS One hundred thirty-two cases of MRSA BSI were documented over 7.5 months in 2004 (incidence, 6.79 per 1000 admissions); 116 isolates were available for genotyping. Characteristics of the 116 evaluable cases included: a mean age 47 years; 62% were male, 82% were African American, and 22% were HIV seropositive. The crude in-hospital mortality rate was 22%. In 107 cases (92%), there was contact with a health care facility within the year prior to infection, and a nosocomial infection (defined as positive blood culture results obtained >48 h after admission) occurred in 49 cases (42%). PFGE demonstrated that 39 (34%) of the 116 isolates were the MRSA USA300 genotype; 34 (29%) were USA100; 42 (36%) were USA500; and 1 (1%) was USA800. MRSA USA300 accounted for 28% of health care-associated BSIs and 20% of nosocomial MRSA BSIs. In multivariate analysis, isolation of the USA300 genotype was associated with injectiondrug use (OR, 3.67; 95% CI, 1.10-12.28) and skin and soft tissue infection (OR, 4.26; 95% CI, 1.08-16.84). Patients who resided in long-term care facilities (OR, 0.09; 95% CI, 0.01-0.82) and those who were treated with antimicrobials in the prior year were less likely to have MRSA USA300 genotype recovered (OR, 0.10; 95% CI, 0.02-0.49). CONCLUSIONS MRSA USA300 genotype, the predominant cause of community-associated MRSA infections in our area (Atlanta, GA), has now emerged as a significant cause of health care-associated and nosocomial BSI. MRSA USA300 as a nosocomial pathogen presents new challenges to infection control programs.

Health care-associated invasive MRSA infections, 2005-2008.

CONTEXT Methicillin-resistant Staphylococcus aureus (MRSA) is a pathogen of public health importance; MRSA prevention programs that may affect MRSA transmission and infection are increasingly common in health care settings. Whether there have been changes in MRSA infection incidence as these programs become established is unknown; however, recent data have shown that rates of MRSA bloodstream infections (BSIs) in intensive care units are decreasing. OBJECTIVE To describe changes in rates of invasive health care-associated MRSA infections from 2005 through 2008 among residents of 9 US metropolitan areas. DESIGN, SETTING, AND PARTICIPANTS Active, population-based surveillance for invasive MRSA in 9 metropolitan areas covering a population of approximately 15 million persons. All reports of laboratory-identified episodes of invasive (from a normally sterile body site) MRSA infections from 2005 through 2008 were evaluated and classified based on the setting of the positive culture and the presence or absence of health care exposures. Health care-associated infections (ie, hospital-onset and health care-associated community-onset), which made up 82% of the total infections, were included in this analysis. MAIN OUTCOME MEASURES Change in incidence of invasive health care-associated MRSA infections and health care-associated MRSA BSIs using population of the catchment area as the denominator. RESULTS From 2005 through 2008, there were 21,503 episodes of invasive MRSA infection; 17,508 were health care associated. Of these, 15,458 were MRSA BSIs. The incidence rate of hospital-onset invasive MRSA infections was 1.02 per 10,000 population in 2005 and decreased 9.4% per year (95% confidence interval [CI], 14.7% to 3.8%; P = .005), and the incidence of health care-associated community-onset infections was 2.20 per 10,000 population in 2005 and decreased 5.7% per year (95% CI, 9.7% to 1.6%; P = .01). The decrease was most prominent for the subset of infections with BSIs (hospital-onset: -11.2%; 95% CI -15.9% to -6.3%; health care-associated community-onset: -6.6%; 95% CI -9.5% to -3.7%). CONCLUSION Over the 4-year period from 2005 through 2008 in 9 diverse metropolitan areas, rates of invasive health care-associated MRSA infections decreased among patients with health care-associated infections that began in the community and also decreased among those with hospital-onset invasive disease.

National burden of invasive methicillin-resistant Staphylococcus aureus infections, United States, 2011.

IMPORTANCE Estimating the US burden of methicillin-resistant Staphylococcus aureus (MRSA) infections is important for planning and tracking success of prevention strategies. OBJECTIVE To describe updated national estimates and characteristics of health care- and community-associated invasive methicillin-resistant Staphylococcus aureus (MRSA) infections in 2011. DESIGN, SETTING, AND PARTICIPANTS Active laboratory-based case finding identified MRSA cultures in 9 US metropolitan areas from 2005 through 2011. Invasive infections (MRSA cultured from normally sterile body sites) were classified as health care-associated community-onset (HACO) infections (cultured ≤ 3 days after admission and/or prior year dialysis, hospitalization, surgery, long-term care residence, or central vascular catheter presence ≤ 2 days before culture); hospital-onset infections (cultured >3 days after admission); or community-associated infections if no other criteria were met. National estimates were adjusted using US census and US Renal Data System data. MAIN OUTCOMES AND MEASURES National estimates of invasive HACO, hospital-onset, and community-associated MRSA infections using US census and US Renal Data System data as the denominator. RESULTS An estimated 80,461 (95% CI, 69,515-93,914) invasive MRSA infections occurred nationally in 2011. Of these, 48,353 (95% CI, 40,195-58,642) were HACO infections; 14,156 (95% CI, 10,096-20,440) were hospital-onset infections; and 16,560 (95% CI, 12,806-21,811) were community-associated infections. Since 2005, adjusted national estimated incidence rates decreased among HACO infections by 27.7% and hospital-onset infections decreased by 54.2%; community-associated infections decreased by only 5.0%. Among recently hospitalized community-onset (nondialysis) infections, 64% occurred 3 months or less after discharge, and 32% of these were admitted from long-term care facilities. CONCLUSIONS AND RELEVANCE An estimated 30,800 fewer invasive MRSA infections occurred in the United States in 2011 compared with 2005; in 2011 fewer infections occurred among patients during hospitalization than among persons in the community without recent health care exposures. Effective strategies for preventing infections outside acute care settings will have the greatest impact on further reducing invasive MRSA infections nationally.

The influence of the composition of the nursing staff on primary bloodstream infection rates in a surgical intensive care unit

OBJECTIVES To determine the risk factors for acquisition of nosocomial primary bloodstream infections (BSIs), including the effect of nursing-staff levels, in surgical intensive care unit (SICU) patients. DESIGN A nested case-control study. SETTING A 20-bed SICU in a 1,000-bed inner-city public hospital. PATIENTS 28 patients with BSI (case-patients) were compared to 99 randomly selected patients (controls) hospitalized > or =3 days in the same unit. RESULTS Case- and control-patients were similar in age, severity of illness, and type of central venous catheter (CVC) used. Case-patients were significantly more likely than controls to be hospitalized during a 5-month period that had lower regular-nurse-to-patient and higher pool-nurse-to-patient ratios than during an 8-month reference period; to be in the SICU for a longer period of time; to be mechanically ventilated longer; to receive more antimicrobials and total parenteral nutrition; to have more CVC days; or to die. Case-patients had significantly lower regular-nurse-to-patient and higher pool-nurse-to-patient ratios for the 3 days before BSI than controls. In multivariate analyses, admission during a period of higher pool-nurse-to-patient ratio (odds ratio [OR]=3.8), total parenteral nutrition (OR=1.3), and CVC days (OR=1.1) remained independent BSI risk factors. CONCLUSIONS Our data suggest that, in addition to other factors, nurse staffing composition (ie, pool-nurse-to-patient ratio) may be related to primary BSI risk. Patterns in intensive care unit nurse staffing should be monitored to assess their impact on nosocomial infection rates. This may be particularly important in an era of cost containment and healthcare reform.

Changes in Invasive Pneumococcal Disease among HIV-Infected Adults Living in the Era of Childhood Pneumococcal Immunization

Context Routine pneumococcal conjugate vaccination for infants began in 2000. Its use markedly decreased invasive pneumococcal disease among children, but did it influence rates of disease among HIV-infected adults? Contribution Between 1998 and 2003, invasive pneumococcal disease among adults infected with HIV living in 7 surveillance areas in the United States decreased from 1127 to 919 cases per 100000 adults with AIDS. Disease caused by serotypes in the vaccine decreased 62%, whereas disease caused by nonvaccine serotypes increased 44%. Implications Indirect evidence suggests that pediatric vaccine use is associated with a decreased incidence of pneumococcal disease among HIV-infected adults. The Editors Apneumococcal conjugate vaccine containing 7 serotypes was recommended for routine use in infants in the United States beginning in 2000 (1). Widespread use of the vaccine caused steep declines in invasive pneumococcal disease among young children (2-4) and was associated with decreased disease attributable to vaccine serotypes among adults, for whom the vaccine is not licensed (3). Effects on disease among unvaccinated persons, often called herd effects, are presumably due to reduced transmission from immunized children. Because 90 pneumococcal serotypes cause human disease, there were concerns that the introduction of a conjugate vaccine containing 7 serotypes would lead to increased disease caused by nonvaccine-type organisms, a phenomenon called serotype replacement. Early postintroduction surveillance showed limited serotype replacement disease in the target age group, with no consistent trend toward increasing disease caused by nonvaccine serotypes among adults (3). To our knowledge, the effects of pediatric use of pneumococcal conjugate vaccine on immunocompromised adults, including those infected with HIV, have not previously been investigated. Persons infected with HIV are particularly susceptible to invasive pneumococcal disease, with a 50- to 100-fold higher incidence than the general U.S. population (5, 6). After the introduction of highly active antiretroviral therapy in the mid-1990s, surveillance in 3 geographic areas of the United States showed a 50% reduction in invasive pneumococcal disease among persons with AIDS (7). However, the incidence of pneumococcal disease among persons with AIDS leveled off by mid-1997 and continued to be approximately 35-fold higher in persons with AIDS than in those without HIV infection or AIDS through 2000 (7). We investigated trends in invasive pneumococcal disease among HIV-infected adults to document changes since the use of pneumococcal conjugate vaccine became widespread in children. Methods Active, laboratory-based surveillance for cases of invasive pneumococcal disease, defined as isolation of Streptococcus pneumoniae from a normally sterile site, was conducted through Active Bacterial Core surveillance of the Emerging Infections Program network (8). We included cases diagnosed between 1 January 1998 and 31 December 2003 among surveillance-area residents who were 18 to 64 years of age. We limited the analyses to 7 surveillance sites, including California (San Francisco County), Connecticut (entire state), Georgia (8-county Atlanta metropolitan area), Maryland (City of Baltimore and 5 neighboring counties), Minnesota (7-county MinneapolisSt. Paul metropolitan area), Oregon (3-county Portland metropolitan area), and Tennessee (Davidson, Hamilton, Knox, Shelby, and Williamson Counties). Information was systematically collected on the HIV status of case-patients at these sites. In 2003, the resident adult population in these 7 areas was 10.8 million (4.5% of the U.S. population between 18 and 64 years of age) (9) and included 9.5% of the estimated number of adults living with AIDS in the United States (10). Surveillance officers routinely contacted all clinical laboratories in their areas to identify cases and conducted audits of laboratory records to ensure complete ascertainment. Recurrent episodes, defined as invasive pneumococcal disease occurring more than 7 days after a previous case in a surveillance-area resident, were included in this analysis. The race and ethnicity as well as HIV status or previous AIDS diagnosis of case-patients were extracted from medical records by using standardized case report forms. Surveillance in Georgia did not prospectively collect information on HIV infection or AIDS for case-patients until 2000; for case-patients in 1999, we retrospectively reviewed medical records to collect this information. Analyses for 1998 exclude Georgia. Pneumococcal isolates were sent to reference laboratories at the Minnesota Department of Health (for case-patients from Minnesota), the Centers for Disease Control and Prevention, or the University of Texas Health Science Center at San Antonio for susceptibility testing by broth microdilution using standard protocols and quality control procedures (3, 11). Nonsusceptible isolates were defined as those with minimum inhibitory concentrations classified as intermediate or resistant for the antibiotic tested, according to the 2002 definitions of the National Committee for Clinical Laboratory Standards (12). Serotyping by the Quellung reaction was done at the Centers for Disease Control and Prevention or the Minnesota Department of Health (Minnesota cases only). The study personnel are listed in the Appendix. AIDS Surveillance Data For aggregated counties in each of the 7 surveillance areas, we obtained the estimated number of persons 18 to 64 years of age living with AIDS (as outlined in the 1993 Centers for Disease Control and Prevention case definition) (13), according to race and ethnicity and sex, on 30 June of each year. We obtained this number from the Centers for Disease Control and Prevention with permission from state AIDS surveillance coordinators. These estimates are derived from case report data by using a maximum likelihood method to account for delays in reporting new AIDS diagnoses and deaths among persons with AIDS (10), 14. Estimates of the number of persons living with HIV infection, not AIDS, were unavailable from 5 sites (California, Connecticut, Georgia, Maryland, and Oregon) that accounted for more than 80% of adults living with AIDS in the surveillance areas. Statistical Analysis For each surveillance area, we calculated the annual incidence rates of invasive pneumococcal disease among persons with AIDS as follows. We divided the number of cases of pneumococcal disease diagnosed during the calendar year among patients documented as having AIDS by the estimated number of persons 18 to 64 years of age living with AIDS. To calculate incidence among adults not infected with HIV, we used cases of pneumococcal disease in persons without documented HIV infection or AIDS in the numerator. For the denominator, we subtracted the number of adults living with AIDS from the total population of persons 18 to 64 years of age who lived in the surveillance areas; this number was obtained from the U.S. Census Bureau (9). As a proxy for the incidence rates among HIV-infected adults, we calculated a ratio of cases of pneumococcal disease among adults with HIV infection or AIDS to the estimated adult population living with AIDS, multiplied by 100000. Ratios for specific race and ethnicity categories were adjusted, assuming that the distribution of race and ethnicity for case-patients missing these data (3% of cases of pneumococcal disease) was the same as the sex-specific distribution of case-patients within each surveillance area for which race and ethnicity data were available. We adjusted data for selected serotypes (that is, conjugate vaccine or nonvaccine serotypes) or antibiotic-resistant pneumococci on the basis of the percentage of cases with isolates available for testing, assuming the distribution of cases missing serotype (9%) or antibiotic susceptibility data (7%) was the same as that of cases with isolates tested across all sites. We calculated 95% CIs for these ratios by using the standard error of the proportion of cases with isolates tested. To assess changes in the ratio of the number of cases of pneumococcal disease among HIV-infected adults to the number of adults living with AIDS before and after the introduction of the pneumococcal conjugate vaccine for children, we calculated percentage change and exact 95% CIs by comparing the average ratio during 1998 and 1999, called the baseline period, with that during 2002 or 2003. For differences or linear trends in proportions of cases or pneumococcal isolates, we calculated P values using chi-square tests; P values less than 0.05 indicated statistical significance. Statistical analyses were conducted with SAS, version 9.0 for Windows (SAS Institute, Inc., Cary, North Carolina), and EpiInfo, version 6.0 (Centers for Disease Control and Prevention, Atlanta, Georgia). Role of the Funding Source The funding source had no role in the design, analysis, or interpretation of the data or in the decision to submit the manuscript for publication. Results From 1998 through 2003, 8582 cases of invasive pneumococcal disease occurred in surveillance-area residents who were 18 to 64 years of age. Of these, 2013 cases occurred in persons with HIV infection or AIDS (Figure 1). When the latter group was excluded, the annual incidence rate in persons who were 18 to 64 years of age during the 1998 to 1999 baseline period averaged 13 cases per 100000 adults without AIDS. By 2003, this rate decreased to 9 cases per 100000, a decrease of 30% (95% CI, 25% to 35%; P< 0.001). Of the 2013 cases of pneumococcal disease among HIV-infected adults, 759 (38%) occurred among adults documented as having AIDS. Based on estimates of the number of adults living with AIDS in the surveillance areas, the incidence of invasive pneumococcal disease among persons with AIDS during the baseline period was 441 cases per 100000 adults. In 2002, the rate was 360 cases per 10000

Preventing the nosocomial transmission of tuberculosis

The resurgence of tuberculosis in the United States since 1985 has been accompanied by an increasing number of reports of nosocomial transmission of tuberculosis (both drug-susceptible and drug-resistant strains) in hospitals, prisons, and shelters [1-15]. Inefficient infection control procedures have contributed to recent outbreaks of tuberculosis, as have increases in the number of patients coinfected with Mycobacterium tuberculosis and the human immunodeficiency virus (HIV) [5, 14]. In several outbreaks, transmission was facilitated because patients with unsuspected tuberculosis were clustered with susceptible immunocompromised patients (for example, in acquired immunodeficiency syndrome [AIDS] wards in large urban hospitals). In addition, recognition of tuberculosis in patients with HIV infection was delayed because atypical presentation and chest radiographic findings or low clinical suspicion led to misdiagnosis and failure to isolate patients with active pulmonary disease [5, 7, 8, 11, 12, 15-20]. Other factors included laboratory delays in identification and susceptibility testing of M. tuberculosis isolates and a failure to recognize the ongoing infectiousness of patients [5, 7, 12, 14]. These recent outbreaks emphasize the importance of effective tuberculosis infection control efforts in health care settings. In December 1990, the Centers for Disease Control and Prevention (CDC) issued guidelines for preventing transmission of tuberculosis in health care settings [13]; revised guidelines were issued in October 1994 [14]. A hierarchy of control measures (administrative, engineering, personal respiratory protective equipment [that is, respirator masks]) have been recommended by CDC to prevent nosocomial transmission of tuberculosis [14]. However, few data are available on the efficacy of these guidelines [16], and CDC has recognized the urgent need to assess the efficacy of isolation in preventing the transmission of tuberculosis [21]. The cost of implementing these recommendations is high [22], particularly for engineering requirements (for example, retrofitting rooms for respiratory isolation) and personal respiratory protective equipment. The Occupational Safety and Health Administration (OSHA) has mandated the use of high-efficiency particulate air (HEPA)-filtered respirator masks [23] as the minimum level of respiratory protection in U.S. health care institutions. These HEPA respirator masks are expensive; a disposable HEPA respirator costs more than

Characterization of Methicillin-Resistant Staphylococcus aureus Isolates Collected in 2005 and 2006 from Patients with Invasive Disease: a Population-Based Analysis

5 per mask, which is more than five times the cost of dust-mist respirators. The efficacy of these HEPA respirator masks compared with that of other types of respirators is unknown [23]. Resources for these expensive engineering and personal respiratory protective equipment mandates are especially difficult to obtain at inner-city public hospitals, which often care for many patients with tuberculosis. We studied the efficacy of expanded tuberculosis infection control measures (consisting primarily of administrative controls) that were implemented at Grady Memorial Hospital, Atlanta, Georgia, after documented transmission of drug-susceptible tuberculosis occurred on several wards of the hospital [10]. We evaluated two measures of health care worker occupational exposure to tuberculosis: 1) tuberculosis exposure episodes [that is, the number of patients with acid-fast bacilli smear-positive pulmonary tuberculosis not admitted into respiratory isolation at hospital admission] and 2) tuberculin skin test results of health care workers at our urban public hospital, which has limited resources and each year cares for more than 200 patients with laboratory-confirmed tuberculosis. Methods Tuberculosis Exposure We measured two aspects of health care worker exposure to tuberculosis before and during implementation of tuberculosis infection control measures at Grady Memorial Hospital, a public, university-affiliated, 1000-bed inner-city hospital in Atlanta, Georgia. We evaluated the number of tuberculosis exposure episodes between 1 July 1991 and 30 June 1994 and the tuberculin skin test conversion results of health care workers at Grady Memorial Hospital between 1 January 1992 and 30 June 1994. An episode of tuberculosis exposure was considered to occur when a patient not placed in respiratory isolation at hospital admission subsequently had a diagnosis of acid-fast bacilli smear-positive and culture-positive pulmonary tuberculosis (on the basis of isolation of M. tuberculosis from sputum or bronchoalveolar lavage fluid specimens) during that admission or within 2 weeks of discharge. Days of tuberculosis exposure were defined as the cumulative number of days that patients with acid-fast bacilli smear-positive, culture-positive pulmonary tuberculosis were not housed in respiratory isolation rooms. We began to prospectively follow tuberculosis exposure episodes on 1 March 1992, after an expanded respiratory isolation policy was implemented. We retrospectively determined the number of tuberculosis exposure episodes that occurred between 1 July 1991 and 29 February 1992 by reviewing laboratory records and patient charts. Acid-Fast Bacilli Smears and Cultures The hospitals clinical microbiology laboratory did acid-fast bacilli smears using a concentrated method and fluorochrome staining [24]; respiratory specimens were decontaminated by standard procedures [25]. Acid-fast bacilli cultures were done by inoculating specimens onto Middlebrook 7H11 agar (Becton Dickinson, Cockeysville, Maryland) and into radiometric broth media (Bactec, Becton Dickinson, Sparks, Maryland). Mycobacterium isolates were identified as M. tuberculosis complex by nucleic acid probes (Gen-Probe, San Diego, California). Tuberculin Skin Testing Tuberculin skin testing for health care workers was done at the hospitals Occupational Health Services Clinic using the Mantoux method; a 0.1-mL (5 tuberculin units) solution of purified protein derivative (Aplisol, Parke-Davis, Morris Plains, New Jersey, or Tubersol, Connaught, Swiftwater, Pennsylvania) was placed intradermally on the volar surface of the forearm and was read 48 to 72 hours later by a member of the Occupational Health Services staff (nurse, physician, or physician assistant). Self-reporting of results by health care workers was not permitted. A positive tuberculin skin test result was defined as an induration of at least 10 mm. A baseline tuberculin skin test was done when the health care worker began working at the hospital; results of this baseline testing were excluded from the analysis. Two-step tuberculin skin testing [14] for new health care workers was not done during the study period. Tuberculin skin testing has been mandatory for all Grady Memorial Hospital employees since 1976. Extremely high compliance (almost 100%) has been assured by the requirement of documentation of a recent tuberculin skin test result (or documentation of a previous positive tuberculin skin test result) before issuance and renewal of the hospitals identification badge, which must be worn by all health care workers. A tuberculin skin test conversion was defined as a documented positive test result following a documented negative result of a test done by the Occupational Health Services staff. We included all health care workers whose tuberculin skin tests were done by the Grady Occupational Health Services during the study period (that is, all Grady Memorial Hospital employees, Grady-based university physician faculty, and housestaff and medical and allied health students who were tested at the Grady Occupational Health Services). We did not include results of tuberculin skin testing of housestaff and students who rotate through Grady Memorial Hospital but who were tested at other sites (for example, at other Emory University-affiliated hospitals). Control Measures Expanded tuberculosis infection control measures were implemented at Grady Memorial Hospital after documented transmission of tuberculosis occurred on several wards in late 1991 and early 1992 [10]. The following are the control measures and the dates they were implemented. 1. Administrative controls. These controls consisted primarily of an expanded respiratory isolation policy that was implemented on 1 March 1992. The previous isolation policy required isolation of patients known or suspected to have tuberculosis; also, under this policy, respiratory isolation was discontinued after 2 weeks of antituberculous therapy. The new expanded respiratory isolation policy included mandatory isolation of all patients with active tuberculosis, those with tuberculosis that was established in the differential diagnosis (or when an acid-fast bacilli sputum smear and culture were ordered), and those with HIV infection (or patients at high risk for HIV infection if serologic status was unknown) who had an abnormal chest radiograph. Isolation could be discontinued only after three consecutive negative acid-fast bacilli sputum smears were obtained or when the patient was discharged from the hospital. Other new administrative controls included increased surveillance by the Epidemiology/Infection Control Department to ensure that all patients with acid-fast bacilli sputum smear and culture specimens received by the clinical microbiology laboratory were in respiratory isolation (1 March 1992); the hiring of a nurse epidemiologist to serve as tuberculosis infection control coordinator (1 July 1992); and expanded health care worker education about tuberculosis (1 March 1992), which accompanied implementation of the expanded respiratory isolation policy. This education was especially targeted to nursing staff, house staff, and attending physicians. The frequency of routine mandatory tuberculin skin testing was increased from yearly to every 6 months and was expanded to cover nonemployee health care workers (such as attending physicians, housestaff, and medical students) (July 1992). 2. Interim engineering contr

Prevalence of Antimicrobial Use in US Acute Care Hospitals, May-September 2011

ABSTRACT This study characterizes 1,984 methicillin-resistant Staphylococcus aureus (MRSA) isolates collected in 2005 and 2006 from normally sterile sites in patients with invasive MRSA infection. These isolates represent a convenience sample of all invasive MRSA cases reported as part of the Active Bacterial Core surveillance system in eight states in the United States. The majority of isolates were from blood (83.8%), joints (4.1%), and bone (4.2%). Isolates were characterized by pulsed-field gel electrophoresis (PFGE); SCCmec typing; susceptibility to 15 antimicrobial agents; and PCR analysis of staphylococcal enterotoxin A (SEA) to SEH, toxic shock syndrome toxin 1, and Panton-Valentine leukocidin. Thirteen established PFGE types were recognized among these isolates, although USA100 and USA300 predominated, accounting for 53.2% and 31.4% of the isolates, respectively. As expected, isolates from hospital onset cases were predominantly USA100, whereas those from community-associated cases were predominantly USA300. USA100 isolates were diverse (Simpsons discriminatory index [DI] = 0.924); generally positive only for enterotoxin D (74.5%); and resistant to clindamycin (98.6%), erythromycin (99.0%), and levofloxacin (99.6%), in addition to β-lactam agents. USA300 isolates were less diverse (DI = 0.566), positive for Panton-Valentine leukocidin (96.3%), and resistant to erythromycin (94.1%) and, less commonly, levofloxacin (54.6%), in addition to β-lactam agents. This collection provides a reference collection of MRSA isolates associated with invasive disease, collected in 2005 and 2006 in the United States, for future comparison and ongoing studies.