Deborah Aragon

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.

Trends in Invasive Methicillin-Resistant Staphylococcus aureus Infections

OBJECTIVE: To describe trends in the incidence of invasive methicillin-resistant Staphylococcus aureus (MRSA) infections in children during 2005–2010. METHODS: We evaluated reports of invasive MRSA infections in pediatric patients identified from population-based surveillance during 2005–2010. Cases were defined as isolation of MRSA from a normally sterile site and classified on the basis of the setting of the positive culture and presence or absence of health care exposures. Estimated annual changes in incidence were determined by using regression models. National age- and race-specific incidences for 2010 were estimated by using US census data. RESULTS: A total of 876 pediatric cases were reported; 340 (39%) were among infants. Overall, 35% of cases were hospital-onset, 23% were health care–associated community-onset, and 42% were community-associated (CA). The incidence of invasive CA-MRSA infection per 100 000 children increased from 1.1 in 2005 to 1.7 in 2010 (modeled yearly increase: 10.2%; 95% confidence interval: 2.7%–18.2%). No significant trends were observed for health care–associated community-onset and hospital-onset cases. Nationally, estimated invasive MRSA incidence in 2010 was higher among infants aged <90 days compared with older infants and children (43.9 vs 2.0 per 100 000) and among black children compared with other races (6.7 vs 1.6 per 100 000). CONCLUSIONS: Invasive MRSA infection in children disproportionately affects young infants and black children. In contrast to reports of declining incidence among adults, there were no significant reductions in health care–associated MRSA infections in children. Concurrently, the incidence of CA-MRSA infections has increased, underscoring the need for defining optimal strategies to prevent MRSA infections among children with and without health care exposures.

Epidemiology of Invasive Group A Streptococcal Infections in the United States, 2005–2012

BACKGROUND Invasive group A Streptococcus (GAS) infections are associated with significant morbidity and mortality rates. We report the epidemiology and trends of invasive GAS over 8 years of surveillance. METHODS From January 2005 through December 2012, we collected data from the Centers for Disease Control and Preventions Active Bacterial Core surveillance, a population-based network of 10 geographically diverse US sites (2012 population, 32.8 million). We defined invasive GAS as isolation of GAS from a normally sterile site or from a wound in a patient with necrotizing fasciitis (NF) or streptococcal toxic shock syndrome (STSS). Available isolates were emm typed. We calculated rates and made age- and race-adjusted national projections using census data. RESULTS We identified 9557 cases (3.8 cases per 100 000 persons per year) with 1116 deaths (case-fatality rate, 11.7%). The case-fatality rates for septic shock, STSS, and NF were 45%, 38%, and 29%, respectively. The annual incidence was highest among persons aged ≥65 years (9.4/100 000) or <1 year (5.3) and among blacks (4.7/100 000). National rates remained steady over 8 years of surveillance. Factors independently associated with death included increasing age, residence in a nursing home, recent surgery, septic shock, NF, meningitis, isolated bacteremia, pneumonia, emm type 1 or 3, and underlying chronic illness or immunosuppression. An estimated 10 649-13 434 cases of invasive GAS infections occur in the United States annually, resulting in 1136-1607 deaths. In a 30-valent M-protein vaccine, emm types accounted for 91% of isolates. CONCLUSIONS The burden of invasive GAS infection in the United States remains substantial. Vaccines under development could have a considerable public health impact.

Patients hospitalized with laboratory-confirmed influenza during the 2010-2011 influenza season: exploring disease severity by virus type and subtype

BACKGROUND  The 2010-2011 influenza season was dominated by influenza A(H3N2) virus, but influenza A(H1N1) pdm09 (pH1N1) and B viruses cocirculated. This provided an opportunity to explore within-season predictors of severity among hospitalized patients, avoiding biases associated with season-to-season differences in strain virulence, population immunity, and healthcare seeking. METHODS  Population-based, laboratory-confirmed influenza hospitalization surveillance data were used to examine the association between virus type/subtype and outcomes in children and adults. Multivariable analysis explored virus type/subtype, prompt antiviral treatment, medical conditions, and age as predictors for severity (intensive care unit admission or death). RESULTS  In children, pH1N1 (adjusted odds ratio [aOR], 2.19; 95% confidence interval [CI], 1.11-4.3), chronic metabolic disease (aOR, 5.23; 95% CI, 1.74-15.69), and neuromuscular disorder (aOR, 4.84; 95% CI, 2.02-11.58) were independently associated with severity. In adults, independent predictors were pH1N1 (aOR, 2.21; 95% CI, 1.66-2.94), chronic lung disease (aOR, 1.46, 95% CI, 1.12-1.89), and neuromuscular disorder (aOR, 1.68; 95% CI, 1.11-2.52).Antiviral treatment reduced the odds of severity among adults (aOR, 0.47; 95% CI, .33-.68). CONCLUSIONS  During the 2010-2011 season, pH1N1 caused more severe disease than H3N2 or B in hospitalized patients. Underlying medical conditions increased severity despite virus strain. Antiviral treatment reduced severity among adults. Our findings underscore the importance of influenza prevention.

Complications Among Adults Hospitalized With Influenza: A Comparison of Seasonal Influenza and the 2009 H1N1 Pandemic

Adults hospitalized with 2009 pandemic influenza were younger than those hospitalized in previous influenza seasons and more likely to have lower respiratory tract complications and corresponding indicators of severe illness including intensive care admission, mechanical ventilation, or death.

Geographic and Temporal Trends in Antimicrobial Nonsusceptibility in Streptococcus pneumoniae in the Post-vaccine era in the United States

BACKGROUND We examined whether observed increases in antibiotic nonsusceptible nonvaccine serotypes after introduction of pneumococcal conjugate vaccine in the United States in 2000 were driven primarily by vaccine or antibiotic use. METHODS  Using active surveillance data, we evaluated geographic and temporal differences in serotype distribution and within-serotype differences during 2000-2009. We compared nonsusceptibility to penicillin and erythromycin by geography after standardizing differences across time, place, and serotype by regressing standardized versus crude proportions. A regression slope (RS) approaching zero indicates greater importance of the standardizing factor. RESULTS  Through 2000-2006, geographic differences in nonsusceptibility were better explained by within-serotype prevalence of nonsusceptibility (RS 0.32, 95% confidence interval [CI], .08-.55 for penicillin) than by geographic differences in serotype distribution (RS 0.71, 95% CI, .44-.97). From 2007-2009, serotype distribution differences became more important for penicillin (within-serotype RS 0.52, 95% CI, .11-.93; serotype distribution RS 0.57, 95% CI, .14-1.0). CONCLUSIONS  Differential nonsusceptibility, within individual serotypes, accounts for most geographic variation in nonsusceptibility, suggesting selective pressure from antibiotic use, rather than differences in serotype distribution, mainly determines nonsusceptibility patterns. Recent trends suggest geographic differences in serotype distribution may be affecting the prevalence of nonsusceptibility, possibly due to decreases in the number of nonsusceptible serotypes.

Early-onset group B streptococcal disease in the United States: potential for further reduction.

OBJECTIVE: To describe lapses in adherence to group B streptococcus (GBS) prevention guidelines among cases of early-onset GBS disease in term and preterm neonates and to estimate the potential for further reduction in disease burden under current prevention strategies. METHODS: We reviewed labor and delivery and prenatal records of mothers of neonates with early-onset GBS disease (aged younger than 7 days with GBS isolated from a normally sterile site) identified at population-based surveillance sites in 2008–2009. We interviewed prenatal care providers about GBS screening practices and obtained relevant laboratory records. We evaluated the data for errors in prenatal screening, laboratory methods, communication of results, and intrapartum antibiotic prophylaxis. Using published data on screening sensitivity and intrapartum prophylaxis effectiveness, we estimated the potential reduction in cases under optimal prevention implementation. RESULTS: Among 309 cases, 179 (57.9%) had one or more implementation errors. The most common error type in term and preterm case-patients was prenatal screening (80 of 222 [36.0%]) and intrapartum prophylaxis (46 of 85 [54.1%]), respectively. We estimated that under optimal implementation, cases of early-onset GBS disease could be reduced by 26–59% with the largest benefit from a single intervention coming from improved use of intrapartum prophylaxis (16% decrease). CONCLUSION: Further reduction of early-onset GBS disease burden is possible under current prevention strategies, particularly with improved implementation of antibiotic prophylaxis. However, even with perfect adherence to recommended practices, the decline in cases may be modest. Therefore, novel prevention approaches such as improved intrapartum assays and vaccines are also needed. LEVEL OF EVIDENCE: II

Effectiveness of Nonadjuvanted Monovalent Influenza A(H1N1)pdm09 Vaccines for Preventing Reverse Transcription Polymerase Chain Reaction–Confirmed Pandemic Influenza Hospitalizations: Case-Control Study of Children and Adults at 10 US Influenza Surveillance Network Sites

Abstract During 2009–2010, we examined 217 patients hospitalized with laboratory-confirmed pandemic influenza in 9 Influenza Hospitalization Surveillance Network sites and 413 age- and community-matched controls and found that a single dose of monovalent nonadjuvanted influenza A(H1N1)pdm09 vaccine was 50% (95% confidence interval, 13%–71%) effective in preventing hospitalization associated with A(H1N1)pdm09 virus infection.

Racial Disparities in Invasive Streptococcus pneumoniae Infections, 1998–2009

BACKGROUND Before the introduction of 7-valent pneumococcal conjugate vaccine (PCV7), invasive pneumococcal disease (IPD) rates among blacks were twice the rates in whites. We measured the effects of trends in PCV7-type and non-PCV7-type IPD rates on racial disparities in overall IPD and estimated the proportion of IPD caused by serotypes included in the 13-valent pneumococcal conjugate vaccine (PCV13). METHODS We analyzed data from the Active Bacterial Core surveillance system, which performs active, laboratory- and population-based surveillance for IPD for 29.2 million people in the United States, for the period 1998-2009. For patients with unknown race, we multiplied imputed race to calculate age-, race-, and serotype-specific IPD incidence rates. RESULTS During 1998-2009, 47 449 IPD cases were identified; race was unknown for 5419 (11%). After multiple imputation, 31 981 (67%) patients were considered white and 13 750 (29%) black. PCV7-type IPD rates in all ages in both races decreased to <1 case per 100 000, whereas there were no decreases in overall IPD rates after 2002. By 2009, PCV13 serotypes caused 71% of cases among whites aged <5 years compared with 58% among blacks (P < .01). PCV13 serotypes caused 50% of IPD cases in whites aged ≥5 years compared with 43% among blacks (P < .01). CONCLUSIONS Despite near elimination of PCV7-type IPD in both races, overall disparities in IPD rates persisted because non-PCV7-type IPD rates are higher among blacks. Whereas PCV13 introduction may reduce racial disparities in IPD, higher valency conjugate vaccines and strategies to directly address underlying causes are needed to eliminate IPD disparities.

Survey of influenza and other respiratory viruses diagnostic testing in US hospitals, 2012–2013

Little is known about laboratory capacity to routinely diagnose influenza and other respiratory viruses at clinical laboratories and hospitals.