Prevention of Antibiotic-Nonsusceptible Invasive Pneumococcal Disease With the 13-Valent Pneumococcal Conjugate Vaccine.

BACKGROUND: Antibiotic-nonsusceptible invasive pneumococcal disease (IPD) decreased substantially after the US introduction of the pediatric 7-valent pneumococcal conjugate vaccine (PCV7) in 2000. However, rates of antibiotic-nonsusceptible non-PCV7-type IPD increased during 2004-2009. In 2010, the 13-valent pneumococcal conjugate vaccine (PCV13) replaced PCV7. We assessed the impact of PCV13 on antibiotic-nonsusceptible IPD rates. METHODS: We defined IPD as pneumococcal isolation from a normally sterile site in a resident from 10 US surveillance sites. Antibiotic-nonsusceptible isolates were those intermediate or resistant to ≥1 antibiotic classes according to 2012 Clinical and Laboratory Standards Institute breakpoints. We examined rates of antibiotic nonsusceptibility and estimated cases prevented between observed cases of antibiotic-nonsusceptible IPD and cases that would have occurred if PCV13 had not been introduced. RESULTS: From 2009 to 2013, rates of antibiotic-nonsusceptible IPD caused by serotypes included in PCV13 but not in PCV7 decreased from 6.5 to 0.5 per 100 000 in children aged <5 years and from 4.4 to 1.4 per 100 000 in adults aged ≥65 years. During 2010-2013, we estimated that 1636 and 1327 cases of antibiotic-nonsusceptible IPD caused by serotypes included in PCV13 but not PCV7 were prevented among children aged <5 years (-97% difference) and among adults aged ≥65 years (-64% difference), respectively. Although we observed small increases in antibiotic-nonsusceptible IPD caused by non-PCV13 serotypes, no non-PCV13 serotype dominated among antibiotic-nonsusceptible strains. CONCLUSIONS: After PCV13 introduction, antibiotic-nonsusceptible IPD decreased in multiple age groups. Continued surveillance is needed to monitor trends of nonvaccine serotypes. Pneumococcal conjugate vaccines are important tools in the approach to combat antibiotic resistance.

The Impact of Obesity and Diabetes on the Risk of Disease and Death due to Invasive Group A Streptococcus Infections in Adults.

BACKGROUND: Invasive group A Streptococcus (iGAS) infections cause significant morbidity and mortality worldwide. We analyzed whether obesity and diabetes were associated with iGAS infections and worse outcomes among an adult US population. METHODS: We determined the incidence of iGAS infections using 2010-2012 cases in adults aged ≥ 18 years from Active Bacterial Core surveillance (ABCs), a population-based surveillance system, as the numerator. For the denominator, we used ABCs catchment area population estimates from the 2011 to 2012 Behavioral Risk Factor Surveillance System (BRFSS) survey. The relative risk (RR) of iGAS was determined by obesity and diabetes status after adjusting for age group, gender, race, and other underlying conditions through binomial logistic regression. Multivariable logistic regression was used to determine whether obesity or diabetes was associated with increased odds of death due to iGAS compared to normal weight and nondiabetic patients, respectively. RESULTS: Between 2010 and 2012, 2927 iGAS cases were identified. Diabetes was associated with an increased risk of iGAS in all racial groups (adjusted risk ratio [aRR] ranged from 2.71 to 5.08). Grade 3 obesity (body mass index [BMI] ≥ 40) was associated with an increased risk of iGAS for whites (aRR = 3.47; 95% confidence interval [CI], 3.00-4.01). Grades 1-2 (BMI = 30.0-<40.0) and grade 3 obesity were associated with an increased odds of death (odds ratio [OR] = 1.55, [95% CI, 1.05, 2.29] and OR = 1.62 [95% CI, 1.01, 2.61], respectively) when compared to normal weight patients. CONCLUSIONS: These results may help target vaccines against GAS that are currently under development. Efforts to develop enhanced treatment regimens for iGAS may improve prognoses for obese patients.

Case-Control Study of Vaccine Effectiveness in Preventing Laboratory-Confirmed Influenza Hospitalizations in Older Adults, United States, 2010-2011.

BACKGROUND: Older adults are at increased risk of influenza-associated complications, including hospitalization, but influenza vaccine effectiveness (VE) data are limited for this population. We conducted a case-control study to estimate VE to prevent laboratory-confirmed influenza hospitalizations among adults aged ≥50 years in 11 US Emerging Infections Program hospitalization surveillance sites. METHODS: Cases were influenza infections (confirmed by reverse-transcription polymerase chain reaction) in adults aged ≥50 years hospitalized during the 2010-2011 influenza season, identified through Emerging Infections Program surveillance. Community controls, identified through home telephone lists, were matched by age group (±5 years), county, and month of hospitalization for case patients. Vaccination status was determined by self-report (with location and date) or medical records. Conditional logistic regression models were used to calculate adjusted VE (aVE) estimates (100 × [1 - adjusted odds ratio]), adjusting for sex, race, socioeconomic factors, smoking, chronic medical conditions, recent hospitalization for a respiratory condition, and functional status. RESULTS: Among case patients, 205 of 368 (55%) were vaccinated, compared with 489 of 773 controls (63%). Case patients were more likely to be of nonwhite race and more likely to have ≥2 chronic health conditions, a recent hospitalization for a respiratory condition, an income <$35 000, and a lower functional status score (P < .01 for all). The aVE was 56.8% (95% confidence interval, 34.1%-71.7%) and was similar across age groups, including adults ≥75 years (aVE, 57.3%; 15.9%-78.4%). CONCLUSIONS: During 2010-2011, influenza vaccination was associated with a significant reduction in the risk of laboratory-confirmed influenza hospitalization among adults aged ≥50 years, regardless of age group.

Does Influenza Vaccination Modify Influenza Severity? Data on Older Adults Hospitalized With Influenza During the 2012-2013 Season in the United States.

BACKGROUND: Some studies suggest that influenza vaccination might be protective against severe influenza outcomes in vaccinated persons who become infected. We used data from a large surveillance network to further investigate the effect of influenza vaccination on influenza severity in adults aged ≥50 years who were hospitalized with laboratory-confirmed influenza. METHODS: We analyzed influenza vaccination and influenza severity using Influenza Hospitalization Surveillance Network (FluSurv-NET) data for the 2012-2013 influenza season. Intensive care unit (ICU) admission, death, diagnosis of pneumonia, and hospital and ICU lengths of stay served as measures of disease severity. Data were analyzed by multivariable logistic regression, parametric survival models, and propensity score matching (PSM). RESULTS: Overall, no differences in severity were observed in the multivariable logistic regression model. Using PSM, adults aged 50-64 years (but not other age groups) who were vaccinated against influenza had a shorter length of ICU stay than those who were unvaccinated (hazard ratio for discharge, 1.84; 95% confidence interval, 1.12-3.01). CONCLUSIONS: Our findings show a modest effect of influenza vaccination on disease severity. Analysis of data from seasons with different predominant strains and higher estimates of vaccine effectiveness are needed.

Tracking Pertussis and Evaluating Control Measures through Enhanced Pertussis Surveillance, Emerging Infections Program, United States.

Despite high coverage with pertussis-containing vaccines, pertussis remains endemic to the United States. There have been increases in reported cases in recent years, punctuated by striking epidemics and shifting epidemiology, both of which raise questions about current policies regarding its prevention and control. Limited data on pertussis reported through the National Notifiable Disease Surveillance System have proved insufficient to answer these questions. To address shortcomings of national pertussis data, the Emerging Infections Program at the US Centers for Disease Control and Prevention launched Enhanced Pertussis Surveillance (EPS), which is characterized by systematic case ascertainment, augmented data collection, and collection of Bordetella pertussis isolates. Data collected through EPS have been instrumental in understanding the rapidly evolving epidemiology and molecular epidemiology of pertussis and have contributed essential information regarding pertussis vaccines. EPS also serves as a platform for conducting critical and timely evaluations of pertussis prevention and control strategies, including targeting of vaccinations and antimicrobial prophylaxis.

Training in Infectious Disease Epidemiology through the Emerging Infections Program Sites.

One objective of the Emerging Infections Program (EIP) of the US Centers for Disease Control and Prevention is to provide training opportunities in infectious disease epidemiology. To determine the extent of training performed since the program's inception in 1995, we reviewed training efforts at the 10 EIP sites. By 2015, all sites hosted trainees (most were graduate public health students and physicians) who worked on a variety of infectious disease surveillance and epidemiologic projects. Trainee projects at all sites were used for graduate student theses or practicums. Numerous projects resulted in conference presentations and publications in peer-reviewed journals. Local public health and health care partners have also benefitted from EIP presentations and training. Consideration should be given to standardizing and documenting EIP training and to sharing useful training initiatives with other state and local health departments and academic institutions.

Improving Accuracy of Influenza-Associated Hospitalization Rate Estimates.

Diagnostic test sensitivity affects rate estimates for laboratory-confirmed influenza-associated hospitalizations. We used data from FluSurv-NET, a national population-based surveillance system for laboratory-confirmed influenza hospitalizations, to capture diagnostic test type by patient age and influenza season. We calculated observed rates by age group and adjusted rates by test sensitivity. Test sensitivity was lowest in adults >65 years of age. For all ages, reverse transcription PCR was the most sensitive test, and use increased from <10% during 2003-2008 to ≈70% during 2009-2013. Observed hospitalization rates per 100,000 persons varied by season: 7.3-50.5 for children <18 years of age, 3.0-30.3 for adults 18-64 years, and 13.6-181.8 for adults >65 years. After 2009, hospitalization rates adjusted by test sensitivity were ≈15% higher for children <18 years, ≈20% higher for adults 18-64 years, and ≈55% for adults >65 years of age. Test sensitivity adjustments improve the accuracy of hospitalization rate estimates.

Human Plague - United States, 2015.

Since April 1, 2015, a total of 11 cases of human plague have been reported in residents of six states: Arizona (two), California (one), Colorado (four), Georgia (one), New Mexico (two), and Oregon (one). The two cases in Georgia and California residents have been linked to exposures at or near Yosemite National Park in the southern Sierra Nevada Mountains of California. Nine of the 11 patients were male; median age was 52 years (range = 14-79 years). Three patients aged 16, 52, and 79 years died.

Pneumonia among adults hospitalized with laboratory-confirmed seasonal influenza virus infection-United States, 2005-2008.

BACKGROUND: Influenza and pneumonia combined are the leading causes of death due to infectious diseases in the United States. We describe factors associated with pneumonia among adults hospitalized with influenza. METHODS: Through the Emerging Infections Program, we identified adults ≥ 18 years, who were hospitalized with laboratory-confirmed influenza during October 2005 through April 2008, and had a chest radiograph (CXR) performed. Pneumonia was defined as the presence of a CXR infiltrate and either an ICD-9-CM code or discharge summary diagnosis of pneumonia. RESULTS: Among 4,765 adults hospitalized with influenza, 1392 (29 %) had pneumonia. In multivariable analysis, factors associated with pneumonia included: age ≥ 75 years, adjusted odds ratio (AOR) 1.27 (95 % confidence interval 1.10-1.46), white race AOR 1.24 (1.03-1.49), nursing home residence AOR 1.37 (1.14-1.66), chronic lung disease AOR 1.37 (1.18-1.59), immunosuppression AOR 1.45 (1.19-1.78), and asthma AOR 0.76 (0.62-0.92). Patients with pneumonia were significantly more likely to require intensive care unit (ICU) admission (27 % vs. 10 %), mechanical ventilation (18 % vs. 5 %), and to die (9 % vs. 2 %). CONCLUSIONS: Pneumonia was present in nearly one-third of adults hospitalized with influenza and was associated with ICU admission and death. Among patients hospitalized with influenza, older patients and those with certain underlying conditions are more likely to have pneumonia. Pneumonia is common among adults hospitalized with influenza and should be evaluated and treated promptly.

Complications and associated bacterial coinfections among children hospitalized with seasonal or pandemic influenza, United States, 2003-2010.

BACKGROUND: Data on the range and severity of influenza-associated complications among children are limited. We describe the frequency and severity of complications in hospitalized children aged <18 years with seasonal influenza (during 2003-2009) and 2009 pandemic influenza A(H1N1) (during 2009-2010). METHODS: Population-based surveillance for laboratory-confirmed influenza hospitalizations was conducted among 5.3 million children in 10 states. Complications were identified by International Classification of Diseases, Ninth Revision (ICD-9) codes in medical records. RESULTS: During 2003-2010, 7293 children hospitalized with influenza were identified, of whom 6769 (93%) had complete ICD-9 code data. Among the 6769 children, the median length of hospitalization was 3 days (interquartile range, 2-4 days), 975 (14%) required intensive care, 359 (5%) had respiratory failure, and 40 (1%) died. The most common complications were pneumonia (in 28% of children), asthma exacerbations (in 22% [793/3616] aged ≥ 2 years), and dehydration (in 21%). Lung abscess/empyema, tracheitis, encephalopathy, bacteremia/sepsis, acute renal failure, and myocarditis were rare (each ≤ 2% of children) but associated with a median hospitalization duration of ≥ 6 days, and 48%-70% of children required intensive care. Bacterial cultures with positive results were identified in 2% of children (107/6769); Staphylococcus aureus and Streptococcus pneumoniae were most commonly identified. CONCLUSIONS: Complications contribute substantially to the disease burden among children hospitalized with influenza, through intensive care requirements and prolonged hospitalization, highlighting the importance of primary prevention with influenza vaccination.

Effect of the 2009 influenza A(H1N1) pandemic on invasive pneumococcal pneumonia.

BACKGROUND: Because pneumococcal pneumonia was prevalent during previous influenza pandemics, we evaluated invasive pneumococcal pneumonia (IPP) rates during the 2009 influenza A(H1N1) pandemic. METHODS: We identified laboratory-confirmed, influenza-associated hospitalizations and IPP cases (pneumococcus isolated from normally sterile sites with discharge diagnoses of pneumonia) using active, population-based surveillance in the United States. We compared IPP rates during peak pandemic months (April 2009-March 2010) to mean IPP rates in nonpandemic years (April 2004-March 2009) and, using Poisson models, to 2006-2008 influenza seasons. RESULTS: Higher IPP rates occurred during the peak pandemic month compared to nonpandemic periods in 5-24 (IPP rate per 10 million: 48 vs 9 (95% confidence interval [CI], 5-13), 25-49 (74 vs 53 [CI, 41-65]), 50-64 (188 vs 114 [CI, 85-143]), and ≥65-year-olds (229 vs 187 [CI, 159-216]). In the models with seasonal influenza rates included, observed IPP rates during the pandemic peak were within the predicted 95% CIs, suggesting this increase was not greater than observed with seasonal influenza. CONCLUSIONS: The recent influenza pandemic likely resulted in an out-of-season IPP peak among persons ≥5 years. The IPP peak's magnitude was similar to that seen during seasonal influenza epidemics.

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.

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.

Association between use of statins and mortality among patients hospitalized with laboratory-confirmed influenza virus infections: a multistate study.

BACKGROUND: Statins may have anti-inflammatory and immunomodulatory effects that could reduce the risk of mortality from influenza virus infections. METHODS: The Centers for Disease Control and Prevention's Emerging Infections Program conducts active surveillance for persons hospitalized with laboratory-confirmed influenza in 59 counties in 10 states. We analyzed data for hospitalized adults during the 2007-2008 influenza season to evaluate the association between receiving statins and influenza-related death. RESULTS: We identified 3043 patients hospitalized with laboratory-confirmed influenza, of whom 1013 (33.3%) received statins and 151 (5.0%) died within 30 days of their influenza test. Patients who received statins were more likely to be older, male, and white; to suffer from cardiovascular, metabolic, renal, and chronic lung disease; and to have been vaccinated against influenza that season. In a multivariable logistic regression model, administration of statins prior to or during hospitalization was associated with a protective odds of death (adjusted odds ratio, 0.59 [95% confidence interval, .38-.92]) when adjusting for age; race; cardiovascular, lung, and renal disease; influenza vaccination; and antiviral administration. CONCLUSIONS: Statin use may be associated with reduced mortality in patients hospitalized with influenza.

Prevention of antibiotic-nonsusceptible Streptococcus pneumoniae with conjugate vaccines.

BACKGROUND: Streptococcus pneumoniae (pneumococcus) caused approximately 44000 US invasive pneumococcal disease (IPD) cases in 2008. Antibiotic nonsusceptibility complicates IPD treatment. Using penicillin susceptibility breakpoints adopted in 2008, we evaluated antibiotic-nonsusceptible IPD trends in light of the introductions of a 7-valent pneumococcal conjugate vaccine (PCV7) in 2000 and a 13-valent pneumococcal conjugate vaccine (PCV13) in 2010. METHODS: IPD cases were defined by isolation of pneumococcus from a normally sterile site in individuals residing in Active Bacterial Core surveillance (ABCs) areas during 1998-2008. Pneumococci were serotyped and tested for antibiotic susceptibility using broth microdilution. RESULTS: During 1998-2008, ABCs identified 43198 IPD cases. Penicillin-nonsusceptible strains caused 6%-14% of IPD cases, depending on age. Between 1998-1999 and 2008, penicillin-nonsusceptible IPD rates declined 64% for children aged <5 years (12.1-4.4 cases per 100000), and 45% for adults aged ≥65 (4.8-2.6 cases per 100000). Rates of IPD nonsusceptible to multiple antibiotics mirrored these trends. During 2007-2008, serotypes in PCV13 but not PCV7 caused 78%-97% of penicillin-nonsusceptible IPD, depending on age. CONCLUSIONS: Antibiotic-nonsusceptible IPD rates remain below pre-PCV7 rates for children <5 and adults ≥65 years old. PCV13 vaccines hold promise for further nonsusceptibility reductions.

Increase in rates of hospitalization due to laboratory-confirmed influenza among children and adults during the 2009-10 influenza pandemic.

BACKGROUND: The Emerging Infections Programs (EIP) network has conducted population-based surveillance for hospitalizations due to laboratory-confirmed influenza among children since 2003, with the network expanding in 2005 to include adults. METHODS: From 15 April 2009 through 30 April 2010, the EIP conducted surveillance among 22.1 million people residing in 10 states. Incidence rates per 100 000 population were calculated using US Census Bureau data. Mean historic rates were calculated on the basis of previously published and unpublished EIP data. RESULTS: During the 2009 pandemic of influenza A virus subtype H1N1 infection, rates of hospitalizations due to laboratory-confirmed influenza were 202, 88, 49, 31, 27, 36, 28, and 27 episodes per 100 000 among persons aged <6 months, 6-23 months, 2-4 years, 5-17 years, 18-49 years, 50-64 years, 65-74 years, and ≥75 years, respectively. Comparative mean rates from previous influenza seasons during which EIP conducted surveillance were 153, 53, 20, 6, 4, 8, 20, and 56 episodes per 100 000 among persons aged <6 months, 6-23 months, 2-4 years, 5-17 years, 18-49 years, 50-64 years, 65-74 years, and ≥75 years, respectively. CONCLUSIONS: During the pandemic, rates of hospitalization due to laboratory-confirmed influenza among individuals aged 5-17 years and 18-49 years increased 5-fold and 6-fold, respectively, compared with mean rates from previous influenza seasons. Hospitalization rates for other pediatric and adult age groups increased, compared with mean rates from previous influenza seasons, whereas the rate among individuals aged ≥75 years decreased.

Reduced influenza antiviral treatment among children and adults hospitalized with laboratory-confirmed influenza infection in the year after the 2009 pandemic.

Influenza antiviral treatment is recommended for all persons hospitalized with influenza virus infection. During the 2010-2011 influenza season, antiviral treatment of children and adults hospitalized with laboratory-confirmed influenza declined significantly compared with treatment during the 2009 pandemic (children, 56% vs 77%; adults, 77% vs 82%; both P < .01).

Influenza-associated hospitalizations by industry, 2009-10 influenza season, United States.

In response to pandemic (H1N1) 2009, data were collected on work status and industry of employment of 3,365 adults hospitalized with laboratory-confirmed influenza during the 2009-10 influenza season in the United States. The proportion of workers hospitalized for influenza was lower than their proportion in the general population, reflecting underlying protective characteristics of workers compared with nonworkers. The most commonly represented sectors were transportation and warehousing; administrative and support and waste management and remediation services; health care; and accommodation and food service.

Description of antiviral treatment among adults hospitalized with influenza before and during the 2009 pandemic: United States, 2005-2009.

BACKGROUND: The 2009 influenza pandemic led to guidelines emphasizing antiviral treatment for all persons hospitalized with influenza, including pregnant women. We compared antiviral use among adults hospitalized with influenza before and during the pandemic. METHODS: The Emerging Infections Program conducts active population-based surveillance for persons hospitalized with community-acquired, laboratory-confirmed influenza in 10 states. We analyzed data collected via medical record review of patients aged ≥18 years admitted during prepandemic (1 October 2005 through 14 April 2009) and pandemic (15 April 2009 through 31 December 2009) time frames. RESULTS: Of 5943 adults hospitalized with influenza in prepandemic seasons, 3235 (54%) received antiviral treatment, compared with 4055 (82%) of 4966 during the pandemic. Forty-one (22%) of 187 pregnant women received antiviral treatment in prepandemic seasons, compared with 369 (86%) of 430 during the pandemic. Pregnancy was a negative predictor of antiviral treatment before the pandemic (adjusted odds ratio [aOR], 0.24; 95% confidence interval [CI], .16-.35) but was independently associated with treatment during the pandemic (aOR, 1.97; 95% CI, 1.32-2.96). Antiviral treatment among adults hospitalized >2 days after illness onset increased from 43% before the pandemic to 79% during the pandemic (P < .001). CONCLUSIONS: Antiviral treatment of hospitalized adults increased during the pandemic, especially among pregnant women. This suggests that many clinicians followed published guidance to treat hospitalized adults with antiviral agents. However, compliance with antiviral recommendations could be improved.

Impact of 13-Valent Pneumococcal Conjugate Vaccine on Invasive Pneumococcal Disease Among Adults With HIV-United States, 2008-2018.

BACKGROUND: People with HIV (PWH) are at increased risk for invasive pneumococcal disease (IPD). Thirteen-valent pneumococcal conjugate vaccine (PCV13) was recommended for use in US children in 2010 and for PWH aged 19 years or older in 2012. We evaluated the population-level impact of PCV13 on IPD among PWH and non-PWH aged 19 years or older. METHODS: We identified IPD cases from 2008 to 2018 through the Active Bacterial Core surveillance platform. We estimated IPD incidence using the National HIV Surveillance System and US Census Bureau data. We measured percent changes in IPD incidence from 2008 to 2009 to 2017-2018 by HIV status, age group, and vaccine serotype group, including serotypes in recently licensed 15-valent (PCV15) and 20-valent (PCV20) PCVs. RESULTS: In 2008-2009 and 2017-2018, 8.4% (552/6548) and 8.0% (416/5169) of adult IPD cases were among PWH, respectively. Compared with non-PWH, a larger proportion of IPD cases among PWH were in adults aged 19-64 years (94.7%-97.4% vs. 56.0%-60.1%) and non-Hispanic Black people (62.5%-73.0% vs. 16.7%-19.2%). Overall and PCV13-type IPD incidence in PWH declined by 40.3% (95% confidence interval: -47.7 to -32.3) and 72.5% (95% confidence interval: -78.8 to -65.6), respectively. In 2017-2018, IPD incidence was 16.8 (overall) and 12.6 (PCV13 type) times higher in PWH compared with non-PWH; PCV13, PCV15/non-PCV13, and PCV20/non-PCV15 serotypes comprised 21.5%, 11.2%, and 16.5% of IPD in PWH, respectively. CONCLUSIONS: Despite reductions post-PCV13 introduction, IPD incidence among PWH remained substantially higher than among non-PWH. Higher-valent PCVs provide opportunities to reduce remaining IPD burden in PWH.

Investigation of a group A streptococcal outbreak among residents of a long-term acute care hospital.

BACKGROUND: In January 2008, a long-term acute care hospital (LTACH) in New Mexico reported a cluster of severe group A Streptococcus (GAS) infections. METHODS: We defined a case as illness in a patient in the LTACH from 1 October 2007 through 3 February 2008 from whom GAS was isolated from a usually sterile site or with illness consistent with GAS infection and GAS isolated from a nonsterile site. To identify carriers, we swabbed the oropharynx and skin lesions of patients and staff. We observed facility procedures to assess possible transmission routes and adherence to infection control practices. We also conducted a case-control study to identify risk factors for infection with use of asymptomatic patients who were noncarriers as control subjects. RESULTS: We identified 11 case patients and 11 carriers (8 patients and 3 staff). No carriers became case patients. Significant risk factors for infection in univariate analysis included sharing a room with an infected or colonized patient (6 [55%] of 11 case patients vs 3 [8%] of 39 control subjects), undergoing wound debridement (64% vs 13%), and receiving negative pressure wound therapy (73% vs 33%). Having an infected or colonized roommate remained associated with case patients in multivariable analysis (odds ratio, 15.3; 95% confidence interval, 2.5-110.9). Suboptimal infection control practices were widespread. CONCLUSIONS: This large outbreak of GAS infection was the first reported in an LTACH, a setting that contains a highly susceptible patient population. Widespread infection control lapses likely allowed continued transmission. Similar to the situation in other care settings, appropriate infection control and case cohorting may help prevent and control outbreaks of GAS infection in LTACHs.