Frequency of Children Diagnosed with Perinatal Hepatitis C, United States, 2018-2020.

We describe hepatitis C testing of 47 (2%) of 2,266 children diagnosed with perinatal hepatitis C who were exposed during 2018-2020 in 7 jurisdictions in the United States. Expected frequency of perinatal transmission is 5.8%, indicating only one third of the cases in this cohort were reported to public health authorities.

Risk Factors for SARS-CoV-2 Infection Among US Healthcare Personnel, May-December 2020.

To determine risk factors for coronavirus disease (COVID-19) among US healthcare personnel (HCP), we conducted a case-control analysis. We collected data about activities outside the workplace and COVID-19 patient care activities from HCP with positive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) test results (cases) and from HCP with negative test results (controls) in healthcare facilities in 5 US states. We used conditional logistic regression to calculate adjusted matched odds ratios and 95% CIs for exposures. Among 345 cases and 622 controls, factors associated with risk were having close contact with persons with COVID-19 outside the workplace, having close contact with COVID-19 patients in the workplace, and assisting COVID-19 patients with activities of daily living. Protecting HCP from COVID-19 may require interventions that reduce their exposures outside the workplace and improve their ability to more safely assist COVID-19 patients with activities of daily living.

Antimicrobial Use in a Cohort of US Nursing Homes, 2017.

Importance: Controlling antimicrobial resistance in health care is a public health priority, although data describing antimicrobial use in US nursing homes are limited. Objective: To measure the prevalence of antimicrobial use and describe antimicrobial classes and common indications among nursing home residents. Design, Setting, and Participants: Cross-sectional, 1-day point-prevalence surveys of antimicrobial use performed between April 2017 and October 2017, last survey date October 31, 2017, and including 15 276 residents present on the survey date in 161 randomly selected nursing homes from selected counties of 10 Emerging Infections Program (EIP) states. EIP staff reviewed nursing home records to collect data on characteristics of residents and antimicrobials administered at the time of the survey. Nursing home characteristics were obtained from nursing home staff and the Nursing Home Compare website. Exposures: Residence in one of the participating nursing homes at the time of the survey. Main Outcomes and Measures: Prevalence of antimicrobial use per 100 residents, defined as the number of residents receiving antimicrobial drugs at the time of the survey divided by the total number of surveyed residents. Multivariable logistic regression modeling of antimicrobial use and percentages of drugs within various classifications. Results: Among 15 276 nursing home residents included in the study (mean [SD] age, 77.6 [13.7] years; 9475 [62%] women), complete prevalence data were available for 96.8%. The overall antimicrobial use prevalence was 8.2 per 100 residents (95% CI, 7.8-8.8). Antimicrobial use was more prevalent in residents admitted to the nursing home within 30 days before the survey date (18.8 per 100 residents; 95% CI, 17.4-20.3), with central venous catheters (62.8 per 100 residents; 95% CI, 56.9-68.3) or with indwelling urinary catheters (19.1 per 100 residents; 95% CI, 16.4-22.0). Antimicrobials were most often used to treat active infections (77% [95% CI, 74.8%-79.2%]) and primarily for urinary tract infections (28.1% [95% CI, 15.5%-30.7%]). While 18.2% (95% CI, 16.1%-20.1%) were for medical prophylaxis, most often use was for the urinary tract (40.8% [95% CI, 34.8%-47.1%]). Fluoroquinolones were the most common antimicrobial class (12.9% [95% CI, 11.3%-14.8%]), and 33.1% (95% CI, 30.7%-35.6%) of antimicrobials used were broad-spectrum antibiotics. Conclusions and Relevance: In this cross-sectional survey of a cohort of US nursing homes in 2017, prevalence of antimicrobial use was 8.2 per 100 residents. This study provides information on the patterns of antimicrobial use among these nursing home residents.

International comparison of pressure ulcer measures in long-term care facilities: Assessing the methodological robustness of 4 approaches to point prevalence measurement.

INTRODUCTION: Pressure ulcer indicators are among the most frequently used performance measures in long-term care settings. However, measurement systems vary and there is limited knowledge about the international comparability of different measurement systems. The aim of this analysis was to identify possible avenues for international comparisons of data on pressure ulcer prevalence among residents of long-term care facilities. MATERIAL AND METHODS: A descriptive analysis of the four point prevalence measurement systems programs used in 28 countries on three continents was performed. The criteria for the description and analysis were based on the scientific literature on criteria for indicator selection, on issues in international comparisons of data and on specific challenges of pressure ulcer measurements. RESULTS: The four measurement systems use a prevalence measure based on very similar numerator and denominator definitions. All four measurement systems also collect data on patient mobility. They differ in the pressure ulcer classifications used and the requirements for a head-to-toe resident examination. The regional or country representativeness of long-term care facilities also varies among the four measurement systems. CONCLUSIONS: Methodological differences among the point prevalence measurement systems are an important barrier to reliable comparisons of pressure ulcer prevalence data. The alignment of the methodologies may be improved by implementing changes to the study protocols, such as aligning the classification of pressure ulcers and requirements for a head-to-toe resident skin assessment. The effort required for each change varies. All these elements need to be considered by any initiative to facilitate international comparison and learning.

Facility-Wide Testing for SARS-CoV-2 in Nursing Homes - Seven U.S. Jurisdictions, March-June 2020.

Undetected infection with SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19) contributes to transmission in nursing homes, settings where large outbreaks with high resident mortality have occurred (1,2). Facility-wide testing of residents and health care personnel (HCP) can identify asymptomatic and presymptomatic infections and facilitate infection prevention and control interventions (3-5). Seven state or local health departments conducted initial facility-wide testing of residents and staff members in 288 nursing homes during March 24-June 14, 2020. Two of the seven health departments conducted testing in 195 nursing homes as part of facility-wide testing all nursing homes in their state, which were in low-incidence areas (i.e., the median preceding 14-day cumulative incidence in the surrounding county for each jurisdiction was 19 and 38 cases per 100,000 persons); 125 of the 195 nursing homes had not reported any COVID-19 cases before the testing. Ninety-five of 22,977 (0.4%) persons tested in 29 (23%) of these 125 facilities had positive SARS-CoV-2 test results. The other five health departments targeted facility-wide testing to 93 nursing homes, where 13,443 persons were tested, and 1,619 (12%) had positive SARS-CoV-2 test results. In regression analyses among 88 of these nursing homes with a documented case before facility-wide testing occurred, each additional day between identification of the first case and completion of facility-wide testing was associated with identification of 1.3 additional cases. Among 62 facilities that could differentiate results by resident and HCP status, an estimated 1.3 HCP cases were identified for every three resident cases. Performing facility-wide testing immediately after identification of a case commonly identifies additional unrecognized cases and, therefore, might maximize the benefits of infection prevention and control interventions. In contrast, facility-wide testing in low-incidence areas without a case has a lower proportion of test positivity; strategies are needed to further optimize testing in these settings.

Hepatitis B Care Continuum Models-Data to Inform Public Health Action.

The application of a care continuum model (CCM) can identify gaps in diagnosis, care, and treatment of populations with a common condition, but challenges are inherent in developing a CCM for chronic hepatitis B. In contrast with treatment for HIV or hepatitis C, treatment is not indicated for all people with chronic hepatitis B, clinical endpoints are not clear for those receiving treatment, and those for whom treatment is not indicated remain at risk for complications. This topical review examines the data elements necessary to develop and apply chronic hepatitis B CCMs at the jurisdictional health department level. We conducted a nonsystematic review of US-based publications in Ovid MEDLINE (1946-present), Ovid Embase (1974-present), and Scopus (not date limited) databases, which yielded 724 publications for review. Jurisdictional health departments, if properly supported, could develop locale-specific focused CCMs using person-level chronic hepatitis B registries, updated longitudinally using electronic laboratory reporting data and case reporting data. These CCMs could be applied to identify disparities and improve rates in testing and access to care and treatment, which are necessary to reduce liver disease and chronic hepatitis B mortality. Investments in public health surveillance infrastructure, including substantial enhancements in electronic laboratory reporting and case reporting and the use of supplementary data sources, could enable jurisdictional health departments to develop modified CCMs for chronic hepatitis B that focus, at least initially, on "early" CCM steps, which emphasize optimization of hepatitis B diagnosis, linkage to care, and ongoing clinical follow-up of diagnosed people, all of which can lead to improved outcomes.

Hepatitis C Virus Testing, Infection, and Cases Reported Through Public Health Surveillance During Expanded Screening Recommendations, United States, 2013-2021.

OBJECTIVES: Hepatitis C virus (HCV) infection is the most common bloodborne infection in the United States. We assessed trends in HCV testing, infection, and surveillance cases among US adults. METHODS: We used Quest Diagnostics data from 2013-2021 to assess trends in the numbers tested for HCV antibody and proportion of positivity for HCV antibody and HCV RNA. We also assessed National Notifiable Diseases Surveillance System 2013-2020 data for trends in the number and proportion of hepatitis C cases. We applied joinpoint regression for trends testing. RESULTS: Annual HCV antibody testing increased from 1.7 million to 4.8 million from 2013 to 2021, and the positivity proportion declined (average, 0.2% per year) from 5.5% to 3.7%. The greatest percentage-point increase in HCV antibody testing occurred in hospitals and substance use disorder treatment facilities and among addiction medicine providers. HCV RNA positivity was stable at about 60% in 2013-2015 and declined to 41.0% in 2021 (2015-2021 average, -3.2% per year). Age-specific HCV RNA positivity was highest among people aged 40-59 years during 2013-2015 and among people aged 18-39 years during 2016-2021. The number of reported hepatitis C cases (acute and chronic) declined from 179 341 in 2015 to 105 504 in 2020 (average decline, -13 177 per year). The proportion of hepatitis C cases among those aged 18-39 years increased by an average of 1.4% per year during 2013-2020; among individuals aged 40-59 years, it decreased by an average of 2.3% per year during 2013-2018. CONCLUSIONS: HCV testing increased, suggesting improved universal screening. Various data sources are valuable for monitoring elimination progress.

Transmission of hepatitis B virus from an orthopedic surgeon with a high viral load.

BACKGROUND: During the evaluation of a needle-stick injury, an orthopedic surgeon was found to be unknowingly infected with hepatitis B virus (HBV) (viral load >17.9 million IU/mL). He had previously completed two 3-dose series of hepatitis B vaccine without achieving a protective level of surface antibody. We investigated whether any surgical patients had acquired HBV infection while under his care. METHODS: A retrospective cohort study of all patients who underwent surgery by the surgeon was conducted. Patients were notified of their potential exposure and need for testing, and samples with positive HBV loads underwent DNA sequencing. Characteristics of the surgical procedures for the cohort were evaluated. RESULTS: A total of 232 (70.7%) of potentially exposed patients consented to testing; 2 were found to have acute infection and 6 had possible transmission (evidence of past exposure without risk factors). Genome sequence analysis of HBV DNA from the infected surgeon and patients with acute infection revealed genetically related virus (>99.9% nucleotide identity). Only age was found to be statistically different between those with confirmed or possible HBV transmission and those who remained susceptible to HBV. CONCLUSIONS: We documented HBV transmission during orthopedic surgery to 2 patients from a surgeon with HBV. This investigation highlights the importance of evaluating individuals who do not respond to 2 series of HBV vaccination, the increased risk of HBV transmission from providers with high viral loads, and the need to evaluate the clinical practice of providers with HBV and implement appropriate procedure-based practice restrictions.

Hepatitis C virus screening and management of seroconversions in hemodialysis facilities.

Over the past two decades, healthcare-associated exposure has increasingly been proved to be a means of hepatitis C virus (HCV) transmission, especially in hemodialysis facilities. The prevalence of HCV among hemodialysis patients is known to be several times greater than that of the general population of the United States, and chronic HCV infection is associated with significant morbidity and mortality among these patients. During 2008-2011, HCV infection outbreaks were identified in multiple US hemodialysis facilities, resulting in at least 46 new HCV infections among hemodialysis patients. These outbreaks, linked to infection control breaches, also highlight the failure of some facilities to follow established guidelines for routine HCV antibody (anti-HCV) screening and response to new HCV infection among hemodialysis patients. Current national guidelines recommend screening of hemodialysis patients for anti-HCV on facility admission and, for susceptible patients, on a semiannual basis. Here, we seek to underscore the importance of compliance with national recommendations for anti-HCV screening of hemodialysis patients and actions to be taken in the event of possible HCV transmission within a hemodialysis facility. These include general steps to ensure that: hemodialysis patients are routinely screened for anti-HCV to facilitate early detection of new infections; newly infected patients are informed of the change in their HCV status and undergo clinical evaluation; and public health officials are notified of new HCV infections in a timely manner. We then focus on the need to assess infection control practices at the facility, with particular attention given to safe handling of injectable medications, hand hygiene and disinfection practices. In the absence of a vaccine, routine screening and adherence to standard infection control practices will remain the key strategies for preventing HCV transmission in hemodialysis units.

Health care-associated hepatitis C virus infections attributed to narcotic diversion.

BACKGROUND: Three cases of genetically related hepatitis C virus (HCV) infection that were unattributable to infection control breaches were identified at a health care facility. OBJECTIVE: To investigate HCV transmission from an HCV-infected health care worker to patients through drug diversion. DESIGN: Cluster and look-back investigations. SETTING: Acute care hospital and affiliated multispecialty clinic. PATIENTS: Inpatients and outpatients during the period of HCV transmission. MEASUREMENTS: Employee work and narcotic dispensing records, blood testing for HCV antibody and RNA, and sequencing of the NS5B gene and the hypervariable region 1 of the E2 gene. RESULTS: 21 employees were recorded as being at work or as retrieving a narcotic from an automated dispensing cabinet in an area where a narcotic was administered to each of the 3 case patients; all employees provided blood samples for HCV testing. One employee was infected with HCV that had more than 95% NS5B sequence homology with the HCV strains of the 3 case patients. Quasi-species analysis showed close genetic relatedness with variants from each of the case patients and more than 97.9% nucleotide identity. The employee acknowledged parenteral opiate diversion. An investigation identified 6132 patients at risk for exposure to HCV because of the drug diversion. Of the 3929 living patients, 3444 (87.7%) were screened for infection. Two additional cases of genetically related HCV infection attributable to the employee were identified. LIMITATION: Of the living patients at risk for HCV exposure, 12.3% were not tested. CONCLUSION: Five cases of HCV infection occurring over 3 to 4 years were attributed to drug diversion by an HCV-infected health care worker. Studies of drug diversion and assessments of strategies to prevent narcotics tampering in all health care settings are needed. PRIMARY FUNDING SOURCE: None.

Outbreak of hepatitis C virus infections at an outpatient hemodialysis facility: the importance of infection control competencies.

In the United States, the prevalence of hepatitis C virus infection among patients treated in hemodialysis facilities is five times higher than among the general population. This study investigated eight new hepatitis C virus infections among patients treated at an outpatient hemodialysis facility. Epidemiologic investigation and viral sequencing demonstrated that transmission likely occurred between patients typically treated during the same or consecutive shifts at the same or a nearby station. Several infection control breaches were observed including lapses involving the preparation, handling, and administration of parenteral medications. Improved infection control education and training for all hemodialysis facility staff is an important component of assuring adherence to appropriate procedures and preventing future outbreaks.

Assessing Pathogen Transmission Opportunities: Variation in Nursing Home Staff-Resident Interactions.

OBJECTIVES: The Centers for Disease Control and Prevention (CDC) recommends implementing Enhanced Barrier Precautions (EBP) for all nursing home (NH) residents known to be colonized with targeted multidrug-resistant organisms (MDROs), wounds, or medical devices. Differences in health care personnel (HCP) and resident interactions between units may affect risk of acquiring and transmitting MDROs, affecting EBP implementation. We studied HCP-resident interactions across a variety of NHs to characterize MDRO transmission opportunities. DESIGN: 2 cross-sectional visits. SETTING AND PARTICIPANTS: Four CDC Epicenter sites and CDC Emerging Infection Program sites in 7 states recruited NHs with a mix of unit care types (≥30 beds or ≥2 units). HCP were observed providing resident care. METHODS: Room-based observations and HCP interviews assessed HCP-resident interactions, care type provided, and equipment use. Observations and interviews were conducted for 7-8 hours in 3-6-month intervals per unit. Chart reviews collected deidentified resident demographics and MDRO risk factors (eg, indwelling devices, pressure injuries, and antibiotic use). RESULTS: We recruited 25 NHs (49 units) with no loss to follow-up, conducted 2540 room-based observations (total duration: 405 hours), and 924 HCP interviews. HCP averaged 2.5 interactions per resident per hour (long-term care units) to 3.4 per resident per hour (ventilator care units). Nurses provided care to more residents (n = 12) than certified nursing assistants (CNAs) and respiratory therapists (RTs) (CNA: 9.8 and RT: 9) but nurses performed significantly fewer task types per interaction compared to CNAs (incidence rate ratio (IRR): 0.61, P < .05). Short-stay (IRR: 0.89) and ventilator-capable (IRR: 0.94) units had less varied care compared with long-term care units (P < .05), although HCP visited residents in these units at similar rates. CONCLUSIONS AND IMPLICATIONS: Resident-HCP interaction rates are similar across NH unit types, differing primarily in types of care provided. Current and future interventions such as EBP, care bundling, or targeted infection prevention education should consider unit-specific HCP-resident interaction patterns.

Patient notification for bloodborne pathogen testing due to unsafe injection practices in the US health care settings, 2001-2011.

BACKGROUND: Syringe reuse and other unsafe injection practices can expose patients to bloodborne pathogens (eg, hepatitis B and C viruses and human immunodeficiency virus). Evidence of such infection control lapses has resulted in patient notifications, but the scope and magnitude of these events have not been well characterized. OBJECTIVES: To summarize patient notification events resulting from unsafe injection practices in the US health care settings. METHODS: We examined records of events that involved communications to groups of patients, conducted during 2001-2011, advising bloodborne pathogen testing stemming from potential exposures to unsafe injection practices. RESULTS: We identified 35 patient notification events related to unsafe injection practices in at least 17 states, resulting in an estimated total of 130,198 patients notified. Among the identified notification events, 83% involved outpatient settings and 74% occurred since 2007, including the 4 largest events (>5000 patients per event). The primary breach identified (≥16 events; 44%) was syringe reuse to access shared medications (eg, single-dose or multidose vials). Twenty-two (63%) notifications stemmed from the identification of viral hepatitis transmission, whereas 13 (37%) were prompted by the discovery of unsafe injection practices, absent evidence of bloodborne pathogen transmission. CONCLUSIONS: Unsafe injection practices represent a form of medical error that have manifested as large-scale adverse events, affecting thousands of patients in a wide variety of health care settings. Our findings suggest that increased oversight and attention to basic infection control are needed to maintain patient safety, along with research to identify best practices for triggering and managing patient notifications.

An investigation of bloodborne pathogen transmission due to multipatient sharing of insulin pens.

On January 30, 2009, nursing staff at a military hospital in Texas reported that single-patient use insulin pens were used on multiple patients. An investigation was initiated to determine if patient-to-patient bloodbome transmission occurred from the practice. Human immunodeficiency virus (HIV), hepatitis B virus (HBV), and hepatitis C virus (HCV) testing was offered to patients hospitalized from August 2007 to January 2009 and prescribed insulin pen injections. Virus from HCV-infected patients' sera was sequenced and compared for relatedness. An anonymous survey was administered to nurses. Of 2,113 patients prescribed insulin pen injections, 1,501 (71%) underwent testing; 6 (0.4%) were HIV positive, 6 (0.4%) were hepatitis B surface antigen positive, and 56 (3.7%) had HCV antibody. No viral sequences from 10 of 28 patients with newly diagnosed and 12 of 28 patients with preexisting HCV infection were closely related. Of 54 nurses surveyed, 74% reported being trained on insulin pen use, but 24% believed nurses used insulin pens on more than one patient. We found no clear evidence of bloodborne pathogen transmission. Training of hospital staff on correct use of insulin pens should be prioritized and their practices evaluated. Insulin pens should be more clearly labeled for single-patient use.

Practices and activities among healthcare personnel with severe acute respiratory coronavirus virus 2 (SARS-CoV-2) infection working in different healthcare settings-ten Emerging Infections Program sites, April-November 2020.

Healthcare personnel with severe acute respiratory coronavirus virus 2 (SARS-CoV-2) infection were interviewed to describe activities and practices in and outside the workplace. Among 2,625 healthcare personnel, workplace-related factors that may increase infection risk were more common among nursing-home personnel than hospital personnel, whereas selected factors outside the workplace were more common among hospital personnel.

Antibiotic-resistant pathogens associated with urinary tract infections in nursing homes: Summary of data reported to the National Healthcare Safety Network Long-Term Care Facility Component, 2013-2017.

OBJECTIVE: Antibiotic resistance (AR) is a growing and highly prevalent problem in nursing homes. We describe selected AR phenotypes from pathogens causing urinary tract infections (UTIs) reported by nursing homes to the National Healthcare Safety Network (NHSN). DESIGN: Pathogens and antibiotic susceptibility testing results for UTI events in nursing homes between January 2013 and December 2017 were analyzed. The pathogen distribution and pooled mean proportion of isolates that tested resistant to select antibiotic agents are reported. SETTING AND PARTICIPANTS: US nursing homes voluntarily participating in the Long-Term Care Facility component of the NHSN. RESULTS: Overall, 243 nursing homes reported 1 or more UTIs: 121 (50%) were nonprofit facilities, median bed size was 91 (range: 9-801), and average occupancy was 87%. In total, 6,157 pathogens were reported for 5,485 UTI events. Moreover, 9 pathogens accounted for 90% of all reported UTIs; the 3 most frequently identified were Escherichia coli (41%), Proteus species (14%), and Klebsiella pneumoniae/oxytoca (13%). Among E. coli, fluoroquinolone, and extended-spectrum cephalosporin resistance were most prevalent (50% and 20%, respectively). Although Staphylococcus aureus and Enterococcus faecium represented <5% of pathogens reported, they had the highest rates of resistance (67% methicillin resistant and 60% vancomycin resistant, respectively). Multidrug resistance was most common in Pseudomonas aeruginosa (11%). For the resistant phenotypes we assessed, 36% of all UTIs reported were associated with a resistant pathogen. CONCLUSIONS: This is the first summary of AR among common pathogens causing UTIs reported to NHSN by nursing homes. Improved understanding of the resistance burden among common infections helps inform facility infection prevention and antibiotic stewardship efforts.

Epidemiology, surveillance, and prevention of hepatitis C virus infections in hemodialysis patients.

Hepatitis C virus (HCV) infection is the most common chronic blood-borne infection in the United States; the prevalence in maintenance hemodialysis patients substantially exceeds that in the general population. In hemodialysis patients, HCV infection has been associated with increased occurrence of cirrhosis and hepatocellular carcinoma and increased mortality. Injection drug use and receipt of blood transfusions before 1992 has accounted for most prevalent HCV infections in the United States. However, HCV transmission among patients undergoing hemodialysis has been documented frequently. Outbreak investigations have implicated lapses in infection control practices as the cause of HCV infections. Preventing these infections is an emerging priority for renal care providers, public health agencies, and regulators. Adherence to recommended infection control practices is effective in preventing HCV transmission in hemodialysis facilities. In addition, adoption of routine screening to facilitate the detection of incident HCV infections and hemodialysis-related transmission is an essential component of patient safety and infection prevention efforts. This article describes the current epidemiology of HCV infection in US maintenance hemodialysis patients and prevention practices to decrease its incidence and transmission.

Nonhospital health care-associated hepatitis B and C virus transmission: United States, 1998-2008.

In the United States, transmission of hepatitis B virus (HBV) and hepatitis C virus (HCV) from health care exposures has been considered uncommon. However, a review of outbreak information revealed 33 outbreaks in nonhospital health care settings in the past decade: 12 in outpatient clinics, 6 in hemodialysis centers, and 15 in long-term care facilities, resulting in 448 persons acquiring HBV or HCV infection. In each setting, the putative mechanism of infection was patient-to-patient transmission through failure of health care personnel to adhere to fundamental principles of infection control and aseptic technique (for example, reuse of syringes or lancing devices). Difficult to detect and investigate, these recognized outbreaks indicate a wider and growing problem as health care is increasingly provided in outpatient settings in which infection control training and oversight may be inadequate. A comprehensive approach involving better viral hepatitis surveillance and case investigation, health care provider education and training, professional oversight, licensing, and public awareness is needed to ensure that patients are always afforded basic levels of protection against viral hepatitis transmission.

Documentation of acute change in mental status in nursing homes highlights opportunity to augment infection surveillance criteria.

Acute change in mental status (ACMS), defined by the Confusion Assessment Method, is used to identify infections in nursing home residents. A medical record review revealed that none of 15,276 residents had an ACMS documented. Using the revised McGeer criteria with a possible ACMS definition, we identified 296 residents and 21 additional infections. The use of a possible ACMS definition should be considered for retrospective nursing home infection surveillance.