Immunogenicity and reactogenicity of high- vs. standard-dose trivalent inactivated influenza vaccine in healthcare workers: a pilot randomized controlled trial.

OBJECTIVES: To compare immunogenicity, reactogenicity and acceptability of high- and standard-dose trivalent inactivated influenza vaccine (HDTIV, SDTIV) in 18- to 64-year-olds. METHODS: We randomized 18- to 64-year-olds to HDTIV or SDTIV in two consecutive years. We collected serum on days 0 and 21, measured haemagglutination inhibition geometric mean titres (GMT) and compared seroconversion, day 21 titres, seroprotection, reactogenicity and acceptability. RESULTS: Immunogenicity was evaluable in 42 of 47 2014 participants, all 33 both-year participants and 87 of 90 2015-only participants. First-dose HDTIV recipients experienced seroconversion more frequently than SDTIV recipients to A(H3N2) in 2014 (13/21, 62% vs. 4/21, 19%, p 0.01) and to all vaccine strains in 2015: (A(H1N1): 24/42, 57% vs. 15/59, 25%; A(H3N2): 42/42, 100% vs. 47/59, 80%; B: 25/42, 60% vs. 13/59, 22%; all p <0.01). Day 21 haemagglutination inhibition GMT were higher in first and two sequential-year HDTIV vs. SDTIV recipients: A(H1N1): GMT 749 and 768 vs. 384 (p <0.0001, p 0.002); A(H3N2): 1238 and 956 vs. 633 (p 0.0003, p 0.1); and B: 1113 and 1086 vs. 556 (p 0.0005, p 0.02). HDTIV was more reactogenic (local pain score 3 vs. 1 of 10 on day 0/1, p 0.0003), but recipients were equally willing to be revaccinated (HDTIV: 76/83 (92%); SDTIV: 76/80 (95%), p 0.54). The ratios of day 21 GMT in SDTIV recipients vaccinated in 0 to 4 prior years to those in SDTIV and HDTIV recipients vaccinated in 15 or more prior years were A(H1N1): 3.73 and 1.38; A(H3N2) 3.07 and 1.16; and B: 2.01 and 1.21. CONCLUSIONS: HDTIV is more immunogenic and reactogenic and as acceptable as SDTIV in 18- to 64-year-olds.

Is the prevalence of antibiotic-resistant organisms changing in Canadian hospitals? Comparison of point-prevalence survey results in 2010 and 2012.

A national point-prevalence survey for infection or colonization with methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE), and for Clostridium difficile infection (CDI) was done in Canadian hospitals in 2010. A follow-up survey was done in November 2012 to determine whether there were any changes in the prevalence of these organisms; we also determined the prevalence of extended-spectrum ß-lactamase (ESBL)-producing Enterobacteriaceae, and carbapenem-resistant Enterobacteriaceae (CREs). Associations between prevalence and infection prevention and control policies were evaluated in logistic regression models. A total of 143 (67% of eligible facilities) hospitals with 29 042 adult inpatients participated in the survey, with representation from all 10 provinces; 132 hospitals participated in 2010 and 2012. There were no significant changes in the median prevalence of MRSA in 2010 (4.3%) compared to 2012 (3.9%), or of CDI in 2010 (0.8%) compared to 2012 (0.9%). A higher median prevalence of VRE was identified in 2012 (1.3%) compared to 2010 (0.5%) (p 0.04), despite decreased VRE screening in 2012. The median prevalence of ESBLs was 0.7% and was 0 for CREs; CREs were reported from only 10 hospitals (7.0%). A policy of routinely caring for patients with MRSA or VRE in a private isolation room was associated with lower prevalence of these organisms. Targeted screening of high-risk patients at admission was associated with lower MRSA prevalence; better hand hygiene compliance was associated with lower VRE prevalence. These data provide national prevalence rates for antibiotic-resistant organisms among adults hospitalized in Canadian hospitals. Certain infection prevention and control policies were associated with prevalence.

Molecular epidemiology of vancomycin-resistant enterococcal bacteraemia: results from the Canadian Nosocomial Infection Surveillance Program, 1999-2009.

OBJECTIVES: Vancomycin-resistant enterococci (VRE) can be associated with serious bacteraemia. The focus of this study was to characterize the molecular epidemiology of VRE from bacteraemia cases that were isolated from 1999 to 2009 as part of Canadian Nosocomial Infection Surveillance Program (CNISP) surveillance activities. METHODS: From 1999 to 2009, enterococci were collected from across Canada in accordance with the CNISP VRE surveillance protocol. MICs were determined using broth microdilution. PCR was used to identify vanA, B, C, D, E, G and L genes. Genetic relatedness was examined using multilocus sequence typing (MLST). RESULTS: A total of 128 cases of bacteraemia were reported to CNISP from 1999 to 2009. In 2007, a significant increase in bacteraemia rates was observed in western and central Canada. Eighty-one of the 128 bacteraemia isolates were received for further characterization and were identified as Enterococcus faecium. The majority of isolates were from western Canada (60.5%), followed by central (37.0%) and eastern (2.5%) Canada. Susceptibilities were as follows: daptomycin, linezolid, tigecycline and chloramphenicol, 100%; quinupristin/dalfopristin, 96.3%; high-level gentamicin, 71.6%; tetracycline, 50.6%; high-level streptomycin, 44.4%; rifampicin, 21.0%; nitrofurantoin, 11.1%; clindamycin, 8.6%; ciprofloxacin, levofloxacin and moxifloxacin, 1.2%; and ampicillin, 0.0%. vanA contributed to vancomycin resistance in 90.1% of isolates and vanB in 9.9%. A total of 17 sequence types (STs) were observed. Beginning in 2006 there was a shift in ST from ST16, ST17, ST154 and ST80 to ST18, ST412, ST203 and ST584. CONCLUSIONS: The increase in bacteraemia observed since 2007 in western and central Canada appears to coincide with the shift of MLST STs. All VRE isolates remained susceptible to daptomycin, linezolid, chloramphenicol and tigecycline.

Audit of antibiotic duration of therapy, appropriateness and outcome in patients with nosocomial pneumonia following the removal of an automatic stop-date policy.

Automatic stop-orders (ASOs) have been utilized to discourage inappropriately prolonged antibiotic therapy. An ASO policy, which required reordering of antibiotics after 7 days of therapy, had been in place at our institution prior to 2002, but was revoked after instances of compromised patient care due to inadvertent and inappropriate interruption of antimicrobial treatment. The objective of this study was to evaluate the impact of revoking the ASO policy on the duration of antibiotic therapy, infection-related outcome (cure vs failure), relapsing infection, occurrence of resistant bacteria and superinfection in patients with nosocomial pneumonia. A retrospective chart review of adult patients (≥ 18 years old) admitted to Sunnybrook Health Sciences Centre with nosocomial pneumonia requiring antibiotic therapy was conducted. Duration of antibiotic therapy, infection-related outcome (cure vs failure), rate of relapsing infection, resistant organisms and superinfection were determined for each cohort. Forty-six eligible adults with nosocomial pneumonia per cohort were included [corrected]. Duration of antibiotic therapy was not significantly different in the pre- (11.4 ± 3.8 days) compared with the post-ASO revocation cohort (10.8 ± 4.1 days; p=0.43). There were also no significant differences between the cohorts with regard to infection-related outcome (cure vs failure), relapsing infection, or the occurrence of resistant bacteria or superinfection (p>0.5). Revocation of the ASO policy for antibiotics at our institution was not associated with a longer duration of antibiotic therapy, or increased incidence of infection-related mortality, relapsing infection, resistant bacteria or superinfection for patients with nosocomial pneumonia.

Evaluation of a new chromogenic medium (StrepB select) for detection of group B Streptococcus from vaginal-rectal specimens.

We compared StrepB Select medium (Select) after enrichment with conventional culture for the detection of Group B Streptococcus (GBS). Postenrichment sensitivities of Select and conventional culture were 98.8% and 92.2%, respectively (P<0.05). Select was superior for detection of GBS from vaginal-rectal specimens. Growth of non-GBS colonies required additional work to exclude the presence of GBS, especially after 48 h of incubation. Incubation of Select beyond 24 h did not significantly increase the yield of GBS.

Factors associated with critical-care healthcare workers' adherence to recommended barrier precautions during the Toronto severe acute respiratory syndrome outbreak.

OBJECTIVE: To assess factors associated with adherence to recommended barrier precautions among healthcare workers (HCWs) providing care to critically ill patients with severe acute respiratory syndrome (SARS). SETTING: Fifteen acute care hospitals in Ontario, Canada. DESIGN: Retrospective cohort study. PATIENTS: All patients with SARS who required intubation during the Toronto SARS outbreak in 2003. PARTICIPANTS: HCWs who provided care to or entered the room of a SARS patient during the period from 24 hours before intubation until 4 hours after intubation. METHODS: Standardized interviews were conducted with eligible HCWs to assess their interactions with the SARS patient, their use of barrier precautions, their practices for removing personal protective equipment, and the infection control training they received. RESULTS: Of 879 eligible HCWs, 795 (90%) participated. In multivariate analysis, the following predictors of consistent adherence to recommended barrier precautions were identified: recognition of the patient as a SARS case (odds ratio [OR], 2.5 [95% confidence interval {CI}, 1.5-4.5); recent infection control training (OR for interactive training, 2.7 [95% CI, 1.7-4.4]; OR for passive training, 1.7 [95% CI, 1.0-3.0]), and working in a SARS unit (OR, 4.0 [95% CI, 1.8-8.9]) or intensive care unit (OR, 4.3 [95% CI, 2.0-9.0]). Two factors were associated with significantly lower rates of consistent adherence: the provision of care for patients with higher Acute Physiology and Chronic Health Evaluation (APACHE) II scores (OR for score APACHE II of 20 or greater, 0.4 [95% CI, 0.28-0.68]) and work on shifts that required more frequent room entry (OR for 6 or more entries per shift, 0.5 [95% CI, 0.32-0.86]). CONCLUSIONS: There were significant deficits in knowledge about self-protection that were partially corrected by education programs during the SARS outbreak. HCWs' adherence to self-protection guidelines was most closely associated with whether they provided care to patients who had received a definite diagnosis of SARS.

Detection of severe acute respiratory syndrome coronavirus in stool specimens by commercially available real-time reverse transcriptase PCR assays.

Three commercially available real-time reverse transcriptase PCR assays (the Artus RealArt HPA coronavirus LightCycler, the Artus RealArt HPA coronavirus Rotor-Gene, and the EraGen severe acute respiratory syndrome coronavirus POL assay) and three RNA extraction methodologies were evaluated for the detection of severe acute respiratory syndrome coronavirus RNA from 91 stool specimens. The assays' sensitivities were highest (58% to 75%) for specimens obtained 8 to 21 days after symptom onset. The assays were less sensitive when specimens were obtained less than 8 days or more than 21 days after the onset of symptoms. All assays were 100% specific.

Hospital-acquired invasive group a streptococcal infections in Ontario, Canada, 1992-2000.

BACKGROUND: A significant proportion of invasive group A streptococcal infections are hospital acquired. No large, prospective studies have characterized this subgroup of cases and evaluated the risk of transmission in hospitals. METHODS: We conducted prospective, population-based surveillance of invasive group A streptococcal infections in Ontario, Canada, from 1992 to 2000. Epidemiologic and microbiologic investigations were conducted to identify cross-transmission. RESULTS: We identified 291 hospital-acquired cases (12.4%) among 2351 cases of invasive group A streptococcal disease. Hospital-acquired invasive group A streptococcal infections are heterogeneous, including surgical site (96 cases), postpartum (86 cases), and nonsurgical, nonobstetrical infections (109 cases). Surgical site infections affected 1 of 100,000 surgical procedures and involved all organ systems. Postpartum infections occurred at a rate of 0.7 cases per 10,000 live births and exhibited an excellent prognosis. Nonsurgical, nonobstetrical infections encompassed a broad range of infectious syndromes (case-fatality rate, 37%). Nine percent of cases were associated with in-hospital transmission. Transmission occurred from 3 of 142 patients with community-acquired cases of necrotizing fasciitis requiring intensive care unit (ICU) admission, compared with 1 of 367 patients with community-acquired cases without necrotizing fasciitis admitted to the ICU and 1 of 1551 patients with other cases (P<.001). Fifteen outbreaks were identified; 9 (60%) involved only 2 cases. Hospital staff were infected in 1 of 15 outbreaks, but colonized staff were identified in 6 (60%) of 10 investigations in which staff were screened. CONCLUSIONS: Presentation of hospital-associated invasive group A streptococcal infections is diverse. Cross-transmission is common; illness occurs in patients but rarely in staff. Isolation of new cases of necrotizing fasciitis and intervention after a single nosocomial case may also prevent transmission.

Rapid detection of methicillin-resistant staphylococci from blood culture bottles by using a multiplex PCR assay.

Rapid detection and accurate identification of methicillin-resistant staphylococci are critical for the effective management of infections caused by these organisms. We describe a multiplex PCR-based assay for the direct detection of methicillin-resistant staphylococci from blood culture bottles (BacT/Alert; Organon-Teknika, Durham, N.C.). A simple lysis method followed by a multiplex PCR assay designed to detect the nuc, mecA, and bacterial 16S rRNA genes was performed. A total of 306 blood culture specimens were collected over a period of 10 months from June 1998 to April 1999, consisting of 236 blood cultures growing staphylococci (including 124 methicillin-resistant Staphylococcus spp.), 50 positive blood cultures which grew organisms other than staphylococci, and 20 blood cultures that were negative for bacterial and fungal pathogens after 5 days of incubation and terminal subculture. DNA extraction, PCR, and detection could be completed in 2.5 h. Of the positive blood cultures with staphylococci, the multiplex PCR assay had a sensitivity and specificity of 99.2% and 100%, respectively. Our results show that rapid, direct detection of methicillin-resistant staphylococci is possible, allowing clinicians to make prompt and effective decisions for the management of patients with staphylococcal bacteremia.

Containing methicillin-resistant S aureus. Surveillance, control, and treatment methods.

In the past two decades, the prevalence of MRSA has increased in healthcare facilities in many countries around the world. The organism, which has caused nosocomial outbreaks, also has become endemic in many hospitals and long-term care facilities. Recently, reports of community-acquired MRSA in persons without known risk factors for the organism have been increasing. Transmission occurs primarily from colonized or infected patients to others through the hands of healthcare personnel. MRSA infection may be life-threatening and cause considerable morbidity, the need for prolonged hospitalization, and increased costs. Treatment options are limited because organisms are typically resistant to multiple antibiotics, but newer agents are being developed. However, there is also reason for concern about the recent emergence of MRSA resistant to glycopeptides, such as vancomycin. Efforts to limit the spread of MRSA should include surveillance and control measures, such as adequate hand hygiene and appropriate contact isolation or barrier precautions.

Evaluation of a latex agglutination test (MRSA-Screen) for detection of oxacillin resistance in coagulase-negative Staphylococci.

The MRSA-Screen (Denka-Seiken, Tokyo, Japan) latex agglutination test was evaluated for its ability to detect PBP 2a from 200 clinical isolates of coagulase-negative staphylococci (CoNS; 84 mecA-positive strains and 116 mecA-negative strains) consisting of 108 Staphylococcus epidermidis, 37 S. saprophyticus, 15 S. haemolyticus, 11 S. hominis, 10 S. capitis, 10 S. warneri, and 3 S. lugdunensis species as well as 6 other species of CoNS. The assay was compared with susceptibility testing with an agar screen plate with oxacillin at 6 microg/ml (OXA6), by oxacillin disk diffusion (DD), by broth microdilution (BMDIL), by the E test, and with Vitek GPS-SV and Vitek GPS-107 susceptibility cards. PCR for the detection of the mecA gene was used as the "gold standard." The sensitivities and specificities for the methods evaluated were as follows: MRSA-Screen, 100 and 100%, respectively; OXA6, 100 and 99%, respectively; DD, 98 and 62%, respectively; BMDIL, 100 and 60%, respectively; E test, 100 and 51%, respectively; Vitek GPS-SV susceptibility card, 98 and 87%, respectively; and Vitek GPS-107 susceptibility card, 100 and 61%, respectively. The MRSA-Screen test accurately and rapidly detected oxacillin resistance in CoNS.

The role of the laboratory in infection prevention and control programs in long-term-care facilities for the elderly.

Hospital infection prevention and control programs rely extensively on diagnostic microbiology laboratory testing. However, specimens for microbiological evaluation are less likely to be obtained from elderly residents of long-term-care facilities (LTCFs). In this article, issues regarding laboratory utilization and the potential role of the microbiology laboratory in infection prevention and control programs in LTCFs are reviewed. The role of the laboratory in infection surveillance, in the management of antimicrobial resistance, and in outbreak investigation are highlighted.

Identifying research priorities on infections in older adults: proceedings of an interdisciplinary workshop.

BACKGROUND: Infections pose a substantial burden to the health of older adults. In this report, we describe the proceedings of a workshop to formulate and prioritize research questions about infections in older adults using an interdisciplinary approach. METHODS: Researchers from four sectors (basic science, clinical sciences, health services and epidemiology/determinants of health) and representatives from various Canadian local, provincial, and federal stakeholder groups were invited to a two-day workshop. Five multi-disciplinary groups and stakeholders from each of three healthcare settings (long term, acute care and community) discussed research priorities for each of the settings. Five to ten research questions were identified for each setting. RESULTS: The research questions proposed ranged from risk factors and outcomes for different infections to the effect of nutrition on infection and the role of alternative and complementary medicine in treating infections. Health service issues included barriers to immunization, prolongation of hospital length of stay by infection, use of care paths for managing infections, and decision-making in determining the site of care for individuals with infections. Clinical questions included risk factor assessment for infection, the effectiveness of preventative strategies, and technology evaluation. Epidemiologic issues included the challenge of achieving a better understanding of respiratory infections in the community and determining the prevalence of colonization with multi-resistant bacteria. CONCLUSIONS: The questions are of direct relevance to researchers in a wide variety of fields. Bringing together a multi-disciplinary group of researchers to frame and prioritize research questions about aging is feasible, participants valued the opinions of people working in other areas.

The evolution of methicillin-resistant Staphylococcus aureus in Canadian hospitals: 5 years of national surveillance.

BACKGROUND: To better understand the epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) in Canadian hospitals, surveillance has been conducted in sentinel hospitals across the country since 1995. We report the results of the first 5 years of the program. METHODS: For each newly identified inpatient with MRSA, medical records were reviewed for demographic and clinical data. Isolates were subjected to susceptibility testing and molecular typing by pulsed-field gel electrophoresis. RESULTS: A total of 4507 patients infected or colonized with MRSA were identified between January 1995 and December 1999. The rate of MRSA increased each year from a mean of 0.95 per 100 S. aureus isolates in 1995 to 5.97 per 100 isolates in 1999 (0.46 per 1000 admissions in 1995 to 4.12 per 1000 admissions in 1999) (p < 0.05). Most of the increase in MRSA occurred in Ontario, Quebec and the western provinces. Of the 3009 cases for which the site of MRSA acquisition could be determined, 86% were acquired in a hospital, 8% were acquired in a long-term care facility and 6% were acquired in the community. A total of 1603 patients (36%) were infected with MRSA. The most common sites of infection were skin or soft tissue (25% of MRSA infections), pulmonary tissues (24%) and surgical sites (23%); 13% of the patients were bacteremic. An epidemiologic link with a previously identified MRSA patient was suspected in 53% of the cases. Molecular typing indicated that most (81%) of the isolates could be classified as related to 1 of the 4 Canadian epidemic strains of MRSA. INTERPRETATION: There has been a significant increase in the rate of isolating MRSA in many Canadian hospitals, related to the transmission of a relatively small number of MRSA strains.

Antibiotic use in Ontario facilities that provide chronic care.

OBJECTIVE: To determine the incidence and variability of antibiotic use in facilities which provide chronic care and to determine how often clinical criteria for infection are met when antibiotics are prescribed in these facilities. DESIGN: A prospective, 12-month, observational cohort study. SETTING: Twenty-two facilities which provide chronic care in southwestern Ontario. PARTICIPANTS: Patients who were treated with systemic antibiotics over the study period. MEASUREMENTS: Characteristics of antibiotic prescriptions (name, dose, duration, and indication) and clinical features of randomly selected patients who were treated with antibiotics. RESULTS: A total of 9,373 courses of antibiotics were prescribed for 2,408 patients (66% of all patients in study facilities). The incidence of antibiotic prescriptions in the facilities ranged from 2.9 to 13.9 antibiotic courses per 1,000 patient-days. Thirty-six percent of antibiotics were prescribed for respiratory tract infections, 33% for urinary infections, and 13% for skin and soft tissue infections. Standardized surveillance definitions of infection were met in 49% of the 1,602 randomly selected patients who were prescribed antibiotics. Diagnostic criteria for respiratory, urinary, and skin infection were met in 58%, 28%, and 65% of prescriptions, respectively. One third of antibiotic prescriptions for a urinary indication were for asymptomatic bacteriuria. Adverse reactions were noted in 6% of prescriptions for respiratory and urinary infections and 4% of prescriptions for skin infection. CONCLUSIONS: Antibiotic use is frequent and highly variable amongst patients who receive chronic care. Reducing antibiotic prescriptions for asymptomatic bacteriuria represents an important way to optimize antibiotic use in this population.

Development of minimum criteria for the initiation of antibiotics in residents of long-term-care facilities: results of a consensus conference.

Establishing a clinical diagnosis of infection in residents of long-term-care facilities (LTCFs) is difficult. As a result, deciding when to initiate antibiotics can be particularly challenging. This article describes the establishment of minimum criteria for the initiation of antibiotics in residents of LTCFs. Experts in this area were invited to participate in a consensus conference. Using a modified delphi approach, a questionnaire and selected relevant articles were sent to participants who were asked to rank individual signs and symptoms with respect to their relative importance. Using the results of the weighting by participants, a modification of the nominal group process was used to achieve consensus. Criteria for initiating antibiotics for skin and soft-tissue infections, respiratory infections, urinary infections, and fever where the focus of infection is unknown were developed.

The economic impact of methicillin-resistant Staphylococcus aureus in Canadian hospitals.

OBJECTIVES: To determine the costs associated with the management of hospitalized patients with methicillin-resistant Staphylococcus aureus (MRSA), and to estimate the economic burden associated with MRSA in Canadian hospitals. DESIGN: Patient-specific costs were used to determine the attributable cost of MRSA associated with excess hospitalization and concurrent treatment. Excess hospitalization for infected patients was identified using the Appropriateness Evaluation Protocol, a criterion-based chart review process to determine the need for each day of hospitalization. Concurrent treatment costs were identified through chart review for days in isolation, antimicrobial therapy, and MRSA screening tests. The economic burden to Canadian hospitals was estimated based on 3,167,521 hospital discharges for 1996 and 1997 and an incidence of 4.12 MRSA cases per 1,000 admissions. SETTING: A tertiary-care, university-affiliated teaching hospital in Toronto, Ontario, Canada. PATIENTS: Inpatients with at least one culture yielding MRSA between April 1996 and March 1998. RESULTS: A total of 20 patients with MRSA infections and 79 colonized patients (with 94 admissions) were identified. This represented a rate of 2.9 MRSA cases per 1,000 admissions. The mean number of additional hospital days attributable to MRSA infection was 14, with 11 admissions having at least 1 attributable day. The total attributable cost to treat MRSA infections was $287,200, or $14,360 per patient The cost for isolation and management of colonized patients was $128,095, or $1,363 per admission. Costs for MRSA screening in the hospital were $109,813. Assuming an infection rate of 10% to 20%, we determined the costs associated with MRSA in Canadian hospitals to be $42 million to $59 million annually. CONCLUSIONS: These results indicate that there is a substantial economic burden associated with MRSA in Canadian hospitals. These costs will continue to rise if the incidence of MRSA increases further.

Adherence to antibiotic guidelines for pneumonia in chronic-care facilities in Ontario.

OBJECTIVES: To evaluate adherence to antibiotic recommendations for the treatment of pneumonia in patients who receive long-term care and to assess outcomes associated with these recommendations. DESIGN: A prospective cohort study. SETTING: Twenty-two facilities that provide long-term care in southern Ontario. PARTICIPANTS: Older adults treated with antibiotics for a presumptive diagnosis of pneumonia and those with radiologically confirmed pneumonia METHODS: Over a 12-month period, older patients who were treated with antibiotics for presumptive pneumonia were prospectively identified. A random sample of these antibiotic courses (646 courses in 638 patients) was reviewed using a standardized data collection form, and demographic and clinical data were collected. Antibiotic courses were classified according to Canadian and American Thoracic Society antibiotic recommendations for pneumonia. In patients with radiologically confirmed pneumonia, the effect of adherence to these recommendations on mortality and persistence of symptoms was assessed. RESULTS: Only 27.6% (178 of 646) of antibiotic prescriptions evaluated met antibiotic recommendations for nursing-home-acquired pneumonia, and the proportion meeting these varied greatly by facility, ranging from 0% to 53% (median 31%). For patients with radiologically confirmed pneumonia, age (adjusted odds ratio [OR] 1.6, 95% confidence interval [CI] 1.0-2.4, per increase in 10 yr, p = 0.02), sex (adjusted OR 3.0, 95% CI 1.1-8.0, p = 0.03), and adherence to recommended antibiotics (OR 3.0, 95% CI 1.3-7.2, p = 0.01) were associated with death. Adherence to the recommended antibiotics was also associated with adverse reactions, which occurred in 10% of prescriptions meeting the recommendations (OR 2.4, 95% CI 1.3-4.6, p = 0.01). CONCLUSIONS: Adherence to recommended guidelines for antibiotic treatment was low and highly variable among study facilities. Use of recommended antibiotic regimens was associated with increased adverse events and worse outcomes in patients with radiologically confirmed pneumonia.