Contact Tracing and Exposure Investigation in Response to the First Case of Monkeypox Virus Infection in the United States During the 2022 Global Monkeypox Outbreak.

BACKGROUND: In May 2022, the first case of monkeypox virus (MPXV) infection in the United States in the current global outbreak was identified. As part of the public health and health care facility response, a contact tracing and exposure investigation was done. OBJECTIVE: To describe the contact tracing, exposure identification, risk stratification, administration of postexposure prophylaxis (PEP), and exposure period monitoring for contacts of the index patient, including evaluation of persons who developed symptoms possibly consistent with MPXV infection. DESIGN: Contact tracing and exposure investigation. SETTING: Multiple health care facilities and community settings in Massachusetts. PARTICIPANTS: Persons identified as contacts of the index patient. INTERVENTION: Contact notification, risk stratification, and symptom monitoring; PEP administration in a subset of contacts. MEASUREMENTS: Epidemiologic and clinical data collected through standard surveillance procedures at each facility and then aggregated and analyzed. RESULTS: There were 37 community and 129 health care contacts identified, with 4 at high risk, 49 at intermediate risk, and 113 at low or uncertain risk. Fifteen health care contacts developed symptoms during the monitoring period. Three met criteria for MPXV testing, with negative results. Two community contacts developed symptoms. Neither met criteria for MPXV testing, and neither showed disease progression consistent with monkeypox. Among 4 persons with high-risk exposures offered PEP, 3 elected to receive PEP. Among 10 HCP with intermediate-risk exposures for which PEP was offered as part of informed clinical decision making, 2 elected to receive PEP. No transmissions were identified at the conclusion of the 21-day monitoring period, despite the delay in recognition of monkeypox in the index patient. LIMITATION: Descriptions of exposures are subject to recall bias, which affects risk stratification. CONCLUSION: In a contact tracing investigation involving 166 community and health care contacts of a patient with monkeypox, no secondary cases were identified. PRIMARY FUNDING SOURCE: None.

Prospective assessment of the effectiveness of standard high-level disinfection for echoendoscopes.

BACKGROUND AND AIMS: Duodenoscopes have been implicated in the transmission of multidrug-resistant organisms (MDROs). Echoendoscopes could potentially transmit infection. The aim of this study was to assess the effectiveness of standard high-level disinfection (HLD) for radial and linear echoendoscopes and to compare it with that of duodenoscopes. METHODS: We performed a prospective single-center study sampling echoendoscopes immediately before use, from the working channel (radial and linear echoendoscopes) and the transducer (radial echoendoscope) or elevator mechanism and transducer (linear echoendoscope). The primary outcome was the proportion of echoendoscopes with any culture showing ≥1 MDRO; secondary outcomes included bacterial growth >0 colony forming units (CFUs) and ≥10 CFUs on either sampling location. We compared these findings with duodenoscope cultures from the previously published DISINFECTS trial. RESULTS: During the study period, 101 echoendoscopes were sampled (n = 50 radial echoendoscopes, n = 51 linear echoendoscopes). No MDROs were recovered. Bacterial growth >0 CFUs was noted in 6% and ≥10 CFUs in 3% of all echoendoscopes. There was no significant difference in growth between radial and linear echoendoscopes (P = .4 for >0 CFU growth; P = .6 for ≥10 CFUs growth). The proportion of transducer and/or elevator mechanism positive for bacterial growth was significantly higher in duodenoscopes as compared with echoendoscopes (P = .02). CONCLUSIONS: After standard HLD, no echoendoscope showed MDRO growth, 6% showed >0 CFUs, and 3% showed ≥10 CFUs bacterial growth. Bacterial growth was higher in duodenoscopes at the level of the transducer and/or elevator mechanism when compared with echoendoscopes.

Randomized Comparison of 3 High-Level Disinfection and Sterilization Procedures for Duodenoscopes.

BACKGROUND AND AIMS: Duodenoscopes have been implicated in the transmission of multidrug-resistant organisms (MDRO). We compared the frequency of duodenoscope contamination with MDRO or any other bacteria after disinfection or sterilization by 3 different methods. METHODS: We performed a single-center prospective randomized study in which duodenoscopes were randomly reprocessed by standard high-level disinfection (sHLD), double high-level disinfection (dHLD), or standard high-level disinfection followed by ethylene oxide gas sterilization (HLD/ETO). Samples were collected from the elevator mechanism and working channel of each duodenoscope and cultured before use. The primary outcome was the proportion of duodenoscopes with an elevator mechanism or working channel culture showing 1 or more MDRO; secondary outcomes included the frequency of duodenoscope contamination with more than 0 and 10 or more colony-forming units (CFU) of aerobic bacterial growth on either sampling location. RESULTS: After 3 months of enrollment, the study was closed because of the futility; we did not observe sufficient events to evaluate the primary outcome. Among 541 duodenoscope culture events, 516 were included in the final analysis. No duodenoscope culture in any group was positive for MDRO. Bacterial growth of more than 0 CFU was noted in 16.1% duodenoscopes in the sHLD group, 16.0% in the dHLD group, and 22.5% in the HLD/ETO group (P = .21). Bacterial growth or 10 or more CFU was noted in 2.3% of duodenoscopes in the sHLD group, 4.1% in the dHLD group, and 4.2% in the HLD/ETO group (P = .36). MRDOs were cultured from 3.2% of pre-procedure rectal swabs and 2.5% of duodenal aspirates. CONCLUSIONS: In a comparison of duodenoscopes reprocessed by sHLD, dHLD, or HLD/ETO, we found no significant differences between groups for MDRO or bacteria contamination. Enhanced disinfection methods (dHLD or HLD/ETO) did not provide additional protection against contamination. However, insufficient events occurred to assess our primary study end-point. ClinicalTrials.gov no: NCT02611648.

Investigation of a Candida guilliermondii Pseudo-outbreak Reveals a Novel Source of Laboratory Contamination.

Candida guilliermondii was isolated from sterile specimens with increasing frequency over a several-month period despite a paucity of clinical evidence suggesting true Candida infections. However, a health care-associated outbreak was strongly considered due to growth patterns in the microbiology laboratory that were more consistent with true infection than environmental contamination. Therefore, an extensive investigation was performed to identify its cause. With the exception of one case, patient clinical courses were not consistent with true invasive fungal infections. Furthermore, no epidemiologic link between patients was identified. Rather, extensive environmental sampling revealed C. guilliermondii in an anaerobic holding jar in the clinical microbiology laboratory, where anaerobic plates were prereduced and held before inoculating specimens. C. guilliermondii grows poorly under anaerobic conditions. Thus, we postulate that anaerobic plates became intermittently contaminated. Passaging from intermittently contaminated anaerobic plates to primary quadrants of aerobic media during specimen planting yielded a colonial growth pattern typical for true specimen infection, thus obscuring laboratory contamination. A molecular evaluation of the C. guilliermondii isolates confirmed a common source for pseudo-outbreak cases but not for the one true infection. In line with Reason's model of organizational accidents, active and latent errors coincided to contribute to the pseudo-outbreak. These included organism factors (lack of growth in anaerobic conditions obscuring plate contamination), human factors (lack of strict adherence to plating order, leading to only intermittent observation of aerobic plate positivity), and laboratory factors (novel equipment). All of these variables should be considered when evaluating possible laboratory-based pseudo-outbreaks.

Determining the Ideal Strategy for Ventilator-associated Pneumonia Prevention. Cost-Benefit Analysis.

RATIONALE: Ventilator-associated pneumonia (VAP) is a common healthcare-associated infection with high associated cost and poor patient outcomes. Many strategies for VAP reduction have been evaluated. However, the combination of strategies with the optimal cost-benefit ratio remains unknown. OBJECTIVES: To determine the preferred VAP prevention strategy, both from the hospital and societal perspectives. METHODS: A cost-benefit decision model with a Markov model was constructed. Baseline probability of VAP, death, reintubation, and discharge from the intensive care unit (ICU) alive were ascertained from clinical trial data. Model inputs were obtained from the medical literature and the U.S. Department of Labor; a device cost was obtained from the manufacturer. Sensitivity analyses were completed to test the robustness of model results. MEASUREMENTS AND MAIN RESULTS: Overall least expensive strategy and the strategy with the best cost-benefit ratio, up to a willingness to pay threshold of $50,000-100,000 per case of VAP averted was sought. We examined a total of 120 unique combinations of VAP prevention strategies. The preferred strategy from the hospital perspective included subglottic suction endotracheal tubes, probiotics, and the Institute for Healthcare Improvement VAP Prevention Bundle. The preferred strategy from the point of view of society also included additional prevention measures (oral care with chlorhexidine and selective oral decontamination). No preferred strategies included silver endotracheal tubes or selective gut decontamination. CONCLUSIONS: Despite their infrequent use, current data suggest that the use of prophylactic probiotics and subglottic endotracheal tubes are cost-effective for preventing VAP from the societal and hospital perspectives.

When policy gets it right: variability in u.s. Hospitals' diagnosis of ventilator-associated pneumonia*.

OBJECTIVE: The Centers for Disease Control has recently proposed a major change in how ventilator-associated pneumonia is defined. This has profound implications for public reporting, reimbursement, and accountability measures for ICUs. We sought to provide evidence for or against this change by quantifying limitations of the national definition of ventilator-associated pneumonia that was in place until January 2013, particularly with regard to comparisons between, and ranking of, hospitals and ICUs. DESIGN: A prospective survey of a nationally representative group of 43 hospitals, randomly selected from the American Hospital Association Guide (2009). Subjects classified six standardized vignettes of possible cases of ventilator-associated pneumonia as pneumonia or no pneumonia. SUBJECTS: Individuals responsible for ventilator-associated pneumonia surveillance at 43 U.S. hospitals. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We measured the proportion of standardized cases classified as ventilator-associated pneumonia. Of 138 hospitals consented, 61 partially completed the survey and 43 fully completed the survey (response rate 44% and 31%, respectively). Agreement among hospitals about classification of cases as ventilator-associated pneumonia/not ventilator-associated pneumonia was nearly random (Fleiss κ 0.13). Some hospitals rated 0% of cases as having pneumonia; others classified 100% as having pneumonia (median, 50%; interquartile range, 33-66%). Although region of the country did not predict case assignment, respondents who described their region as "rural" were more likely to judge a case to be pneumonia than respondents elsewhere (relative risk, 1.25, Kruskal-Wallis chi-square, p = 0.03). CONCLUSIONS: In this nationally representative study of hospitals, assignment of ventilator-associated pneumonia is extremely variable, enough to render comparisons between hospitals worthless, even when standardized cases eliminate variability in clinical data abstraction. The magnitude of this variability highlights the limitations of using poorly performing surveillance definitions as methods of hospital evaluation and comparison, and our study provides very strong support for moving to a more objective definition of ventilator-associated complications.

National survey of infectious disease fellowship program directors: A call for subspecialized training in infection prevention and control and healthcare epidemiology.

OBJECTIVE: The importance of infection prevention and control and healthcare epidemiology (IPC/HE) in healthcare facilities was highlighted during the COVID-19 pandemic. Infectious disease (ID) clinicians often hold leadership positions in IPC/HE teams; however, there is no standard for training or certification of ID physicians specializing in IPC/HE. We evaluated the current state of IPC/HE training in ID fellowship programs. DESIGN: A national survey of ID fellowship program directors was conducted to assess current IPC/HE training components in programs and plans for expanded offerings. SETTING AND PARTICIPANTS: All ID fellowship program directors in the United States and Puerto Rico. METHODS: Surveys were distributed using Research Electronic Data Capture (REDCap) to program directors in March 2023, with 2 reminder emails; the survey closed after 4 weeks. RESULTS: Of 166 program directors, 54 (32.5%) responded to the survey. Among respondent programs, 49 (90.7%) of 54 programs reported didactic training in IPC/HE averaging 4.4 hours over the course of the fellowship. Also, 18 (33.3%) of 54 reported a dedicated IPC/HE training track. Furthermore, 23 programs (42.6%) reported barriers to expanding training. There was support (n = 47, 87.0%) for formal IPC/HE certification from a professional society within the standard fellowship. CONCLUSIONS: Despite the COVID-19 pandemic highlighting the need for ID medical doctors with IPC/HE expertise, formal training in ID fellowship remains limited. Most program directors support formalization of IPC/HE training by a professional organization. Creation of standardized advanced curriculums for ID fellowship training in IPC/HE could be considered by the Society of Healthcare Epidemiology of America (SHEA) to grow, retain, and enhance the IPC/HE physician workforce.

Asymptomatic screening for severe acute respiratory coronavirus virus 2 (SARS-CoV-2) as an infection prevention measure in healthcare facilities: Challenges and considerations.

Testing of asymptomatic patients for severe acute respiratory coronavirus virus 2 (SARS-CoV-2) (ie, "asymptomatic screening) to attempt to reduce the risk of nosocomial transmission has been extensive and resource intensive, and such testing is of unclear benefit when added to other layers of infection prevention mitigation controls. In addition, the logistic challenges and costs related to screening program implementation, data noting the lack of substantial aerosol generation with elective controlled intubation, extubation, and other procedures, and the adverse patient and facility consequences of asymptomatic screening call into question the utility of this infection prevention intervention. Consequently, the Society for Healthcare Epidemiology of America (SHEA) recommends against routine universal use of asymptomatic screening for SARS-CoV-2 in healthcare facilities. Specifically, preprocedure asymptomatic screening is unlikely to provide incremental benefit in preventing SARS-CoV-2 transmission in the procedural and perioperative environment when other infection prevention strategies are in place, and it should not be considered a requirement for all patients. Admission screening may be beneficial during times of increased virus transmission in some settings where other layers of controls are limited (eg, behavioral health, congregate care, or shared patient rooms), but widespread routine use of admission asymptomatic screening is not recommended over strengthening other infection prevention controls. In this commentary, we outline the challenges surrounding the use of asymptomatic screening, including logistics and costs of implementing a screening program, and adverse patient and facility consequences. We review data pertaining to the lack of substantial aerosol generation during elective controlled intubation, extubation, and other procedures, and we provide guidance for when asymptomatic screening for SARS-CoV-2 may be considered in a limited scope.

Use of expert consensus to develop a shared list of procedures with potential for aerosol generation during the coronavirus disease 2019 (COVID-19) pandemic.

The coronavirus disease 2019 (COVID-19) pandemic highlighted the lack of agreement regarding the definition of aerosol-generating procedures and potential risk to healthcare personnel. We convened a group of Massachusetts healthcare epidemiologists to develop consensus through expert opinion in an area where broader guidance was lacking at the time.

Risk factors for Staphylococcus aureus postpartum breast abscess.

BACKGROUND: Staphylococcus aureus (SA) breast abscesses are a complication of the postpartum period. Risk factors for postpartum SA breast abscesses are poorly defined, and literature is conflicting. Whether risk factors for methicillin-resistant SA (MRSA) and methicillin-susceptible SA (MSSA) infections differ is unknown. We describe novel risk factors associated with postpartum breast abscesses and the changing epidemiology of this infection. METHODS: We conducted a cohort study with a nested case-control study (n = 216) involving all patients with culture-confirmed SA breast abscess among >30 000 deliveries at our academic tertiary care center from 2003 through 2010. Data were collected from hospital databases and through abstraction from medical records. All SA cases were compared with both nested controls and full cohort controls. A subanalysis was completed to determine whether risk factors for MSSA and MRSA breast abscess differ. Univariate analysis was completed using Student's t test, Wilcoxon rank-sum test, and analysis of variance, as appropriate. A multivariable stepwise logistic regression was used to determine final adjusted results for both the case-control and the cohort analyses. RESULTS: Fifty-four cases of culture-confirmed abscess were identified: 30 MRSA and 24 MSSA. Risk factors for postpartum SA breast abscess in multivariable analysis include in-hospital identification of a mother having difficulty breastfeeding (odds ratio, 5.00) and being a mother employed outside the home (odds ratio, 2.74). Risk factors did not differ between patients who developed MRSA and MSSA infections. CONCLUSIONS: MRSA is an increasingly important pathogen in postpartum women; risk factors for postpartum SA breast abscess have not changed with the advent of community-associated MRSA.

Assessing changes to N95 respirator filtration efficiency, qualitative and quantitative fit, and seal check with repeated vaporized hydrogen peroxide (VHP) decontamination.

N95 respirators were reprocessed using vaporized hydrogen peroxide to supplement limited supplies during the COVID-19 pandemic. In this study, we found no statistically significant differences in qualitative and quantitative fit or filtration efficiency with reprocessing. Filtration efficiency remained above 95% even at 25 cycles of reprocessing without statistically significant change from cycle 20-25 compared to cycle 0 (P = .10, P = .05, respectively). Vaporous hydrogen peroxide is an effective option to augment N95 respirator supplies.

At the vanguard: Leaders' perspectives on establishing healthcare system infection prevention programs.

Hospitals are increasingly consolidating into health systems. Some systems have appointed healthcare epidemiologists to lead system-level infection prevention programs. Ideal program infrastructure and support resources have not been described. We informally surveyed 7 healthcare epidemiologists with recent experience building and leading system-level infection prevention programs. Key facilitators and barriers for program structure and implementation are described.

Multisociety statement on coronavirus disease 2019 (COVID-19) vaccination as a condition of employment for healthcare personnel.

This consensus statement by the Society for Healthcare Epidemiology of America (SHEA) and the Society for Post-Acute and Long-Term Care Medicine (AMDA), the Association for Professionals in Epidemiology and Infection Control (APIC), the HIV Medicine Association (HIVMA), the Infectious Diseases Society of America (IDSA), the Pediatric Infectious Diseases Society (PIDS), and the Society of Infectious Diseases Pharmacists (SIDP) recommends that coronavirus disease 2019 (COVID-19) vaccination should be a condition of employment for all healthcare personnel in facilities in the United States. Exemptions from this policy apply to those with medical contraindications to all COVID-19 vaccines available in the United States and other exemptions as specified by federal or state law. The consensus statement also supports COVID-19 vaccination of nonemployees functioning at a healthcare facility (eg, students, contract workers, volunteers, etc).

Treatment with fluoroquinolones or with beta-lactam-beta-lactamase inhibitor combinations is a risk factor for isolation of extended-spectrum-beta-lactamase-producing Klebsiella species in hospitalized patients.

Antibiotic exposure exerts strong selective pressure and is an important modifiable risk factor for antibiotic resistance. We aimed to identify the role of various antibiotics as risk factors for the isolation of extended-spectrum-beta-lactamase (ESBL)-producing Klebsiella spp. in hospitalized patients at a tertiary-care hospital. A parallel multivariable model was created to compare two groups of cases with either nosocomially acquired ESBL- or non-ESBL-producing Klebsiella spp. to a common control group of hospitalized patients (a case-case-control design). Seventy-eight ESBL cases, 358 non-ESBL cases, and 444 controls were analyzed. Significant factors associated with the isolation of Klebsiella spp. were an age of >65 years, transfer from a health care facility, an intensive care unit (ICU) stay, and the presence of a comorbid malignancy or lung, hepatic, or renal disease. A propensity score was generated from the above, and our ability to discriminate between Klebsiella cases and controls (area under the receiver-operating-characteristic [ROC] curve, 0.78) was good. The ESBL phenotype was tightly linked with fluoroquinolone resistance (95% versus 18%, P < 0.001). Factors associated with isolation of ESBL Klebsiella spp. in a multivariable analysis, adjusting for the propensity score, included exposure to beta-lactam-beta-lactamase inhibitor combinations (odds ratio [OR], 10.17; 95% confidence interval [CI], 1.19 to 86.92) and to fluoroquinolones (OR, 2.86; 95% CI, 1.37 to 5.97). Exposure to broad-spectrum cephalosporins was statistically associated with ESBL Klebsiella spp. only among the subgroup of patients not treated with fluoroquinolones. In our institution, where the ESBL-producing-Klebsiella phenotype is coselected with fluoroquinolone resistance, fluoroquinolone and beta-lactam-beta-lactamase inhibitor combinations, rather than cephalosporins, are the main risk factors for ESBL isolates. Formulary interventions to limit the spread of ESBL-producing isolates should be tailored to each setting.

The discontinuation of contact precautions for methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus: Impact upon patient adverse events and hospital operations.

BACKGROUND: Contact precautions for endemic methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE) are a resource-intensive intervention to reduce healthcare-associated infections, potentially impeding patient throughput and limiting bed availability to isolate other contagious pathogens. We investigated the impact of the discontinuation of contact precautions (DcCP) for endemic MRSA and VRE on patient outcomes and operations metrics in an acute care setting. METHODS: This is a retrospective, quasi-experimental analysis of the 12 months before and after DcCP for MRSA and VRE at an academic medical centre. The frequency for bed closures due to contact isolation was measured, and personal protective equipment (PPE) expenditures and patient satisfaction survey results were compared using the Wilcoxon signed-rank test. Using an interrupted time series design, emergency department (ED) admission wait times and rates of patient falls, pressure ulcers and nosocomial MRSA and VRE clinical isolates were compared using GEEs. RESULTS: Prior to DcCP, bed closures for MRSA and/or VRE isolation were associated with estimated lost hospital charges of $9383 per 100 bed days (95% CI: 8447 to 10 318). No change in ED wait times or change in trend was observed following DcCP. There were significant reductions in monthly expenditures on gowns (-61.0%) and gloves (-16.3%). Patient satisfaction survey results remained stable. No significant changes in rates or trends were observed for patient falls or pressure ulcers. Incidence rates of nosocomial MRSA (1.58 (95% CI: 0.82 to 3.04)) and VRE (1.02 (95% CI: 0.82 to 1.27)) did not significantly change. CONCLUSIONS: DcCP was associated with an increase in bed availability and revenue recovery, and a reduction in PPE expenditures. Benefits for other hospital operations metrics and patient outcomes were not identified.

Identification of a norovirus outbreak on a hematopoietic stem cell transplant unit and development and implementation of a novel infection prevention algorithm for controlling transmission.

Controlling norovirus transmission in units with immunocompromised patients is challenging. We present a cluster of norovirus cases that occurred on a stem-cell transplant unit and the prevention efforts that were implemented to limit the outbreak. Protocols developed to control this cluster may provide a model for other facilities.

Methicillin-resistant Staphylococcus aureus colonization, behavioral risk factors, and skin and soft-tissue infection at an ambulatory clinic serving a large population of HIV-infected men who have sex with men.

We conducted a prospective cohort study of 795 outpatients, many of whom were human immunodeficiency virus-infected men who have sex with men, to characterize risk of skin and soft-tissue infection (SSTI) associated with methicillin-resistant Staphylococcus aureus (MRSA) nares and perianal colonization. Multivariate analysis revealed that perianal colonization, drug use, and prior SSTIs were strongly associated with development of an SSTI. Of the patients who were colonized with MRSA at study entry, 36.7% developed an SSTI during the ensuing 12 months, compared with 8.1% of persons who were not colonized with MRSA.

The Epidemiology and Prevention of Candida auris.

PURPOSE OF REVIEW: Candida auris has recently emerged as a pathogen with the potential for nosocomial transmission and outbreaks. The aim of this review is to summarize the global dissemination of this pathogen, characterize patient and facility characteristics associated with infection and outbreaks, and outline evidence to support interventions to prevent of transmission in the healthcare setting. RECENT FINDINGS: C. auris has emerged separately in four clades, with international spread within a decade of its first identification and report. Acquisition and infection have predominantly been identified as healthcare-associated events. The presence of invasive devices, intensive care, and broad-spectrum antibiotic and antifungal use may be important risk factors for the development of infection due to C. auris. Nosocomial transmission is likely associated with colonization density and suboptimal infection prevention practices. The optimal strategy for reducing transmission from the environment requires further study. Candida auris is a recently emerging fungal pathogen that may cause nosocomial infections and outbreaks. Based on observed transmission patterns and interventions, key prevention measures outlined in the review include case finding and surveillance, hand hygiene, and environmental disinfection.

Who needs a blood culture? A prospectively derived and validated prediction rule.

The study objective was to derive and validate a clinical decision rule for obtaining blood cultures in Emergency Department (ED) patients with suspected infection. This was a prospective, observational cohort study of consecutive adult ED patients with blood cultures obtained. The study ran from February 1, 2000 through February 1, 2001. Patients were randomly assigned to derivation (2/3) or validation (1/3) sets. The outcome was "true bacteremia." Features of the history, co-morbid illness, physical examination, and laboratory testing were used to create a clinical decision rule. Among 3901 patients, 3730 (96%) were enrolled with 305 (8.2%) episodes of true bacteremia. A decision rule was created with "major criteria" defined as: temperature > 39.5 degrees C (103.0 degrees F), indwelling vascular catheter, or clinical suspicion of endocarditis. "Minor criteria" were: temperature 38.3-39.4 degrees C (101-102.9 degrees F), age > 65 years, chills, vomiting, hypotension (systolic blood pressure < 90 mm Hg), neutrophil% > 80, white blood cell count > 18 k, bands > 5%, platelets < 150 k, and creatinine > 2.0. A blood culture is indicated by the rule if at least one major criterion or two minor criteria are present. Otherwise, patients are classified as "low risk" and cultures may be omitted. Only 4 (0.6%) low-risk patients in the derivation set and 3 (0.9%) low-risk patients in the validation set had positive cultures. The sensitivity was 98% (95% confidence interval [CI] 96-100%) (derivation) and 97% (95% CI 94-100%) (validation). We developed and validated a promising clinical decision rule for predicting bacteremia in patients with suspected infection.