Assessment of Claimant, Clinical, and Financial Characteristics of Teleradiology Medical Malpractice Cases.

Background The increasing use of teleradiology has been accompanied by concerns relating to risk management and patient safety. Purpose To compare characteristics of teleradiology and nonteleradiology radiology malpractice cases and identify contributing factors underlying these cases. Materials and Methods In this retrospective analysis, a national database of medical malpractice cases was queried to identify cases involving telemedicine that closed between January 2010 and March 2022. Teleradiology malpractice cases were identified based on manual review of cases in which telemedicine was coded as one of the contributing factors. These cases were compared with nonteleradiology cases that closed during the same time period in which radiology had been determined to be the primary responsible clinical service. Claimant, clinical, and financial characteristics of the cases were recorded, and continuous or categorical data were compared using the Wilcoxon rank-sum test or Fisher exact test, respectively. Results This study included 135 teleradiology and 3474 radiology malpractices cases. The death of a patient occurred more frequently in teleradiology cases (48 of 135 [35.6%]) than in radiology cases (685 of 3474 [19.7%]; P < .001). Cerebrovascular disease was a more common final diagnosis in the teleradiology cases (13 of 135 [9.6%]) compared with the radiology cases (124 of 3474 [3.6%]; P = .002). Problems with communication among providers was a more frequent contributing factor in the teleradiology cases (35 of 135 [25.9%]) than in the radiology cases (439 of 3474 [12.6%]; P < .001). Teleradiology cases were more likely to close with indemnity payment (79 of 135 [58.5%]) than the radiology cases (1416 of 3474 [40.8%]; P < .001) and had a higher median indemnity payment than the radiology cases ($339 230 [IQR, $120 790-$731 615] vs $214 063 [IQR, $66 620-$585 424]; P = .01). Conclusion Compared with radiology cases, teleradiology cases had higher clinical and financial severity and were more likely to involve issues with communication. © RSNA, 2024 See also the editorial by Mezrich in this issue.

Burden of serious harms from diagnostic error in the USA.

BACKGROUND: Diagnostic errors cause substantial preventable harms worldwide, but rigorous estimates for total burden are lacking. We previously estimated diagnostic error and serious harm rates for key dangerous diseases in major disease categories and validated plausible ranges using clinical experts. OBJECTIVE: We sought to estimate the annual US burden of serious misdiagnosis-related harms (permanent morbidity, mortality) by combining prior results with rigorous estimates of disease incidence. METHODS: Cross-sectional analysis of US-based nationally representative observational data. We estimated annual incident vascular events and infections from 21.5 million (M) sampled US hospital discharges (2012-2014). Annual new cancers were taken from US-based registries (2014). Years were selected for coding consistency with prior literature. Disease-specific incidences for 15 major vascular events, infections and cancers ('Big Three' categories) were multiplied by literature-based rates to derive diagnostic errors and serious harms. We calculated uncertainty estimates using Monte Carlo simulations. Validity checks included sensitivity analyses and comparison with prior published estimates. RESULTS: Annual US incidence was 6.0 M vascular events, 6.2 M infections and 1.5 M cancers. Per 'Big Three' dangerous disease case, weighted mean error and serious harm rates were 11.1% and 4.4%, respectively. Extrapolating to all diseases (including non-'Big Three' dangerous disease categories), we estimated total serious harms annually in the USA to be 795 000 (plausible range 598 000-1 023 000). Sensitivity analyses using more conservative assumptions estimated 549 000 serious harms. Results were compatible with setting-specific serious harm estimates from inpatient, emergency department and ambulatory care. The 15 dangerous diseases accounted for 50.7% of total serious harms and the top 5 (stroke, sepsis, pneumonia, venous thromboembolism and lung cancer) accounted for 38.7%. CONCLUSION: An estimated 795 000 Americans become permanently disabled or die annually across care settings because dangerous diseases are misdiagnosed. Just 15 diseases account for about half of all serious harms, so the problem may be more tractable than previously imagined.

An analysis of medical malpractice claims against medical oncologists from a national database: Implications for safer practice.

Malpractice claims data include valuable information about patient safety. We used mixed methods to analyze claims against medical oncologists (MO) from 2008 to 2019 using a national database. MO claims were compared to a group of other internal medicine subspecialties (OIMS). Logistic regression was used to examine correlates of closing with an indemnity payment. A subset of claims against MO were thematically analyzed using a validated safety incident taxonomy as a framework. 456 claims against MO were compared with 5771 claims against OIMS. MO claims closed with indemnity payments 29.8% of the time versus OIMS 30.3% (p = 0.87). Median MO and OIMS indemnity payments were similar ($190,591 vs. $233,432; p = 0.20). Correlates of MO claims closing with payment included patient assessment, communication among providers, and safety and security as contributing factors. Thematic analysis identified provider cognitive error, adverse drug events and relational problems as the most common safety incidents. MO malpractice claims have similar outcomes to OIMS. We demonstrate the proof-of-concept of applying a safety incident taxonomy to medical malpractice. Finding ways to reduce patient exposure to provider cognitive errors, adverse drug reactions, and communication breakdowns should be strategic priorities for safer cancer care.

Honoring the public trust: curbing the bane of physician sexual misconduct.

The Federation of State Medical Boards defines physician sexual misconduct as any 'behavior that exploits the physician-patient relationship in a sexual way.' Although several attempts have been made in recent years to clarify its incidence in the United States, physician sexual misconduct is almost certainly underreported. Physician sexual misconduct represents a severe and irreversible violation of the compact underlying the patient-physician relationship and can have far-reaching consequences on the lives of patients and their families. In addition, the credibility of and trust in physicians, both essential to the provision of medical care, could well erode in the eyes of the public at large if egregious cases of physician sexual misconduct are perceived as having gone unpunished. Although all physician licensees accused of sexual misconduct are entitled to the presumption of innocence and due process, complaints made by patients must be taken seriously and vigorously pursued. In this article, we discuss the ongoing challenge of physician sexual misconduct and provide recommendations to improve its reporting and curb its incidence.

Association of Simulation Training With Rates of Medical Malpractice Claims Among Obstetrician-Gynecologists.

OBJECTIVE: To compare malpractice claim rates before and after participation in simulation training, which focused on team training during a high-acuity clinical case. METHODS: We performed a retrospective analysis comparing the claim rates before and after simulation training among 292 obstetrician-gynecologists, all of whom were insured by the same malpractice insurer, who attended one or more simulation training sessions from 2002 to 2019. The insurer provided malpractice claims data involving study physicians, along with durations of coverage, which we used to calculate claim rates, expressed as claims per 100 physician coverage years. We used three different time periods in our presimulation and postsimulation training claim rates comparisons: the entire study period, 2 years presimulation and postsimulation training, and 1 year presimulation and postsimulation training. Secondary outcomes included indemnity payment amounts, percent of claims paid, and injury severity. RESULTS: Compared with presimulation training, malpractice claim rates were significantly lower postsimulation training for the full study period (11.2 vs 5.7 claims per 100 physician coverage years; P<.001) and the 2 years presimulation and postsimulation training (9.2 vs 5.4 claims per 100 physician coverage years; P=.043). For the 1 year presimulation and postsimulation training comparison, the decrease in claim rates was nonsignificant (8.8 vs 5.3 claims per 100 physician coverage years; P=.162). Attending more than one simulation session was associated with a greater reduction in claim rates. Postsimulation claim rates for physicians who attended one, two, or three or more simulation sessions were 6.3, 2.1, and 1.3 claims per 100 physician coverage years, respectively (P<.001). Compared with presimulation training, there was no significant difference in the median or mean indemnity paid, percent of claims on which an indemnity payment was made, or median severity of injury after simulation training. CONCLUSION: We observed a significant reduction in malpractice claim rates after simulation training. Wider use of simulation training within obstetrics and gynecology should be considered.

Rates and Characteristics of Medical Malpractice Claims Against Hospitalists.

BACKGROUND: Hospitalists practice in high-stakes and litigious settings. However, little data exist about the malpractice claims risk faced by hospitalists. OBJECTIVE: To characterize the rates and characteristics of malpractice claims against hospitalists. DESIGN, SETTING, AND PARTICIPANTS: An analysis was performed of malpractice claims against hospitalists, as well as against select other specialties, using data from a malpractice claims database that includes approximately 31% of US malpractice claims. MAIN OUTCOMES AND MEASURES: For malpractice claims against hospitalists (n = 1,216) and comparator specialties (n = 18,644): claims rates (using a data subset), percentage of claims paid, median indemnity payment amounts, allegation types, and injury severity. RESULTS: Hospitalists had an annual malpractice claims rate of 1.95 claims per 100 physician-years, similar to that of nonhospitalist general internal medicine physicians (1.92 claims per 100 physician-years), and significantly greater than that of internal medicine subspecialists (1.30 claims per 100 physician-years) (P < .001). Claims rates for hospitalists nonsignificantly increased during the study period (2009-2018), whereas claims rates for four of the five other specialties examined significantly decreased over this period. The median indemnity payment for hospitalist claims was $231,454 (interquartile range, $100,000-$503,015), significantly higher than the amounts for all the other specialties except neurosurgery. The greatest predictor of a hospitalist case closing with payment (compared with no payment) was an error in clinical judgment as a contributing factor, with an adjusted odds ratio of 5.01 (95% CI, 3.37-7.45). CONCLUSION: During the study period, hospitalist claims rates did not drop, whereas they fell for other specialties. Hospitalists' claims had relatively high injury severity and median indemnity payment amounts. The malpractice environment for hospitalists is becoming less favorable.

Early serious illness communication in hospitalized patients: A study of the implementation of the Speaking About Goals and Expectations (SAGE) program.

BACKGROUND: Early conversations about patients' goals and values in advancing serious illness (serious illness conversations) can drive better healthcare. However, these conversations frequently happen during acute illness, often near death, without time to realize benefits of early communication. METHODS: The Speaking About Goals and Expectations (SAGE) Program, adapted from the Serious Illness Care Program, is a multicomponent intervention designed to foster earlier and more comprehensive serious illness conversations for patients admitted to the hospital. We present a quality improvement study of the SAGE Program assessing older adults admitted to a general medicine service at the Brigham & Women's Hospital in Boston, Massachusetts. Our primary outcomes included the proportion of patients with at least one documented conversation, the timing between first conversation documented and death, the quality of conversations, and their interprofessional nature. Secondary outcomes assessed evaluations of the training and hospital utilization. RESULTS: We trained 37 clinicians and studied 133 patients split between the SAGE intervention and a comparison population. Intervention patients were more likely to have documented serious illness conversations (89.1% vs. 26.1%, p < 0.001); these conversations occurred earlier (mean of 598.9 vs. 180.8 days before death, p < 0.001) and included more key elements of conversation (mean of 6.56 vs. 1.78, p < 0.001). CONCLUSIONS: This study demonstrated significant differences in the frequency and quality of serious illness conversations completed earlier in the illness course for hospitalized patients. IMPLICATIONS: Programs designed to drive serious illness conversations earlier in the hospital may be an effective way to improve care for patients not reached in the ambulatory setting. LEVEL OF EVIDENCE: Prospectively designed trial, non-randomized sample.

The Effect of Clinical Volume on Annual and Per-Patient Encounter Medical Malpractice Claims Risk.

OBJECTIVES: The relationship between medical malpractice risk and one of the fundamental characteristics of physician practice, clinical volume, remains undefined. This study examined how the annual and per-patient encounter medical malpractice claims risk varies with clinical volume. METHODS: Clinical volume was determined using health insurance charges and was linked at the physician level to malpractice claims data from a malpractice insurer. The annual medical malpractice claims risk was expressed as the percent of physicians with a malpractice claim, and the per-encounter medical malpractice claims risk was expressed as malpractice claims per 1000 patient encounters. Both of these malpractice claims risk metrics were analyzed as a function of clinical volume, using linear and spline regression. RESULTS: As clinical volume increased, the percent of physicians with a malpractice claim increased linearly. Among all physicians studied, for each decile increase in clinical volume, there was a 0.373% increase in physicians with a malpractice claim (95% confidence interval, 0.301%-0.446%; P < 0.0001). As clinical volume increased, the rate of malpractice claims per 1000 patient encounters decreased. This relationship between clinical volume and per-encounter claims risk was nonlinear. There was a clinical volume threshold, below which decreasing clinical volume was associated with increasing per-encounter claims risk, and above which claims risk no longer significantly varied with increases in clinical volume. CONCLUSIONS: Clinical volume is a crucial determinant of physician malpractice risk, with higher-volume physicians having higher annual risk but lower per-encounter risk. Clinical volume data should be incorporated into analyses of malpractice risk.

Rate of diagnostic errors and serious misdiagnosis-related harms for major vascular events, infections, and cancers: toward a national incidence estimate using the "Big Three".

BACKGROUND: Missed vascular events, infections, and cancers account for ~75% of serious harms from diagnostic errors. Just 15 diseases from these "Big Three" categories account for nearly half of all serious misdiagnosis-related harms in malpractice claims. As part of a larger project estimating total US burden of serious misdiagnosis-related harms, we performed a focused literature review to measure diagnostic error and harm rates for these 15 conditions. METHODS: We searched PubMed, Google, and cited references. For errors, we selected high-quality, modern, US-based studies, if available, and best available evidence otherwise. For harms, we used literature-based estimates of the generic (disease-agnostic) rate of serious harms (morbidity/mortality) per diagnostic error and applied claims-based severity weights to construct disease-specific rates. Results were validated via expert review and comparison to prior literature that used different methods. We used Monte Carlo analysis to construct probabilistic plausible ranges (PPRs) around estimates. RESULTS: Rates for the 15 diseases were drawn from 28 published studies representing 91,755 patients. Diagnostic error (false negative) rates ranged from 2.2% (myocardial infarction) to 62.1% (spinal abscess), with a median of 13.6% [interquartile range (IQR) 9.2-24.7] and an aggregate mean of 9.7% (PPR 8.2-12.3). Serious misdiagnosis-related harm rates per incident disease case ranged from 1.2% (myocardial infarction) to 35.6% (spinal abscess), with a median of 5.5% (IQR 4.6-13.6) and an aggregate mean of 5.2% (PPR 4.5-6.7). Rates were considered face valid by domain experts and consistent with prior literature reports. CONCLUSIONS: Diagnostic improvement initiatives should focus on dangerous conditions with higher diagnostic error and misdiagnosis-related harm rates.

Serious misdiagnosis-related harms in malpractice claims: The "Big Three" - vascular events, infections, and cancers.

Background Diagnostic errors cause substantial preventable harm, but national estimates vary widely from 40,000 to 4 million annually. This cross-sectional analysis of a large medical malpractice claims database was the first phase of a three-phase project to estimate the US burden of serious misdiagnosis-related harms. Methods We sought to identify diseases accounting for the majority of serious misdiagnosis-related harms (morbidity/mortality). Diagnostic error cases were identified from Controlled Risk Insurance Company (CRICO)'s Comparative Benchmarking System (CBS) database (2006-2015), representing 28.7% of all US malpractice claims. Diseases were grouped according to the Agency for Healthcare Research and Quality (AHRQ) Clinical Classifications Software (CCS) that aggregates the International Classification of Diseases diagnostic codes into clinically sensible groupings. We analyzed vascular events, infections, and cancers (the "Big Three"), including frequency, severity, and settings. High-severity (serious) harms were defined by scores of 6-9 (serious, permanent disability, or death) on the National Association of Insurance Commissioners (NAIC) Severity of Injury Scale. Results From 55,377 closed claims, we analyzed 11,592 diagnostic error cases [median age 49, interquartile range (IQR) 36-60; 51.7% female]. These included 7379 with high-severity harms (53.0% death). The Big Three diseases accounted for 74.1% of high-severity cases (vascular events 22.8%, infections 13.5%, and cancers 37.8%). In aggregate, the top five from each category (n = 15 diseases) accounted for 47.1% of high-severity cases. The most frequent disease in each category, respectively, was stroke, sepsis, and lung cancer. Causes were disproportionately clinical judgment factors (85.7%) across categories (range 82.0-88.8%). Conclusions The Big Three diseases account for about three-fourths of serious misdiagnosis-related harms. Initial efforts to improve diagnosis should focus on vascular events, infections, and cancers.

Rates and Characteristics of Paid Malpractice Claims Among US Physicians by Specialty, 1992-2014.

Importance: Although physician concerns about medical malpractice are substantial, national data are lacking on the rate of claims paid on behalf of US physicians by specialty. Objective: To characterize paid malpractice claims by specialty. Design, Setting, and Participants: A comprehensive analysis was conducted of all paid malpractice claims, with linkage to physician specialty, from the National Practitioner Data Bank from January 1, 1992, to December 31, 2014, a period including an estimated 19.9 million physician-years. All dollar amounts were inflation adjusted to 2014 dollars using the Consumer Price Index. The dates on which this analysis was performed were from May 1, 2015, to February 20, 2016, and from October 25 to December 16, 2016. Main Outcomes and Measures: For malpractice claims (n = 280 368) paid on behalf of physicians (in aggregate and by specialty): rates per physician-year, mean compensation amounts, the concentration of paid claims among a limited number of physicians, the proportion of paid claims that were greater than $1 million, severity of injury, and type of malpractice alleged. Results: From 1992-1996 to 2009-2014, the rate of paid claims decreased by 55.7% (from 20.1 to 8.9 per 1000 physician-years; P < .001), ranging from a 13.5% decrease in cardiology (from 15.6 to 13.5 per 1000 physician-years; P = .15) to a 75.8% decrease in pediatrics (from 9.9 to 2.4 per 1000 physician-years; P < .001). The mean compensation payment was $329 565. The mean payment increased by 23.3%, from $286 751 in 1992-1996 to $353 473 in 2009-2014 (P < .001). The increases ranged from $17 431 in general practice (from $218 350 in 1992-1996 to $235 781 in 2009-2014; P = .36) to $114 410 in gastroenterology (from $276 128 in 1992-1996 to $390 538 in 2009-2014; P < .001) and $138 708 in pathology (from $335 249 in 1992-1996 to $473 957 in 2009-2014; P = .005). Of 280 368 paid claims, 21 271 (7.6%) exceeded $1 million (4304 of 69 617 [6.2%] in 1992-1996 and 4322 of 54 081 [8.0%] in 2009-2014), and 32.1% (35 293 of 109 865) involved a patient death. Diagnostic error was the most common type of allegation, present in 31.8% (35 349 of 111 066) of paid claims, ranging from 3.5% in anesthesiology (153 of 4317) to 87.0% in pathology (915 of 1052). Conclusions and Relevance: Between 1992 and 2014, the rate of malpractice claims paid on behalf of physicians in the United States declined substantially. Mean compensation amounts and the percentage of paid claims exceeding $1 million increased, with wide differences in rates and characteristics across specialties. A better understanding of the causes of variation among specialties in paid malpractice claims may help reduce both patient injury and physicians' risk of liability.

A Population-Based Care Improvement Initiative for Patients at Risk for Delirium, Alcohol Withdrawal, and Suicide Harm.

BACKGROUND: In a population-based approach, a hospital-wide interprofessional care redesign at Brigham and Women's Hospital (BWH; Boston), was conducted to provide optimal evidence-informed care for patients at risk for delirium, alcohol abuse, and suicide harm (DASH). The initiative involved enhanced screening and the introduction of new care management guidelines and order sets pertaining to the DASH diagnoses. METHODS: An interprofessional group from medicine, nursing, and psychiatry jointly led a hospitalwide effort for the improvement of care and outcomes of patients presenting with a DASH diagnosis (delirium, alcohol withdrawal, and suicide harm). The care improvement process consisted of four phases: (1) development of guidelines, (2) imple mentation/rollout, (3) integration into practice, and (4) sustainability, including ongoing practice development and evaluation. RESULTS: Implementation outcomes were evaluated using eight parameters-acceptability, adoption, appropriateness, feasibility, fidelity, implementation cost, penetration, and sustainability. Internal billing data and ICD-9-CM [International Classification of Diseases, Ninth Revision, Clinical Modification] diagnostic codes were used to identify the DASH population. Patients were compared pre- and postprogram implementation for fiscal years 2010 through 2013. The average length of stay, reported as the number of midnights in the hospital, remained consistent for DASH patients-9.3-10.0 days (versus 5.3-6.0 days for BWH over all). The DASH readmission rate decreased by 9%-from 15.1% to 13.7%, approaching the overall BWH rate of 13.3%. CONCLUSION: Close nurse-physician collaboration, including joint leadership and simultaneous rollout for nurses and physicians, contributed to the initiative's effective implementation.

Liability impact of the hospitalist model of care.

BACKGROUND: An increasingly large proportion of inpatient care is provided by hospitalists. The care discontinuities inherent to hospital medicine raise concerns about malpractice risk. However, little published data exist on the medical liability risks associated with care by hospitalists. OBJECTIVE: We sought to determine the risks and outcomes of malpractice claims against hospitalists in internal medicine. DESIGN: Retrospective observational analysis. MEASUREMENTS: Using claims data from a liability insurer-maintained database of over 52,000 malpractice claims, we measured the rates of malpractice claims against hospitalists compared to other physician specialties, types of allegations against hospitalists, contributing factors, and the severity of injury in and outcomes of these claims. RESULTS: Hospitalists had a malpractice claims rate of 0.52 claims per 100 physician coverage years (PCYs), which was significantly lower than that of nonhospitalist internal medicine physicians (1.91 claims per 100 PCYs), emergency medicine physicians (3.50 claims per 100 PCYs), general surgeons (4.70 claims per 100 PCYs), and obstetricians-gynecologists (5.56 claims per 100 PCYs) (P < 0.001 for all comparisons). The most common allegation types made against hospitalists were for errors in medical treatment (41.5%) and diagnosis (36.0%). The most common contributing factors underlying claims were deficiencies in clinical judgment (54.4%) and communication (36.4%). Of the claims made against hospitalists, 50.4% involved the death of the patient. CONCLUSIONS: Despite fears of increased liability from the hospitalist model of care, hospitalists in internal medicine are subject to medical malpractice claims less frequently when compared to other internal medicine physicians and specialties.

Staphylococcal vaccines and immunotherapies.

Staphylococcus aureus is an important pathogen in the hospital and in the community, and it is increasingly resistant to multiple antibiotics. A nonantimicrobial approach to controlling S aureus is needed. The most extensively tested vaccine against S aureus, which is a capsular polysaccharide-based vaccine known as StaphVAX, showed promise in an initial phase 3 trial, but was found to be ineffective in a confirmatory trial, leading to its development being halted. Likewise, a human IgG preparation known as INH-A21 (Veronate) with elevated levels of antibodies to the staphylococcal surface adhesins ClfA and SdrG made it into phase 3 testing, where it failed to show a clinical benefit. Several novel antigens are being tested for potential inclusion in a staphylococcal vaccine, including cell wall-anchored adhesin proteins and exotoxins. Given the multiple and sometimes redundant virulence factors of S aureus that enable it to be such a crafty pathogen, if a vaccine is to prove effective, it will have to be multicomponent, incorporating several surface proteins, toxoids, and surface polysaccharides.

Vaccination and passive immunisation against Staphylococcus aureus.

Staphylococcus aureus, an important bacterial pathogen in the hospital and the community, has become increasingly resistant to multiple antibiotics. Non-antimicrobial approaches to controlling S. aureus are clearly needed. Because many individuals who are susceptible to staphylococcal infections are not competent to mount an effective immune response, passive as well as active immunisation strategies have been explored. A capsular polysaccharide-based vaccine (StaphVAX) showed promise in an initial phase III trial in haemodialysis patients, but was found to be ineffective in a confirmatory trial. Likewise, a human immunoglobulin G (IgG) preparation known as INH-A21 (Veronate) with elevated levels of antibodies to the staphylococcal surface adhesins ClfA and SdrG made it into phase III testing, where it failed to show a clinical benefit in neonates. A number of novel antigens are in pre-clinical trials, including cell-wall-anchored adhesins, surface polysaccharides and exotoxoids. Given the multiple and sometimes redundant virulence factors of S. aureus that enable it to be such a crafty pathogen, if a vaccine is to prove effective it will of necessity be multicomponent, incorporating a number of surface proteins, toxoids and surface polysaccharides.

Immunization with Staphylococcus aureus clumping factor B, a major determinant in nasal carriage, reduces nasal colonization in a murine model.

Staphylococcus aureus is responsible for a wide range of infections, including soft tissue infections and potentially fatal bacteremias. The primary niche for S. aureus in humans is the nares, and nasal carriage is a documented risk factor for staphylococcal infection. Previous studies with rodent models of nasal colonization have implicated capsule and teichoic acid as staphylococcal surface factors that promote colonization. In this study, a mouse model of nasal colonization was utilized to demonstrate that S. aureus mutants that lack clumping factor A, collagen binding protein, fibronectin binding proteins A and B, polysaccharide intercellular adhesin, or the accessory gene regulator colonized as well as wild-type strains colonized. In contrast, mutants deficient in sortase A or clumping factor B (ClfB) showed reduced nasal colonization. Mice immunized intranasally with killed S. aureus cells showed reduced nasal colonization compared with control animals. Likewise, mice that were immunized systemically or intranasally with a recombinant vaccine composed of domain A of ClfB exhibited lower levels of colonization than control animals exhibited. A ClfB monoclonal antibody (MAb) inhibited S. aureus binding to mouse cytokeratin 10. Passive immunization of mice with this MAb resulted in reduced nasal colonization compared with the colonization observed after immunization with an isotype-matched control antibody. The mouse immunization studies demonstrate that ClfB is an attractive component for inclusion in a vaccine to reduce S. aureus nasal colonization in humans, which in turn may diminish the risk of staphylococcal infection. As targets for vaccine development and antimicrobial intervention are assessed, rodent nasal colonization models may be invaluable.