Methicillin-resistant Staphylococcus aureus (MRSA) is an emerging concern in infectious disease practice. Although MRSA infections occur in a wide variety of anatomic sites, the majority of studies considering the risk factors for methicillin resistance among S. aureus infections have focused on MRSA bacteremia.

To describe risk factors associated with methicillin resistance among S. aureus infections at different anatomic sites.

We collected information on the demographic and clinical characteristics of patients examined at the Atlanta Veterans Affairs Medical Center with S. aureus infections during the period from June 2007 through May 2008. We used multivariate logistic regression to describe factors significantly associated with methicillin resistance.

There were 568 cases of S. aureus infection among 528 patients. We identified 352 cases (62%) of MRSA infection and 216 cases (38%) of methicillin-sensitive S. aureus infection. The adjusted odds of methicillin resistance were higher among infections that occurred among patients who had a prior history of MRSA infection (odds ratio [OR], 3.9 [95% confidence interval {CI}, 2.3–6.4]) or resided in a long-term care facility during the past 12 months (OR, 2.0 [95% CI, 1.0-4.0]) but were lower for infections that occurred among patients who had undergone a biopsy procedure during the past 12 months (OR, 0.7 [95% CI, 0.6-0.9]). Most cases of infection were community-onset infections (523 [92%] of 568 cases), and about one-half (278 [49%]) were not healthcare associated.

Compared with previous studies of methicillin resistance among patients with S. aureus bacteremia, we found similar factors to be associated with methicillin resistance among S. aureus isolates recovered from more diverse anatomic sites of infection. Of note, nearly one-half of our cases of MRSA infection were not healthcare associated.

To reduce the use of amoxicillin-clavulanate after high-resistance rates in Escherichia coli were detected.

Intervention study; the interventions were introduced successively over a 4-year period while closely monitoring the resistance patterns.

A 260-bed acute-care hospital in Switzerland.

Introduction of therapeutic guidelines for specific departments or indications, which proposed alternative antibiotics to amoxicillin-clavulanate. The perioperative prophylactic use of amoxicillin-clavulanate was eliminated completely.

The absolute amount of amoxicillin-clavulanate consumed decreased by 23%, from 24.8 g per 100 patient days in 1992 to 18.5 g per 100 patient days in 1995. The number of courses, a parameter that takes the prophylactic use into account, decreased by 62% from 2.3 per 100 patient days in 1992 to 0.9 per 100 patient days in 1995. The percentage of sensitive strains increased from 54.9% (n=512) in 1992 and 54.0% (n=506) in 1993 to 72.1% (n=546) in 1994 and 83.1% (n=668) in 1995. No major changes were detected for other antimicrobials, such as cotrimoxazole, tetracycline, or cefuroxime, used in this 4-year period.

A decrease in the use of amoxicillin-clavulanate was followed by an increase in susceptibility of E coli to it. It was not possible to prove a causative relationship. Only a temporal association was discovered. The reduction of the use of amoxicillin-clavulanate was achieved through the implementation of treatment guidelines, facilitated through a close collaboration among the clinical pharmacists, the infection control practitioner, the microbiology laboratory, and the physicians in charge of the respective departments.

Administration of antimicrobials to patients with asymptomatic bacteriuria (ASB) is a common error that can lead to worse outcomes. However, controlled analyses quantifying the commonality and impact of this practice are lacking. We analyzed the independent predictors for antimicrobials misuse in ASB and quantified the impact of this practice on clinical outcomes.

Retrospective case-control and cohort analyses for calendar year 2017.

Tertiary-care, university-affiliated medical center.

The study included adult (>18 years) patients with positive urine culture. Pregnant women, renal transplant recipients, and patients who underwent urologic procedures were excluded.

ASB was determined according to US Centers for Disease Control and Prevention (CDC) criteria. Multivariable logistic regression models were constructed to analyze predictors and outcomes associated with antimicrobial use for patients with ASB.

The study included 1,530 patient-unique positive urine cultures. Among these patients, 610 patients (40%) were determined to have ASB. Of the 696 isolates, 219 (36%) were multidrug-resistant organisms (MDROs). Also, 178 (29%) patients received antimicrobials specifically due to the ASB. Independent predictors for improper administration of antimicrobials were dependent functional status (adjusted odds ratio [aOR], 2.3; 95% CI, 1.4–3.6) and male sex (aOR, 2; 95% CI, 1.25–2.6). Use of antimicrobials was independently associated with re-hospitalizations (aOR, 1.7; 95% CI, 1.1–2.6) and later, acute Clostridioides difficile infections (CDI) in the following 90 days (aOR, 4.5; 95% CI, 2–10.6).

ASB is a common condition, frequently resulting from an MDRO. Male sex and poor functional status were independent predictors for mistreatment, and this practice was independently associated with rehospitalizations and CDI in the following 90 days.

The coronavirus disease 2019 pandemic caused substantial changes to healthcare delivery and antibiotic prescribing beginning in March 2020. To assess pandemic impact on Clostridioides difficile infection (CDI) rates, we described patients and trends in facility-level incidence, testing rates, and percent positivity during 2019–2020 in a large cohort of US hospitals.

We estimated and compared rates of community-onset CDI (CO-CDI) per 10,000 discharges, hospital-onset CDI (HO-CDI) per 10,000 patient days, and C. difficile testing rates per 10,000 discharges in 2019 and 2020. We calculated percent positivity as the number of inpatients diagnosed with CDI over the total number of discharges with a test for C. difficile. We used an interrupted time series (ITS) design with negative binomial and logistic regression models to describe level and trend changes in rates and percent positivity before and after March 2020.

In pairwise comparisons, overall CO-CDI rates decreased from 20.0 to 15.8 between 2019 and 2020 (P < .0001). HO-CDI rates did not change. Using ITS, we detected decreasing monthly trends in CO-CDI (−1% per month, P = .0036) and HO-CDI incidence (−1% per month, P < .0001) during the baseline period, prior to the COVID-19 pandemic declaration. We detected no change in monthly trends for CO-CDI or HO-CDI incidence or percent positivity after March 2020 compared with the baseline period.

While there was a slight downward trajectory in CDI trends prior to March 2020, no significant change in CDI trends occurred during the COVID-19 pandemic despite changes in infection control practices, antibiotic use, and healthcare delivery.

To evaluate whether resistance to third-generation cephalosporins and/or aztreonam was associated with a higher mortality rate among patients with nosocomial Klebsiella pneumoniae infections.

Retrospective cohort study.

Tertiary care university hospital.

A total of 143 patients with nosocomial infections due to K. pneumoniae were evaluated. Death within 21 days after diagnosis of infection was the outcome. Demographic data, invasive procedures, presence and severity of underlying conditions, infection diagnosis, anatomic site of isolation, and treatment of infection, as well as resistance to third-generation cephalosporins and/or aztreonam, were evaluated for association with the outcome.

The mortality associated with nosocomial K. pneumoniae infections was 22% in our study. Drug resistance was found in isolates from 48% of case patients. Multivariate analysis demonstrated that the severity of the patient's underlying condition (odds ratio, 12.50; P<.01) and isolation of the microorganism from the blood or from another usually sterile site (odds ratio, 2.94; P = .03) were associated with death. On the other hand, the presence of resistance to cephalosporins and/or aztreonam did not affect mortality, and the use of inadequate treatment was not significantly associated with increased mortality. When only the severe cases of infection were analyzed, the results were unchanged.

Resistance to cephalosporins and/or aztreonam did not affect mortality, and the use of inadequate treatment was not significantly associated with increased mortality. The reasons for this are not clear. It is possible that the severity of the underlying disease and the patient's condition have a larger role than the K. pneumoniae infection in determining the outcome, and initially inadequate treatment may not have an impact sufficient to cause irreversible damage, allowing treatment to be changed to an effective drug.

To evaluate measles seroprev-among cohorts of new employees and to evaluate vaccine responses of susceptible adult healthcare workers.

New employees were screened for measles susceptibility as part of employee evaluations. Anti-IgG measles antibody tests were completed on 2,473 workers. Demographic, measles history, and measles vaccination information was collected using a short questionnaire. Susceptible workers were vaccinated and screened for vaccine responses following vaccination.

Ninety-three workers (4%) were seronegative, and 56 (2%) were equivocal. Individuals in the youngest cohort (born after 1956) were significantly more likely to be susceptible than those in the middle cohort (born 1951 to 1956) and those in the oldest cohort (born before 1951) (P<0.01). The middle cohort included eight (5%) of the 149 seronegative or equivocal workers. Among the members of the youngest cohort, those from the United States were more likely to be susceptible (P<0.01) than those from outside the United States.

Of the 106 vaccinated susceptible workers whose follow-up serologies were determined, 90 (85%) developed positive IgG serologies, six had equivocal results, and 10 were seronegative. Eleven of the 16 non- or hyporesponders were revaccinated and re-evaluated; nine developed low positive IgG antimeasles levels, one exhibited an equivocal response, and one failed to respond.

A small but important proportion of healthcare workers are susceptible to measles. Whenever feasible, measles immunity programs for healthcare workers should include workers born before 1957. Of workers born after 1956, those from outside the United States are more likely to be immune than workers from inside the United States. Using the currently available vaccine, revaccination of initial non- or hyporesponders appears to be effective.

To develop a model to assess the impact of a program of testing surgeons for human immunodeficiency virus (HIV) on the risk of HIV acquisition by their patients.

A Monte Carlo simulation model of physician-to-patient transmission of human immunodeficiency virus (HIV) infection using three different rates of physician-to-patient transmission per percutaneous exposure event (0.15%, 0.3%, 0.6%). Data from the model were developed from a review of the medical literature and from subjective probability estimates when data were not available. We used this model to estimate on a national basis the annual number of cases of HIV transmission from surgeons to patients with and without surgeon testing and practice limitations.

The annual number of transmitted cases would range from 0.5 ( 0.3), assuming a surgeon HIV prevalence of 0.1% and a surgeon-to-patient transmission rate of 0.15%, to 36.9 (±11.6), assuming a surgeon HIV prevalence of 2% and a surgeon-to-patient transmission rate of 0.6%. After one screening cycle, a mandatory screening program would be expected to reduce the annual transmissions to 0.05 (± 0.03) and 3.1 ( 1. 1), respectively.

Patients are at low risk of acquiring HIV infection from an infected physician during an invasive procedure. The potential costs of such a program extended beyond the costs of testing and counseling. In communities with high HIV prevalence, screening surgeons and limiting their practices may decrease patient access to care. A disability insurance program also would be required to protect surgeons and trainees performing invasive procedures. Screening surgeons for HIV infection would be a costly undertaking that would reduce but not completely eliminate this risk.