Epidemiology, Disposition, and Treatment of Ambulatory Veterans With Skin and Soft Tissue Infections

Arterial leg ulcers-Bacterial patterns, antimicrobial resistance and clinical characteristics, a retrospective single-centre cohort, 2012-2021

OBJECTIVE

Severe wound infections in patients with peripheral artery disease (PAD) are common, potentially life- and limb-threatening, and difficult to treat. Evidence on patients with infected leg ulcers in PAD is scarce. This study aims to provide insight into the microbiological patterns and antimicrobial resistance (AMR) of specific pathogens in patients with arterial leg ulcers.

METHODS AND DESIGN

In this retrospective, consecutive, single-centre study 16,553 patients underwent an endovascular revascularization procedure between 2012 and 2021. Of these, 1,142 patients had PAD Rutherford category 5 or 6 with infected leg ulcers. Logistic regression was used to identify risk factors for Staphylococcus aureus-associated infections.

RESULTS

A total of 3,431 bacterial isolates were detected, of which 2,335 (68.1%) bacterial isolates were gram-positive and 1,096 (31.9%) were gram-negative species. The most prevalent bacteria were S. aureus (18.6%), Enterococcus faecalis (9.1%) and S. epidermidis (7.8%). Pseudomonas aeruginosa (5.6%), Proteus mirabilis (3.7%) and Escherichia coli (3.4%). The resistance of S. aureus isolates to clindamycin was 11.0%. Resistance to oxacillin was rare (1.5%). P. aeruginosa is frequently resistant to ciprofloxacin (14.4%) whilst intrinsically resistant to trimethoprim/sulfamethoxazole. P. mirabilis and E. coli were frequently resistant to both ciprofloxacin (7.3; 20.7%) and trimethoprim/sulfamethoxazole (24.6; 22.6%), respectively. Resistance to amoxicillin/clavulanic acid was high among E. coli isolates (36.8%). Multi-drug resistance (MDR) was rare among S. aureus and P. aeruginosa isolates. In contrast, the proportion of MDR was high in E. coli isolates. End-stage renal disease was independently positively associated with S. aureus identification (p = .042).

CONCLUSION

S. aureus was the most common pathogen in arterial leg ulcers with end-stage renal disease being an independent risk factor. Clindamycin resistance was common, making empirical therapy likely to fail. Isolated E. coli species had a high proportion of MDR.

In Vitro Activity of Ceftaroline and Comparators against Bacterial Isolates Collected Globally from Patients with Skin and Soft Tissue Infections: ATLAS Program 2019-2020

The objective of this study was to assess the in vitro activity of ceftaroline and a panel of comparator agents against isolates causing skin and soft tissue infections (SSTIs) collected in Africa/Middle East, Asia-Pacific, Europe, and Latin America from 2019-2020. Minimum inhibitory concentrations (MIC) were determined using European Committee on Antimicrobial Susceptibility Testing criteria. All the methicillin-susceptible Staphylococcus aureus (MSSA) isolates were susceptible to ceftaroline. Across all regions, ceftaroline demonstrated potent activity against methicillin-resistant S. aureus (MRSA, susceptibility 89.5-93.7%) isolates. Susceptibility to vancomycin, daptomycin, linezolid, teicoplanin, trimethoprim sulfamethoxazole, and tigecycline was ≥94.1% in MSSA and MRSA isolates. Against β-hemolytic streptococci isolates, ceftaroline demonstrated very potent activity (MIC90 0.008-0.03 mg/L) across all regions. All β-hemolytic streptococci isolates were susceptible to linezolid, penicillin, and vancomycin (MIC90 0.06-2 mg/L). Among the extended-spectrum β-lactamases (ESBL)-negative Enterobacterales tested (E. coli, K. pneumoniae, and K. oxytoca), susceptibility to ceftaroline was high (88.2-98.6%) in all regions. All ESBL-negative Enterobacterales were susceptible to aztreonam. Potent activity was observed for amikacin, cefepime, and meropenem (94.1-100%) against these isolates. Overall, ceftaroline showed potent in vitro activity against isolates of pathogens causing SSTIs. Continuous surveillance of global and regional susceptibility patterns is needed to guide appropriate treatment options against these pathogens.

International Validation of a Methicillin-Resistant Staphylococcus aureus Risk Assessment Tool for Skin and Soft Tissue Infections

INTRODUCTION

To promote judicious prescribing of methicillin-resistant Staphylococcus aureus (MRSA)-active therapy for skin and soft tissue infections (SSTI), we previously developed an MRSA risk assessment tool. The objective of this study was to validate this risk assessment tool internationally.

METHODS

A multicenter, prospective cohort study of adults with purulent SSTI was performed at seven international sites from July 2016 to March 2018. Patient MRSA risk scores were computed as follows: MRSA infection/colonization history (2 points); previous hospitalization, previous antibiotics, chronic kidney disease, intravenous drug use, human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS), diabetes with obesity (1 point each). Predictive performance of MRSA surveillance percentage, MRSA risk score, and estimated MRSA probability (surveillance percentage adjusted by risk score) were quantified using the area under the receiver operating characteristic curves (aROC) and compared. Performance characteristics of different risk score thresholds across varying baseline MRSA prevalence were examined.

RESULTS

Two hundred three patients were included. Common SSTI were wounds (28.6%), abscess (25.1%), and cellulitis with abscess (20.7%). Patients with higher risk scores were more likely to have MRSA (P < 0.001). The MRSA risk score aROC (95%CI) [0.748 (0.678-0.819)] was significantly greater than MRSA surveillance percentage [0.646 (0.569-0.722)] (P = 0.016). Estimated MRSA probability aROC [0.781 (0.716-0.845)] was significantly greater than surveillance percentage (P < 0.001) but not the risk score (P = 0.192). The estimated negative predictive value (NPV) of an MRSA score ≥ 1 (i.e., a score of 0) was greater than 90% when MRSA prevalence was 30% or less.

CONCLUSION

The MRSA risk score and estimated MRSA probability were significantly more predictive of MRSA compared with surveillance percentage. An MRSA risk score of zero had high predictive value and could help avoid unnecessary empiric MRSA coverage in low-acuity patients. Further study, including impact of such risk assessment tools on prescribing patterns and outcomes are required before implementation.

Associations of HLA-A and HLA-B with vancomycin-induced drug reaction with eosinophilia and systemic symptoms in the Han-Chinese population

Vancomycin is a commonly used antibiotic; however, it can cause life-threatening severe cutaneous adverse reactions, such as drug reaction with eosinophilia and systemic symptoms (DRESS). A previous study has reported a strong association between HLA-A*32:01 and vancomycin-induced DRESS in European ethnicity. Herein, we aim to investigate the genetic predisposition of vancomycin-induced DRESS in the Han-Chinese population. In this study, we enrolled a total of 26 patients with vancomycin-induced DRESS, 1,616 general population controls, and 51 subjects tolerant to vancomycin. In vitro granulysin-based lymphocyte activation tests (LAT) were conducted among 6 vancomycin-induced DRESS patients who were concomitantly receiving other medicines. HLA-A and HLA-B genotypes were determined by sequencing-based typing. Our results found that vancomycin-induced DRESS was associated with HLA-A*32:01 [odds ratio (OR) = 7.8, 95% confidence interval (CI) = 1.7-35.8; p-value = 0.035], HLA-B*07:05 (OR = 32.3, 95% CI = 2.8-367.7; p-value = 0.047), HLA-B*40:06 (OR = 4.7, 95% CI = 1.3-16.1; p-value = 0.036) and HLA-B*67:01 (OR = 44.8, 95% CI = 7.2-280.4; p-value = 0.002) when comparing the vancomycin-induced DRESS patients with the general population controls. LAT results showed that granulysin significantly increased in the vancomycin-induced DRESS patients upon vancomycin stimulation (4.7 ± 3.7 fold increased), but not upon other co-medicines. This study identified that, in addition to HLA-A*32:01, HLA-B*07:05, HLA-B*40:06, and HLA-B*67:01 were also genetic markers for vancomycin-induced DRESS in the Han-Chinese population. Associations of ethnic variances in HLA with vancomycin-DRESS were observed.

Identification of Inappropriate Antibiotic Orders During Implementation of a Multidisciplinary Antimicrobial Stewardship Program Within the Primary Care Setting

OBJECTIVE

The aim of the study was to describe implementation of an outpatient antibiotic stewardship program at primary care practices in South Florida and the proportion of appropriate and inappropriate orders and reasons for inappropriateness during the intervention.

METHODS

An antibiotic stewardship committee at a large hospital system implemented aspects of The Core Elements of Outpatient Antibiotic Stewardship at outpatient facilities in 2018. Interventions included an education/awareness campaign directed at prescribers (audit and feedback, routine education at prescribers' meetings, availability of updated guidelines in a shared drive and antibiogram via intranet) and patients (posters, tear-off sheets on symptom relief for viral illness). Orders were evaluated using clinical documentation, current antibiogram, and Infectious Diseases Society of America guidelines. An appropriate order was defined as a correct antibiotic and dose/frequency and duration of therapy. An inappropriate antibiotic order was defined as not meeting 1 or more of the abovementioned conditions. Descriptive statistics assessed the data.

RESULTS

In this retrospective review of 2934 oral antibiotic orders from January 1 to December 31, 2018, 2565 (87.4%) were necessary while 369 (12.6%) were unnecessary. Of 2565 necessary orders, 1448 (56.5%) were appropriate while 1117 (43.5%) were inappropriate. Of 1117 inappropriate orders, 24.9% had all 3 conditions; 41.5% of inappropriate orders were solely due to wrong duration of therapy.

CONCLUSIONS

Although our institution demonstrated commitment to optimizing antibiotic prescribing by providing resources to clinicians and patients about evidence-based antibiotic prescribing, inappropriate antibiotic prescribing was persistent. The interventions used must continue to evolve and include point-of-care access to guidelines and clinical decision support tools.