P195 Secondary infection rates and antibiotic prescribing in a COVID-19 HDU population

Journal article

Introduction

Secondary infection in COVID-19 has been associated with adverse outcomes and high mortality. The prevalence of secondary infection in COVID-19 and optimal antimicrobial strategies remain unclear.

Methods

Retrospective case-note review of patients with COVID-19 admitted to our institution’s high dependency unit (HDU) from March to June 2020. Patients were PCR-positive for SARS-CoV-2 or had classical CT appearances and a compatible clinical presentation for COVID-19. Microbiological tests, antimicrobial prescriptions and clinical outcomes were recorded.

Results

84 patients were identified. Median age was 68.5 years and 29/84 (34.5%) were female. Respiratory support included HFNO (n=39), CPAP (n=56), non-invasive ventilation (n=3) and invasive ventilation (n=14). Overall mortality was 36/84 (42.9%). 6/84 patients (7.1%) had evidence of secondary infection (>10⁵ CFUs on bronchoalveolar lavage (BAL); positive sputum culture or positive blood culture excluding skin contaminants). 28/84 (33.3%) had a respiratory sample sent: BAL n=10; sputum culture n=2; Legionella antigen n=15; throat swab multiplex PCR n=3; Biofire respiratory viral panel n=7. BAL was positive in 3/10 cases (Enterococcus faecium; Serratia marcescens and Escherichia coli; Pseudomonas aeruginosa). One sputum culture was positive for M. abscessus. 71/84 (84.5%) had blood cultures. 8 (11.2%) were positive, of which 6 were considered skin contaminants and not deemed true secondary infection (coagulase negative Staphylococci n=5; Lysinibacillus sp. n=1; Proteus mirabilis n=1; Staphylococcus epidermidis and Serratia marcescens n=1). All 84 patients received antimicrobials. 32 (38.1%) received a macrolide, predominantly azithromycin. Macrolide usage was not associated with mortality or admission length, but was associated with increased intubation rate (28.1% vs 9.6%, p=0.027) Initial antibiotic treatment was monotherapy in 45 (53.6%) cases and dual therapy in 39 (46.4%). Initial treatment with two antibiotics versus monotherapy was not associated with mortality but was associated with increased intubation rate (25.6% vs 8.9%, p=0.040) and increased mean admission length (16.5 vs 11.6 days, p=.036).

Discussion

Robust evidence of secondary infection in patients with COVID-19 was uncommon in our cohort. Increased intubation rates in patients prescribed a macrolide and those initially prescribed dual antibiotic therapy is likely to reflect more severe disease. There is considerable potential for enhanced antimicrobial stewardship in further waves of COVID-19.

Authors: Zhang, S; Bickler, G; Porter, B; Hallifax, R; Rahman, N

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: BMJ Publishing Group
• Journal: Thorax
• Volume: 76
• Issue: Suppl 1
• Pages: A195.1-A195
• Publication date: 2021-01-21
• DOI: 10.1136/thorax-2020-btsabstracts.340
• EISSN: 1468-3296
• ISSN: 0040-6376
• Language: English
• Keywords: Tuberculosis; Population; Blood culture; Medicine; Immunology; Lung; Antibiotics; Erythromycin; Internal medicine; Microbiology; Pneumonia; Bronchoalveolar lavage; Enterococcus faecium; Sputum culture; Sputum; Gastroenterology; Pathology