Infection Control & Hospital Epidemiology (2019), 40, 365–367 doi:10.1017/ice.2018.335
Concise Communication
Droplet aerosol dissemination of carbapenem-resistant Acinetobacter baumannii surrounding ventilated patients
Madelyn Mousa BMSc1, David Schwartz PhD2, Yehuda Carmeli MD1,2 and Amir Nutman MD1,2 1Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel and 2National Center for Infection Control and Antibiotic Resistance, Tel-Aviv Sourasky Medical Center, Tel-Aviv, Israel
Abstract
We measured droplet aerosol dissemination of carbapenem-resistant Acinetobacter baumannii (CRAB) by sampling air surrounding 10 ven- tilated patients with CRAB isolated in sputum. Over 70 hours, we sampled 252,000 L of air; CRAB was detected in 39,600 L (16%). CRAB growth was higher during patient care, notably suctioning and sheet changing.
(Received 26 July 2018; accepted 10 November 2018)
Acinetobacter baumannii is a rapidly emerging nosocomial patho- gen associated with a high fatality rate.1 It contaminates the hos- pital environment and its prolonged survival on dry surfaces and resistance to disinfectants lead to outbreaks that are hard to con- tain.2 Carbapenem-resistant Acinetobacter baumannii (CRAB) has been isolated from bed surfaces, curtains, and medical equip- ment.3,4 Although aerial spread of A. baumannii was described more than 30 years ago,5 it was ignored at the time. Recently there is renewed interest in the topic.6 Contamination of air may occur because of respiratory ejection from the mouth and nose or shed- ding of bacteria from skin and infected lesions,7 as well as through actions such as bed making.8 We aimed to measure droplet aerosol dissemination of
CRAB in the environment surrounding ventilated patients with CRAB respiratory infection or colonization and to determine whether specific treatment activities were associated with greater dissemination.
Methods Setting and study sample
The study was conducted from September to December 2016 at Tel-Aviv Sourasky Medical Center, Israel, a tertiary care center with endemic CRAB: the incidence of microbiologically confirmed CRAB infections was 41.8 per 100,000 patient days in 2016 (Israeli Ministry of Health, unpublished data). We recruited adult venti- lated patients with sputum cultures growing CRAB in the previous 7 days. Patients were hospitalized in intensive care units (ICUs) or medical step-down units with routine air handling of 10 air changes per hour. We collected the following data: age, gender,
Author for correspondence: Amir Nutman, Email:
amirn@tlvmc.gov.il PREVIOUS PRESENTATION: This research was first presented at the 28th European
Congress of Clinical Microbiology and Infectious Diseases on April 22, 2018, in Madrid, Spain.
Cite this article: Mousa M, et al. (2019). Droplet aerosol dissemination of carbapenem-
resistant Acinetobacter baumannii surrounding ventilated patients. Infection Control & Hospital Epidemiology, 40: 365–367,
https://doi.org/10.1017/ice.2018.335
© 2019 by The Society for Healthcare Epidemiology of America. All rights reserved.
ward, current antibiotic treatment, and timing of last chlorhexidine bath. We recorded all patient care activities performed during air sampling. The ethical review board of the Tel-Aviv Sourasky Medical Center approved this study.
Microbiological methods
Air sampling Air sampling was performed using the Buck Bio-Culture pump (Model B30120, AP Buck,Orlando, FL), a sieve impactor-type bio- aerosol sampling pump designed to draw air onto a standard agar plate. The air sampler was placed 1.5mfrom the patient’s head at a height of 1 m. Air sampling was performed continuously for 7 hours for each patient. The sampler was calibrated to 60 L per minute, and agar plates were changed every 30 minutes (1800 L of air sampled per plate). Two types of agar media were used (3.5 hours each) to compare yields: a nonselective 5% blood agar plate and a selective CHROMagar MDR Acinetobacter plate (both from Hylabs, Rehovot, Israel).
Clinical and environmental sampling Cultures were taken from tracheal aspirate. The buccal mucosa was sampled by swab. Sterile premoistened sponges were used to sample each patient’s skin and the immediate environment as previously described: bed rail, bed sheet, a 10-cm2 wall portion, outlets near the head of the bed, and monitor screens.4
Sample processing Air-inoculated plates and samples were transferred to the labora- tory soon after sampling. Swab and sponge samples were inocu- lated directly onto CHROMagar MDR Acinetobacter plates and after overnight enrichment in brain-heart infusion broth. Samples were incubated at 37°C overnight. The numbers of colo- nies grown per plate were counted. Colonies grown on blood agar plates were subcultured on CHROMagar MDR Acinetobacter plates. Acinetobacter baumannii identification was confirmed by MALDI-TOF using VITEK-MS (bioMérieux, Marcy-l’Étoile, France).9
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