Observational Study
Copyright ©The Author(s) 2016. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Methodol. Mar 26, 2016; 6(1): 126-132
Published online Mar 26, 2016. doi: 10.5662/wjm.v6.i1.126
Efficient management and maintenance of ultrasonic nebulizers to prevent microbial contamination
Yoko Ida, Hiroaki Ohnishi, Kouji Araki, Ryoichi Saito, Shin Kawai, Takashi Watanabe
Yoko Ida, Hiroaki Ohnishi, Kouji Araki, Takashi Watanabe, Clinical Laboratory, Kyorin University Hospital, Tokyo 181-8611, Japan
Yoko Ida, Ryoichi Saito, Department of Microbiology and Immunology, Graduate School of Health Care Sciences, Tokyo Medical and Dental University, Tokyo 113-8510, Japan
Hiroaki Ohnishi, Takashi Watanabe, Department of Laboratory Medicine, Kyorin University School of Medicine, Tokyo 181-8611, Japan
Shin Kawai, Department of General Medicine, Kyorin University School of Medicine, Tokyo 181-8611, Japan
Author contributions: Saito R and Watanabe T designed the research; Ida Y, Aaraki K and Kawai S performed the research (patients’ data collection, bacterial culture and genetic analysis); Ida Y and Ohnishi H wrote the paper.
Institutional review board statement: As this study only handles data regarding bacteria that are non-human subjects, ethical issues do not arise from this manuscript. Therefore, this study does not require the approvement by the review board.
Informed consent statement: As this study only handles data regarding bacteria, no informed consent is necessary for this manuscript.
Conflict-of-interest statement: All the authors declare that there are no potential conflicts of interest relating to this manuscript.
Data sharing statement: No additional data are available.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Hiroaki Ohnishi, MD, PhD, Department of Laboratory Medicine, Kyorin University School of Medicine, 6-20-2 Shinkawa, Mitaka, Tokyo 181-8611, Japan. onishi@ks.kyorin-u.ac.jp
Telephone: +81-422-475511 Fax: +81-422-793471
Received: July 28, 2015
Peer-review started: August 6, 2015
First decision: September 28, 2015
Revised: December 12, 2015
Accepted: January 5, 2016
Article in press: January 7, 2016
Published online: March 26, 2016
Processing time: 233 Days and 21.2 Hours
Abstract

AIM: To seek the cause of Burkholderia cepacia complex (Bcc) infection outbreak and evaluate the efficacy of new methods for nebulizer maintenance.

METHODS: We investigated the annual number of Bcc isolates recovered from clinical samples in our hospital between 1999 and 2013. Swab samples were randomly collected for bacterial culture before patient use from 10 each of the two machine types in August 2001; these included 20 samples from each of the following: Drain tubes, operating water chambers, oscillators, and nebulizing chambers. In addition, 10 samples each of nebulizer solutions before and after use were cultured. For environmental investigation, 10 samples were collected from sinks in the nurse stations of the wards where patients positive for Bcc were hospitalized. Numbers of Bcc isolates were compared before and after introduction of new methods for nebulizer maintenance in October 2001. In addition, randomly amplified polymorphic DNA (RAPD) assay was applied to find the genetic divergence of the Bcc isolates obtained from clinical samples and nebulizers.

RESULTS: From January 1999 to December 2013, a total of 487 Bcc isolates were obtained from clinical specimens from 181 patients. Notably, 322 (66.1%) Bcc isolates were obtained from clinical specimens from 1999 to 2001, including 244 (115 patients) from sputum and 34 (11 patients) from blood. During this period, 14 isolates were obtained from nebulizer components. Among these, six were derived from nebulizer drain tubes, five from operating water chambers, and one from the oscillator before patient use, and two from nebulizer solutions after patient use. When Bcc was isolated from the nebulizer solution after patient use, Bcc was simultaneously detected in other parts of the nebulizer. Bcc was not isolated from any nebulizer solution before use. RAPD assays revealed similar DNA profiles in isolates obtained from patients and nebulizers. Investigation revealed damaged diaphragms in many nebulizers. The new maintenance methods for nebulizers, including restriction of the usage period, thorough disinfection, and routine check for diaphragm breakage, remarkably reduced Bcc isolation (165 isolates from patients in 12 years and 0 isolate from nebulizers in periodical sampling). In particular, Bcc has been isolated from blood from only one patient since the new methods were introduced.

CONCLUSION: Appropriate maintenance of ultrasonic nebulizers is crucial for preventing Bcc contamination of nebulizers and subsequent respiratory tract and blood infections.

Keywords: Prevention; Contamination; Burkholderia cepacia; Randomly amplified polymorphic DNA assay; Ultrasonic nebulizer

Core tip: In this study, we sought the cause of an outbreak of Burkholderia cepacia complex (Bcc) infection among inpatients using ultrasonic nebulizers and evaluated the efficacy of new methods for nebulizer maintenance introduced following the outbreak. Precise investigation revealed damaged diaphragms in many nebulizers, which we speculated would be the major cause of Bcc contamination of nebulizers and subsequent Bcc infection. The new maintenance methods for nebulizers, including restriction of the usage period, thorough disinfection, and routine check for diaphragm breakage, remarkably reduced Bcc isolation from nebulizers and patients’ samples.