|Year : 2020 | Volume
| Issue : 3 | Page : 293-295
Detection of airborne bacteria from patient spaces in tuberculosis hospital
Taeuk Kang, Taeyoon Kim, Sungweon Ryoo
Clinical Research Center, Masan National Tuberculosis Hospital, Changwon-Si, Gyeongsangnamdo, South Korea
|Date of Submission||26-Jun-2020|
|Date of Decision||11-Aug-2020|
|Date of Acceptance||01-Jul-2020|
|Date of Web Publication||28-Aug-2020|
Clinical Research Center, Masan National Tuberculosis Hospital, Changwon, Gyeongsangnamdo, 51755
Source of Support: None, Conflict of Interest: None
Background: The spread of nosocomial bacterial infection greatly threatens public health and the impact of nosocomial infection worsens if highly pathogenic bacteria, Mycobacterium tuberculosis as an instance, involves. In this study, we have investigated the presence of airborne M. tuberculosis in a specialized tuberculosis hospital. Methods: The study sites selected were waiting room I, II, and ward VI patient lounge, Masan National Tuberculosis Hospital, where the modern ventilation system is on the operation for opportunistic infection prevention. The air samples were collected from the different sites three times for 1 day, and after air collection, air sampled disposable filter membrane was incubated for 4 weeks on nine Middlebrook 7H11 agar plates. Results: Our data showed that out of nine incubated 7H11 plate agars, four plates showed bacterial growth and these grown bacterial colonies were isolated and identified. Among bacterial species identified, there was a colony of Mycobacterium mageritense, one of nontuberculous Mycobacteria. Although there was no M. tuberculosis, the cause of tuberculous disease and transmitted through the nosocomial infection, all pathogens detected were known to be associated with nosocomial infection. Conclusions: Hospitals dealing with infectious diseases should always be wary that ventilation system does not guarantee safety from airborne pathogen exposure hence should continuously monitor the presence of other hospital-associated infection causing pathogenic microorganisms.
Keywords: Airborne detection, Mycobacterium, nosocomial infection
|How to cite this article:|
Kang T, Kim T, Ryoo S. Detection of airborne bacteria from patient spaces in tuberculosis hospital. Int J Mycobacteriol 2020;9:293-5
|How to cite this URL:|
Kang T, Kim T, Ryoo S. Detection of airborne bacteria from patient spaces in tuberculosis hospital. Int J Mycobacteriol [serial online] 2020 [cited 2020 Oct 1];9:293-5. Available from: http://www.ijmyco.org/text.asp?2020/9/3/293/293540
| Introduction|| |
The nosocomial Mycobacterium tuberculosis infection is a global public health concern due to its high mortality and ease transmission., However, the prevalence of M. tuberculosis in hospital, especially airborne M. tuberculosis, was relatively poorly investigated as previous studies focused on nosocomial infection by Escherichia spp., Staphylococcus spp., and Shigella spp., Furthermore, nonpatient wards were never been assessed despite high nosocomial infection chance.
In this study, we investigated on airborne mycobacteria detection present in nonpatient wards of tuberculosis-specialized hospital at different times for the comparative purpose.
| Methods|| |
The Masan National Tuberculosis Hospital is tuberculosis-specialized national hospital located in Korea. The explore sites for sampling are followed: patient waiting room I and II, and ward VI patient lounge. In all places, HEPA filter was installed and pressure gap of ≥2.5 Pa is maintained. These sites were selected because high mobility of both patients and nonpatients was observed. The patient waiting room was divided into two separate rooms for segregation purpose, whereas waiting room I is for individuals with tuberculosis positive and waiting room II is for individuals with tuberculosis diagnostics undone.
Air sampling and microbiological analysis
Air sampling was carried out on October 31, 2019. The MD8 air sampler (Sartorius Stedim Biotech GmbH, Germany) was mounted on a 1.5-m tall stand equipped with gelatin filter. MD8 air sampler showed comparable capability when compared to other air samplers. The air sampler was operated for 1200 s at air flow rate of 50 L/min in the morning, noon, and afternoon, 08:00, 12:00, and 16:00, respectively. For sampling, the total volume of 1000.0 L was selected because during internal pilot testing, air sampling more than 1000.0 L caused filter clogging. In every sampling event, air sampled gelatin filter was directly placed onto prepared PANTA antibiotic mixture-supplemented Middlebrook 7H11 agar plate (DB Difco, USA) by making contact at sampling site. The PANTA antibiotic mixture was added to Middlebrook 7H11 agar to prevent fungal contamination. Each agar plate with gelatin filter was wrapped with micropore film (3M, USA) and incubated at 37°C for 28 days. For microbiological identification, agar plates were sent to Samkwang Medical Laboratory, Korea. This institution performed microbiological identification by utilizing Vitek 2 system (bioMérieux, Marcy l'E'toile, France).
| Results|| |
The aim of this study was to investigate the presence of airborne M. tuberculosis in nonpatient sites to evaluate the possible chance of nosocomial tuberculosis infection. Furthermore, bacteria other than M. tuberculosis grown on plates were identified to determine whether they are capable to cause infection.
Overall, out of nine captured air samples, colonies were found in four plates [Figure 1], which were from the patient lounge, waiting room I, and waiting room II at 08:00 and patient lounge at 16:00. No colonies observed in all plates at 12:00 and 16:00 except the patient lounge [Table 1]. Interestingly, each site showed the presence of different bacteria species. For the patient lounge, Staphylococcus spp. was found from both air samples collected at 08:00 and 16:00, but other than that, Corynebacterium spp. was also found sampled at 16:00. The two waiting rooms have similarities to each other that Sphingomonas paucimobilis was identified in both; however, unlike waiting room I, waiting room II has more bacterial species. Sphingomonas sanguinis and Mycobacterium mageritense were observed in waiting room II [Table 1]. Subsequently, M. tuberculosis was not present in any of the captured air samples. The CFU/m3 calculated for the patient lounge, waiting room I, waiting room II at 08:00, and patient lounge at 16:00 were 1, 2, 3, and 151, respectively [Table 1]. The result suggests that the time of the day influences the popularity of bacteria.
|Figure 1: The result of bacterial growth on Middlebrook 7H11 agar plate with air sampled gelatin filter from different sites (a) Middlebrook 7H11 agar plate with gelatin filter, from patient lounge at 08:00, incubated for 28 days at 37°C. Blue arrow is Staphylococcus spp. (b) Middlebrook 7H11 agar plate with gelatin filter, from patient lounge at 16:00, incubated for 28 days at 37°C. Blue arrow is Staphylococcus spp. and red arrow is Corynebacterium spp. (c) Middlebrook 7H11 agar plate with gelatin filter, from waiting room I at 08:00, incubated for 28 days at 37°C. Blue arrows are Sphingomonas paucimobilis (d) Middlebrook 7H11 agar plate with gelatin filter, from waiting room II at 08:00, incubated for 28 days at 37°C. Blue arrow is Sphingomonas paucimobilis, red arrow is Mycobacterium mageritense and black arrow is Sphingomonas sanguinis|
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| Discussion|| |
When investigating nosocomial infection, surface bacterial detection is the well-studied and sufficiently standardized when compared to airborne bacterial detection; however, previous studies showed that airborne pathogen could cause nosocomial infection. Hence, airborne bacterial detection cannot be overlooked.
The results of those previous studies showed that the most prevalent bacteria are Staphylococcus spp., Unlike the previous studies, our data indicate that Corynebacterium spp. was the most prevalent, where CFU/m3 is 150. We have identified a total number of 5 bacterial species from the air samples, namely Staphylococcus spp., Corynebacterium spp., S. paucimobilis, S. sanguinis, and M. mageritense. To the best of our knowledge, we firstly report the growth of S. paucimobilis and S. sanguinis on 7H11 agar plate, which is the selective medium designed for Mycobacteria spp. According to the literature review, all of bacterial species above were reported to be associated with hospital-acquired infection.,, Furthermore, these bacteria are presumed to be resistant against polymyxin B, nalidixic acid, trimethoprim acid, and azlocillin as their growth observed despite the addition of PANTA antibiotic mixture during media preparation. Both Staphylococcus and Corynebacterium were not identified at its species level due to the limitation of Vitek 2 system.
| Conclusion|| |
We concerned the presence of M. tuberculosis from collected air samples since that implies air contamination by M. tuberculosis. Fortunately, no M. tuberculosis was isolated; however, the result data were highly intriguing and medically significant because non mycobacteria were detected. In this study, the limitation presents since the exact prevalence of airborne pathogens was not demonstrated because Middlebrook 7H11 agar was used. For further investigation, the use of general purpose medium is highly recommended to demonstrate the prevalence of pathogens other than Mycobacteria spp.
Financial support and sponsorship
This study was financially supported by the evaluation of removal performance of dangerous pathogen project (PNK6760) of Surface Technology Division, Korea Institute of Materials Science, Republic of Korea.
Conflicts of interest
There are no conflicts of interest.
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