vol.62-2 (2024/7/31)

The current status of airborne microorganism measurement methods

Methods for measuring suspended microorganisms can be broadly divided into (1) culture methods, which measure viable bacteria using a culture medium, and (2) non-culture methods, which can be further divided into rapid and real-time methods. This article describes the advantages and limitations of the culture, rapid and real-time methods for the measurement of microorganisms. It also reviews the characteristics of typical representative instruments for real-time measurement of bioaerosols and describes measurement results in real environmental settings.

Introduce of rapid microbial detection device using fluorescent staining methods and examples of airborne microorganism measurement

Measuring the number of bacteria using the culture method requires at least several days to obtain results, and only the types of microorganisms that are suitable for the culture medium conditions can be measured. To date, various rapid detection methods have been proposed to replace culture methods. This time, we will introduce an example of fluorescent staining, which is a direct observation method.
First, we compared the bacterial count results using Escherichia coli NCTC9001 using the fluorescent staining method and culture methods (the number of colony forming units (CFU) and turbidity method (OD)). Next, as measurement examples using the fluorescent staining method, we conducted (1) verification of detection of airborne microorganisms in the test space and (2) under the actual environment, and (3) verification of the antibacterial effect of spray type drugs. The results suggested that the fluorescent staining method solves the time issue in counting bacteria and allows for comparable or more detailed control of bacterial counts compared to conventional methods.

Introduction of a microbiological analyzer for sensitive and rapid detection of ATP at the level of one microbial cell

Since microorganisms are invisible to the naked eye, and they can be visually confirmed when forming colonies by incubating under the appropriate culture media and temperature. Cultivation of microorganisms takes time: 4 to 7 days for pharmaceutical water used in pharmaceuticals, and 14 days for sterility tests used in release testing for sterile pharmaceutical products. HORIBA has developed Rapica, a rapid microbiological test system that can detect extremely small amounts of ATP possessed by microorganisms in a short time without culturing. We introduce its features and applications in this article.

Bio particle counter by laser induced fluorescence

The Bio Particle Counter (BPC) is an instrument that continuously measures the size and number of particulates and viable particulates in real time. BPC is categorized instruments known as Rapid Microbiology Method (RMM). Recently, PIC/S GMP Annex 1 and other guidelines have recommended the consideration of RMM in the manufacture of sterile products. The RMM-based measuring instruments including BPC help improve the level of microbiological control and reduce risk in biological clean rooms.

A compact real-time bioaerosol instrument using laser-induced fluorescence method

Preventing infection by pathogens has become an urgent issue in various human environments, but there are currently few measuring instruments that can be easily used on the spot in real time. In this paper, the relationship between biological substances and fluorescence is firstly explained, and then the research on bioaerosol detection and identification to date and the status of commercialized product technologies that have been put into practical use are introduced. Commercially available products are relatively large and expensive, so the details of an inexpensive and small bioaerosol measuring device that we have been investigating in recent years are explained. Furthermore, basic performance evaluation results of the optical system and some field measurement examples using this device are shown, and future directions are also discussed.

A systematic review of acrolein determination method and behavior in indoor and outdoor air

Acrolein, an unsaturated aldehyde, is a common eye and throat irritant. Recent studies, by the Japan Bioassay Research Center (JBRC) and the International Agency for Research on Cancer (IARC) have conclusively identified it as carcinogenicity in animal experiments, thereby suggesting potential carcinogenicity in humans, leading to its classification as 2A.
In the United States, acrolein in the atmosphere is considered to be an important toxic substance, prompting active research both indoors and outdoors. Efforts to measure acrolein levels are also underway. Guidelines for air quality and indoor air quality have been established in the United States and Canada, and pollution prevention measures are being strongly promoted.
In this report, we have consolidated literature spanning from the late 1970s to 2023, with an aim to provide basic material for setting indoor guidelines and championing pollution prevention initiatives in Japan.

Healthcare facilities

This section outlines basic knowledge and the latest case studies on bio-clean room planning for healthcare facilities. The guidelines and manuals pertinent to biological clean rooms in healthcare facilities encompass HEAS-02-2022, the ASHRAE HVAC Design Manual for Hospitals and Clinics (Second Edition, 2013), and AIJES-A0002-2013. Moreover, given that carbon dioxide cannot be eliminated by filters in HVAC systems, the efficiency of filtration cannot be appraised solely on the basis of carbon dioxide concentration. Nonetheless, by performing a conversion that incorporates filtration considerations, the assessment of its effectiveness becomes feasible. Recent trends and examples in the design of air conditioning and ventilation systems for healthcare facilities with a focus on air cleanliness, especially in operating rooms, intensive care units and protective environments are described.