The health crisis of Candida auris and an outbreak at Princess Margaret Hospital (PMH).
Candida auris was first described in Japan in 2009. It is of concern because this fungus is resistant to most of the common antifungal medications. When it was first identified in Japan, it was a relatively minor problem, causing only localised ear infections. However in recent years, Candida auris has been reported to be a major problem in USA, accumulating over 700 cases, all of which involving all kinds of infections andsome strains are resistant to all antifungal medications. Both Centers of Disease Control and Prevention (CDC USA) and World Health Organization (WHO) have recommended contact isolation for patients who are infected or colonised with this fungus.
The Centre for Health Protection (CHP) has recently reported a large outbreak of 16 cases related to PMH (as of 12th August 2019), from in-patients who have been in the hospital since May, both in the ICU and the rest in other wards. This is a big concern because Candida auris is indeed a Multi-Drug Resistant Organisms (MDRO) and appropriate infection control and preventive measures must be taken.
What is the new technology of the MALDI-TOF?
One of the most dramatic advance for the microbiology laboratory is the MALDI-TOF for which K. Tanaka, the inventor was awarded the Nobel Prize in 2002. The MALDI-TOF is the acronym for the technical name of technique, which is M
light. For simplicity, it is often called MS
which stands for Mass Spectrometry. It is an innovative technology that will forever eliminate the need for many identification tests in the Microbiology laboratory. In brief, the biological material is hit by a laser beam that will convert it to molecules with charges. The MS simply analyses these molecules and within an hour, organism will be identified to the species level. In the near future, it will even be able to detect antibiotics sensitivity and bio-typing at the same time.
The Hong Kong Adventist Hospital has installed this machine in the laboratory since September 2015. Today, this machine is only available in the most advanced hospitals in the territory. It is extremely useful for rapid identification of microorganisms and enables >70% of the routine microbiology reports to be completed earlier by 2 days of the turnover time, in comparison to 4-6 days before using the MALDI.
Why the MALDI-TOF makes a key difference?
Candida has many species and identification is difficult and slow, often requiring 2-3 days. The common ones such as Candida albicans can frequently be identified, but for others including Candida auris, they are usually reported simply as “Candida species”. However, with the help of MALDI-TOF, Candida auris can be accurately identified within an hour. To ensure the accurate identification of Candida auris, the computer database has to be updated to the relevant version (i.e. Saramis Ver. 4.14 or equivalent) and this is already installed in the laboratory of Adventist Hospital. Even since September 2015, the HKAH laboratory has been using the machine to identify Candida auris to the species level. This is how technology can make a difference and it was already implemented in the hospital well before the PMH outbreak. If Candida auris was isolated at the Adventist Hospital, it would be identified and the case would be alerted for Infection Control to take further action.
With the outbreak progressing in PMH, all patients admitted to HKAH-SR in the last month will be screened for Candida auris.
The MALTI-TOF is definitely the most reliable and without doubt the most rapid method for the identification of this organism. Indeed technology, at the right time for the right situation can make a difference.
念珠菌屬有不同的品種，而要正確識別每一項品種有若干的難度，而且往往需時甚久，常需要2-3天才有報告結果。常見的白色念珠菌較易識別，但其他的種類包括耳念珠菌，常只被分類為「念珠菌屬」。但MALDI-TOF能在1小時內識別耳念珠菌。為了提高識別的準確度，MALDI-TOF儀器需要更新至相關的版本（如Saramis Ver. 4.14 或同等的版本），而香港港安醫院的MALDI-TOF儀器亦已更新至同樣的版本。自2015年9月開始，香港港安醫院便已運用MALDI-TOF來識別耳念珠菌，比起瑪嘉烈醫院耳念珠菌爆發事件來得要早。若耳念珠菌事件發生在港安醫院，相信在很短的時間內便能被識別，同時醫院能及早通知香港衞生防護中心作進一步的行動。