The Microbiologist was slowly meandering through the daily authorisation, trying to stay awake and not authorise something important without seeing it first… honestly we do really pay attention but it can be a little dull authorising out more than a hundred urine results a day!
Suddenly something caught their eye. A wound swab was growing Candida auris. The Microbiologist sat up straight in his chair (I am notorious for slouching at the duty desk!) and picked up the phone to find out more.
Suddenly something caught their eye. A wound swab was growing Candida auris. The Microbiologist sat up straight in his chair (I am notorious for slouching at the duty desk!) and picked up the phone to find out more.
The Nurse gave an account of the patient and the details slowly began to unfold….
“The patient had been repatriated to the UK following a stay in hospital in Pakistan after they had fallen and broken their hip. They were now well and awaiting discharge planning. The wound swab had been taken from a small pressure ulcer on the patient’s heel”.
The Nurse added, very pleased with herself, that when the swab was taken the wound was actually clean with no signs of infection (so why take the swab in the first place!?! NB the swab should never have been taken!).
Even though the patient appeared to “only” be colonised with this new organism the Microbiologist knew he would have to let the Infection Control Team know the news... and they weren’t going to be happy…this was still going to need an Infection Control investigation and tracing of "at risk" patients! And all on a Friday afternoon...
But why was the Microbiologist so interested in Candida auris? What makes it special and why all the fuss?
What is Candida auris?
Candida auris is described as an emerging pathogen which can be associated with invasive infections in healthcare settings and resistance to antifungal antibiotics.
C. auris gained notoriety in the UK in 2015 by causing a large outbreak at the Royal Brompton Hospital, London, on the cardiothoracic intensive care unit. Cross infection was identified with asymptomatic carriers and wide-spread surface and equipment contamination. It took stringent infection control procedures including strict barrier precautions of all patients as well as 3 times a day room cleaning to eventually control the outbreak.
Emerging pathogen or emerging technology?
Is C. auris really emerging or is the technology better at identifying it? C. auris was first described in Japan in 2009 after a case of otitis externa (which is not commonly caused by any Candida spp.). In fact it is called “auris” because it was first isolated from an ear! After this, further cases were described in South Korea and India and the fungus eventually spread to many countries in the World. However, most of the countries that have described cases of C. auris are wealthy, have good disease and antimicrobial resistance surveillance systems in place and have the infrastructure to test patients for the causes of their infections.
It has been argued that C. auris isn’t actually new at all but rather the technology for identifying Candida spp. has improved and so we now recognise that C. auris is actually a distinct species of Candida rather than it being misidentified. The current list of misidentifications in systems other than MaldiTOF or molecular testing includes:
It is hard to know if we have seen C. auris in the past masquerading under one of the other names because we aren’t able to go back in time to test all of these isolates. However in my experience I have only seen infrequent cases of Candida guilliermondii, Candida lusitaniae and Candida parapsilosis as blood stream infections, so in my opinion it is likely that C. auris really does represent an emerging pathogen and not just a change in laboratory technology.
Why is C. auris such a concern?
In addition to difficulties in identifying the fungus, infection with C. auris has a number of features that make it particularly concerning:
How is C. auris identified?
It is critical that any isolate from an invasive infection is identified to species level. This includes all isolates from normally sterile sites and especially the blood stream. Ideally identification should be performed using MaldiTOF or PCR but if these are not available then laboratories need to be alert to the fact that C. auris can be misidentified and if any of the possible species listed above are found then these need to be confirmed using one of the more reliable methods in case it is actually C. auris.
In the UK any C. auris isolate should be sent to the Mycology Reference Laboratory in Bristol for confirmation of identification and antifungal sensitivities.
“The patient had been repatriated to the UK following a stay in hospital in Pakistan after they had fallen and broken their hip. They were now well and awaiting discharge planning. The wound swab had been taken from a small pressure ulcer on the patient’s heel”.
The Nurse added, very pleased with herself, that when the swab was taken the wound was actually clean with no signs of infection (so why take the swab in the first place!?! NB the swab should never have been taken!).
Even though the patient appeared to “only” be colonised with this new organism the Microbiologist knew he would have to let the Infection Control Team know the news... and they weren’t going to be happy…this was still going to need an Infection Control investigation and tracing of "at risk" patients! And all on a Friday afternoon...
But why was the Microbiologist so interested in Candida auris? What makes it special and why all the fuss?
What is Candida auris?
Candida auris is described as an emerging pathogen which can be associated with invasive infections in healthcare settings and resistance to antifungal antibiotics.
C. auris gained notoriety in the UK in 2015 by causing a large outbreak at the Royal Brompton Hospital, London, on the cardiothoracic intensive care unit. Cross infection was identified with asymptomatic carriers and wide-spread surface and equipment contamination. It took stringent infection control procedures including strict barrier precautions of all patients as well as 3 times a day room cleaning to eventually control the outbreak.
Emerging pathogen or emerging technology?
Is C. auris really emerging or is the technology better at identifying it? C. auris was first described in Japan in 2009 after a case of otitis externa (which is not commonly caused by any Candida spp.). In fact it is called “auris” because it was first isolated from an ear! After this, further cases were described in South Korea and India and the fungus eventually spread to many countries in the World. However, most of the countries that have described cases of C. auris are wealthy, have good disease and antimicrobial resistance surveillance systems in place and have the infrastructure to test patients for the causes of their infections.
It has been argued that C. auris isn’t actually new at all but rather the technology for identifying Candida spp. has improved and so we now recognise that C. auris is actually a distinct species of Candida rather than it being misidentified. The current list of misidentifications in systems other than MaldiTOF or molecular testing includes:
- Candida haemulonii (most common misidentification)
- Candida duobushaemulonii
- Rhodotorula glutinis
- Candida sake
- Candida catenulata
- Candida famata
- Candida guilliermondii
- Candida lusitaniae
- Candida parapsilosis
It is hard to know if we have seen C. auris in the past masquerading under one of the other names because we aren’t able to go back in time to test all of these isolates. However in my experience I have only seen infrequent cases of Candida guilliermondii, Candida lusitaniae and Candida parapsilosis as blood stream infections, so in my opinion it is likely that C. auris really does represent an emerging pathogen and not just a change in laboratory technology.
Why is C. auris such a concern?
In addition to difficulties in identifying the fungus, infection with C. auris has a number of features that make it particularly concerning:
- C. auris can cause invasive blood stream infections with a high mortality in excess of 50%
- C. auris is often resistant to antifungals
- C. auris spreads easily in healthcare facilities
How is C. auris identified?
It is critical that any isolate from an invasive infection is identified to species level. This includes all isolates from normally sterile sites and especially the blood stream. Ideally identification should be performed using MaldiTOF or PCR but if these are not available then laboratories need to be alert to the fact that C. auris can be misidentified and if any of the possible species listed above are found then these need to be confirmed using one of the more reliable methods in case it is actually C. auris.
In the UK any C. auris isolate should be sent to the Mycology Reference Laboratory in Bristol for confirmation of identification and antifungal sensitivities.
How is C. auris treated?
C. auris is usually resistant to Fluconazole (90%) and some are also resistant to Amphotericin B (40%) and the echinocandins (5%) such as Caspofungin. About 40% of C. auris are resistant to at least 2 classes of antifungal. This means that C. auris can be resistant to all of the commonly used antifungals available in the NHS and treatment can be a nightmare!
The current first line therapy for C. auris is an echinocandin such as Caspofungin as 95% of isolates remain sensitive. If the patient does not respond then other treatment options include adding in Amphotericin B, as this improves the activity of both drugs together, or to consider using Isavuconazole, a new azole antifungal with better activity than Fluconazole. In fact Isavuconazole resistance has so far only been described in 1-2% of C. auris isolates making this an attractive choice.
Infection control
If a case of C. auris is identified then it is imperative that action is taken to try and prevent further spread of the fungus.
C. auris is usually resistant to Fluconazole (90%) and some are also resistant to Amphotericin B (40%) and the echinocandins (5%) such as Caspofungin. About 40% of C. auris are resistant to at least 2 classes of antifungal. This means that C. auris can be resistant to all of the commonly used antifungals available in the NHS and treatment can be a nightmare!
The current first line therapy for C. auris is an echinocandin such as Caspofungin as 95% of isolates remain sensitive. If the patient does not respond then other treatment options include adding in Amphotericin B, as this improves the activity of both drugs together, or to consider using Isavuconazole, a new azole antifungal with better activity than Fluconazole. In fact Isavuconazole resistance has so far only been described in 1-2% of C. auris isolates making this an attractive choice.
Infection control
If a case of C. auris is identified then it is imperative that action is taken to try and prevent further spread of the fungus.
Careful antibiotic prescribing |
Avoid the use of Fluconazole as this is likely to select out more C. auris in the patients “normal” flora |
Hand Hygiene |
With soap and water or alcohol hand gel |
PPE |
Personal protective equipment is used to prevent members of staff acquiring infections as well as preventing their clothing from becoming contaminated with infectious microorganisms. PPE including gloves and plastic aprons should be worn when there is a risk of exposure to blood or other body fluids Remove ALL PPE before leaving room |
Isolation |
Side room preferably with own toilet facility |
Environmental decontamination |
Deep cleaning of the clinical area daily and after patient is discharged using chlorine based products |
Patient care |
If patients require investigations in other departments, inform those departments of patient’s condition in advance Patient should be last on a list and deep cleaning commence after patient’s departure |
Microbiology laboratory |
Enhanced awareness of the need to isolate Candida species and need for additional resources if extensive contact tracing is required |
Whilst it is strictly speaking not notifiable in the UK it would be wise to alert Public Health England (PHE) to patients with C. auris in case there are further patients that the identifying hospital is not aware of but which PHE might have been told about.
If a patient is identified as being colonised (as was the case with the patient in this scenario) or infected with C. auris then further cases of infection or colonisation should be sought. A contact is anyone who has a link to the patient in time, place or person i.e. been in the same hospital bay or side-room, at the same time or just after the index patient, or cared for by the same healthcare staff.
Three screening samples should be taken, on consecutive days, from any patient identified as a contact. Normal “bacteriology” wound swabs can be used (black charcoal swabs) and can be plated onto commercially available Candida selective agar in the laboratory e.g. CHROMagar Candida. Patients should only be considered clear if ALL three samples are negative. If a patient tests positive then their contacts should also be traced. Sites to screen include:
So fortunately for us our patient never developed an infection with his C. auris and no further cases of C. auris where identified through contact tracing. Personally I was just a teeny weeny bit disappointed; I was really looking forward to using Isavuconazole for the first time… oh well, better all-round really…!
If a patient is identified as being colonised (as was the case with the patient in this scenario) or infected with C. auris then further cases of infection or colonisation should be sought. A contact is anyone who has a link to the patient in time, place or person i.e. been in the same hospital bay or side-room, at the same time or just after the index patient, or cared for by the same healthcare staff.
Three screening samples should be taken, on consecutive days, from any patient identified as a contact. Normal “bacteriology” wound swabs can be used (black charcoal swabs) and can be plated onto commercially available Candida selective agar in the laboratory e.g. CHROMagar Candida. Patients should only be considered clear if ALL three samples are negative. If a patient tests positive then their contacts should also be traced. Sites to screen include:
- Nose, throat and groin
- Urine if catheter present
- Sputum or endotracheal secretions if oral thrush present or mechanically ventilated
- Surgical drains if present
- Intravenous access devices e.g. cannulas, central venous catheters, if present
- Wounds or ulcers
So fortunately for us our patient never developed an infection with his C. auris and no further cases of C. auris where identified through contact tracing. Personally I was just a teeny weeny bit disappointed; I was really looking forward to using Isavuconazole for the first time… oh well, better all-round really…!
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