Explained: Yeast Pathogen Behind Delhi Outbreak Evolving Quickly, Resistant To Disinfectants, Read All About It

A dangerous and rare yeast pathogen that caused two outbreaks among infants in a Delhi hospital is evolvind quickly and is highly resistant to disinfectants, according to a study.

Earlier in 2021-22, 10 children were infected over six months. One of the infected children died. While nine children surviveda after treatment, the pathogen continues to remain highly resistant to disinfectants commonly used in hospitals. 

The study raises concerns over the risk of acquiring infections during stay in hospital, particularly among children and older adults with weakened immune or under-developed immune systems or immunocompromised people. 

Here we explain what's the rare pathogen, what we know of Delhi outbreaks, and what the study found.

What we know of the rare pathogen?

The pathogen behind infections is known as Lodderomyces elongisporus. It is a dangerous and a rare pathogen. 

The Lodderomyces elongisporus typically infects immunocompromised adult patients or intravenous drug users, but has now begun to strike premature infants.

The Lodderomyces elongisporus was first discovered in 1952, according to Cecilia M. Thompson et al in paper The Brief Case: A Case of Prosthetic Valve Endocarditis Due to Lodderomyces elongisporus.

"While it has been recovered from fresh fruit, fruit concentrates, and soft drinks, L. elongisporus has also been recovered from insects. There are a growing number of recent case reports of this organism as a pathogen associated with catheter-related bloodstream infections, and it has been recovered from both blood and catheter tip cultures from febrile patients. Risk factors for L. elongisporus fungemia include intravenous drug use and catheterization," note Cecilia et al in their paper in Journal of Clinical Microbiology.

What we know of Delhi infections?

The Lodderomyces elongisporus —dangerous, rare yeast pathogen— was behind two outbreaks in a neonatal intensive care unit (ICU) in Delhi in 2021-22.

Neonatology refers to the medical sub-speciality that deals with young babies, including premature babies. It is a sub-speciality of pediatrics, the broader specialisation that deals with children as a whole. A neonatal intensive care unit is specially meant for younger babies, including newly borns.

In the Delhi outbreaks, clusters of infection occurred in the fall of 2021 and in early 2022. 

Despite repeated deep cleaning in the intensive care unit, 10 infants were infected over six months, the researchers said. Nine survived after being treated with antifungal medications, they said.

What did the study find?

The findings, published in the journal mBio, show that while infected patients can be treated with antifungal medications, the yeast is remarkably resistant to the strong disinfectant bleach commonly used to sanitise hospital rooms.

The pathogen is evolving quickly and reproducing at a much higher rate than related pathogens such as Candida auris, a drug-resistant fungus that can cause persistent and severe infections and widespread outbreaks.

While an outbreak of this nature is relatively rare, invasive fungal infections in neonatal intensive care units are increasing significantly worldwide, the researchers said.

Fungal sepsis caused by the Candida species and other fungi has become a significant cause of illness and death in already vulnerable preterm, low birth-weight babies, they said.

"The findings are worrisome because the hospital environment seems to be selecting for stress-resistant fungal pathogens. They are adapting and evolving very, very quickly," said Jianping Xu, a professor at McMaster University and a lead author of the study.

Researchers at the University of Delhi’s VP Chest Institute took samples from the infants and swabbed the neonatal ICU. They found the railing and temperature-control panel of the open care warmer were contaminated with L. elongisporus.

Through genome sequencing, the team determined there were two closely related genotype clusters–one which spread from infant to infant and another found on the hospital equipment.

Further testing showed a close relationship between the hospital strains and those found in the wider world on the surface of apples, according to the researchers.

In previous research, the team had found apples treated with fungicide could be spreading drug-resistant pathogens, including L. elongisporus, suggesting fruits as a possible source of transmission.

"This yeast is among a growing list of fungi capable of causing severe infections among humans," said Xu.

"The genetic mechanisms underlying their adaptations to humans, and to hospital and natural environments warrant further investigation and measures to contain their spread and persistence," the scientist said.

If these pathogens can be stopped from entering into hospital environments where many immunocompromised people are, then there is a much higher chance of controlling them, the researchers added.

(With PTI inputs)