An elderly patient was brought in to hospital having fallen in the garden where he had been for 3 days because he was unable to get himself back on his feet. He was unkempt and had a number of areas of broken skin on his head and neck as well as his arms. These wounds were infested with maggots which looked to have started to digest the healthy skin at the base of the wounds. The patient was very unwell with high blood inflammatory markers, renal failure and sepsis. He was started on IV Piptazobactam for sepsis of unknown origin.
The following day blood cultures were positive for a small Gram-negative bacillus in the aerobic bottle only. Initial thoughts were that the bacterium might be a Pseudomonas spp. but the isolate was identified using MaldiTOF (Matrix-assisted laser desorption ionisation time of flight) as Wohlfahrtiimonas chitiniclastica. Only a select few of the Biomedical Scientists knew what this was and none of the Microbiologists had heard of it before. So what is it and what is the significance in this patient?
What is Wohlfahrtiimonas chitiniclastica?
Wohlfahrtiimonas chitiniclastica is an aerobic Gram-negative bacillus which is part of the normal flora of certain species of flies including Wohlfahrtia magnifica, Lucilia sericata, Chrysomya megacephala and Musca domestica. In the UK Lucilia sericata is the likely host, more commonly known as the green bottle fly.
What is Wohlfahrtiimonas chitiniclastica?
Wohlfahrtiimonas chitiniclastica is an aerobic Gram-negative bacillus which is part of the normal flora of certain species of flies including Wohlfahrtia magnifica, Lucilia sericata, Chrysomya megacephala and Musca domestica. In the UK Lucilia sericata is the likely host, more commonly known as the green bottle fly.
The first part of the name is derived from the species of fly from which it was first isolated but the second part “chitiniclastica” means “chitin-cleaving” which describes its symbiotic role in the larvae of these flies where it helps to break open the larvae to allow the fly to emerge… clever huh?
The larvae of these flies usually cause infestations of wounds of various livestock including sheep, goats and cattle, but occasionally humans also become infested. Initially the larvae digest dead tissue, and in fact the larvae of Lucilia sericata are used medically in larval therapy to debride necrotic tissue from wounds and ulcers (known affectionately as maggot therapy!). Eventually the larvae can go on to eat the underlying healthy tissue as well and this is when problems really start to occur. NB in larval therapy the maggots are removed before this occurs!!
The larvae of these flies usually cause infestations of wounds of various livestock including sheep, goats and cattle, but occasionally humans also become infested. Initially the larvae digest dead tissue, and in fact the larvae of Lucilia sericata are used medically in larval therapy to debride necrotic tissue from wounds and ulcers (known affectionately as maggot therapy!). Eventually the larvae can go on to eat the underlying healthy tissue as well and this is when problems really start to occur. NB in larval therapy the maggots are removed before this occurs!!
People will decorate their cakes in the oddest of ways!
So why the heck had the Microbiologists not heard of this bacterium before?
The first reports of infection with W. chitiniclastica appear around 2008 but it is unlikely that this was the first time this bacterium was ever seen. What is more likely is that methods of bacterial identification underwent a bit of a change around this time. In particular the increased availability of methods such as MaldiTOF and PCR allowed this previously unrecognised bacterium to become known. MaldiTOF has certainly made the job of identifying bacteria easier.
How does infection with Wohlfahrtiimonas chitiniclastica present?
There is no specific type of infection associated with this particular bacterium as only a handful of cases have yet been described in the literature, including wound infections, cellulitis, osteomyelitis and sepsis. However, the cases that have been reported are all associated with some form of myiasis or infestation with fly larvae and subsequent destruction of body tissues.
How is Wohlfahrtiimonas chitiniclastica treated?
There is no specific antibiotic for Wohlfahrtiimonas chitiniclastica. Most of the patients in the literature have been treated with a cephalosporin. The most important part of treatment is to debride any dead or diseased tissue and remove maggots as they appear. The wounds then need to be kept covered with sterile dressings to ensure they do not become infested again.
Our patient underwent wound debridement and the maggots were manually removed as they appeared. It was thought that the bacterium got in to the patient’s blood stream through the infested wounds. The patient required a long period of rehabilitation but eventually he was able to go home. He was given an emergency alarm to wear around his neck in case he fell enabling someone to come to his aid preventing him from such a fate again.
So how did a select few of our Biomedical Scientists know Wohlfahrtiimonas?
When Bruker launched its version of the MaldiTOF they gave out t-shirts to a number of Biomedical Scientists with words on the front saying “What have you isolated today?” and on the back yep you’ve guessed it, it said… “Wohlfahrtiimonas chitiniclastica”. The idea was to have something so unusual that no one would know what it was… and that they’d need a MaldiTOF to identify it. What a great marketing message, however after this Bruker had to change the message… I don’t think they really mind, it was a great identification by their MaldiTOF after all.
So what is the most obscure or unusual bacterium you have isolated?
The first reports of infection with W. chitiniclastica appear around 2008 but it is unlikely that this was the first time this bacterium was ever seen. What is more likely is that methods of bacterial identification underwent a bit of a change around this time. In particular the increased availability of methods such as MaldiTOF and PCR allowed this previously unrecognised bacterium to become known. MaldiTOF has certainly made the job of identifying bacteria easier.
How does infection with Wohlfahrtiimonas chitiniclastica present?
There is no specific type of infection associated with this particular bacterium as only a handful of cases have yet been described in the literature, including wound infections, cellulitis, osteomyelitis and sepsis. However, the cases that have been reported are all associated with some form of myiasis or infestation with fly larvae and subsequent destruction of body tissues.
How is Wohlfahrtiimonas chitiniclastica treated?
There is no specific antibiotic for Wohlfahrtiimonas chitiniclastica. Most of the patients in the literature have been treated with a cephalosporin. The most important part of treatment is to debride any dead or diseased tissue and remove maggots as they appear. The wounds then need to be kept covered with sterile dressings to ensure they do not become infested again.
Our patient underwent wound debridement and the maggots were manually removed as they appeared. It was thought that the bacterium got in to the patient’s blood stream through the infested wounds. The patient required a long period of rehabilitation but eventually he was able to go home. He was given an emergency alarm to wear around his neck in case he fell enabling someone to come to his aid preventing him from such a fate again.
So how did a select few of our Biomedical Scientists know Wohlfahrtiimonas?
When Bruker launched its version of the MaldiTOF they gave out t-shirts to a number of Biomedical Scientists with words on the front saying “What have you isolated today?” and on the back yep you’ve guessed it, it said… “Wohlfahrtiimonas chitiniclastica”. The idea was to have something so unusual that no one would know what it was… and that they’d need a MaldiTOF to identify it. What a great marketing message, however after this Bruker had to change the message… I don’t think they really mind, it was a great identification by their MaldiTOF after all.
So what is the most obscure or unusual bacterium you have isolated?
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