A new report in NEJM Evidence has highlighted two cases of destructive meningitis that occurred in infants. These cases were due to severe infections with a bacterium called Paenibacillus, which is normally a part of microbial communities that live in soil. Infections with Paenibacillus thiaminolyticus are considered uncommon, although increasing numbers of infections in infants are leading researchers to reconsider that opinion. Experts are now warning clinicians to be on the lookout for this infection in infants.
These infections were first reported in Uganda. In several cases, infants experienced seizures, a buildup of cerebrospinal fluid (CSF), and serious brain injury. Now cases are being reported in multiple states in the US.
In these case reports in NEJM Evidence, scientists noted that one 2-month-old who had been born after a 26-week pregnancy was affected. Blood and CSF samples from this patient suggested that Paenibacillus thiaminolyticus was present, and no other pathogens were detected. Brain imaging showed serious problems that required a brain shunt.
Although a variety of antibiotics were given along with nutrient supplements to eliminate the infection, the patient still showed significant neurological problems, such as the inability to sit unsupported at 8 months of age.
Another infant who was also born premature at 33 weeks got the infection when they were about 37 days old. Blood and CSF samples from this patient also suggested the presence of Paenibacillus thiaminolyticus and no other pathogens. This patient began to experience a disintegration of brain tissue, known as liquefactive meningoencephalitis. Unfortunately, although treatments were attempted, the patient died at 11 months.
After more complex lab testing was performed, clinicians used genetic testing to determine that both patients had actually been infected with Paenibacillus dendritiformis, and not Paenibacillus thiaminolyticus, as initially suspected. This work highlighted that Paenibacillus species can be very challenging to accurately identify with microscopy tools alone.
Further analysis showed that the microbes that were isolated in these two cases carried genes that increased their resistance to antibiotics, and their pathogenicity.
The best antibiotic treatment for P. thiaminolyticus infections is still unclear. These pathogens appear to carry genes that make them resistant to powerful anitbiotics like β-lactam drugs and vancomycin. Some reports have suggested that meropenem, along with thiamine supplementation to prevent the destruction of brain tissue, could be an option. The loss of thiamine in brain tissue seems to worsen infections.
The source of these infections is also unclear. These microbes seem to be able to live in both soil and water, but no reservoir has been found yet. In Uganda, affected infants haver lived in close proximity to large bodies of water or excessive rainfall, but scientists still don’t known if these associations are relevant to the US cases.
Now, researchers are trying to spread awareness among clinicians so that affected infants can be identified and treated as quickly as possible, to try to improve the likelihood of a good outcome.
Sources: Medical Express, NEJM Evidence
