Bacterium and Viral Coinfection Contributes to Postinfectious Hydrocephalus

Neonatal sepsis often precedes postinfectious hydrocephalus (PIH), although the manifestations of hydrocephalus typically emerge in the months after the neonatal period as sufficient cerebrospinal fluid (CSF) accumulates such that cranial expansion garners medical attention.

Postinfectious hydrocephalus (PIH), is the most common cause of pediatric hydrocephalus worldwide, yet the microbial pathogens underlying this disease remain to be elucidated. Of the estimated 400,000 new cases each year, about half are estimated to be postinfectious, with the largest number of cases in low- and middle-income countries, especially sub-Saharan Africa.

A team of international scientists collaborating with the Columbia University's Mailman School of Public Health (New York, NY, USA) analyzed samples from 100 patients, 64 with post-infectious hydrocephalus (PIH) and 36 with non-post-infectious hydrocephalus (NPIH), all of whom were less than three months old who were seen at the CURE Children's Hospital of Uganda (Mbale, Uganda)

Blood was sampled with aseptic technique at the time of surgery, either at the time of catheter placement for an intravenous line or during venipuncture for routine laboratory testing. Cerebrospinal fluid (CSF) was obtained at the time of initial surgery. The team used both Sanger-based sequencing of bacterial 16S ribosomal DNA V1-V4 regions and next-generation sequencing of the V1-V2 and V4 regions. A broad screen for viral presence was performed in two different ways: VirCapSeq oligomer concentration and total RNA sequencing analysis. For the viruses that appeared abundant in either PIH or NPIH, polymerase chain reaction (PCR) confirmation was performed.

Using a targeted viral detection capture approach called VirCapSeqVERT, the investigators uncovered 11 viral strains across slightly more than a third of CSF samples. Cytomegalovirus was found among a portion of post-infectious hydrocephalus patients' CSF samples, but not among non-post-infectious hydrocephalus patients. Cytomegalovirus is a common virus that typically causes minor symptoms in adults but may lead to neurological damage in infants who acquire it early in life. The team grew three Paenibacillus isolates in culture and used whole-genome sequencing analysis to identify them as P. thiaminolyticus. V1-V4 Sanger sequencing of subcloned amplicons identified Paenibacillus as a predominant organism within the PIH cohort (23 of 64), but not within the NPIH cohort (0 of 36). A hybrid method was used to reconstruct the genome of a P. thiaminolyticus isolate, combining short-read sequencing, optical mapping (Bionano Genomics, San Diego, CA, USA), and nanopore long contiguous sequencing (MinION, Oxford Nanopore Technologies, Oxford, UK).

The authors concluded that their findings showed that an unbiased pan-microbial approach enabled characterization of Paenibacillus in CSF samples from PIH cases, and point toward a pathway of more optimal treatment and prevention for PIH and other proximate neonatal infections.

Edith Mbabazi-Kabachelor, MD, MPH, director of research at CURE Children's Hospital of Uganda and a co-author of the study, said, “Hydrocephalus is the most common childhood neurosurgical condition that we see in the population that we serve. If hydrocephalus is left untreated in children less than two years old, the progressive increase in head size will lead to further brain damage, resulting in the majority of these children dying, and those that survive being left with severe cognitive and physical disability.” The study was published on September 30, 2020 in the journal Science Translational Medicine.

Related Links:
Columbia University's Mailman School of Public Health
CURE Children's Hospital of Uganda
Bionano Genomics
Oxford Nanopore Technologies