Serotype 34 Causes Pneumococcal Meningitis in Child With Cochlear Implants

A 2-year-old boy in Hokkaido, Japan, who had received both the 13-valent (PCV13) and 20-valent (PCV20) pneumococcal conjugate vaccines developed meningitis caused by Streptococcus pneumoniae serotype 34, a nonvaccine serotype, according to a case report published in IDCases.¹

The child had bilateral congenital sensorineural hearing loss and bilateral cochlear implants (CIs). Two months after discharge, he was readmitted with a suspected recurrence, and the right CI was explanted while the left was replaced.¹

Meningitis Despite an Up-to-Date Immunization Record

The boy's history included recurrent otitis media and inner ear malformations: a right common cavity and left cochlear hypoplasia type I. During left cochlear implantation at 11 months of age, a cerebrospinal fluid (CSF) leak was encountered and sealed, which the authors said suggested preexisting communication between the inner ear and subarachnoid space. A small CSF leak was again noted and sealed when he underwent right implantation at 1 year of age, and a right-sided infection later required mastoidectomy.¹

He had received 4 doses of the Haemophilus influenzae type b vaccine, 3 doses of PCV13, and a single dose of PCV20 8 months before admission, with no known immunodeficiency.¹

He arrived with a 2-day history of fever and vomiting. On admission he was febrile and lethargic, with a positive Brudzinski sign but no nuchal rigidity. The CDC lists fever, lethargy, and vomiting among the symptoms that may occur in pneumococcal meningitis.^1,2

Laboratory work showed a white blood cell count of 23,900/μL, C-reactive protein of 33.1 mg/dL, and procalcitonin of 28.4 ng/mL. His CSF contained 4798 cells/μL, and Gram staining showed phagocytosed Gram-positive diplococci. A multiplex PCR assay detected S. pneumoniae, and blood and CSF cultures confirmed it. Serotyping by the Quellung reaction identified serotype 34, and multilocus sequence typing characterized the isolate as ST3116, which the authors described as the predominant lineage among serotype 34 in Japan.¹

Treatment Choices and the Recurrence

The isolate was fully susceptible to penicillin and cefotaxime and was resistant to erythromycin. Clinicians started empiric intravenous meropenem and vancomycin with adjunctive dexamethasone, and the boy defervesced within 2 days. After susceptibility results came back, antibiotics were de-escalated to intravenous ampicillin for a 14-day course.¹

The authors said details of his surgical history were not yet fully available at admission because the implantation had been performed at another facility, and they could not initially rule out congenital immunodeficiency. In retrospect, they wrote, the presentation could have been managed as community-acquired bacterial meningitis, for which a third-generation cephalosporin such as ceftriaxone or cefotaxime plus vancomycin would have been appropriate.¹

A CI-associated infection was suspected during the first admission, but implant removal was deferred to preserve hearing because the infectious focus remained unlocalized.¹

Two months after discharge, the boy returned with fever, vomiting, and systemic inflammation, including a white blood cell count of 15,400/μL and procalcitonin of 10.5 ng/mL. His CSF showed neutrophilic pleocytosis at 5645 cells/μL, but cultures and PCR were negative. Suspecting recurrent CI-associated pneumococcal meningitis, clinicians started dexamethasone, cefotaxime, and vancomycin, and he improved rapidly.¹

Given his history of recurrent right-sided postoperative infections, the right CI was deemed the probable infectious nidus and was explanted. The left CI was replaced because its electrode array extended into the internal auditory canal. All 8 specimens cultured during the CI-related surgery were negative for bacterial growth. He was discharged on postoperative day 3 without neurological sequelae and remains in long-term follow-up.¹

The authors noted that negative cultures do not necessarily exclude an implant-associated infection, because the implants were removed after antimicrobial therapy had begun. They said neither implant-associated infection nor biofilm formation could be confirmed, although both remain possible contributors to the recurrence.¹

Serotype Replacement and Risk Factors

The authors pointed to Japanese surveillance data showing that pediatric invasive pneumococcal disease caused by PCV13 serotypes decreased markedly while the proportion caused by nonvaccine serotypes increased, which they described as ongoing serotype replacement. In a 2023 study of 353 pneumococcal isolates from children in Hokkaido, serotype 34 accounted for 9.1% and was the fifth most prevalent nonPCV13/PCV20 serotype. Serotype 34 has generally not been among the major serotypes causing invasive disease in Japan, the authors wrote, though it has been reported to cause both meningitis and non-meningitis invasive disease.¹

Nationwide Children's Hospital says PCV15 and PCV20 have replaced PCV13 and are given as a series of four shots at ages 2 months, 4 months, 6 months, and 12 to 15 months. The hospital notes that the vaccine helps protect against some of the many types of pneumococcal bacteria.³

Cleveland Clinic lists cochlear implants and CSF leak among risk factors for pneumococcal disease. The case report's authors wrote that children with congenital inner ear malformations are predisposed to bacterial meningitis even without implantation and that CI recipients are a recognized high-risk group. They attributed that risk to CSF leakage, a history of otitis media, and underlying inner ear malformations.^1,4

The CDC identifies acute otitis media as the most common presentation of pneumococcal disease in young children and lists mastoiditis and meningitis among its possible complications. It also says neurologic sequelae, including hearing loss, can occur in as many as 50% of pneumococcal meningitis survivors.²

The authors concluded that managing this population requires prompt antimicrobial therapy, vigilant long-term follow-up, and ongoing surveillance for non-vaccine serotypes. In persistent or recurrent disease, they wrote, the indwelling device should be evaluated as a possible local reservoir, and removal or replacement should be considered when clinically indicated.¹

REFERENCES

1. Maruo Y, Shimomura H, Hirakawa S, et al. Pneumococcal meningitis caused by non-vaccine serotype 34 after vaccination with the 20-valent pneumococcal conjugate vaccine in a child with inner ear malformations and bilateral cochlear implants: A case report. IDCases. 2026;46:e02760. Published 2026 Sep 15. doi:10.1016/j.idcr.2026.e02760

2. Centers for Disease Control and Prevention. Clinical features of pneumococcal disease. Pneumococcal Disease. February 24, 2026. Accessed September 29, 2026. https://www.cdc.gov/pneumococcal/hcp/clinical-signs/index.html

3. Nationwide Children's Hospital. Pneumococcal infection in children. Health Library. Date last reviewed February 1, 2025. Accessed September 29, 2026. https://www.nationwidechildrens.org/conditions/health-library/pneumococcal-infection-in-children

4. Cleveland Clinic. Pneumococcal disease. Health Library. Last updated March 26, 2026. Accessed September 29, 2026. https://my.clevelandclinic.org/health/diseases/24231-pneumococcal-disease