A strain of the bacteria Streptococcus pneumoniae, which causes ear infections in children, has been detected that is resistant to all FDA-approved antibiotics for treatment of ear infections and is not covered by the pneumococcal 7-valent conjugate vaccine, according to a new study from the US.
In the study, doctors examined the shifts in bacteria causing ear infections following the introduction of 7-valent conjugate vaccine in the strains of Streptococcus pneumoniae that cause acute otitis media (AOM), with particular attention to certain pneumococcal serotypes and antibiotic susceptibility.
Among 1,816 children in whom AOM was diagnosed, tympanocentesis was performed in 212, yielding 59 cases of S pneumoniae infection. The researchers found that one strain of S pneumoniae belonging to serotype 19A was a new genotype and was resistant to all antibiotics approved by the FDA for use in children with AOM. This strain was identified in nine cases.
Four children infected with this strain had been unsuccessfully treated with two or more antibiotics, including high-dose amoxicillin or amoxicillin-clavulanate and three injections of ceftriaxone; three had recurrent AOM; and for two others, the infection was the first one in their life.
The first four cases required tympanostomy and grommet insertion after additional unsuccessful antibiotic therapies. Levofloxacin was used in the subsequent five cases, with resolution of infection without surgery.
“While the studied children represent a relatively small subset of all children in our practice with AOM, these observations are clearly worrisome, especially since there are no new antibiotics in phase III clinical trials for AOM in children. The study suggests that an expanded pneumococcal conjugate vaccine to include additional serotypes may be needed sooner than thought, with an outer-membrane protein-based vaccine to follow,” the study’s authors reported.