Analysis of Streptococcus pneumoniae and Haemophilus influenzae isolated from middle ear fluid before and after the introduction of government subsidies for pneumococcal and H. influenzae type b vaccines in Japan.

This study aimed to identify trends in frequency, serotype, and antimicrobial susceptibility of Streptococcus pneumoniae and Haemophilus influenzae isolated from middle ear fluid specimens of children aged≤15 years (mean, 2 years), before and after the introduction of the 7-valent pneumococcal conjugate vaccine (PCV7) and the H. influenzae type b vaccine, at a pediatric facility in Japan. Sixty-six S. pneumoniae and 88 H. influenzae strains were isolated from 820 middle ear fluid samples. Serotyping and antimicrobial susceptibility testing were performed. The study time-frame was divided into period 1 (2007-2010) and period 2 (2011-2014), according to the availability of vaccine public funding. The S. pneumoniae detection rate decreased from 9.6% in period 1-6.1% in period 2 (p = 0.042). PCV7 serotypes decreased from 56.8% to 9.1% (p = 0.0002). No significant change was observed for the 13-valent pneumococcal conjugate vaccine (PCV13) serotypes: 72.7% in period 1 and 59.1% in period 2. Penicillin-resistant strains (penicillin G-MIC ≥2 µg/mL) decreased from 25% to 4.5% (p = 0.038). Detection rates for H. influenzae did not change significantly: 10.3% in period 1 and 11.3% in period 2. Serotypes were mostly non-typeable: 97.9% in period 1 and 90.2% in period 2, and only one serotype b strain was isolated in each period. The frequency of ampicillin-resistant strains (MIC ≥4 µg/mL) did not change. These results show a preventative effect of PCV7 on otitis media due to S. pneumoniae. PCV7 was replaced with PCV13 in 2013 in Japan; therefore, a further decrease in pneumococcal otitis media is anticipated in the future.

[Pediatric Patient with anaerobic Bacterial Meningitis Who was Infected through a Spinal Congenital Dermal Sinus Route].

We report the case of a pediatric patient in whom a spinal congenital dermal sinus was detected after the onset of anaerobic bacterial meningitis. The patient was a 4-month-old boy. He had a recurrent fever for 2 weeks before admission. On admission, he presented with a convulsive status and a bulging anterior fontanel. The previously consulted physician had made a diagnosis of bacterial meningitis. Spinal fluid cultures tested positive for Peptoniphilus asaccharolyticus. Magnetic resonance imaging (MRI) showed a spinal subdural abscess and cranial subdural hydrops; therefore, the patient was transported to our hospital for surgical treatment. A sacral dimple was noted on his lower back, and an MRI showed a spinal congenital dermal sinus. Antimicrobial therapy, cranial subdural aspiration, dermal sinus excision, and drainage were performed. He was discharged on the 60th hospital day. When pathogens such as Staphylococcus aureus or Escherichia coli, Proteus sp. or anaerobic bacteria invade through a dermal sinus, it can result in meningitis. Involvement of a dermal sinus should be suspected when meningitis is caused by these pathogens or when recurrent meningitis occurs.

[Analysis of Non-serotype b Encapsulated Haemophilus influenzae Isolated from Pediatric Patients].

We analyzed non-serotype b encapsulated Haemophilus influenzae (non-b Hi) isolated from pediatric patients at Chiba Children's Hospital during 2000-2012. Among 3,532 clinical isolates of H. influenzae, there were 57 (1.6%) strains of non-b Hi, 152 (4.3%) of serotype b H. influenzae (Hib), and 3,323 (94.1%) of non-typeable H. influenzae (NTHi). Fifty-seven strains of non-b Hi were serotyped useing the slide agglutination test and PCR. Twenty-nine strains were identified as type e (Hie) and 28 as type f (Hif), and the results according to the slide agglutination test and PCR were completely identical. Whereas 52 of 57 strains (91.2%) were isolated from respiratory specimen, only one Hif strain (1.8%) was isolated from a sterile site. There were 47 (82.4%) ß-lactamase-non-producing ampicillin (ABPC)-sensitive strains (BLNAS), 5 (8.8%) ß-lactamase-producing strains (BLP), and only 1 (1.8%) ß-lactamase-non-producing ABPC-resistant strain (BLNAR). Thus the frequency of non-b Hi was lower than that of Hib. The source of non-b Hi was similar to that of NTHi, which was mainly isolated from respiratory specimen. Antimicrobial resistant pattern of non-b Hi was different from that of Hib in which the frequency of BLP was relatively high, and NTHi in which that of BLNAR was high. An increase of invasive H. influenzae infections caused by NTHi, Hie, and Hif was reported in the countries where Hib vaccine had been widely used. Because it is assumed that invasive non-Hib infection will be predominant in the near future in Japan, serotyping of invasive strains is crucial. Continuous monitoring of distribution of non-b Hi in the clinical isolates of H. influenzae is also important.

Analysis of Haemophilus influenzae serotype f isolated from three Japanese children with invasive H. influenzae infection.

In Japan, publicly subsidized Haemophilus influenzae serotype b vaccines became available in 2011; consequently, the incidence of invasive H. influenzae infection in paediatric patients of less than 5 years of age decreased dramatically. In 2013, the first case of H. influenzae serotype f (Hif) meningitis in a Japanese infant was reported, and another case of Hif meningitis in a Japanese infant was observed in 2013. We experienced a fatal paediatric case of Hif bacteraemia in 2004; therefore, we conducted an analysis of the three Hif strains isolated from these three Japanese children with invasive Hif infections. All three strains were ß-lactamase-non-producing, ampicillin-sensitive strains, with MICs of 1 µg ml(-1) or less. However, one of the three strains showed slightly elevated MICs for ampicillin (1 µg ml(-1)), cefotaxime (0.25 µg ml(-1)) and meropenem (0.13 µg ml(-1)). A molecular analysis by multilocus sequence typing identified all three strains as sequence type (ST) 124, which is a predominant invasive Hif strain in many countries. SmaI-digested PFGE showed variable DNA fragmentation patterns among the strains, suggesting that some highly virulent strains have originated from a single ST124 clone and caused invasive Hif infections in Japan. Additional studies are needed to determine the factors that have led to the clonal expansion of virulent ST124 strains.