Clonality behind the increase of multidrug-resistance among non-invasive pneumococci in Southern Finland.

Multidrug-resistance among Streptococcus pneumoniae isolates, especially of serotype 19A, has increased in several countries recently. Even before the introduction of the pneumococcal conjugate vaccine into the Finnish National Vaccination Programme, the proportion of multidrug-resistant (MDR) pneumococci had doubled from 2007 to 2008, when it reached 3.6% in Southern Finland. Our aim was to look for a possible association between antimicrobial susceptibility and clonality among the MDR isolates. Twelve non-invasive isolates non-susceptible to penicillin, erythromycin, clindamycin, trimethoprim/sulfamethoxazole, and doxycycline from 2008 were available for serotyping, genotyping by multilocus sequence typing (MLST), and detection of genes encoding macrolide resistance and adherence-promoting pili. Two isolates were also resistant to ceftriaxone. Five serotypes, 19F, 19A, 6B, 23F, and 14, and six genotypes from three genetic lineages were found, among which CC320 was the largest. All isolates in this study carried the erm(B) macrolide resistance gene, and the CC320 isolates additionally carried the mef(A/E) macrolide resistance gene. Eleven isolates carried pilus islet 1, while the CC320 isolates also carried the pilus islet 2 genes. The findings emphasize the importance of the careful monitoring of antimicrobial susceptibility and serotype distribution among pneumococci, especially now that antimicrobials and pneumococcal vaccines are in widespread use.

Prevalence of pilus-encoding islets and clonality of pneumococcal isolates from children with acute otitis media.

We characterized the prevalence of pilus islets 1 (PI-1) and 2 (PI-2) and the clonality of Streptococcus pneumoniae isolates taken from children with acute otitis media (AOM) to study the association between pilus existence and AOM disease potential prior to pneumococcal conjugate vaccine and increased antimicrobial resistance. The study material consisted of 75 pneumococcal isolates cultured from the middle ear fluid and/or nasopharyngeal aspirate of 56 children with AOM in Finland during the period 1990-1992. Isolates were studied for antimicrobial susceptibility and were serotyped, genotyped by multilocus sequence typing (MLST), and tested for the presence of pneumococcal PI-1 and PI-2 genes. All isolates were susceptible to penicillin, 14 different serotypes were found, and 20% of the isolates were positive for PI-1 genes. PI-2 genes were not found. MLST showed high heterogeneity: 52 AOM isolates belonged to 18 known clonal complexes (CC). PI-1 was associated with serotypes 6A, 6B, and 9V, and genotype CC490. In the time prior to 7-valent pneumococcal conjugate vaccine (PCV7) and increased antimicrobial resistance, pneumococcal AOM isolates carried PI-1 genes at a rather low prevalence. PI-2 genes were not detected. PI-1 was related to serotype rather than genotype. The importance of PI-1 in AOM infections and its association with the spread of antimicrobial resistance requires further research.

A report of Streptococcus pneumoniae serotype 6D in Europe.

Serotype 6D of Streptococcus pneumoniae has been reported in Asia and the Fijian islands among nasopharyngeal carriage isolates. We now report a 6D isolate from a Finnish adult with invasive pneumococcal disease. Interestingly, the Finnish isolate and Asian isolate capsule gene loci are almost identical.

Invasive infections caused by Neisseria meningitidis, Haemophilus influenzae and Streptococcus pneumoniae among children in St Petersburg, Russia.

This study investigated the causes of invasive bacterial infections in children aged <15 years in St Petersburg, Russia, during 2001-2003, using culture and antigen detection methods (rapid antigen latex agglutination (RAL)) for normally sterile body fluids. A pathogen was detected in 90 cases (culture 50, RAL 40). Neisseria meningitidis was the most common pathogen (66%), followed by Haemophilus influenzae (19%) and Streptococcus pneumoniae (16%). Meningitis was the main clinical diagnosis (68/90, 76%), with N. meningitidis serogroup B, H. influenzae type b (Hib), and S. pneumoniae serogroup 1 being the most common isolates. Hib was less prevalent in St Petersburg than it was in industrialised countries before the introduction of Hib vaccinations.

A successful, diverse disease-associated lineage of nontypeable pneumococci that has lost the capsular biosynthesis locus.

Streptococcus pneumoniae strains which fail to produce a polysaccharide capsule are commonly isolated from carriage and disease contexts. Here we use a multilocus approach to distinguish genuine nontypeable pneumococci from closely related nontypeable streptococcal isolates in a data set of 121 untypeable pneumococci from nasopharyngeal swabs and middle ear fluid of Finnish children and demonstrate that 70 of these belong to a pneumococcal lineage which has lost its capsular locus. Strains of this relatively old lineage include sequence types 344, 448, and 449. Comparison with the multilocus sequence typing database shows that strains of this lineage have spread intercontinentally and have been isolated from carriage, mucosal, and invasive disease. Furthermore we note a particular association of this nontypeable lineage with outbreaks of conjunctivitis. The diversification and geographic spread of this lineage suggest that loss of capsule is not inconsistent with long-term persistence and raise questions about the capsule's role in pneumococcal transmission.

Capsular polysaccharide types of Streptococcus pneumoniae isolated from maxillary sinus effusion.

Pneumococcal capsular polysaccharide vaccines may be a novel way of treating patients with recurrent sinusitis. To evaluate the pneumococcal capsular polysaccharide types of strains causing sinusitis, 55 pneumococcal strains isolated from maxillary sinus effusion were analyzed. The most frequently occurring types were 3 (13%), 19F (11%), 6B (9%) and 23F (9%).

Bacteriology of acute otitis media in a cohort of Finnish children followed for the first two years of life.

BACKGROUND: Timely information on the bacteriology of primary, noncomplicated acute otitis media (AOM) may today be needed more than ever, because of the increasing antimicrobial resistance of its major bacterial causes and because of the potential of new pneumococcal and other bacterial vaccines for prevention of AOM. METHODS: The study followed 329 children from 2 to 24 months of age at scheduled healthy visits and sick visits at the study clinic. Whenever AOM was diagnosed during the follow-up, myringotomy was performed and middle ear fluid was aspirated for bacterial culture. RESULTS: At least one middle ear fluid sample was available from 772 AOM events; Streptococcus pneumoniae (Pnc) was isolated in 201 (26%), Moraxella catarrhalis (Mc) in 177 (23%) and Haemophilus influenzae (Hi) in 174 events (23%). The incidence of Pnc AOM peaked at 12 months of age, whereas the incidence of Mc AOM showed the first peak at 6 months and Hi AOM at 20 months. Pnc AOM showed less prominent seasonality in occurrence than Mc and Hi AOM. Hi was a rare cause of the first 2 AOM episodes (13%) but became increasingly common from the third episode on (32% on average). CONCLUSIONS: Pnc, Mc and Hi were almost equally common findings in AOM. Pnc seems to be the most pathogenic of these three, the role of Mc is increasing and Hi is clearly associated with recurrent AOM.

Nasopharyngeal carriage of Streptococcus pneumoniae in Finnish children younger than 2 years old.

To describe the natural course of nasopharyngeal carriage of Streptococcus pneumoniae and its relationship to acute otitis media (AOM), 329 Finnish children were followed from ages 2 to 24 months. In total, 3024 nasopharyngeal (NP) swabs (obtained at 10 scheduled healthy visits) and 2007 NP aspirates (obtained during respiratory infections) were cultured. Carriage during health increased gradually (9%-43%) with age. Within 4 age intervals, carriage was lower during health (13%-43%) than during respiratory infection without AOM (22%-45%). Higher proportions of positive samples were found during AOM (45%-56%), in particular during pneumococcal AOM (97%-100%). Antimicrobial treatment reduced carriage only temporarily. The most frequent NP serotypes were 6B, 6A, 11, 19F, and 23F. Both age and health status were important determinants of NP carriage of S. pneumoniae and these features should be considered carefully during analysis of carriage rates.

Bacterial etiology of acute myringitis in children less than two years of age.

BACKGROUND: Acute myringitis is an inflammation of the tympanic membrane that occurs alone or in association with external otitis or otitis media. The two clinical entities, based on physical examination, are bullous myringitis and hemorrhagic myringitis. OBJECTIVES: To investigate the association of concomitant middle ear disease with acute myringitis and to analyze the bacteriologic findings of the middle ear fluid in children with acute myringitis. METHODS: A prospective longitudinal cohort study of 2028 children age 7 to 24 months at primary care level in the Finnish Otitis Media Vaccine Trial. Matched case-control design for analysis of bacterial pathogen distribution. RESULTS: There were 82 children in whom 92 ears were diagnosed with acute bullous myringitis and 37 children in whom 40 ears were diagnosed with hemorrhagic myringitis during the follow-up. Middle ear disease was associated with bullous myringitis in 97% of ears and with hemorrhagic myringitis in 82% of ears. Bacterial pathogen distribution was similar to that of acute otitis media, although a higher proportion of Streptococcus pneumoniae was detected in both bullous and hemorrhagic acute myringitis. CONCLUSIONS: Middle ear fluid was present in vast majority of ears with acute myringitis in young children. The same etiologic bacteria were found in acute myringitis as in acute otitis media, but S. pneumoniae was the major pathogen. Acute bullous myringitis should be treated as acute otitis media in children <2 years of age.

Comparison of nasal swab culture, quantitative culture of nasal mucosal tissue and PCR in detecting Streptococcus pneumoniae carriage in rats.

It is not known how well nasopharyngeal swab culture represents pneumococcal carriage status. We tested this by comparing swab culture to quantitative culture and quantitative PCR of mucosal tissue in a rat model of pneumococcal carriage. Quantitative culture and quantitative PCR identified significantly more carriers compared to swab culture (differences 15% and 33%, 95% CI 1-28% and 16-47%, p=0.04 and 0.001, respectively). The sensitivity and specificity of swab culture was 75/92% and 63/100% compared to quantitative tissue culture and quantitative PCR, respectively. The quantitative estimates of culture and PCR were very similar (Pearson correlation coefficient 0.79, p<0.001). In conclusion, even a well-controlled swab sampling markedly underestimates pneumococcal carriage rate, and simultaneous use of quantitative culture and PCR increases the number of positive samples by about one third.