Serotyping and antibiotic resistance of Streptococcus pneumoniae isolated from pediatric infections in central Greece

Global serotype distribution among Streptococcus pneumoniae isolates causing otitis media in children: potential implications for pneumococcal conjugate vaccines

Acute otitis media (AOM) is the most common infection following pneumococcal colonization of the upper respiratory tract. Streptococcus pneumoniae causes 30-60% of AOM cases worldwide. However, not all pneumococcal serotypes cause disease and an association exists with nasopharyngeal colonization by certain serotypes and their propensity to cause AOM. This review examines the global serotype distribution relationship between pneumococcal serotypes and AOM in children aged <18 years and demonstrates that the most common pneumococcal serotypes causing AOM globally are 3, 6A, 6B, 9V, 14, 19A, 19F, and 23F.

Serotype distribution of Streptococcus pneumoniae in north-western Greece and implications for a vaccination programme

Serotypes and antibiotic sensitivities were determined for 338 strains of Streptococcus pneumoniae from children of north-western Greece with invasive pneumococcal disease (IPD), acute otitis media (AOM) and nasopharyngeal carriage. The most common serotypes among the isolates from IPD were 14 and 19F, while 3, 19F, 9V and 14 were the major cause of AOM. In these groups, the heptavalent conjugate vaccine for pneumococci (7vPCV) seems to cover 90.5% of the serotypes isolated from children less than 2 years old. Serotypes 23F and 6B were the most prevalent in carrier strains. Overall, 23.7% of the isolates were penicillin nonsusceptible (PNS), 97% were fully susceptible to cefotaxime, 29% were resistant to erythromycin, 11.2% to co-trimoxazole and 1.2% to clindamycin.

Characteristics of Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis and Staphylococcus aureus isolated from the nasopharynx of healthy children attending day-care centres in the Czech Republic

Nasopharyngeal carriage of potential pathogens was studied in 425 healthy 3- to 6-year-old children attending 16 day-care centres (DCCs) in nine Czech cities during the winter 2004-2005. The overall carriage of pathogens was 62.8% (Streptococcus pneumoniae, 38.1%; Haemophilus influenzae, 24.9%; Moraxella catarrhalis, 22.1%; Staphylococcus aureus, 16%). An age-related downward trend was observed for colonization with respiratory pathogens in contrast to Staph. aureus whose carriage was significantly higher among older children. The following serotypes of colonizing S. pneumoniae were the most predominant: 23F (20.6%), 6A (15.1%), 6B (12.7%), 18C (7.8%), 15B and 19F (6% each). The majority (94.3%) of H. influenzae isolates were non-typable; among capsulated isolates, serotype b was not found. Decreased susceptibility to penicillin was determined in 3% of pneumococci; 4.6% of H. influenzae strains and 85.1% of M. catarrhalis strains produced beta-lactamase. As for non-beta-lactam antibiotics, pneumococci resistant to trimethoprim-sulphamethoxazole were the most common (15.7%) among the attendees.

Serotypes and antimicrobial susceptibilities of 1033 pneumococci isolated from children in Greece during 2001–2004

Pneumococci (n = 1033) isolated in the major paediatric hospitals of Athens during 2001-2004 from children with invasive infections (n = 186), non-invasive infections (n = 641) and healthy carriers (n = 206) were studied. The most prevalent serotypes were serotypes 14 (44.6%), 19F (43.5%) and 6B (22.8%) in invasive, non-invasive and carriage isolates, respectively. Among invasive isolates, the potential coverage by the seven-valent conjugate vaccine was 75.3%. Resistance rates to penicillin, amoxycillin, cefotaxime, erythromycin, co-trimoxazole, clindamycin, tetracycline and chloramphenicol were 44.6%, 2.7%, 1.2%, 43.6%, 43.5%, 12.4%, 34.7% and 5.9%, respectively. The M-phenotype accounted for 68.0% of the erythromycin-resistant isolates. All isolates were susceptible to ofloxacin.

Genetic relatedness of resistant and multiresistant Streptococcus pneumoniae strains, recovered in the Athens area, to international clones

The prevalence of resistance to antibiotics was examined among 318 Streptococcus pneumoniae strains isolated during 1998 and 1999 in a children's hospital in Athens. The rate of resistance to penicillin was 25.8% (intermediate 22%, resistant 3.8%); 42.5% of the strains were resistant to > or = 1 antibiotic and 20% were multidrug resistant. Resistance to penicillin was lowest in invasive strains (8.3%) and highest in ear isolates (31%). A review of the same microbiology laboratory's records revealed that there has been a gradual increase in penicillin resistance since 1988-1989, when it was 5%. Capsular types were determined for 77 strains resistant to > or = 1 antibiotic, and 69 (90%) of them belonged to the following five serotypes: 19F, 14, 9V, 23F, and 6B. Seventy-five strains were analyzed by pulsed-field gel electrophoresis (PFGE) and 59/75 (79%) shared five electrophoretic types. The largest cluster consisted of 19 serotype 19F strains, of which 18 were nonsusceptible to penicillin and most were multidrug resistant and shared a common and distinct electrophoretic pattern not resembling any known clone. A group of 17 strains that were nonsusceptible to penicillin belonged to serotypes 9V (10), 14 (6), and 19F (1) and shared a common PFGE type similar to the international clone Spain9V-3. Seven serotype 23F strains, of which five were multidrug resistant, belonged to the international clone Spain23F-1. Among the strains susceptible to penicillin but resistant to non-beta-lactam antibiotics, the largest cluster consisted of 13 isolates resistant to erythromycin that belonged to serotype 14 and shared an electrophoretic pattern characteristic of the clone England14-9. Finally, three serotype 6B strains were penicillin susceptible and multidrug resistant and had features similar to the Mediterranean 6B clone. The introduction and spread of several antibiotic-resistant international clones accounts at least in part for the increase in pneumococcal resistance observed in recent years in the Athens metropolitan area.

Epidemiology of invasive childhood pneumococcal infections in Greece

A retrospective study was conducted to identify the epidemiologic characteristics of invasive pneumococcal infections among children <14 y of age in our geographic region. During a 5-y period, from 1995 to 1999, 590 cases of invasive pneumococcal infection were identified in Aghia Sophia Children's Hospital, Athens, Greece. The male to female ratio was 1.4:1 and 64% of patients were younger than 5 y of age. The overall annual incidence rate was estimated as 44/100,000 children <14y of age, whereas the incidence rate for children <5y of age was 100/100,000. The most common types of infections were pneumonia (472 cases; 133 definite and 339 probable), bacteraemia without focus (79 cases), and meningitis (33 cases). A seasonal variation of invasive pneumococcal infections was noted, with two peaks--one during spring and the other during autumn. Only two cases with meningitis died and one developed permanent neurological sequelae, representing a case-fatality rate for meningitis of 6%. Serogroups 14, 19, 6, 18, 23, 4 and 9 were the most prevalent, comprising 77% of 92 serotyped isolates.

CONCLUSION

Invasive pneumococcal infections cause considerable morbidity in the paediatric population in the Athens metropolitan area. Sixty-six percent of the serotypes causing invasive pneumococcal disease in our region are included in the 7-valent conjugate vaccine.

Prevalence and patterns of resistance of Streptococcus pneumoniae strains isolated from carriers attending day care centers in the area of Athens

The prevalence and patterns of Streptococcus pneumoniae resistance to antibiotics was examined in 146 nasopharyngeal carrier strains obtained during April and May, 1997, from 382 healthy children attending eight day care centers (DCCs) in the area of Athens. Reduced susceptibility to at least one antibiotic was found in 32.6% as follows: penicillin 11.4% (intermediate), cefotaxime 0.8% (intermediate), trimethoprim-sulfamethoxazole 22.7%, erythromycin 13.6%, tetracycline 11.4%, chloramphenicol 8.3%. Most of the nonsusceptible to penicillin isolates belonged to serogroups 23, 9, and 19. Multidrug resistance was detected in 11.4% of S. pneumoniae isolates including five penicillin nonsusceptible serogroup 23 strains. More than half of the multidrug resistant strains were susceptible to penicillin and belonged to serogroups 6 (4), 23 (1), 19 (1), and 1(1). Strains that belonged to the same serogroup/serotype and had identical resistance patterns appeared to cluster in some DCCs. Antibiotic use in the previous month was associated with reduced susceptibility to penicillin (p = 0.007) and multidrug resistance (p = 0.012). In conclusion, a moderate prevalence of reduced susceptibility to penicillin in pneumococcal carrier strains was found in our community. Multidrug resistance was common and was often associated with susceptibility to penicillin. Several distinct patterns of resistance were observed, suggesting the spread of resistant clones to our country.

Pneumococcal acute otitis media in children

OBJECTIVES

To evaluate the clinical and laboratory findings of Streptococcus pneumoniae acute otitis media in children during a 1 year period.

METHODS

From October 1995 to September 1996, 113 children aged 2 months to 14 years (median 18 months), with S. pneumoniae acute otitis media were studied. Susceptibility testing was performed by the Kirby-Bauer method and the E-test, and serotyping by the Quellung reaction.

RESULTS

E-test assays detected five isolates (4.4%) to be highly resistant to penicillin and 13 (11.5%) that had intermediate resistance. All isolates were found to be susceptible to vancomycin, rifampicin and cefotaxime. In total, 25 isolates (22.1%) were resistant to one or more drugs. Fifty per cent of the penicillin-resistant or intermediately resistant S. pneumoniae isolates were resistant to multiple drugs, whereas only 2.1% of the penicillin-susceptible isolates were resistant to multiple drugs. The predominating serogroups of the isolates with reduced susceptibility to penicillin were the 19 (61.1%), 9 (16.7%), 23 (11.1%), 6 (5.5%) and 14 (5.5%) whereas those of the susceptible isolates were the 19 (26.3%), 14 (13.7%), 3 (11.6%), 6 (11.6%), 9 (8.4%), 1 (5.3%) and 12 (5.3%).

CONCLUSIONS

Streptococcus pneumoniae isolates from children with acute otitis media were penicillin-insensitive in 15.9%. The multiresistant S. pneumoniae isolates belonged to serogroups: 19 (45.4%), 9 (27.3%), 6 (18.2%) and 23 (9.1%).