Open Access Research article

Risk factors for nasopharyngeal carriage of drug-resistant Streptococcus pneumoniae: data from a nation-wide surveillance study in Greece

Ioannis Katsarolis1*, Garyphallia Poulakou1, Antonios Analitis2, Irini Matthaiopoulou1, Emmanuel Roilides3, Charalampos Antachopoulos3, Dimitrios A Kafetzis4, Georgios L Daikos5, Regina Vorou1, Christina Koubaniou6, Ioannis Pneumatikos7, Georgios Samonis8, Vasiliki Syriopoulou9, Helen Giamarellou1 and Kyriaki Kanellakopoulou1

Author Affiliations

1 4th Dept of Internal Medicine, Athens Medical School, ATTIKON University General Hospital, Athens Greece

2 Department of Hygiene and Epidemiology, Athens Medical School, Athens Greece

3 3rd Dept of Pediatrics, Aristotle University of Thessaloniki, Hippokration Hospital, Thessaloniki, Greece

4 2nd Dept of Pediatrics, Athens Medical School, P. & A. Kyriakou Children's Hospital, Athens Greece

5 1st Dept of Propaedeutic Medicine, Athens Medical School, Laiko General Hospital, Athens Greece

6 Pneumonology Department, University of Ioannina Medical School, Ioannina Greece

7 Alexandroupolis University Hospital, Democritus University of Thrace Medical School, Alexandroupolis Greece

8 Department of Internal Medicine, University Hospital of Herakleion, Herakleion Crete, Greece

9 1st Department of Pediatrics, Athens Medical School, Aghia Sophia Children's Hospital, Athens Greece

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BMC Infectious Diseases 2009, 9:120  doi:10.1186/1471-2334-9-120

Published: 29 July 2009



A nation-wide surveillance study was conducted in Greece in order to provide a representative depiction of pneumococcal carriage in the pre-vaccination era and to evaluate potential risk factors for carriage of resistant strains in healthy preschool children attending daycare centers.


A study group was organized with the responsibility to collect nasopharyngeal samples from children. Questionnaires provided demographic data, data on antibiotic consumption, family and household data, and medical history data. Pneumococcal isolates were tested for their susceptibility to various antimicrobial agents and resistant strains were serotyped.


Between February and May 2004, from a total population of 2536 healthy children, a yield of 746 pneumococci was isolated (carriage rate 29.41%). Resistance rates differed among geographic regions. Recent antibiotic use in the last month was strongly associated with the isolation of resistant pneumococci to a single or multiple antibiotics. Serotypes 19F, 14, 9V, 23F and 6B formed 70.6% of the total number of resistant strains serotyped.


Recent antibiotic use is a significant risk factor for the colonization of otherwise healthy children's nasopharynx by resistant strains of S pneumoniae. The heptavalent pneumococcal conjugate vaccine could provide coverage for a significant proportion of resistant strains in the Greek community. A combined strategy of vaccination and prudent antibiotic use could provide a means for combating pneumococcal resistance.