Multidrug-resistant Streptococcus pneumoniae in Poland: identification of emerging clones

Abstract

Penicillin resistance among Streptococcus pneumoniae isolates has rapidly emerged in Poland during the last decade and has reached prevalence levels of up to 14.4% in 1997. In order to investigate the nature of this increase, a molecular epidemiological analysis of non-penicillin-susceptible multidrug-resistant pneumococci isolated in 1995 and 1996 was conducted. Thirty-seven patients who suffered mainly from upper respiratory tract infections and pneumococcal pneumonia were enrolled in this study. The medical centers to which the patients were admitted were located in 16 Polish towns across the country. Eight distinct BOX PCR types were observed, representing 14 subtypes. Restriction fragment end labeling (RFEL) analysis divided the pneumococcal strains into 16 distinct types. By combining the BOX PCR and RFEL data, four genetically distinct clusters of strains were identified. Two clusters represented the genetic clones 23F and 9V, which have recently emerged all over the world. The two other genetic clusters, which represented serotypes 23F and 6B, clearly predominated in the analyzed collection of Polish non-penicillin-susceptible pneumococcal strains. Since the latter clusters did not match any of the 133 RFEL types of non-penicillin-susceptible pneumococci collected in 15 other countries, their Polish clonal origin is most likely.

FIG. 1

Map of Poland. The medical centers collaborating in this study are as follows: 1, Mother and Child Institute, Warsaw; 2, Health Care Center Praga-Polnoc, Warsaw; 3, Nieklanska Street Hospital, Warsaw; 4, Sienna Street Hospital, Warsaw; 5, Health Care Center, Kolobrzeg; 6, Regional Hospital, Gdansk; 7, Health Care Center, Tczew; 8, Health Care Center, Braniewo; 9, Regional Children’s Hospital Olsztyn; 10, Regional Hospital, Suwalki; 11, Medical University, Bydgoszcz; 12, Health Care Center, Gorzow Wielkopolski; 13, Health Care Center, Czestochowa; 14, Health Care Center, Kedzierzyn Kozle; 15, Jan Bober Center for Microbiology and Autovaccines, Krakow; 16, Health Care Center, Myslenice; 17, Health Care Center, Mielec; 18, Health Care Center, Sanok; and 19, Regional Hospital, Lomza.

FIG. 2

Genetic relatedness of 37 Polish non-penicillin-susceptible pneumococcal strains based on the RFEL banding patterns of the isolates. The RFEL fingerprints, their relatedness (dendrogram), strain numbers, and genetic cluster codes (Roman numerals) are depicted. Cluster codes I to IV refer to clusters of pneumococcal strains displaying RFEL types with homologies higher than 80% that are confirmed to be genetically related by BOX PCR typing (identical BOX PCR types or subtypes).

FIG. 3

DNA fingerprint patterns of the 14 distinct BOX PCR (sub)types represented by the 37 Polish non-penicillin-susceptible pneumococcal strains. Lane numbers indicate BOX PCR type codes. Numbers at the left indicate the sizes of standard DNA fragments in base pairs.

FIG. 4

DNA fingerprint patterns of the pbp1a (n = 5), pbp2b (n = 7), and pbp2x (n = 8) genotypes represented by the 37 Polish non-penicillin-susceptible pneumococcal strains. Lane numbers indicate PBP genotype codes. Numbers at the left indicate the sizes of standard DNA fragments in base pairs.