Use of random amplified polymorphic DNA PCR to examine epidemiology of Stenotrophomonas maltophilia and Achromobacter (Alcaligenes) xylosoxidans from patients with cystic fibrosis

Abstract

Stenotrophomonas maltophilia and Achromobacter (Alcaligenes) xylosoxidans have been increasingly recognized as a cause of respiratory tract colonization in cystic fibrosis (CF). Although both organisms have been associated with progressive deterioration of pulmonary function, demonstration of causality is lacking. To examine the molecular epidemiology of S. maltophilia and A. xylosoxidans in CF, isolates from patients monitored for up to 2 years were fingerprinted using a PCR-based randomly amplified polymorphic DNA (RAPD-PCR) method. Sixty-one of 69 CF centers screened had 183 S. maltophilia culture-positive patients, and 46 centers had 92 A. xylosoxidans-positive patients. At least one isolate from each patient was genotyped, and patients with > or =10 positive cultures (12 S. maltophilia cultures, 15 A. xylosoxidans cultures) had serial isolates genotyped. In addition, centers with multiple culture-positive patients were examined for evidence of shared clones. There were no instances of shared genotypes among different CF centers. Some patients demonstrated isolates with a single genotype throughout the observation period, and others had intervening or sequential genotypes. At the six centers with multiple S. maltophilia culture-positive patients and the seven centers with multiple A. xylosoxidans-positive patients, there were three and five instances of shared genotypes, respectively. The majority of shared isolates were from pairs who were siblings or otherwise epidemiologically linked. These findings suggest RAPD-PCR typing can distinguish unique CF isolates of S. maltophilia and A. xylosoxidans, person-to-person transmission may occur, there are not a small number of clones infecting CF airways, and patients with long-term colonization may either have a persistent organism or may acquire additional organisms over time.

FIG. 1

A. xylosoxidans polymorphisms from five patients (A, B, C, D, and E) from the same CF center. The polymorphisms were generated using RAPD primer 270. Sequential isolates from patient A are listed as A1 through A4.

FIG. 2

Identical A. xylosoxidans polymorphisms from two siblings (A and B). The polymorphisms shown here were generated using RAPD primer 270 and are arranged longitudinally. The genotypes were identical with primer 272. Sequential isolates from patient A are in lanes A1 through A3; those for patient B are in lanes B1 through B6. The DNA from lane A3 did not produce optimal amplification of polymorphisms.

FIG. 3

S. maltophilia polymorphisms from a single patient. The polymorphisms are arranged longitudinally. The pattern seen here is ABAB (lanes 1, 2 through 8, 9 through 12, and 13 through 17, respectively). The DNA from lanes 4 and 12 did not produce optimal amplification of polymorphisms. Molecular size markers were run in lane m.