ABSTRACT Distinctive international clones of penicillin-nonsusceptible and multidrug-resistant Streptococcus pneumoniae are increasingly being reported. We investigated the spread of these clones in Canada through an active surveillance that was carried out at 11 Canadian pediatric tertiary care centers from 1991 to 1998. All penicillin-nonsusceptible isolates were serotyped, tested for antibiotic susceptibility, and genotyped by pulsed-field gel electrophoresis (PFGE) and random amplified polymorphic DNA (RAPD). Forty-five penicillin-nonsusceptible S. pneumoniae isolates were evaluated. Eleven serotype 9V isolates and six serotype 14 isolates displayed identical RAPD and PFGE fingerprint profiles. Twelve (70%) of these isolates were encountered in Quebec. The 9V/14 clone and the Spanish-French clone had similar PFGE fingerprint patterns. Eight isolates of serotype 23F and two isolates of serogroup 14 had the same fingerprint profiles and displayed resistance to three or more antibiotic drug classes. This clone was first detected in Calgary (Alberta) and in 1996 appeared simultaneously in various regions of Canada. This clone showed a PFGE fingerprint pattern similar to that of the Spanish-U.S. 23F clone. Our data show the emergence across Canada of two international clones of penicillin-nonsusceptible S. pneumoniae: (i) serotypes 9V and 14 related to the Spanish-French clone and (ii) the 23F Spanish-U.S. clone. The source of the first clone was in Quebec and the second international clone was probably originated from the United States. The exact reasons for the successful spread of these clones within Canada and their contribution to increased resistance to antibiotics have yet to be explored.

Pseudomonas aeruginosa is the most common respiratory pathogen in patients with cystic fibrosis (CF), but the predominant mechanism by which it is acquired is controversial. To determine the frequency of patient-to-patient spread, we evaluated P. aeruginosa isolates from 174 patients treated at the CF clinics in Vancouver, BC, Canada, since 1981. Multiple isolates were obtained from each patient and genetically typed by random amplified polymorphic DNA and pulsed field gel electrophoresis analyses. A total of 157 genetic types of P. aeruginosa was identified, 123 of which were unique to individual patients. A total of 34 types was shared by more than one patient; epidemiologic evidence linked these individuals only in the cases of 10 sibships and 1 pair of unrelated patients. We conclude that there is an extremely low risk in Vancouver for patients with CF to acquire P. aeruginosa from other patients. It appears that prolonged close contact, such as occurs between siblings, is necessary for patient-to-patient spread. The major source of acquisition of P. aeruginosa in CF appears to be from the environment. Considering these observations, we do not recommend segregation of patients with CF on the basis of their colonization status with P. aeruginosa.

Infection with Burkholderia cepacia complex in patients with cystic fibrosis (CF) results in highly variable clinical outcomes. The purpose of this study was to determine if there are genomovar-specific disparities in transmission and disease severity. B. cepacia complex was recovered from 62 patients with CF on > or =1 occasions (genomovar III, 46 patients; genomovar II [B. multivorans], 19 patients; genomovar IV [B. stabilis], 1 patient; genomovar V [B. vietnamiensis], 1 patient; and an unclassified B. cepacia complex strain, 1 patient). Patient-to-patient spread was observed with B. cepacia genomovar III, but not with B. multivorans. Genomovar III strains replaced B. multivorans in 6 patients. Genomovar III strains were also associated with a poor clinical course and high mortality. Infection control practices should be designed with knowledge about B. cepacia complex genomovar status; patients infected with transmissible genomovar III strains should not be cohorted with patients infected with B. multivorans and other B. cepacia genomovars.

We evaluated 819 isolates referred to us as ''Burkholderia cepacia'' from cystic fibrosis (CF) clinics and research laboratories from five countries; 28 (3.4%) were not B. cepacia. A further 12 (1.5%) organisms appeared to be other Burkholderia species, but identification could not be confirmed by conventional means. The most prevalently misidentified organisms were Stenotrophomonas maltophilia, Alcaligenes xylosoxidans, and Comamonas acidovorans. Many of these organisms grew on oxidation-fermentation polymyxin-bacitracin-lactose (OFPBL) and Pseudomonas cepacia agars, selective media currently used for B. cepacia isolation. We developed a new medium, B. cepacia selective agar (BCSA), which is more enriched for the growth of B. cepacia yet which is more selective against other organisms than currently available selective agars, A total of 190 of 191 (99.5%) isolates of B. cepacia from patients with CF grew on BCSA without vancomycin, whereas 100% grew on OFPBL agar and 179 (94.2%) grew on P. cepacia agar. Of 189 other gram-negative and gram-positive organisms tested, 10 (5.3%) grew on BCSA without vancomycin. The addition of vancomycin to BCSA lowered the false positivity rate to 3.7% without further inhibition of B. cepacia. The false positivity rates for OFPBL and P. cepacia agars were 19.6 and 13.8%, respectively. Isolates of B. cepacia from CF patients grew most quickly on BCSA, with 201 of 205 (98.0%) being readily visible within 24 h, whereas 182 (88.8%) grew on OFPBL agar and 162 (79.0%) grew on P. cepacia agar within 24 h, We propose that the use of BCSA will allow investigators to overcome many of the difficulties associated with the identification of B. cepacia and should be considered for use as a primary isolation agar for specimens from patients with CF.

Pseudomonas aeruginosa isolates recovered from chronically colonized patients with cystic fibrosis (CF) are phenotypically different from those collected from other patients or from the environment. To assess whether alterations in motility, mucoidy, and serum susceptibility represented an adaptation to chronic infection or replacement by a new strain, sequential P. aeruginosa isolates of known phenotype collected from 20 CF patients were typed by random amplified polymorphic DNA (RAPD) analysis. A total of 35 RAPD strain types were found among 385 isolates from 20 patients, and only two patients had P. aeruginosa strains of the same RAPD fingerprint. Eight strain pairs representative of the first eight RAPD types were also analyzed by SpeI macrorestriction followed by pulsed-field gel electrophoresis (PFGE); the strain types found by both fingerprinting techniques correlated exactly. In 11 of 20 patients, the RAPD types of serial P. aeruginosa isolates remained stable despite alterations in isolate motility, colonial morphology, and lipopolysaccharide phenotype. However, in isolates collected from one CF patient, a single band change in RAPD fingerprint and CeuI PFGE profile correlated with the appearance of an RpoN mutant phenotype, suggesting that the altered phenotype may have been due to a stable genomic rearrangement. Secretion of mucoid exopolysaccharide, loss of expression of RpoN-dependent surface factors, and acquisition of a serum-susceptible phenotype in P. aeruginosa appear to evolve during chronic colonization in CF patients from specific adaptation to infection rather than from acquisition of new bacterial strains.

We fingerprinted a collection of 627 Burkholderia cepacia isolates from 255 patients with cystic fibrosis (CF) and 43 patients without CF and from the environment, by a PCR-based randomly amplified polymorphic DNA (RAPD) method with primers selected for their ability to produce discriminatory polymorphisms. The RAPD typing method was found to be reproducible and discriminatory, more sensitive than PCR ribotyping, and able to group epidemiologically related B. cepacia strains previously typed by both pulsed-field gel electrophoresis and conventional ribotyping. Seven strain types infecting multiple CF patients were found at several different CF treatment centers in Canada, the United States, the United Kingdom, France, and Australia, indicating the presence of epidemic strain types. Most CF patients were each colonized with a single strain type, and several patients harbored the same strain type for 5 or more years. B. cepacia isolates recovered from other clinical sources (44 isolates examined) and from the environment (58 isolates examined) possessed RAPD fingerprints that were generally distinct from CF-associated strain types (525 isolates examined). RAPD is a versatile fingerprinting method for studying the epidemiology of B. cepacia.

Although Pseudomonas aeruginosa chronically colonizes most older patients with cystic fibrosis (CF), bacterial features responsible for its persistence are understood poorly. We observed that many P. aeruginosa isolates from chronically colonized patients were nonmotile and resistant to phagocytosis by macrophages. P. aeruginosa isolates were collected from 20 CF patients for up to 10 years. Isolates from early colonization were highly motile and expressed both flagellin and pilin. However, many isolates from chronically colonized patients lacked flagellin expression and were nonmotile; a total of 1,030 P. aeruginosa CF isolates were examined, of which 39% were nonmotile. Moreover, sequential isolates recovered from several of the CF patients were consistently nonmotile for up to 10 years. Lack of motility was rare among environmental isolates (1.4%) and other clinical isolates (3.7%) of P. aeruginosa examined. Partial complementation of motility in nonmotile P. aeruginosa isolates was achieved by introduction of extra copies of the rpoN locus carried on plasmid pPT212, indicating that the alternate sigma factor, RpoN, may be involved in the coordinate regulation of virulence factors during CF infection. We hypothesize that the nonmotile phenotype may provide P. aeruginosa a survival advantage in chronic CF infection by enabling it to resist phagocytosis and conserve energy.

Pseudomonas aeruginosa colonizes the respiratory tract of most older patients with cystic fibrosis. The means by which these bacteria are acquired and the risk for patient-to-patient spread among subjects with cystic fibrosis are poorly understood. We studied the spread of Ps. aeruginosa within a hospital environment. Pseudomonas was rarely recovered from the inanimate environment surrounding patients with cystic fibrosis or from hand or rectal cultures of patients who were colonized in the oropharynx. There was transient cross-colonization with Ps. aeruginosa between patients with cystic fibrosis sharing a hospital room in three of seven pairs studied. In all cases the ‘new’ isolate was recoverable only once and was not found during a 2-year follow-up. Three of four sibling pairs with cystic fibrosis shared the same Ps. aeruginosa serotype(s). The risk of sustained cross-colonization by Ps. aeruginosa between patients with cystic fibrosis appears to be minimal, except under conditions of prolonged close contact.