A total of 120 Burkholderia cepacia complex isolates collected during 2004 -2010 from 66 patients in two cystic fibrosis reference centers in Argentina were analyzed. Burkholderia contaminans was the species most frequently recovered (57.6%), followed by Burkholderia cenocepacia (15%), a species distribution not reported so far. The recA-PCR-based techniques applied to the B. contaminans isolates revealed that 85% of the population carried the recA-ST-71 allele. Our results showed the utility of BOX-PCR genotyping in analyzing B. contaminans diversity. This approach allowed us to address clonal transmission during an outbreak and the genetic changes occurring in infecting bacteria over the course of chronic infection.
Burkholderia cepacia complex species are capable of causing chronic and often severe respiratory tract infections in cystic fibrosis (CF) patients and other types of infections in immunocompromised patients. Although many CF patients remain infected by these bacteria and yet stay relatively healthy for prolonged periods, others either have a severe decline in their pulmonary status or die shortly after the initial colonization (1). In Argentina, the first reports of B. cepacia complex bacteria infecting CF patients started around 1990. At that time, Burkholderia spp. were recovered sporadically and with a very low prevalence (Ͻ0.1%). The prevalence increased over the last decade from 0.2 to 3.6%, depending on the medical center. In early 2004, an outbreak involving main Argentine CF care centers occurred, and the proportion of patients from whom B. cepacia complex species were recovered ranged from 19 to 36% (2-4). Currently, through strict infection control procedures, the prevalence of Burkholderia spp. in local patients has decreased to approximately 10%. Recent worldwide surveillance studies concerning the distribution of B. cepacia complex species in CF patients have cited B. multivorans and B. cenocepacia as the most frequently recovered species. These species account for approximately 80% of the infected patients, and the prevalence of one or the other is geographically and temporally dependent (5-7). Unlike this worldwide situation, in Argentina a relatively high prevalence of B. contaminans followed by B. cenocepacia has been observed (3, 4). To our knowledge, no other geographical region has been reported in the literature to have such a high occurrence of B. contaminans infecting CF patients. In view of this particular scenario, coupled with the lack of biodiversity information available for B. contaminans species, we decided to study this local population by recA-PCR-based techniques and by repetitive element sequence-based PCR (rep-PCR) approaches. These methods allowed us to address the genetic diversity of B. contaminans isolates recovered during that outbreak along with the genetic changes occurring in the infecting bacteria over the course of a chronic infection.