A single-day point-prevalence study of faecal carriers in long-term care hospitals in Madrid (Spain) depicts a complex clonal and polyclonal dissemination of carbapenemase-producing Enterobacteriaceae

The objective of this study was to describe the prevalence and microbiological characteristics of carbapenemase-producing Enterobacteriaceae (CPE) colonizing patients in long-term care hospitals (LTCHs) in Madrid, Spain. Three LTCHs were included in a single-day point-prevalence survey (September 2013). Rectal swabs, collected from all hospitalized patients (137 in LTCH-A, 121 in LTCH-B and 83 in LTCH-C), were plated onto chromogenic media. Population structure (PFGE and MLST), genes encoding carbapenemases and ESBLs and plasmids carrying carbapenemase genes were characterized. The prevalence of CPE carriers was 4.1% (14/341) [2.9% (4/137), LTCH-A; 4.1% (5/121), LTCH-B; and 6.0% (5/83), LTCH-C]. OXA-48 was the most prevalent carbapenemase (nine Klebsiella pneumoniae, two Escherichia coli, one Enterobacter cloacae and one Citrobacter braakii) followed by VIM-1 (one K. pneumoniae and one Raoultella ornithinolytica). One patient (LTCH-C) was co-colonized with OXA-48-producing K. pneumoniae and E. coli. K. pneumoniae and E. coli isolates also coproduced CTX-M-15 (naEuroS=aEuroS11) or CTX-M-9 (naEuroS=aEuroS1) enzymes. K. pneumoniae clustered into six PFGE types corresponding to ST11 (naEuroS=aEuroS1), ST15 (naEuroS=aEuroS6), ST307 (naEuroS=aEuroS1) and ST405 (naEuroS=aEuroS2). E. coli from LTCH-A and LTCH-C exhibited two different PFGE types associated with ST68. OXA-48 and VIM-1 enzymes were found in different clones in LTCH-A and LTCH-C. However, OXA-48 was the only carbapenemase detected in LTCH-B, mainly associated with K. pneumoniae ST15. KPC, IMP and NDM enzymes were not detected. bla(OXA-48) was located on an similar to 60 kb plasmid with a pOXA-48a-IncL/M backbone. We describe the first point-prevalence study of CPE faecal carriers in LTCHs in Spain. OXA-48, the most prevalent carbapenemase, showed a complex dissemination pattern with clonal and polyclonal bacterial populations.