Multiresistant Gram-negative bacteria: the role of high-risk clones in the dissemination of antibiotic resistance

Abstract

Multilocus sequence typing reveals that many bacterial species have a clonal structure and that some clones are widespread. This underlying phylogeny was not revealed by pulsed-field gel electrophoresis, a method better suited to short-term outbreak investigation. Some global clones are multiresistant and it is easy to assume that these have disseminated from single foci. Such conclusions need caution, however, unless there is a clear epidemiological trail, as with KPC carbapenemase-positive Klebsiella pneumoniae ST258 from Greece to northwest Europe. Elsewhere, established clones may have repeatedly and independently acquired resistance. Thus, the global ST131 Escherichia coli clone most often has CTX-M-15 extended-spectrum β-lactamase (ESBL), but also occurs without ESBLs and as a host of many other ESBL types. We explore this interaction of clone and resistance for E. coli, K. pneumoniae, Acinetobacter baumannii- a species where three global lineages dominate--and Pseudomonas aeruginosa, which shows clonal diversity, but includes the relatively 'tight' serotype O12/Burst Group 4 cluster that has proved adept at acquiring resistances--from PSE-1 to VIM-1 β-lactamases--for over 20 years. In summary, 'high-risk clones' play a major role in the spread of resistance, with the risk lying in their tenacity--deriving from poorly understood survival traits--and a flexible ability to accumulate and switch resistance, rather than to constant resistance batteries.

Prevalence of plasmid-mediated quinolone resistance determinants among oxyiminocephalosporin-resistant Enterobacteriaceae in Argentina

“…Notably, some PMQR determinants have been described in multiresistant clones with worldwide distribution (Woodford et al 2011), such as E. coli ST131 and K. pneumoniae ST11, which were also detected in the present study, further underscoring the ability of these resistance mechanisms to disseminate.…”

Primary mechanisms mediating aminoglycoside resistance in the multidrug-resistant Pseudomonas aeruginosa clinical isolate PA7

“…In fact, P. aeruginosa is exposed to high levels of reactive oxygen species in cystic fibrosis lungs, where mexXY overexpression mutants accumulate due to DNA damage resulting from the inflammatory response (Smith et al, 2006;Fraud & Poole, 2011). The multidrug-resistant O12 clone clusters very tightly, includes only clinical isolates and emerged during the 1980s, perhaps by selection from heavy antibiotic use (Pirnay et al, 2009;Woodford et al, 2011). O12 might be more dominant due, in part, to the presence of oprA in hospitals in which antimicrobials, such as aminoglycosides, promoting MexXY-OprA-mediated multidrug resistance were used.…”

Successful control of an outbreak of colonization by Klebsiella pneumoniae carbapenemase-producing K. pneumoniae sequence type 258 in a neonatal intensive care unit, Italy

“…1 KPCs are often associated with internationally successful K. pneumoniae clones, such as sequence type (ST) 258, which are endemic in many geographic areas, including Italy. 1 Gram-negative bacteria cause w20e40% of all late-onset sepsis in the neonatal intensive care units (NICUs) and are frequently associated with adverse clinical outcomes. 2,3 Colonization with multidrug-resistant (MDR) Gram-negative organisms is also, therefore, of great concern, due to the possibility of infection.…”