Carbapenem and multidrug resistance in Gram-negative bacteria in a single centre in Italy: Considerations on in vitro assay of active drugs

Maria Lina Mezzatesta, Carla Caio, Floriana Gona, Roberta Cormaci, Iasmine Salerno, Tiziana Zingali, Carmelo Denaro, Mauro Gennaro, Cristiana Quattrone, Stefania Stefani

Research output: Contribution to journalArticle

Abstract

In intensive care units (ICUs), the most important causes of nosocomial bacterial infections are mainly multidrug-resistant (MDR) and extensively drug-resistant (XDR) Acinetobacter baumannii and Klebsiella pneumoniae strains. Mortality related to these infections is very high due to lack of effective therapy and the severity of patient conditions. This study aimed to assess the prevalence of carbapenem resistance genes in 77 carbapenem-resistant Gram-negative bacteria isolated from severe infections (bloodstream, pulmonary and urinary tract) during the period 1 January to 31 July 2013 in a general ICU in Catania, Italy, and to examine their susceptibility to tigecycline and colistin using two different methods. In total, 52 A. baumannii belonging to the same sequence type (ST) 2 clone and carrying the blaOXA-23 gene as well as 25 K. pneumoniae carrying blaKPC-3 were isolated. Four distinct pulsotypes were identified in K. pneumoniae, which correlated with four distinct STs: ST258 and ST512, spread worldwide, and ST147 and ST395 detected for the first time in Italy. A. baumannii isolates showed an XDR profile and were fully susceptible only to colistin; all KPC-producing K. pneumoniae isolates were MDR, whilst colistin was active against 19 of 25 strains. These results show that broth microdilution (BMD) is a reliable in vitro susceptibility test for colistin, above all K. pneumoniae, whilst both the gradient test and BMD are suitable for tigecycline susceptibility testing of A. baumannii.

Original languageEnglish
Pages (from-to)112-116
Number of pages5
JournalInternational Journal of Antimicrobial Agents
Volume44
Issue number2
DOIs
Publication statusPublished - 2014

Keywords

  • Acinetobacter baumannii
  • Carbapenemase
  • Colistin
  • Klebsiella pneumoniae
  • Tigecycline

ASJC Scopus subject areas

  • Microbiology (medical)
  • Infectious Diseases
  • Pharmacology (medical)
  • Medicine(all)

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    Mezzatesta, M. L., Caio, C., Gona, F., Cormaci, R., Salerno, I., Zingali, T., Denaro, C., Gennaro, M., Quattrone, C., & Stefani, S. (2014). Carbapenem and multidrug resistance in Gram-negative bacteria in a single centre in Italy: Considerations on in vitro assay of active drugs. International Journal of Antimicrobial Agents, 44(2), 112-116. https://doi.org/10.1016/j.ijantimicag.2014.04.014