title: In vitro susceptibility and resistance phenotypes in contemporary Citrobacter isolates in a University Hospital in Crete, Greece.
abstract: BACKGROUND
  Data on Citrobacter spp. susceptibility are scarce. We sought to study the evolution in the susceptibility of 385 Citrobacter spp. at the University Hospital of Heraklion, Crete, Greece during a six-year period (2010-2015).
  
  
  METHODS
  Non-duplicate strains isolated from inpatients (intensive care unit, oncology, surgery, internal medicine, paediatrics) and outpatients were studied using Vitek 2. Phenotypic confirmatory tests were applied for detection of β-lactamases and aminoglycoside modifying enzymes.
  
  
  RESULTS
  C. freundii (172, 44.7%) and C. koseri (166, 43.1%) were the most commonly isolated species. C. braakii (34), C. amalonaticus (6), C. youngae (6) and C. sedlakii (1) were the remaining isolates. Colistin and fosfomycin were the most active antibiotics (both 99.2%) followed by carbapenems (99%) aminoglycosides (96.6-98.4%), tigecycline (96.1%), cefepime (94.8%), ciprofloxacin (94.3%), tetracycline (92.7%), trimethoprim/sulphamethoxazole (91.4%), chloramphenicol (88.1%), piperacillin/tazobactam (86.5%) and 3rd generation cephalosporins (85.7%). C. freundii were more resistant than C. koseri. Antibiotic resistance did not increase during the study period for most antibiotics. Lower susceptibility to all antibiotics was observed among multi-drug resistant (MDR) strains. AmpC was the most common resistant mechanism (10.9%); carbapenemases (1.3%) and aminoglycoside modifying enzymes (2.9%) were also detected. All AmpC producers were resistant to cephalosporins but not to carbapenems. In all but one isolates aminoglycoside resistance was accompanied by acquired β-lactamases.
  
  
  CONCLUSIONS
  Although Citrobacter species in general were susceptible, antibiotic susceptibility testing is required for the detection of resistant isolates.
authors.affiliation: a Department of Clinical Microbiology , University Hospital of Heraklion , Heraklion , Greece.
authors.forename: Sofia
authors.initials: S
authors.lastname: Maraki
authors.affiliation: b Alfa Institute of Biomedical Sciences (AIBS) , Athens , Greece.|c Department of Internal Medicine-Infectious Diseases , Iaso General Hospital , Athens , Greece.
authors.forename: Konstantinos Z
authors.initials: KZ
authors.lastname: Vardakas
authors.affiliation: d Department of Internal Medicine , University of Crete School of Medicine , Heraklion , Greece.
authors.forename: Viktoria-Eirini
authors.initials: VE
authors.lastname: Mavromanolaki
authors.affiliation: e Department of Applied Mathematics and Physics , National Technical University of Athens , Athens , Greece.
authors.forename: Margarita
authors.initials: M
authors.lastname: Kyriakidou
authors.affiliation: e Department of Applied Mathematics and Physics , National Technical University of Athens , Athens , Greece.
authors.forename: George
authors.initials: G
authors.lastname: Spais
authors.affiliation: d Department of Internal Medicine , University of Crete School of Medicine , Heraklion , Greece.
authors.forename: Diamantis P
authors.initials: DP
authors.lastname: Kofteridis
authors.affiliation: d Department of Internal Medicine , University of Crete School of Medicine , Heraklion , Greece.
authors.forename: George
authors.initials: G
authors.lastname: Samonis
authors.affiliation: b Alfa Institute of Biomedical Sciences (AIBS) , Athens , Greece.|c Department of Internal Medicine-Infectious Diseases , Iaso General Hospital , Athens , Greece.|f Department of Medicine , Tufts University School of Medicine , Boston , MA , USA.
authors.forename: Matthew E
authors.initials: ME
authors.lastname: Falagas
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002954:Citrobacter / Q000145:classification / Q000187:drug effects* / Q000302:isolation & purification*; D024881:Drug Resistance, Bacterial; D004756:Enterobacteriaceae Infections / Q000453:epidemiology / Q000382:microbiology*; D006115:Greece / Q000453:epidemiology; D006785:Hospitals, University; D006801:Humans; D011446:Prospective Studies
chemical_list: D000900:Anti-Bacterial Agents
keywords: AAC(3); AAC(6); ESBL; KPC; MBL