title: [Problematic bacteria].
abstract: BACKGROUND
  Because of the special characteristics of the critical patients, infections are one of the primary complications they suffer so that multiresistant microorganisms take on a special importance in this type of patient.
  
  
  METHODS
  Search in Medline using the words ICU (Intensive Care Unit), multidrug resistant, critical patient.
  
  
  METHODS
  Glycopeptide resistant enterococci show a reduced prevalence in our setting and the VISA and hVISA are isolated sporadically. MRSA is, on the other hand, a major problem. In 2003-2005, it was already accounting for 28 %-38 % of the S. aureus isolated in the ICU, with a high percentage of fluoroquinolone (>90 %) and macrolide (>65 %) co-resistance. The extended-spectrum beta-lactamase producing enterobacteria (BLEE) also are a growing problem, worsened by their frequent co-resistance with fluoroquinolones, about 30 % according to some studies. Carbapenem resistance in A. baumannii has doubled in recent years, with values greater than 50 %, almost always associated to enzymes of the OXA group. P. aeruginosa also maintains high resistance values (25 %-30 % of resistance to imipenem, ceftazidime or ciprofloxacin), but more stable. However, high rates of multi-resistance are also observed, now about 50 % of the isolations of imipenem resistant P. aeruginosa are also to fluoroquinolones. As a whole, recent studies show that the multiresistance has multiplied in recently years by 5 in P. aeruginosa and by 7 in A. baumannii.
  
  
  CONCLUSIONS
  Multiresistant bacteria infections are one of the greatest problems to combat in critical patients and control of their spreading and the development of active antimicrobials against them is one of the principal challenges at present.
authors.affiliation: Departamento de Microbiologia, Hospital Universitario de Salamanca, Salamanca, Spain. jlmubel@usal.es
authors.forename: J L
authors.initials: JL
authors.lastname: Muñoz Bellido