Isolation of uncommon respiratory and enteric Acinetobacter baumannii from hematologic patients and emergence of tigecycline-resistance

Abstract

Acinetobacter baumannii is a Gram-negative, non-fermentative, nonmotile, oxidase-negative organism, whose natural habitat still remains unclear. It commonly behaves as an opportunistic pathogen which is associated with nosocomial outbreaks worldwide. Infections caused by this bacterium were often ignored in the past years, as it was considered as a ubiquitous organism, characterized by low virulence. Recently, several studies emphasized mutidrug-resistance by A. baumannii as a cause for serious concern in the field of nosocomial infections. MDR strains are especially responsible for significant morbidity and mortality among immunosuppressed hosts, patients with severe underlying diseases or receiving cytotoxic or broad-spectrum antibiotic therapies, and patients subjected to invasive procedures (such as catheterization). Cases of VAP (ventilator-associated pneumonia), catheter infections, urinary tract infections, soft tissue and abdominal infections, bacteremia, ostemomyelitis, and meningitis have been reported, mostly occuring after admission to and during hospitalization in burn or intensive care units (ICU). Recently, A. baumannii has also been known to infect combact associated wounds. Importance of this species as a nosocomial pathogen is greatly due to its ability to survive for long periods on dry or wet surfaces (such as bed rails, computer keyboards, hands of health care workers) and to its tendency to be intrinsically drug resistant or to easily acquire new resistance determinants against all existing antimicrobials. 1 Reid G.E. Grim S.A. Aldeza C.A. Janda W.M. Clark N.M. Rapid development of Acinetobacter baumannii resistance to tigecycline. Pharmacotherapy. 2007; 27: 1198-1201 Crossref PubMed Scopus (116) Google Scholar , 2 Mai M.-H. Tsai H.-C. Lee S.S.-J. Wang Y.-H. Chen Y.-S. Wann S.-R. et al. Multidrug-resistant Acinetobacter baumannii in ventilator associated pneumonia at a medical center in southern Taiwan. J Microbiol Immunol Infect. 2007; 40: 401-405 PubMed Google Scholar , 3 Robert E. Siegel M.D. Emerging Gram-negative antibiotic resistance: daunting challenges, declining sensitivities, and dire consequences. Respir Care. 2008; 53: 471-479 PubMed Google Scholar , 4 Mezzatesta M.L. Trovato G. Gona F. Nicolosi V.M. Nicolosi D. Caratolli A. et al. In vitro activity of tigecycline and comparators against carbapenem-susceptible and resistant Acinetobacter baumannii clinical isolates in Italy. Ann Clin Microbiol Antimicrob. 2008; 7: 4 Crossref PubMed Scopus (46) Google Scholar , 5 Perez F. Hujer A.M. Hujer Km Decker B.K. Rather P.N. Bonomo R.A. Global challenge of multidrug-resistant Acinetobacter baumannii. Antimicrob Agents Chemother. 2007; 51: 3471-3484 Crossref PubMed Scopus (958) Google Scholar , 6 Hu W.S. Yao S.-H. Fung C.-P. Hsieh Y.P. Liu C.P. Lin J.F. An OXA-66/OXA-51-like carbapenemase and possibly an efflux pump are associated with resistance to imipenem in Acinetobacter baumannii. Antimicrob Agents Chemother. 2007; 51: 3844-3852 Crossref PubMed Scopus (91) Google Scholar , 7 Ho Y.-H. Wang L.-S. Chao H.-J. Chang K.C. Su C.F. Successful treatment of meningitis caused by multidrug-resistant Acinetobacter baumannii with intravenous and intrathecal colistin. J Microbiol Immunol Infect. 2007; 40: 537-540 PubMed Google Scholar , 8 Schafer J.J. Mangino J.E. Multidrug-resistant Acinetobacter baumannii osteomyelitis from Iraq. Emerg Infect Dis. 2008; 14: 512-514 Crossref PubMed Scopus (28) Google Scholar