Naslov
In vitro testing of carbapenem-resistant Acinetobacter baumannii to colistin (polymyxin E)
(In vitro testing of carbapenem-resistant Acinetobacter baumannii to colistin (polymixin E))

Autori
Goić-Barišić, Ivana ; Bedenić, Branka ; Tonkić, Marija ; Novak, Anita ; Punda-Polić, Volga

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Abstracts of the European Congress of Clinical Microbiology and Infectious Diseases : ECCMID ; u: Clinical Microbiology and Infection. Supplement 14 (2008) (S7) ; Posters S121–S666 ; P1165 / - , 2008, S323-S323

Skup
European Congress of Clinical Microbiology and Infectious Diseases

Mjesto i datum
Barcelona, Španjolska, 18.04.2008. - 22.04.2008

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
Acinetobacter baumannii; karbapenemi; oksacilinaze
(Acinetobacter baumannii; carbapenems; oxacillinases)

Sažetak
Acinetobacter baumannii is recognized as an increasingly important opportunistic gram-negative pathogen frequently associated with nosocomial outbreaks worldwide. Carbapenem-resistant strains of A. baumannii have been reported in almost all European counties. Thus more toxic agents such as polymyxins have been used as alternative therapeutic drugs against multidrug-resistant Acinetobacter baumannii infections. At present there is no agreement about how to look for colistin resistance. The Societe Francaise de Microbiologie uses a cut off of 2 mg/l by broth microdilution testing, whereas the British Society for Antimicrobial Chemotherapy sets a cut off of 4 mg/l or less as sensitive, and 8 mg/l or more as resistant. There are not currently any US standards for measuring disk diffusion sensitivity to polimyxin and CLSI (formerly NCCLS) documents do currently provide interpretative criteria for minimal inhibitory concentration by broth microdilution testing of polymyxins in Acinetobacter spp. Twenty-nine non-repetitive A. baumannii isolates with carbapenem resistance profile were obtained from patients hospitalised at different Intensive Care Units inside University Hospital Split and tested by broth microdilution to polymyxin (colistin sulphate). Pseudomonas aeruginosa ATCC 27853 was used as control strain. Isolates were recovered from blood cultures, urine samples and bronchial secretions. Although disk diffusion sensitivity to polymyxin is not standardised, the diameter of inhibition zone to colistin (10µ g) was measured. Results: From total number of tested strains, twenty-two isolates (22/29) displayed minimum inhibitory concentration of 2 mg/l and six isolates (6/29) 4 mg/l. One isolate displayed MIC of 128 mg/l to polymyxin. All isolates of A. baumannii displayed intermediate or resistant profile to imipenem (MICs 8-16 mg/L) and meropenem (MICs 8-64 mg/L). Minimum inhibitory concentrations were also determined for ceftazidime, cefepime, ceftriaxone, amikacin, gentamicin, ciprofloxacin and piperacillin-tazobactam by broth microdilution according to CLSI (formerly NCCLS) recommendation. All isolates were multidrug-resistant exhibiting high resistance to ceftazidime (>128 mg/L), cefepime (64-128 mg/L), ceftriaxone (>128 mg/L) piperacillin/tazobactam (64/4->128/4 mg/L), amikacin (128 mg/L), gentamicin (>128 mg/L), and ciprofloxacin (16-64 mg/L). All isolates displayed diameter of inhibition zone to colistin by disk diffusion more than 11 mm. According to currently available criteria for interpretative reading for broth microdilution testing of polymixins in Acinetobacter spp, we found variance in susceptibility of our isolates to polymyxin. Against CLSI standard, most of our isolates (28/29) displayed susceptibility to polymyxin representing MIC values of 4 mg/l or less as sensitive. Regarding the results obtained with a disk diffusion test, we recommendation necessary of the confirmation by a dilution method, especially in the case of serius infections.

Izvorni jezik
Engleski

Znanstvena područja
Temeljne medicinske znanosti

Napomena
Dot: 10.1111/j.1469-0691.2008.02007.x

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