Affiliations: *National Institute of Health, Department of Medical Sciences, Nonthaburi 11000, Thailand.Tel. 662 951 0000 ext. 99415. Fax 662 589 9867, e-mail: firstname.lastname@example.org
Source: Poster presentation in The 9th Western Pacific Congress on Chemotherapy and Infectious Diseases (9th WPCCID) “Regional Infectious Disease Problems of Global Concern” December 1-5, 2004. Queen Sirikit Convention Center, Bangkok, Thailand. Program & Abstracts page 203
Introduction: Acinetobacter spp.have been ranked as the most top five isolates from clinical specimens for at least 7 consecutive years. Routine identification in hospitals is limited by few phenotypic tests (conventional biochemical tests) and reported in non-standardized phenotypic names-not in the recent 21 genomospecies (gsp.). Lack of gsp. information prevented detailed examination of epidemiology as well as antimicrobial susceptibility by species.
Objective: (1) To report the susceptibility data of Acinetobacter spp. by gsp. (2) To examine the trend of antimicrobial resistance of each gsp. by years.
Methods: One hundred and fifty eight strains of Acinetobacter spp. were randomly selected from Department of Medical Sciences, Thailand-Culture Collection (DMST-CC). These isolates were received during 1980-2004 from 28 hospitals located in various regions of Thailand. They were originally identified by conventional biochemical test and in this study by PCR-RFLP technique using
primers amplifying recA gene and subsequently digested 426 bp of PCR product with TasI restricted enzyme. The susceptibility against 15 antimicrobial agents were determined by standardized disk diffusion and agar dilution technique as described by the National Committee for Clinical Laboratory Standards (NCCLS).
Results: Of 158 Acinetobacter isolates, 61 originally labeled as A. baumannii by conventional biochemical test was identified as gsp.2 (A. baumannii) 49 strains (71%), TU13 =10 (15%), gsp.3 =5 (7%), gsp.10 =1 (1%), gsp.5 =1 (1%), and unidentified =4(6%). Out of 158 isolates 109 (75%) could be identified by PCR-RFLP into 11 gsp. as follows: A. baumannii =49 isolates, A. junii =21, TU13 =16, gsp.3 =15, close to TU13 =8, A. haemolyticus =3, gsp 8 =2, gsp.10 =2, gsp.1 =1, gsp 6 =1, TU14 =1 isolate. On the basis of genotypic identification (PCR-RFLP), Acinetobacter identified as A. baumannii was the only gsp. which resistant to imipenem (8%). All isolates of other gsp. are susceptible to imipenem. A. baumannii is resistant to other 14 drugs in the range of 24-78%. Besides imipenem, A. baumannii has lowest resistance against ampicillin-sulbactam at the percentage of 24. Gsp.3 and gsp. TU13 which are 2 of 6 gsp. in A. calcoaceticus-baumannii complex (Acb cpx) were resistant to 15 drugs at the rate 0-80 and 0-63% respectively. Gsp.5 (A. junii) which was the most prevalence among none Acb cpx. has low rate of resistant to 15 drug at the range of 0-14%.
In the two different periods of 1980-1999 and 2000-2004, resistance of A. baumannii against 15 drugs was increased at the rate of 5-27% whereas Acinetobacter of all other gsp. were at the rate of 3-14%.
Conclusions: Antimicrobial resistance among Acinetobacter is dependent on genomospecies. To obtain the accurated trend and rate of antimicrobial susceptibility result in a surveillance study, these group of organisms should be definitely identified to genomospecies.