Antibiotic Resistance Gram-Negative Date

887 Pages·2010·5.46 MB·English

When citing these abstracts please use the following reference:
Author(s) of abstract. Title of abstract [abstract]. Int J Infect Dis 2010;14S1: Abstract number.

Please note that the official publication of the International Journal of Infectious Diseases 2010, Volume 14, Supplement 1

is available electronically on http://www.ijidonline.com/
Final Abstract Number: 23.001
Session: Antibiotic Resistance Gram-Negative
Date: Wednesday, March 10, 2010
Time: 12:30-13:30
Room: Poster & Exhibition Area/Ground Level
Type: Poster Presentation

Clinico epidemiologic and molecular characterization of metallo beta lactamases (MBLs)
producing nosocomial Pseudomonas aeruginosa (PSA)
S. Chatterjee1, A. Kumar2, K. N. prasad3, D. Mathai1, A. Manoharan1
1Christian Medical College and Hospital, Vellore, Tamil Nadu, India, 2Amrita Institute of Medical
Science, Kochi, India, 3Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow,
India

Background: The high prevalence of co-resistance to betalactam, aminoglycoside and quinolone
against PSA has necessitated increased use of carbapenems. MBL production among PSA is
one of the several mechanisms causing carbapenem resistance (CARB-R) transferable by
integrons. We surveyed MBL production among PSA isolates collected via multicentric
surveillance study.
Methods: During March-September 2009 BMPLIII received 75 consecutively collected PSA
causing infections of (skin and soft tissue-48, blood and respiratory tract 11 each, and other sites,
5) from four (50-AIMS,Kochi, 21-SGPGIMS, 2-MGIMS,2-AIIMS,Delhi) Indian Medical centers.
Antimicrobial susceptibility testing by Kirby Bauer method against ceftazidime (CZD),
cefepime(FEP), piperacillin/tazobactam (TZP), ticarcillin /clavulanic acid (TIM), gentamicin (GEN),
amikacin(AK), ciprofloxacin(CIP), imipenem(IMP), meropenem(MEM), aztreonam(ATM) and
colistin(CL) was done. MBL was screened by the Combined Disk Diffusion Test (CDDT) method
using 0.5M EDTA (930(cid:2)g) as the inhibitor with IMP, positives (inhibition (cid:1)7mm) confirmed by
IMP+EDTA Etest and PCR (VIM and IMP genes).
Results: Of the 75 PSA isolates, 12(16%) were MBL producers. Diabetes mellitus was found to
be the major risk factor in PSA infections. Overall resistance to CIP 50.7 %> CZD 37.3% >AK 36
%> FEP 34.7%. Resistance pattern among MBL/NMBL was CZD(91.7%/23.8%),
FEP(91.7%/20.6%), TZP(91.7%/15.9%), TIM(100%/27%), GEN(100%/23.8), AK(100%/20.6%),
CIP(100%/38.1%), IMP(100%/6.3%), MEM(75%/9.5%), ATM(91.7%/38.1%). Resistance to IMP
and MEM was 22.7% and 21.3% respectively. All isolates were susceptible to CL. MDR
(resistant to (cid:1)2 classes of antimicrobials) was 34(45.3%).Overall 14(18.7%) were CDDT positive.
IMP+EDTA Etest and PCR confirmed 12 to be MBL positives. Among the MBL isolates, one
was also positive for IMP gene, which on sequencing was confirmed to be IMP 7. Sensitivity and
specificity of CDDT was 100% and 96.8% respectively when compared to PCR. History of prior
antibiotic usage of aminoglycosides (66.7%), 3rd generation cephalosporins (58.3%), quinolones
(58.3%), carbapenems (50%), penicillins (25%), betalactam+betalactamase inhibitors (8.3%)
was noted for the patients with MBL infection. Clinical improvement or cure with modification of
initial antibiotics was found in 63.6% (7/11) patients with MBL PSA.

PCR for VIM and IMP gene in PSA
Conclusion: MBL production is an important mechanism of CARB-R among PSA. Spread should
be further minimized by using carbapenems judiciously in the treatment of PSA infections. CDDT
is a useful method for screening MBL. VIM type of MBL was seen among all MBL positive
isolates.
When citing these abstracts please use the following reference:
Author(s) of abstract. Title of abstract [abstract]. Int J Infect Dis 2010;14S1: Abstract number.

Please note that the official publication of the International Journal of Infectious Diseases 2010, Volume 14, Supplement 1

is available electronically on http://www.ijidonline.com/

Final Abstract Number: 23.002
Session: Antibiotic Resistance Gram-Negative
Date: Wednesday, March 10, 2010
Time: 12:30-13:30
Room: Poster & Exhibition Area/Ground Level
Type: Poster Presentation

The resistance patterns of Pseudomonas aeruginosa in hospitals from Greece
and Romania and its importance for the therapy of nosocomial infections and infection control
practices
L. M. Junie1, S. KASTANAKIS2, M. Petrascu1, C. Bobo(cid:3) 1, A. Tsouri 2, P. Karagianni 2, E.
Papadomanolaki2, G. Aleuraki2, M. Gatzima2, I. Varthalitis3
1University of Medicine and Pharmacy , Cluj Napoca, Romania, 2St. George General Hospital ,
Chania, Greece, 3Infection Control Committee, Chania, Greece

Background: One of the most difficult problems in hospitals is the appearance of an increased
number of Pseudomonas antibiotic resistant strains. The objective of our study is to describe the
resistance pattern of Pseudomonas aeruginosa strains.
Methods: For isolating Pseudomonas aeruginosa strains, the usual nutritive media were used.
Identification was made with Vitek2 system (BioMerieux). The susceptibility to the antibiotics of
strains was performed by Kirby Bauer method as recommended by CLSI and Vitek2 system.
Were tested 229 strains isolated from urine and surgical wounds, in Cluj Napoca, Romania, and
36 strains isolated from blood samples in Chania, Greece. The majority of the strains (86.1%)
were isolated from patients in wards and a percentage of 13.8 from Intensive Care Unit.
Results: The strains isolated in Romania from urine showed a high resistance to beta-lactamins,
remaining susceptible to Carbenicillin, Carbapenems, Ceftazidime and Cefepime. Over 80% of
the strains, were resistant to others of third generation cephalosporins. The strains isolated from
blood, presented resistance to Aztreonam (30.43%) and Ceftazidime (13%). 13% were resistant
to Imipenem and Meropenem. Pseudomonas aeruginosa isolated strains in Romania, showed
resistance to Amikacin (71.4% isolated strains from urine and 29.7% from surgical wounds), and
a low resista322nce to Gentamycin (18.6%), Tobramycin (25%). 29.6% were resistant to Colistin.
The strains isolated in Chania, showed resistance to Gentamycin (21.4%). All strains isolated
from urine, were resistant to Pefloxacin and a high resistance was detected to Nalidixic acid
(75%), Ciprofloxacin (75%) and Ofloxacin (50%). The strains isolated from surgical wounds,
presented a resistance to quinolones, oscillating between 33.1% and 51.9%. The isolated strains
from blood showed resistance to Nalidixic acid (38.5%), Pefloxacin (38.5%) and Ciprofloxacin
(38.5)
Conclusion: Our results could reflect the implication of some hospital multi resistant
Pseudomonas aeruginosa strains in nosocomial infections. In Greece, a decline in drugs
resistance of Pseudomonas strains has been noted. As a fact, it is rather encouraging, and
probably we can attribute it to adherence to infection control practices and prudent
chemotherapeutic agents use as proposed by Infectious Diseases Control Committee. The
majority of the strains was detected in ward patients and owing to reduced morbidity factors
compared with patients in ICU, the reduced resistance to antibiotics can be explained.
When citing these abstracts please use the following reference:
Author(s) of abstract. Title of abstract [abstract]. Int J Infect Dis 2010;14S1: Abstract number.

Please note that the official publication of the International Journal of Infectious Diseases 2010, Volume 14, Supplement 1

is available electronically on http://www.ijidonline.com/

Final Abstract Number: 23.003
Session: Antibiotic Resistance Gram-Negative
Date: Wednesday, March 10, 2010
Time: 12:30-13:30
Room: Poster & Exhibition Area/Ground Level
Type: Poster Presentation

Extended spectrum (cid:1)-lactamase production at the Komfo Anokye Teaching Hospital, Kumasi,
Ghana
Y. Adu-Sarkodie
School of Medical Sciences, KUMASI, Ghana

Background: In recent times enterobacteriaceae isolated at the Komfo Anokye TeachingHospital
(KATH) have shown significant resistance to 2nd and 3rd generation cephalosporins. In 2006, 18-
32% of all enterobacteriaceae isolated from urine and blood were resistant to the cephalosporins
cefuroxime, ceftriaxone , ceftazidime and cefotaxime. These antibiotics are the mainstay for the
treatment of severe infections in the hospital. Microbial resistance to these antibiotics if due to the
production of Extended spectrum (cid:1)-lactamases (ESBL) may also indicate resistance to the
fluoroquinolones, aminoglycosides and other antibiotics. This limits therapeutic options for the
treatment of severe infections. We studied the extent of ESBL production amongst Klebsiella sp
and E. Coli at KATH.
Methods: ESBL production in 300 non-selected, non-duplicate isolates of Klebesiella sp and
E.coli obtained from blood, urine, wounds, and sputum of both in-patients and out-patients was
determined by the combined disc method using ceftazidime, ceftriaxone and cefpodoxime discs
singly and in combination with clavulanic acid.
Results: 44% and 55% respectively of E.coli and Klebsiella sp ( 57.8% K.pneumo, ) were ESBL
producers. ESBL production in the organisms was commoner in in-patients (75.4%) than out-
patients (24.6%), though not statistically significant (OR=1.40, 95% CI 0.79-2.46, p=0.31). In
general, ESBL producing organisms apart from being resistant to cephalosporins were also
resistant to gentamicin and ciprofloxacin. They were however susceptible to the carbapenems.
Conclusion: The high level of ESBL production found in these enterobacteriaceae with the
resultant microbial resistance to available cephalosporins and other agents implies difficulties with
the choice of therapeutic options for the treatment of severe infections. Carbapenems are
expensive on the Ghanaian market and their use in non-severe infections (as may be suggested
by these results) may be inappropriate. Both prescribers and pharmaceutical agents will need to
reflect soberly on their contribution to this sordid state of affairs. We need to put an end to our
practice of cracking nuts with sledge hammers!
When citing these abstracts please use the following reference:
Author(s) of abstract. Title of abstract [abstract]. Int J Infect Dis 2010;14S1: Abstract number.

Please note that the official publication of the International Journal of Infectious Diseases 2010, Volume 14, Supplement 1

is available electronically on http://www.ijidonline.com/

Final Abstract Number: 23.004
Session: Antibiotic Resistance Gram-Negative
Date: Wednesday, March 10, 2010
Time: 12:30-13:30
Room: Poster & Exhibition Area/Ground Level
Type: Poster Presentation

Antimicrobial susceptibility profile of Pseudomonas aeruginosa strains isolated at a tertiary-care
University Hospital (S. Orsola Hospital, Bologna, Italy)
R. Manfredi
University of Bologna, Bologna, Italy

Background: The increased rate of antimicrobial resistance among Gram-negative bacilli and
Enterobacteriaceae is a general concern,especially in the hospital setting.A prospective
microbiological monitoring including a continued surveillance of antimicrobial susceptibility rates
of all relevant pathogens,is ongoing at our Hospital.
Methods: The temporal variations of in vitro antimicrobial sensitivity rates were registered at
quarterly intervals for all suitable Pseudomonas aeruginosa strains,during the year 2008.The
same pathogen cultured more than once from the same patient within one month,has been
considered once.
Results: Among Pseudomonas aeruginosa isolates (494 strains tested on the whole),the best
performance was obtained by the old colistin (colimycin),with a 100% susceptibility rate,followed
by piperacillin-tazobactam (73.9-78.6.4% of tested strains),amikacin (71.7-84.5% of tested
strains),imipenem (69.9-79.1% of tested strains),ceftazidime (from 68.0 to 82.5% of tested
strains),tobramycin (from 63.0 to 76.4% of tested strains).On the other hand,significantly less
effective sensitivity profiles were shown by gentamicin (57.5% to 71.3% of tested
strains),ciprofloxacin (51.3-68.0% of tested strains),aztreonam (59.5-61.2% of tested
strains),ticarcillin-clavulanate (54.2-66.9%),and mezlocillin (45.3-54.2% of tested strains).When
examining temporal trends of antibiotic sensitivity figures in the examinewd period (January-
December 2008), significantly favorable changes were observed only for ceftazidime and
ciprofloxacin (p<.025).
Conclusion: A prospective surveillance study of antimicrobial susceptibility rates of a major
hospital-associated organism like Pseudomonas aeruginosa is of remarkable importance,to
establish reliable guidelines of antibiotic treatment and prophylaxis, on local-regional basis.
Piperacillin-tazobactam, amikacin,imipenem,and the same ceftazidime still maintain a reliable role
in eventual,empiric regimens to be added pending microbial isolation and in vitro susceptibility
studies,since they remained active in nearly 80% of hospital isolates of the last year 2008.Colistin
maintained full in vitro activity against all Pseudomonas strains observed over time. An
appreciable increase of sensitivity rates to ceftazidime and ciprofloxacin was also observed over
the last year 2008.
When citing these abstracts please use the following reference:
Author(s) of abstract. Title of abstract [abstract]. Int J Infect Dis 2010;14S1: Abstract number.

Please note that the official publication of the International Journal of Infectious Diseases 2010, Volume 14, Supplement 1

is available electronically on http://www.ijidonline.com/

Final Abstract Number: 23.005
Session: Antibiotic Resistance Gram-Negative
Date: Wednesday, March 10, 2010
Time: 12:30-13:30
Room: Poster & Exhibition Area/Ground Level
Type: Poster Presentation

Characterization of ertapenem resistance in Klebsiella pneumoniae from Croatia
B. Bedenic1, J. Vranes2, Z. Bosnjak3, A. Budimir4, S. Kalenic3
1School of Medicine, University of Zagreb, Clinical Hospital Center Zagreb, Zagreb, Croatia,
2Zagreb Institue of Public Health "Andrija Stampar", Zagreb, Croatia, 3Clinical Hospital Center
Zagreb, Zagreb, Croatia, 4School of Medicine University of Zagreb, Clinical Hospital Center
Zagreb, Zagreb, Croatia

Background: Klebsiella pneumoniae isolates with reduced susceptibility to carbapenems were
recently reported in USA, UK, Turkey and some other countries of the world. Recently eight
Klebsiella pneumoniae strains with reduced susceptibility to carbapenems were isolates in four
different hospitals in Croatia. The aim of the study was to determine the mechanisms of
ertapenem resistance in these strains.
Methods: Antibiotic susceptibilities were determined by broth microdilution method according to
CLSI. Transferability of ertapenem resistance was determined by conjugation (broth mating
method) using E. coli A15 R- as recipient. Production of metallo (cid:3)-lactamases was detected by
double-disk synergy test and E test. (cid:2)-lactamases were characterized by PCR with primers
specific for extended-spectrum (cid:3)-lactamases, plasmid-mediated ampC (cid:3)-lactamases, metallo (cid:3)-
lactamases of VIM and IMP series, KPC and OXA-48 (cid:3)-lactamases. Genotyping of the strains
was performed by PFGE.
Results: All strains were resistant to ceftazidime, cefotaxime, ceftriaxone, piperacillin alone and
combined with tazobactam, amoxycillin/clavulanate, gentamicin and ciprofloxacin. All except one
strains showed resistance to ertapenem, intermediate susceptibility or resistance to meropenem
and intermediate susceptibility or full susceptiblity to imipenem. One strain was resistant to all
three carbapenems. Ertapenem resistance was not transferable by conjugation to E. coli recipient
in neither of our strains. PCR revealed the presence of blaSHV and blaCTX-M genes. Multiplex
PCR was positive for group 1 CTX-M (cid:3)-lactamases. Sequencing of representative blaCTX-M
genes revealed the presence of CTX-M-15 beta-lactamase. The strain resistant to all three
carbapenem was positive by E test for MBLs. However, PCR was negative for VIM and IMP (cid:3)-
lactamases. No KPC or plasmid-mediated ampC (cid:3)-lactamases were found. The strains were not
clonally related as shown by PFGE and displayed distinct PFGE fingerprints.
Conclusion: This is the first report of carbapenem resistant Klebsiellae in Croatia. Ertapenem
resistance in Klebsiella was previously reported in UK, Turkey and Israel mainly due to the
production of CTX-M (cid:3)-lactamases of group 1 combined with porin loss (OmpK36 or OmpK35).
The characterization of outer membrane porins needs to be done to clarify the mechanisms of
ertapenem resistance in our strains. Further testing is necessary to determine the mechanism of
carbapenem resistance in the strain with positive E test–MBL.
When citing these abstracts please use the following reference:
Author(s) of abstract. Title of abstract [abstract]. Int J Infect Dis 2010;14S1: Abstract number.

Please note that the official publication of the International Journal of Infectious Diseases 2010, Volume 14, Supplement 1

is available electronically on http://www.ijidonline.com/

Final Abstract Number: 23.006
Session: Antibiotic Resistance Gram-Negative
Date: Wednesday, March 10, 2010
Time: 12:30-13:30
Room: Poster & Exhibition Area/Ground Level
Type: Poster Presentation

Changing trends in antimicrobial resistance among salmonella serotypes in Southern India
S. rao1, B. Kabir2
1kasturba Medical College & Hospital ,Manipal, Karnataka, India, 2Kasturba Medical College and
Hospital, Madhav Nagar, Manipal, India

Background: Enteric fever caused by drug resistant Salmonella enterica serotype Typhi and
Salmonella enterica serotype Paratyphi A has been the major public health concern in the Indian
Subcontinent.
Methods: A Retrospective analysis of antibiogram and resistance pattern to Ciprofloxacin,
Nalidixic acid, Ceftriaxone Azithromicin and other routine antibiotics to Salmonella isolates from
PUO cases from blood cultures during 2005-2006 combined with a follow up during 2007-2008
represents the data presented in this study.
Results: Of the 2247 from PUO cases 198 salmonella species (65 were Salmonella typhi, 132
Salmonella paratyphi A and 1 Salmonella enteritidis. Salmonella typhi and Salmonella paratyphi
A serotypes were sensitive to Chloramphenicol, Ampicillin, Cotrimoxazole, and Cefriaxone and
sensitive /intermediate to Ciprofloxacin and resistant to Nalidixic acid (except one). MIC for
Ciprofloxacin and Nalidixic acid resistance strains was 0.5/1 (cid:1)g/ml except for 3 MDR salmonella
strains which had MIC value of 16 (cid:1)g/ml. This was reflected on disc diffusion test as intermediate
zone of inhibition. Retrospective blood culture analysis of 2005-2006 has shown that MDR
Salmonella typhi was common isolate then and the strains were sensitive for Ciprofloxacin (MIC
being 0.125(cid:1)g/ml). No antibiotic resistant Salmonella paratyphi A was isolated during this period.
Conclusion: Salmonella strains with Nalidixic acid resistance and reduced susceptibility and MIC
to Ciprofloxacin have emerged as major cause of enteric fever in Indian Subcontinent. Nalidixic
acid susceptibility (30(cid:1)g disc) can be reliably used to monitor Ciprofloxacin resistance.
When citing these abstracts please use the following reference:
Author(s) of abstract. Title of abstract [abstract]. Int J Infect Dis 2010;14S1: Abstract number.

Please note that the official publication of the International Journal of Infectious Diseases 2010, Volume 14, Supplement 1

is available electronically on http://www.ijidonline.com/

Final Abstract Number: 23.007
Session: Antibiotic Resistance Gram-Negative
Date: Wednesday, March 10, 2010
Time: 12:30-13:30
Room: Poster & Exhibition Area/Ground Level
Type: Poster Presentation

Molecular epidemiology of aminoglycosides resistance in Acinetobacter spp. with emergence of
multidrug-resistant strains in hospitalized patients in Iran
R. Moniri1, R. Kheltabadi Farahani2
1Kashan University of Medical Sciences, Kashan, Iran, Islamic Republic of, 2Kashan University Of
Medical Sciences , Kashan, Iran, Islamic Republic of

Background: Acinetobacter spp. is emerging as an important nosocomial pathogen and is
characterized by increasing antimicrobial resistance. Our aim was to evaluate antimicrobial
susceptibility and aminoglycosides resistance genes of Acinetobacter spp. isolated from
hospitalized patients.
Methods: Sixty isolates were identified as Acinetobacter species. The isolates were tested for
antibiotic resistance by disc diffusion method for 12 antimicrobials. The presence of aphA6,
aacC1 aadA1, and aadB genes were detected using PCR.
Results: From the isolated Acinetobacter spp. the highest resistance rate showed against
amikacin, tobramycin, and ceftazidim, respectively; while isolated bacteria were more sensitive to
ampicillic/subactam. More than 66% of the isolates were resistant to at least three classes of
antibiotics, and 27.5% of MDR strains were resistant to all seven tested classes of antimicrobials.
The higher MDR rate presented in bacteria isolated from the ICU and blood samples. More than
60% of the MDR bacteria were resistance to amikacin, ceftazidim, ciprofloxacin,
piperacillin/tazobactam, doxycycline, tobramycin and levofloxacin. Also, more than 60% of the
isolates contained phosphotransferase aphA6, and acetyltransferase genes aacC1, but
adenylyltransferase genes aadA1 (41.7%), and aadB (3.3%) were less prominent. In this study
21.7% of the strains contain three aminoglycoside resistance genes (aphA6, aacC1 and aadA1).
Conclusion: The rising trend of resistance to aminoglycosides poses an alarming threat to
treatment of such infections. The findings showed that clinical isolates of Acinetobacter spp. in
our hospital carrying various kinds of aminoglycoside resistance genes.
When citing these abstracts please use the following reference:
Author(s) of abstract. Title of abstract [abstract]. Int J Infect Dis 2010;14S1: Abstract number.

Please note that the official publication of the International Journal of Infectious Diseases 2010, Volume 14, Supplement 1

is available electronically on http://www.ijidonline.com/

Final Abstract Number: 23.008
Session: Antibiotic Resistance Gram-Negative
Date: Wednesday, March 10, 2010
Time: 12:30-13:30
Room: Poster & Exhibition Area/Ground Level
Type: Poster Presentation

Incidence of Carbapanemase Resistance Gene (KPC) among Klebsiella pneumoniae isolates
and its Clinical Implications
B. Yegneswaran, W. Numsuwan, D. Alcid
Drexel University College of Medicine / St Peter's University Hospital, New Brunswick, NJ, USA

Background: Carbapenem antibiotics (Imipenem, Ertapenem, and Meropenem) idicated for
infections caused by extended-spectrum {beta}-lactamase (ESBL) carrying pathogens.
Carbapenem resistance has been unusual in isolates of Klebsiella pneumoniae. The aim of this
study is to identify the prevalence of KPC positive Klebsiella pneumoniae, and it's clinical
significance.
Methods: All isolates of Klebsiella pneumoniae species from October 1, 2007 to September 30,
2009 were tested for the presence of KPC gene using the modified Hodge test. Medical records
of patients with KPC were studied.
Results: Over the period of two-years 40,309 samples were submitted for culture and sensitivity,
out of which 7,836 were positive. Of the positives, there were 106 isolates of K pneumoniae and
11 were ESBL positive. Of the ESBL producing isolates, 8 carried the Carbapenem-hydrolyzing
(cid:1)-lactamase. Of the eight, three isolates were reported as being susceptible to Imipenem.
Although all the eight isolates were resistant using the Hodge test. Piperacillin/Tazobactam (PT)
and Vancomycin were the antibiotic used 7 of the 8 patients prior to isolation of Klebsiella
pneumoniae resistant to Carbapenems. One patient was excluded in outcome as one patient’s
sample was clinically thought to be a contaminant was not treated. 3 patients in whom resistance
to carbapenem was reported had their antibiotic was changed to Tigecycline and Polymyxin B
resulting in clinical improvement. Of the remaining 4 patients who were reported as sensitive to
carbapenem three patients had to undergo a repeat surgery due to clinical deterioration and one
patient clinically died.
Conclusion: The incidence of KPC gene at our hospital was 7.5%. KPC positive isolatesare
rapidly emerging pathogens. It is very important to keep this organism in mind as if not treated
there is a 100% probability of having a poor outcome. There is a complete cross resistance to all
Carbapenems containing KPC, therefore if KPC is present, the K pneumoniae will be resistant to
all Carbapenem regardless of the routine susceptibility testing as shown in three isolates that are
KPC positive but susceptible to Imipenem. Current automated systems used for susceptibility
testing may not accurately identify all these isolates. We must also control the use of antibiotics
specially PT to prevent emergence of KPC positive organisms.
When citing these abstracts please use the following reference:
Author(s) of abstract. Title of abstract [abstract]. Int J Infect Dis 2010;14S1: Abstract number.

Please note that the official publication of the International Journal of Infectious Diseases 2010, Volume 14, Supplement 1

is available electronically on http://www.ijidonline.com/

Final Abstract Number: 23.009
Session: Antibiotic Resistance Gram-Negative
Date: Wednesday, March 10, 2010
Time: 12:30-13:30
Room: Poster & Exhibition Area/Ground Level
Type: Poster Presentation

In vitro activity of Tigecycline against molecularly defined Carbapenemase producing
Acinetobacter baumannii
M. Hackel1, P. Higgins2, H. Seifert2, S. Bouchillon1, B. Johnson1, R. Badal1, J. johnson1, D.
Hoban1, S. Hawser3, M. Dowzicky4
1International Health Management Associates, Inc., Schaumburg, IL, USA, 2Institute for Medical
Microbiology, Cologne, Germany, 3IHMA Europe Sàrl, Epalinges, Switzerland, 4Pfizer Inc,
Collegeville, PA, USA

Background: Acinetobacter baumannii are important opportunistic pathogens with increasing
rates of multi-antibiotic resistance due to both intrinsic and acquired mechanisms. Carbapenems
are often used to treat these infections, however carbapenem resistance is increasingly reported,
leaving few therapeutic options. This resistance is most often associated with acquired or
intrinsic OXA-group carbapenemase production. While A. baumannii carry the intrinsic OXA-51-
like carbapenemase gene, carbapenem resistance has only been associated with these genes
when the insertion sequence ISAba1 is upstream. In this study, we evaluated the in vitro activity
of tigecycline against genetically defined A. baumannii from the Tigecycline Evaluation
Surveillance Trial.
Methods: A total 352 imipenem resistant Acinetobacter baumanii from 35 countries (2004 to
2006) were evaluated. MICs were determined by broth microdilution and interpreted according to
CLSI guidelines. Carbapenemase genes were detected by multiplex PCR.
Results: All isolates tested in this study contained an OXA-51-like gene. Additional genotypes
are listed below.

Conclusion: Tigecycline demonstrated excellent in vitro activity against carbapenem resistant A.
baumannii regardless of carbapenemase type. Tigecycline’s in vitro activity against isolates with
either intrinsic ISAba1-OXA-51 or the acquired oxacillinases (OXA-23, OXA-40 and OXA-58)
suggests that it may be effective against resistant isolates of this clinically important pathogen.
When citing these abstracts please use the following reference:
Author(s) of abstract. Title of abstract [abstract]. Int J Infect Dis 2010;14S1: Abstract number.

Please note that the official publication of the International Journal of Infectious Diseases 2010, Volume 14, Supplement 1

is available electronically on http://www.ijidonline.com/

Final Abstract Number: 23.010
Session: Antibiotic Resistance Gram-Negative
Date: Wednesday, March 10, 2010
Time: 12:30-13:30
Room: Poster & Exhibition Area/Ground Level
Type: Poster Presentation

Molecular typing of multi-drug resistant Acinetobacter baumannii from London hospitals
D. Wareham, D. Bean
Queen Mary University London, London, United Kingdom

Background: Acinetobacter baumannnii has emerged as a major nosocomial pathogen causing
outbreaks of infection in the immunosuppressed and critically ill worldwide. A number of
molecular typing techniques have been developed for use in both local surveillance and global
epidemiological studies. We applied a recently described multi-locus sequence typing (MLST)
scheme to multi-drug resistant A. baumannii (MDRAB) recovered from London Hospitals in
comparison with other molecular methods.

Methods: Sixteen MDRAB were identified using multiplex PCR for OXA-carbapenemases and
included representatives previously assigned to the UK ‘South East’, OXA-23 (1) and OXA-23 (2)
clones. Stains were typed using pulsed field gel electrophoresis (PFGE), random-amplified
polymorphic DNA-PCR (RAPD), a multiplex PCR typing (MPT) scheme (ompA, csuE and
blaOXA-51 like genes) and an A. baumannii MLST scheme (gltA, gyrB, gdhB, recA, cpn60, gpi,
rpoD).
Results: Five clearly distinguishable profiles were observed using PFGE and six with RAPD.
MPT typing assigned all but one of the strains (OXA-23 (2) representative) to group 1. Four allelic
profiles (sequence types ST) were obtained using MLST, two of which appeared to be novel.
Comparison of results revealed isolates designated ‘South East’ clone by PFGE / RAPD
belonged to the previously described ST22 and those designated OXA-23 (1) to ST53. The allelic
profile of the OXA-23 clone 2 strain was novel and contained a new gyrB allele.
Conclusion: Molecular techniques were comparable for typing UK MDRAB. Isolates belonging to
ST22, (found previously in Italy, Portugal, Czech Republic, China, Korea and Australia) and
isolates belonging to ST53 (found previously in Italy) were the most frequently types, highlighting
the widespread dissemination of these clones. Two novel sequence types were identified and are
undergoing further investigation.