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P26 Molecular characterization of carbapenem resistance in Acinetobacter baumannii isolates from Zagreb, Croatia
Friday, June 19, 2009 Conclusion: This study demonstrated the presence of 36% MBLs producing imipenem-resistant strains among the clinical isolates of P. aeruginosa. blaIMP and blaVIM were present predominantly among the MBL genes and these genes were found to be present in Class I integron. These findings provided the new target genes for PCR in the diagnosis of P. aeruginosa and also help the clinicians to prescribe the appropriate drugs for the patients. P26 Molecular characterization of carbapenem resistance in Acinetobacter baumannii isolates from Zagreb, Croatia B. Bedenic1 *, J. Vranes2 , A. Budimir, Z. Herljevic, S. Kalenic. 1 School of Medicine, University of Zagreb, Clinical Hospital Center Zagreb, Zagreb, Croatia, 2 School of Medicine, University of Zagreb, Zagreb Institute of Public Health, Zagreb, Croatia Background and aim: Recently an increasing trend of carbapenem resistance has been observed in Acinetobacter baumannii. Carbapenem resistance results from metallo-b-lactamases, carbapenem hidrolyzing oxacillinases, loss of outer membrane proteins, efflux and often combined mechanisms of resistance. The aim of the study was to characterize carbapenem hydrolyzing enzymes in A. baumannii strains from Zagreb, Croatia. Material and methods: Thirty three carbapenem resistant Acinetobacter baumannii isolates were collected from various clinical specimens and hospital units during 2008 in Clinical Hospital Center Zagreb, Croatia. The susceptibility to a wide range of antibiotics was determined by broth microdilution method according to CLSI. Metallo-b-lactamases (MBL) were detected by E test and by PCR with primers specific for IMP and VIM MBLs. The presence of blaOXA genes was determined by PCR with primers specific for OXA-51, OXA-69, OXA-23, OXA-24 and OXA-58 b-lactamases. ISAbaI insertion sequence was determined by PCR as described previously. Results: All strains were resistant to ceftazidime, cefotaxime, piperacillin/tazobactam and gentamicin. Isolates were intermediate or resistant to cefepime, imipenem and meropenem. 30% of the strains were resistant to ciprofloxacin. No resistance to colistin and ampicillin/sulbactam was noticed. The strains were negative for MBLs by E test. No blaVIM and blaIMP genes were detectd. PCR detected the presence of OXA-51/69 b-lactamase. OXA-23, OXA-24 and OXA-58 b-lactamases were not found. ISAbaI insertion sequence was found upstreams of blaOXA-51 gene in all tested strains. Conclusions: This study found the presence of OXA-51/69 b-lactamase in all tested isolates which is a naturally occuring oxacillinases in A. baumannii found im most strains with a variable expression. However, the level of carbapenem resistance depends on the amount of b-lactamase. The presence of ISAbaI insertion sequence upstreams of the blaOXA-51 gene in our isolates most likely increased the expression of the gene and was associated with carbapenem resistance. Our isolates were multidrug resistant and pose serious therapeutic problem in the hospital. Colistin and ampicillin/sulbactam are in most cases the only therapeutic option. Molecular typing of the strains by pulsed-field gel electrophoresis needs to be done to determine if the strains are clonally related. P27 Correlation between nalidixic acid and ciprofloxacin susceptibility of salmonellae in a teaching hospital in Riyadh, Saudi Arabia A. Somily1 *. 1 King Khalid university, Riyadh, Saudi Arabia Introduction: Antibiotic therapy is seldom indicated in acute enteritis resulting from salmonella infection. However in extraintestinal infections prompt and appropriate antimicrobial therapy is essential and the clinician needs to be aware of the occurrence of resistant strains. Ciprofloxacin is now widely used as the drug of choice for these severe salmonella infections where antibiotic therapy is indicated. The emergence and spread of infections caused by Salmonella spp with reduced susceptibility 0.125 mg/ml, but 1 mg/ml) which is still
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to the fluoroquinolones (MICs considered susceptible by CLSI has been associated with delayed treatment response to fluoroquinolones therapy. This has especially been recognized in cases of enteric fever due to such strains. Our aim from this study is to determine the naidixic acid resistance in salmonella species and correlate this with the minimal inhibitory concentration (MIC) of ciprofloxacin. Method: This was a prospective study at King Khalid University Hospital bacteriology laboratory, during the period from January to December 2007. All isolates of salmonellae collected from all type of clinical specimens were tested for susceptibility to nalidixic acid (30 mg) disk diffusion method and E-test method (AB Biodisk Solna, Sweden) was used to determine ciprofloxacin MIC. The two results were compared. Patients demographic and clinical information was collected and analyzed using SPSS software. Result: During the study period we isolated 182 salmonella spp mostly from males 62% versus 38% females. Sixty two percent of patients were children fifteen year of age or less. Saudi nationality accounted for 77% of the patients and there were no significant difference between the in number between inpatients and out patients. Most common symptoms associated with diarrhea in patients were fever in 13 patients followed by abdominal pain in 8 patients. Salmonella serotype D1 was the most common serotype isolated (34.6%) followed by serotype B (24%) while C1 accounted for (11.5%) of patents. Resistance to ampicillin, third generation cephalosporin and trimethoprim/sulfamethoxazole were 36%, 3.3% and 16% respectively. Eighty one (44.5%) of the isolates were resistant to nalidixic acid. Eighty two (45%) of these isolates had MIC of 0.125 mg/ml to ciprofloxacin of these 73 (89%) were resistant to nalidixic acid. One Hundred (55%) of isolates had MIC of <0.125 mg/ml to ciprofloxacin of these 92 (92%) were sensitive to nalidixic acid. Conclusion: Automated system like MicroScan (MicroScan Walk Away System 96, Dade Behring Inc., West Sacramento CA95691, USA) which is routinely used routinely in our laboratory can not accurately detect decrease susceptibility of salmonella spp to ciprofloxacin if MIC of 1 mg/ml is used as a break point. It is prudent to use nalidixic acid disk diffusion susceptibility method to detect ciprofloxacin decreased susceptibility of salmonella spp with higher degree of correlation approaching 90%. We recommend using nalidixic acid disk diffusion on all samonella spp susceptibility testing to predict ciprofloxacin susceptibilities. However ciprofloxacin MIC testing might be indicated in case of sterile body site isolates of salmonella where the MIC of 0.06 mg/ml suppose to correlate with good clinical response.
Antimicrobials: Surveillance and epidemiology of drug resistance in Gram positive and Gram negative organisms P28 Clonal diversity of high level gentamicin resistant Enterococcus faecalis isolated from clinical samples in Tehran, Iran M. Saifi1 *, M. Pourshafie1 , M. Soltan Dallal2 , S. Aghaei3 . 1 Pasteur Institute of Iran, Tehran, Iran, 2 School of public health Tehran University, Tehran, Iran, 3 Karaj Azad University, Karaj, Iran Objectives: Enterococci are one of the leading causes of nosocomial infections. Following the worldwide increased of high-level gentamicin resistace (HLGR) among enterococcal isolates; we report in the present study the isolation of HLGR Enterococcus faecalis (HLGR-EF) from clinical samples, and clonal relatedness of them in Tehran-Iran. Methods: From September 2006 to 2007, 266 enterococcal isolates were detected from the patients referred to 5 medical centers in Tehran. All strains were identified to species level by conventional and PCR methods. CLSI recommendations were used for antimicrobial susceptibility and gentamicin MICs of HLGR-EF isolates. Analysis of gentamicin resistant genes was done by PCR method. Boichemical fingerprint typing (PhP typing) was applied for primary typing of enterococcal population. Analysis of the SmaI restriction digest of
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to the fluoroquinolones (MICs considered susceptible by CLSI has been associated with delayed treatment response to fluoroquinolones therapy. This has especially been recognized in cases of enteric fever due to such strains. Our aim from this study is to determine the naidixic acid resistance in salmonella species and correlate this with the minimal inhibitory concentration (MIC) of ciprofloxacin. Method: This was a prospective study at King Khalid University Hospital bacteriology laboratory, during the period from January to December 2007. All isolates of salmonellae collected from all type of clinical specimens were tested for susceptibility to nalidixic acid (30 mg) disk diffusion method and E-test method (AB Biodisk Solna, Sweden) was used to determine ciprofloxacin MIC. The two results were compared. Patients demographic and clinical information was collected and analyzed using SPSS software. Result: During the study period we isolated 182 salmonella spp mostly from males 62% versus 38% females. Sixty two percent of patients were children fifteen year of age or less. Saudi nationality accounted for 77% of the patients and there were no significant difference between the in number between inpatients and out patients. Most common symptoms associated with diarrhea in patients were fever in 13 patients followed by abdominal pain in 8 patients. Salmonella serotype D1 was the most common serotype isolated (34.6%) followed by serotype B (24%) while C1 accounted for (11.5%) of patents. Resistance to ampicillin, third generation cephalosporin and trimethoprim/sulfamethoxazole were 36%, 3.3% and 16% respectively. Eighty one (44.5%) of the isolates were resistant to nalidixic acid. Eighty two (45%) of these isolates had MIC of 0.125 mg/ml to ciprofloxacin of these 73 (89%) were resistant to nalidixic acid. One Hundred (55%) of isolates had MIC of <0.125 mg/ml to ciprofloxacin of these 92 (92%) were sensitive to nalidixic acid. Conclusion: Automated system like MicroScan (MicroScan Walk Away System 96, Dade Behring Inc., West Sacramento CA95691, USA) which is routinely used routinely in our laboratory can not accurately detect decrease susceptibility of salmonella spp to ciprofloxacin if MIC of 1 mg/ml is used as a break point. It is prudent to use nalidixic acid disk diffusion susceptibility method to detect ciprofloxacin decreased susceptibility of salmonella spp with higher degree of correlation approaching 90%. We recommend using nalidixic acid disk diffusion on all samonella spp susceptibility testing to predict ciprofloxacin susceptibilities. However ciprofloxacin MIC testing might be indicated in case of sterile body site isolates of salmonella where the MIC of 0.06 mg/ml suppose to correlate with good clinical response.
Antimicrobials: Surveillance and epidemiology of drug resistance in Gram positive and Gram negative organisms P28 Clonal diversity of high level gentamicin resistant Enterococcus faecalis isolated from clinical samples in Tehran, Iran M. Saifi1 *, M. Pourshafie1 , M. Soltan Dallal2 , S. Aghaei3 . 1 Pasteur Institute of Iran, Tehran, Iran, 2 School of public health Tehran University, Tehran, Iran, 3 Karaj Azad University, Karaj, Iran Objectives: Enterococci are one of the leading causes of nosocomial infections. Following the worldwide increased of high-level gentamicin resistace (HLGR) among enterococcal isolates; we report in the present study the isolation of HLGR Enterococcus faecalis (HLGR-EF) from clinical samples, and clonal relatedness of them in Tehran-Iran. Methods: From September 2006 to 2007, 266 enterococcal isolates were detected from the patients referred to 5 medical centers in Tehran. All strains were identified to species level by conventional and PCR methods. CLSI recommendations were used for antimicrobial susceptibility and gentamicin MICs of HLGR-EF isolates. Analysis of gentamicin resistant genes was done by PCR method. Boichemical fingerprint typing (PhP typing) was applied for primary typing of enterococcal population. Analysis of the SmaI restriction digest of