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A1.27 Comparative minimal inhibitory and resistance prevention drug concentrations of azithromycin, clarithromycin, erythromycin and telithromycin against 260 clinical isolates of Streptococcus pneumoniae
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Free Papers~International Journal of Antimicrobial Agents 26S (2005) $65 Sl12
strains possessing the met (A) gene are resistant only to 14- and 15membered macrolides (M phenotype). Study Design: A cross sectional prevalence study Setting: University hospital in Hong Kong Population: Streptococcus pneumoniae isolates from hospital patients Methodology: Clinical isolates of S. pneumoniae were collected from four district hospitals in Hong Kong between 2003 and 2004 and screened for erythromycin resistance by disc susceptibility testing using atan dard methods. Mechanisms of erythromyein resistance were determined phenotypically using a 3 disc method (azithromycin, spimmycin and clindamycin). DNA was extracted from all eib~ttu'omycin non susceptible strains and amplified using PCR to identify the met(A) and erm(B) genes. MIC for erytln'omycin was detelmined by E test. Results: Out of 162 clinical isolates of S. pneumoniae collected, 40 isolates (24.7%) were susceptible, 14 (8.6%:) intermediate and 108 (:67%:) resistant to erythromycin. One hundred and one (101 or 83%) of e~ytln'omycin resistant strains were co-resistm~t to penicillin wliile overall 94% were co-msistmlt to at least one other drug. Phenotypically 58 isolates (48%) were MLSB type and 64 (152%1) M type. All MLSB type had the erm(B) gene while 3% of the M type did not have the met(A) gene. Eight strains (6%:) possessed both genes and 7 of these had an MIC of 256 mg/L. Conclusion: OvemU levels of erythromycin resistance remain high in Hong Kong. There was a relatively even distribution of resistance mechanisms indicating an increase in the ermB gene carriage in recent years in this region.
A1.27
Comparative Minimal Inhibitory and Resistance Prevention Drug Concentrations of Azithromycin, Clarithromycin, Erythromycin and Telithromycin against 260 Clinical Isolates of Streptococcus pneumoniae Joseph M. BLONDEAU, Shantelle BORSOS. Royal University Hospital;
U)tiversiiy of Saskatchewan, Saskatoon, SK, Canada Objectives: To deteia~ine and compare minimal inhibitory and resistance prevention drug concentration of azalide, macrolide and ketolide compounds against recently collected (:2003 2005:) clinical isolates of Streptococcus pneumoniae Significance: Differentiating compounds based on their ability to pro vent the selection of resistant sub population from high density bacterial inocula may lead to mm'e appropriate use of these compounds. Study Design: In vitro measurements of in vitro susceptibility based on standard MIC versus resistance prevention concentration testing Setting: Clinical Microbiology Department serving three acute care hospitals and community based physician practices Population: All patients from whom a specimen was submitted for diagnosis of a msph'atoi5~ tract infection. Methodology; Minimal inhibitmy concentration testing using 100 000 colony forming units per n ~ t e r and resistance prevention concentration testing with 1 10 billion organisms on agar plates containing varying drug concentration were performed. Results: For 260 clinical isolates, MIC50/90 (gg/ml) results for azithromycin, clarittn'omycin, eiytln'omycin and telittn'omcyin respectively were 0.125/8, 0.031~, 0.063/4, 0.008/0.063 and 72.5-84% were susceptible to the first 3 drugs and 100% to telittn'omycin. The percentage of organisms with MICs > 1 gg/ml was not statistically different for azithromycin (17%:), clarithromycin (16%) and azithromycin (16%) but was lower for telithromycin (< 1%). RPC50/90 (gg/ml) values respectively were 1/32, 0.25/16, 0.5/2, 0.031/0.25 and the pel,centage of isolates with RPC values of >1 It.g/ml respectively were 75, 27 (p<0.0001 vs azittn'omycin), 36 (p<0.0001 vs azitln'omycin), 0.2 (p<0.0001 for azithromyein, clarithromyein, erythromycin. Conclusion: Subpopulations with RPC values of > 1 g/ml were more readily selected for S. pneumoniae clinical isolates in the presence of azitln'omycin than the other compounds. The rank of order of potency
based on those measurements were telitln'omycin > clatitliromycin > erythromycin > azithromycin. Selective use of the more active compounds may slow the rate of escalating maerolide resistance with S. pneumoniae.
A1,28
Carriage of Streptococcus pneuraoniae in Primary School Children in a Minority Population in a Mountainous Region of Guangxi Province of China Maumen BOOST, Margaret O'DONOGHUE. Sehool of Nursing, The
Hong Kong Polyteehnic lJ)tiversi~, Kowloon, Hong Kong SAR Objectives: To determine the prevalence of carriage and antibiotic resistance of Streptococcus pneumoniae in a rural minority population in China Significance; There is limited knowledge of levels of carriage and antibiotic lesistance in Southern China. Carriage levels in primary school clfildren in Hong Kong and Guangzhou axe lower than for most developed countries. This may be attributable to climatic or genetic factors. Investigation of a rural population may help explain low carriage rates in Southern China. Antibiotic resistance is attributed to high or inappropriate use of antibiotics. Levels of resistance in S. pneumoniae have risen rapidly in Asia especially in areas of high antibiotic use. This study investigates resistance levels in an area of low antibiotic use. Study Design: Cross sectional prevalence study Setting: A rural community, Du'an County, Guangxi, PRC Population: Primary school children Methodology: Nasopharyngeal swabs were collected from 608 chil dren, mainly of the Xiao and Zhuang minority people, attending five primary schools in a remote region of Guangxi. Cultures were perfoirned on Columbia blood agar and colonies resembling S. pneumoniae were identified by Gram smear, optoehin sensitivity, and bile solubility. Antibi otic susceptibility testing was performed by disc diffusion and resistance to oxacillin confirmed by MIC for penicillin. Isolates were serotyped using antisera-coated latex beads. Results: Of 611 clfildren sampled, 48 (17.9%) carried S. pneumoniae. There was no significant difference in carriage levels between schools with carriage levels ranging from 5.9- 10.3%. There was considerable erythromycin and tetracycline resistance (48 and 69% respectively:), but penicillin resistance, which was observed in isolates from four schools, was 19% with no high level resistance. The most common serotypes were 19F, 3, 23F, and 6. Conclusiml: Carriage rates were low compared to rural areas elsewhei~e in Asia. Resistance levels to tetracycline and eib~ttu'omycin were high in spite of low rates of antibiotic use.
A1.29
Telithromycin Susceptibility and Macrolide Resistance Mechanisms of Pneumococcal Strains Isolated from Pediatric Patients in Southwestern Japan Masaaki IKENAGA, Kensuke NAGAI, Kenji GOTO, Hidenobu HIDAKA, Hiroyasu KOGA, Kenji MASUNAGA, Naoki TSUMURA. Kurume
U)ziversiiy Sehool of Medicine, Kurume, Japan Objectives: To determine the maerolide resistance mechanisms in Streptococcus pneumoniae strains and their susceptibility to telithromyein and other maerolides Significance: The prevalence of macrolide resistance among Streptococcus pneumoniae continues to be a problem for Ueatment of msphatmy infections in clfildmn. Telitln'omycin (TEL) is a ketolide, active against common respiratory tract pathogens, including macrolide resistant S.
p~eumoniae. Study Design: Analytical study
Population; Streptococcus pneumoniae isolates from pediatric patients
Free Papers~International Journal of Antimicrobial Agents 26S (2005) $65 Sl12
strains possessing the met (A) gene are resistant only to 14- and 15membered macrolides (M phenotype). Study Design: A cross sectional prevalence study Setting: University hospital in Hong Kong Population: Streptococcus pneumoniae isolates from hospital patients Methodology: Clinical isolates of S. pneumoniae were collected from four district hospitals in Hong Kong between 2003 and 2004 and screened for erythromycin resistance by disc susceptibility testing using atan dard methods. Mechanisms of erythromyein resistance were determined phenotypically using a 3 disc method (azithromycin, spimmycin and clindamycin). DNA was extracted from all eib~ttu'omycin non susceptible strains and amplified using PCR to identify the met(A) and erm(B) genes. MIC for erytln'omycin was detelmined by E test. Results: Out of 162 clinical isolates of S. pneumoniae collected, 40 isolates (24.7%) were susceptible, 14 (8.6%:) intermediate and 108 (:67%:) resistant to erythromycin. One hundred and one (101 or 83%) of e~ytln'omycin resistant strains were co-resistm~t to penicillin wliile overall 94% were co-msistmlt to at least one other drug. Phenotypically 58 isolates (48%) were MLSB type and 64 (152%1) M type. All MLSB type had the erm(B) gene while 3% of the M type did not have the met(A) gene. Eight strains (6%:) possessed both genes and 7 of these had an MIC of 256 mg/L. Conclusion: OvemU levels of erythromycin resistance remain high in Hong Kong. There was a relatively even distribution of resistance mechanisms indicating an increase in the ermB gene carriage in recent years in this region.
A1.27
Comparative Minimal Inhibitory and Resistance Prevention Drug Concentrations of Azithromycin, Clarithromycin, Erythromycin and Telithromycin against 260 Clinical Isolates of Streptococcus pneumoniae Joseph M. BLONDEAU, Shantelle BORSOS. Royal University Hospital;
U)tiversiiy of Saskatchewan, Saskatoon, SK, Canada Objectives: To deteia~ine and compare minimal inhibitory and resistance prevention drug concentration of azalide, macrolide and ketolide compounds against recently collected (:2003 2005:) clinical isolates of Streptococcus pneumoniae Significance: Differentiating compounds based on their ability to pro vent the selection of resistant sub population from high density bacterial inocula may lead to mm'e appropriate use of these compounds. Study Design: In vitro measurements of in vitro susceptibility based on standard MIC versus resistance prevention concentration testing Setting: Clinical Microbiology Department serving three acute care hospitals and community based physician practices Population: All patients from whom a specimen was submitted for diagnosis of a msph'atoi5~ tract infection. Methodology; Minimal inhibitmy concentration testing using 100 000 colony forming units per n ~ t e r and resistance prevention concentration testing with 1 10 billion organisms on agar plates containing varying drug concentration were performed. Results: For 260 clinical isolates, MIC50/90 (gg/ml) results for azithromycin, clarittn'omycin, eiytln'omycin and telittn'omcyin respectively were 0.125/8, 0.031~, 0.063/4, 0.008/0.063 and 72.5-84% were susceptible to the first 3 drugs and 100% to telittn'omycin. The percentage of organisms with MICs > 1 gg/ml was not statistically different for azithromycin (17%:), clarithromycin (16%) and azithromycin (16%) but was lower for telithromycin (< 1%). RPC50/90 (gg/ml) values respectively were 1/32, 0.25/16, 0.5/2, 0.031/0.25 and the pel,centage of isolates with RPC values of >1 It.g/ml respectively were 75, 27 (p<0.0001 vs azittn'omycin), 36 (p<0.0001 vs azitln'omycin), 0.2 (p<0.0001 for azithromyein, clarithromyein, erythromycin. Conclusion: Subpopulations with RPC values of > 1 g/ml were more readily selected for S. pneumoniae clinical isolates in the presence of azitln'omycin than the other compounds. The rank of order of potency
based on those measurements were telitln'omycin > clatitliromycin > erythromycin > azithromycin. Selective use of the more active compounds may slow the rate of escalating maerolide resistance with S. pneumoniae.
A1,28
Carriage of Streptococcus pneuraoniae in Primary School Children in a Minority Population in a Mountainous Region of Guangxi Province of China Maumen BOOST, Margaret O'DONOGHUE. Sehool of Nursing, The
Hong Kong Polyteehnic lJ)tiversi~, Kowloon, Hong Kong SAR Objectives: To determine the prevalence of carriage and antibiotic resistance of Streptococcus pneumoniae in a rural minority population in China Significance; There is limited knowledge of levels of carriage and antibiotic lesistance in Southern China. Carriage levels in primary school clfildren in Hong Kong and Guangzhou axe lower than for most developed countries. This may be attributable to climatic or genetic factors. Investigation of a rural population may help explain low carriage rates in Southern China. Antibiotic resistance is attributed to high or inappropriate use of antibiotics. Levels of resistance in S. pneumoniae have risen rapidly in Asia especially in areas of high antibiotic use. This study investigates resistance levels in an area of low antibiotic use. Study Design: Cross sectional prevalence study Setting: A rural community, Du'an County, Guangxi, PRC Population: Primary school children Methodology: Nasopharyngeal swabs were collected from 608 chil dren, mainly of the Xiao and Zhuang minority people, attending five primary schools in a remote region of Guangxi. Cultures were perfoirned on Columbia blood agar and colonies resembling S. pneumoniae were identified by Gram smear, optoehin sensitivity, and bile solubility. Antibi otic susceptibility testing was performed by disc diffusion and resistance to oxacillin confirmed by MIC for penicillin. Isolates were serotyped using antisera-coated latex beads. Results: Of 611 clfildren sampled, 48 (17.9%) carried S. pneumoniae. There was no significant difference in carriage levels between schools with carriage levels ranging from 5.9- 10.3%. There was considerable erythromycin and tetracycline resistance (48 and 69% respectively:), but penicillin resistance, which was observed in isolates from four schools, was 19% with no high level resistance. The most common serotypes were 19F, 3, 23F, and 6. Conclusiml: Carriage rates were low compared to rural areas elsewhei~e in Asia. Resistance levels to tetracycline and eib~ttu'omycin were high in spite of low rates of antibiotic use.
A1.29
Telithromycin Susceptibility and Macrolide Resistance Mechanisms of Pneumococcal Strains Isolated from Pediatric Patients in Southwestern Japan Masaaki IKENAGA, Kensuke NAGAI, Kenji GOTO, Hidenobu HIDAKA, Hiroyasu KOGA, Kenji MASUNAGA, Naoki TSUMURA. Kurume
U)ziversiiy Sehool of Medicine, Kurume, Japan Objectives: To determine the maerolide resistance mechanisms in Streptococcus pneumoniae strains and their susceptibility to telithromyein and other maerolides Significance: The prevalence of macrolide resistance among Streptococcus pneumoniae continues to be a problem for Ueatment of msphatmy infections in clfildmn. Telitln'omycin (TEL) is a ketolide, active against common respiratory tract pathogens, including macrolide resistant S.
p~eumoniae. Study Design: Analytical study
Population; Streptococcus pneumoniae isolates from pediatric patients