- Email: [email protected]
P101 Aeromonas species isolated from stool cultures and their susceptibilities to various antibiotics
Posters / International Journal of Antimicrobial Agents 42S2 (2013) S41–S159
Objectives: To clarify the ratio of resistant isolates against various antimicrobials in C. koseri , we performed this study. Methods: We used total of 373 non-duplicate C. koseri isolated from various clinical specimen from 75 hospitals in western part of Japan in the period from 2008 to 2010. The MICs of various antimicrobials against the isolates were determined by the two-fold serial agar dilution method as described by the CLSI. The resistant isolates to antimicrobials were interpreted as showing more than following breakpoint MIC. Antimicrobials (their breakpoint MIC) used in this study as follows; ampicillin (8), piperacillin (8), piperacillin/ tazobactam (8/4), faropenem (2), cefazolin (8), cefotiam (8), cefmetazole (16), flomoxef (8), cefpodoxime (2), cefditoren (2), aztoreonam (8), imipenem (4), meropenem (4), levofloxacin (2), minocycline (4), gentamicin (4), tobramicin (4), amikacin (16), isepamicin (16), trimethoprim/sulfamethoxazole (2/38), and fosfomycin (64). Results: The susceptibility ratios of penicillins, faropenem, cephalosporins except ceftazidime and aztreonam against all 373 C. koseri isolates were less than 50%. The susceptibility ratios of piperacillin/ tazobactam, ceftazidime, cefmetazole, and flomoxef were 52.5, 52.8, 53.1, and 85.3, respectively. Imipenem and meropenem inhibited the growth of all 373 C. koseri isolates at 2 and 4 mcg/ml. The ratios of levofloxacin, minocycline, fosfomycin, and trimethoprim/sulfamethoxazole were 33.8, 39.9, 98.9, and 63.5%. Concerning aminoglycosides, the susceptibility ratios of tobramycin, gentamicin, amikacin, and isepamicin were 76.9, 81.2, 97.9, 98.4%. Six of all 373 isolates showed high aminoglycoside-resistance; the MIC of all aminoglycosides used were more than 128 mcg/ml. Twenty-five of all 373 isolates showed resistance against all antimicrobials except carbapenems, amikacin, tobramycin, and fosfomycin. Conclusion: Most of C. koseri isolates have acquired beta-lactam resistance. The major factors of mechanisms of resistance were plasmid-mediated beta-lactamases, such as CTX-M-2, CTX-M-15, SHV-12, DHA-1, etc. About 7% of all isolates have acquired multi-drug resistance. P99 In vitro antimicrobial property of Rhodomyrtus tomentosa (Ait.) Hassk. against Streptococcus agalactiae isolated from cultured tilapia P. Na-Phatthalung1 *, N. Suanyuk2 , S.P. Voravuthikunchai1 . Department of Microbiology, 2 Department of Aquaculture, Prince of Songkla University, Songkhla, Thailand E-mail address : [email protected]
1
Introduction: Streptocuccus agalactiae is an important fish pathogen in freshwater farms that resulted in a continuous decrease of tilapia production in aquaculture. Ethanol extract of Rhodomyrtus tomentosa leaf and its purified compound, rhodomyrtone has been previously demonstrated to possess a strong antibacterial activity against Grampositive pathogens. Objectives: The purpose of this study was to investigate the in vitro antimicrobial activity of the Rhodomyrtus tomentosa extract on S. agalactiae isolated from tilapia during an outbreak in Southern, Thailand. Methods: Antimicrobial activity of the ethanol extract was performed using broth microdilution method. Time-kill assay was also conducted to evaluate the bactericidal effect of the extract. Scanning electron microscope (SEM) was used to observe morphological changes of bacterial cells after exposure to the extract. In addition, the effect of an oxidative stress on bacterial cells after treatment with the extract was studied using hydrogen peroxide sensitivity assay. Results: Remarkable minimum inhibitory concentrations (MIC) of the Rhodomyrtus tomentosa extract against S. agalactiae (n = 10) were ranged from 31.25 to 62.5 mg/mL. The extract was demonstrated bacteriostatic activity against a representative strain in time-kill studies. Additionally, SEM revealed an irregular shape, different size, and nondividing of S. agalactiae cells after treated with sub-MIC (0.25×MIC) of Rhodomyrtus tomentosa extract. Interestingly, treatment with the extract at sub-MIC (0.125×MIC and 0.25×MIC) significantly increased sensitivity to hydrogen peroxide of exponential phase bacteria. Conclusion: These results suggested that Rhodomyrtus tomentosa is a promising candidate for a new antimicrobial agent against
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S. agalactiae which should be further study as an alternative for prevention and control of streptococcal infection in aquaculture. Using an antimicrobial agent base on natural source can reduce the residual levels of antibiotics in fish products and harmful effects to human health. Reference(s) Limsuwana S, et al . (2009) Phytomedicine. 16: 645–651.
P100 Antibiotic susceptiblity pattern of Klebsiella pneumoniae from clinical samples at a tertiary hospital in Ile-Ife, South Western Nigeria A.O. Oladipo1 *, S.J. Udoh1 . 1 Medical Microbiology and Parasitology, Obafemi Awolowo University Teaching Hospitals Complex (OAUTHC), Ile-Ife, Nigeria E-mail address : [email protected] Introduction: In the recent years, klebsiella pneumoniae has become important pathogen in nosocomial infections worldwide. All the isolates of klebsiella pneumoniae identified from January-December 2012 were subjected to antibiotic sensitivity testing on Mueller Hinton agar by modified Kirby–Bauer disc diffusion method using NCCLS guidelines. K. pneumoniae were most frequently isolated from urine 604 (42.5%), sputum 240 (29.9%) followed by blood 180 (42.9%), pus 86 (37.0%) and CSF with the least incidence of 34 (14.8%). All strains were resistant to antibiotics such as amoxycilin 64%, gentamicin 92.6%, erythromycin 82.3%, trimethoprim 88% sulfamethoxazole 96.3%, tetracycline 88.5%, ciprofloxacin 31.2%, nitrofurantoin 31.2%, ceftazidime 69%, cefotaxime 74%, ceftriaxone 79.6% while sensitivity to imipenem was 100% by all the organisms. This study suggested that there is a need for regular antibiotic stewardship and strict surveillance in the hospitals to prevent misuse of available antimicrobials. Keywords: Kebsiella pneumoniae , Gram-negative, noscomial infection Objectives: To determine the antibiotic susceptiblity pattern of k. pneumoniae isolated from samples of patients attending aTertiary Hospitals at Ile-Ife, Nigeria Methods: K. pneumoniae strains were identified by their morphology and biochemical characteristics according to the standards. Antibiotic sensitivity testing was done for all the isolates on Mueller–Hinton agar by modified Kirby–Bauer disc diffusion technique (Bauer, 1990). Results: 1144 clinical samples were cultured from various sites from patients at Obafemi Awolowo University Teaching Hospitals Complex, Ile-Ife. K. pneumoniae were most frequently isolated from urine 604 (42.5%), sputum 240 (29.9%) followed by blood 180 (42.9%), pus 86 (37.0%) and CSF with the least incidence of 34 (14.8%). All isolates were resistant to different antibiotics such as amoxycilin 64%, gentamicin 92.6%, erythromycin 82.3%, trimethoprim, Sulfamethoxazole 96.3% tetracycline 88.5%, ciprofloxacin 31.2% nitrofurantoin 31.2%, ceftazidime 69%, cefotaxime 74%, ceftriaxone 79.6% with all the organisms showing 100% sensitivity to imipenem. Conclusion: All of the strains isolated were sensitive to imipenem. A major increase in resistance and decrease in sensitivity was observed for all the drugs tested towards k. pneumoniae strains isolated from blood, sputum, urine, CSF and pus samples. This study suggested that there is also a need to emphasize on the rational use of antimicrobials and regular antimicrobial susceptibility surveillance is essential.
P101 Aeromonas species isolated from stool cultures and their susceptibilities to various antibiotics B. Ongen1 *, M. Ilktac1 , A. Aydın1 , H. Nazik1 . 1 Medical Microbiology Department, Istanbul University, Istanbul Medical Faculty, Istanbul, Turkey E-mail address : [email protected] Introduction: Aeromonas spp. are emerging agents of gastroenteritis. Since most of the species produce inducible type chromosomal betalactamase, resistance can develop during beta-lactam therapy [1].
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Posters / International Journal of Antimicrobial Agents 42S2 (2013) S41–S159
Objectives: It was aimed to investigate the frequency of Aeromonas spp. in stool samples of patients with gastroenteritis between January 2007 and June 2012 and to determine their antibiotic susceptibilities. Methods: Stool samples were inoculated onto 5% sheep blood agar, MacConkey agar, Hektoen enteric agar, selenite F and Gram negative broth. Media were incubated aerobically at 35–37°C. Oxidase positive Gram negative rods on blood agar were investigated for Aeromonas spp. by API 32 GN and VITEK 2 systems (bioMerieux). ´ Amoxicillin–clavulanic acid, ampicillin–sulbactam, piperacillin–tazobactam, cefoxitine, cefotaxime, ceftazidime, cefepime, imipenem, meropenem, ertapenem, aztreonam, gentamicin, amikacin, ciprofloxacin, levofloxacin, co-trimoxazole, tetracycline and chloramphenicol susceptibilities were determined by disc diffusion method according to CLSI M45-A2 criteria [2]. Results: 60 (0.6%) Aeromonas spp. were isolated from 10,666 stool samples. Between 2007–2012; Aeromonas spp. was isolated at the rates of 0.4%, 0.12%, 0.45%, 0.2%, 1.1% and 0.7% respectively. Fortythree (72%) isolates were identified as A. hydrophila/caviae, 8 (13%) as A. sobria , 3 (5%) as A. veronii and 6 (10%) as Aeromonas spp. Polymorphonuclear leukocytes were positive for 25% of the samples in which Aeromonas was isolated. Of the stool samples in which Aeromonas spp. was isolated, approximately ¾ were watery with mucus and 6% were watery with blood and mucus. Antibiotic susceptibility testing was carried out for 52 isolates and all isolates were found to be susceptible to imipenem, meropenem and cefepime. The highest resistance rate was for ampicillin– sulbactam (92%) followed by amoxicillin–clavulanic acid (63%) and co-trimoxazole (37%). Except for tetracycline (19.2%) and cefoxitin (13.5%), resistance rates of other antibiotics were found to be lower than 10%. Conclusion: As a result, in diarrheagenic patients, the presence of Aeromonas spp. and their antibiotic susceptiblities should be followed up. Reference(s) [1] Horneman AJ, Ali A. Aeromonas . In Versalovic J, Carroll KC, Funke, G, Jorgensen JH, Landry M, Warnock DW (eds): Manual of Clinical Microbiology, 10th ed. ASM Press, Washington (2011). [2] Clinical Laboratory Standards Institute (CLSI). Methods for antimicrobial dilution and disk susceptibility testing of infrequently isolated or fastidious bacteria; Approved guideline, 2nd ed. M45-A2. Wayne PA: CLSI (2010).
P102 Usefulness of measuring vancomycin MIC against MRSA between 1 and 2 mg/mL for making predictions of clinical effectiveness and outcome H. Shimizu1 *, T. Yamaguchi1 , I. Nakamura1 , S. Fukushima1 , Y. Mizuno1 , T. Matsumoto1 . 1 Department of Infection Control and Prevention, Tokyo Medical University, Tokyo, Japan E-mail address : [email protected] Objectives: Recently “VCM MIC creep” has been reported all over the world and treatment failure has been of concern in the patients infected with MRSA strains at MIC = 2 mg/mL. We sought to confirm the actual distribution of VCM MIC and verify the usefulness of measuring VCM MIC between 1 and 2 mg/mL in consideration of clinical effectiveness and outcome. Methods: We collected a total of 96 MRSA strains which were isolated from blood cultures (from 72 patients) at Tokyo Medical University Hospital from January 2009 to June 2012. The most frequent primary site of infection was central venous lines (n = 23, 31.9%), followed by iliopsoas muscle abscess (n = 5, 6.9%), osteomyelitis (n = 4, 5.6%), and skin and soft tissue infections (n = 4, 5.6%). The VCM MICs were evaluated by using a modified consecutive dilution (0.06, 0.12, 0.25, 0.5, 0.75, 1, 1.25, 1.5, 1.75, 2, 2.25, 2.5, 2.75, 3, 3.25, 3.5, 3.75, and 4 mg/mL) frozen panel prepared by Eiken Chemical (Tokyo, Japan). Each bacterial solution was produced by manual adjustment to 2 McFarland turbidity. The MICs were evaluated after a 24hour incubation period. The relationships between VCM MIC and clinical effectiveness and outcome were examined by retrospective analysis. Clinical effectiveness was ranked at 4 levels: “effective”, “ineffective”, “partially effective”, and “judgment impossible”. We defined “ineffective” as the case in which at least one of four criteria
(white blood cell count, C-reactive protein, body temperature, and blood pressure) worsened. Results: Among the 96 strains isolated from blood, the VCM MIC distribution ranged from 0.5 to 2.75 mg/mL. The most common MIC was 1 mg/mL (41/96 strains [42.7%]), followed by 24 (25.0%), 17 (17.7%), 6 (6.3%), 3 (3.1%), and 2 (2.1%) of 96 strains having MICs of 0.75, 1.25, 0.5, 2, and 1.5 mg/mL, respectively. Fifty eight of 72 patients received VCM as an initial drug. The rate of ineffective cases was 41.7% (5/12 cases) with the MRSA strain at MIC 1.25 mg/mL, and 28.2% (11/39 cases) with the stain at MIC < 1.25 mg/mL. The overall 30-day mortality rate was 66.7% (4/6 cases) with the strain at MIC 1.5 mg/mL and 21.2% (11/52 cases) with the strain at MIC < 1.5 mg/mL. Conclusion: We showed that the majority of MRSA strains at VCM MIC = 2 mg/mL, if evaluated by using commercial dilution panel (0.5, 1, 2, 4, 8, and 16 mg/mL), was shown to be MIC = 1.25 mg/mL. However, the rate of clinically ineffective cases and the mortality rate increase around the VCM MICs = 1.25 and 1.5 mg/mL, respectively. We suggest that measuring VCM MIC against MRSA between 1 and 2 mg/mL is critically useful for making predictions of clinical effectiveness and outcome. P103 Prevalence of constitutive and inducible resistance to clindamycin in staphylococci isolates in Aliebne Abitaleb Hospital in Rafsanjan, Iran M. Tashakori1 *, F. Mohseni Moghadam1 , H. Esmaeili1 , M. Karimi1 , E. Jafari1 , P. Jafarpour1 . 1 Rafsanjan University of Medical Science, rafsanjan, Iran, Islamic Republic of E-mail address : [email protected] Introduction: Macrolide resistance is the most widespread and clinically important mechanism of resistance encountered with Grampositive organisms. Resistance to clindamycin (CL) in staphylococci is both constitutive and inducible. Objectives: In this present study, we evaluated the prevalence of the constitutive and inducible resistance to CL among isolated staphylococci in Ali-Ebne Abitaleb Hospital in Rafsanjan, Iran 2011. Methods: This descriptive-analytical study was conducted on 100 staphylococci isolates. All collected isolates were identified based on conventional laboratory methods. Susceptibility to oxacillin, cefoxitin, erythrocyin and clindamycin (CL) was performed by agar disk diffusion method according to CLSI guidelines. D-test was carried out for all the isolates with resistant phenotype for erythromycin and susceptible phenotype for CL. Results: Of the 100 staphylococcus isolates, 66% were susceptible to CL, 27% had constitutive and 7% had inducible resistance to Cl. The frequencies of constitutive and inducible resistance for CL in methicillin resistant Staphylococcus aureus (MRSA) were 51.2% and 12.82% respectively. statistical analysis revealed the inducible resistance in MRSA isolates to be 3.92 times more frequent than that in MSSA isolates Conclusion: In conclusion, we found a high prevalence of inducible clindamycin resistance phenotype among MRSA isolates in our region. we recommended that whenever clindamycin is intended to be used for staphylococcal infections, D-Test should be performed to facilitated the appropriate treatment of patients. P104 MICs distribution of vancomycin and teicoplanin of Staphylococcus aureus recovered from patients with bacteraemia C.-Y. Tsai1 *, C.-H. Lee, J.-W. Liu. 1 Kaohsiung Chang Gung Memorial Hospital, Kaohsiung, Taiwan, Kaohsiung, Taiwan E-mail address : [email protected] Introduction: Both vancomycin and teicoplanin are glycopeptide to treat methicillin-resistant Staphylococcus aureus (MRSA). Over the past decade, more and more studies have reported the factors associated with therapeutic failure in patients with MRSA bacteraemia demonstrated the relationship between vancomycin treatment failure and higher vancomycin minimal inhibitory concentration (MIC, 2 mg/L) values. But there were limited clinical data to teicoplanin.
Objectives: To clarify the ratio of resistant isolates against various antimicrobials in C. koseri , we performed this study. Methods: We used total of 373 non-duplicate C. koseri isolated from various clinical specimen from 75 hospitals in western part of Japan in the period from 2008 to 2010. The MICs of various antimicrobials against the isolates were determined by the two-fold serial agar dilution method as described by the CLSI. The resistant isolates to antimicrobials were interpreted as showing more than following breakpoint MIC. Antimicrobials (their breakpoint MIC) used in this study as follows; ampicillin (8), piperacillin (8), piperacillin/ tazobactam (8/4), faropenem (2), cefazolin (8), cefotiam (8), cefmetazole (16), flomoxef (8), cefpodoxime (2), cefditoren (2), aztoreonam (8), imipenem (4), meropenem (4), levofloxacin (2), minocycline (4), gentamicin (4), tobramicin (4), amikacin (16), isepamicin (16), trimethoprim/sulfamethoxazole (2/38), and fosfomycin (64). Results: The susceptibility ratios of penicillins, faropenem, cephalosporins except ceftazidime and aztreonam against all 373 C. koseri isolates were less than 50%. The susceptibility ratios of piperacillin/ tazobactam, ceftazidime, cefmetazole, and flomoxef were 52.5, 52.8, 53.1, and 85.3, respectively. Imipenem and meropenem inhibited the growth of all 373 C. koseri isolates at 2 and 4 mcg/ml. The ratios of levofloxacin, minocycline, fosfomycin, and trimethoprim/sulfamethoxazole were 33.8, 39.9, 98.9, and 63.5%. Concerning aminoglycosides, the susceptibility ratios of tobramycin, gentamicin, amikacin, and isepamicin were 76.9, 81.2, 97.9, 98.4%. Six of all 373 isolates showed high aminoglycoside-resistance; the MIC of all aminoglycosides used were more than 128 mcg/ml. Twenty-five of all 373 isolates showed resistance against all antimicrobials except carbapenems, amikacin, tobramycin, and fosfomycin. Conclusion: Most of C. koseri isolates have acquired beta-lactam resistance. The major factors of mechanisms of resistance were plasmid-mediated beta-lactamases, such as CTX-M-2, CTX-M-15, SHV-12, DHA-1, etc. About 7% of all isolates have acquired multi-drug resistance. P99 In vitro antimicrobial property of Rhodomyrtus tomentosa (Ait.) Hassk. against Streptococcus agalactiae isolated from cultured tilapia P. Na-Phatthalung1 *, N. Suanyuk2 , S.P. Voravuthikunchai1 . Department of Microbiology, 2 Department of Aquaculture, Prince of Songkla University, Songkhla, Thailand E-mail address : [email protected]
1
Introduction: Streptocuccus agalactiae is an important fish pathogen in freshwater farms that resulted in a continuous decrease of tilapia production in aquaculture. Ethanol extract of Rhodomyrtus tomentosa leaf and its purified compound, rhodomyrtone has been previously demonstrated to possess a strong antibacterial activity against Grampositive pathogens. Objectives: The purpose of this study was to investigate the in vitro antimicrobial activity of the Rhodomyrtus tomentosa extract on S. agalactiae isolated from tilapia during an outbreak in Southern, Thailand. Methods: Antimicrobial activity of the ethanol extract was performed using broth microdilution method. Time-kill assay was also conducted to evaluate the bactericidal effect of the extract. Scanning electron microscope (SEM) was used to observe morphological changes of bacterial cells after exposure to the extract. In addition, the effect of an oxidative stress on bacterial cells after treatment with the extract was studied using hydrogen peroxide sensitivity assay. Results: Remarkable minimum inhibitory concentrations (MIC) of the Rhodomyrtus tomentosa extract against S. agalactiae (n = 10) were ranged from 31.25 to 62.5 mg/mL. The extract was demonstrated bacteriostatic activity against a representative strain in time-kill studies. Additionally, SEM revealed an irregular shape, different size, and nondividing of S. agalactiae cells after treated with sub-MIC (0.25×MIC) of Rhodomyrtus tomentosa extract. Interestingly, treatment with the extract at sub-MIC (0.125×MIC and 0.25×MIC) significantly increased sensitivity to hydrogen peroxide of exponential phase bacteria. Conclusion: These results suggested that Rhodomyrtus tomentosa is a promising candidate for a new antimicrobial agent against
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S. agalactiae which should be further study as an alternative for prevention and control of streptococcal infection in aquaculture. Using an antimicrobial agent base on natural source can reduce the residual levels of antibiotics in fish products and harmful effects to human health. Reference(s) Limsuwana S, et al . (2009) Phytomedicine. 16: 645–651.
P100 Antibiotic susceptiblity pattern of Klebsiella pneumoniae from clinical samples at a tertiary hospital in Ile-Ife, South Western Nigeria A.O. Oladipo1 *, S.J. Udoh1 . 1 Medical Microbiology and Parasitology, Obafemi Awolowo University Teaching Hospitals Complex (OAUTHC), Ile-Ife, Nigeria E-mail address : [email protected] Introduction: In the recent years, klebsiella pneumoniae has become important pathogen in nosocomial infections worldwide. All the isolates of klebsiella pneumoniae identified from January-December 2012 were subjected to antibiotic sensitivity testing on Mueller Hinton agar by modified Kirby–Bauer disc diffusion method using NCCLS guidelines. K. pneumoniae were most frequently isolated from urine 604 (42.5%), sputum 240 (29.9%) followed by blood 180 (42.9%), pus 86 (37.0%) and CSF with the least incidence of 34 (14.8%). All strains were resistant to antibiotics such as amoxycilin 64%, gentamicin 92.6%, erythromycin 82.3%, trimethoprim 88% sulfamethoxazole 96.3%, tetracycline 88.5%, ciprofloxacin 31.2%, nitrofurantoin 31.2%, ceftazidime 69%, cefotaxime 74%, ceftriaxone 79.6% while sensitivity to imipenem was 100% by all the organisms. This study suggested that there is a need for regular antibiotic stewardship and strict surveillance in the hospitals to prevent misuse of available antimicrobials. Keywords: Kebsiella pneumoniae , Gram-negative, noscomial infection Objectives: To determine the antibiotic susceptiblity pattern of k. pneumoniae isolated from samples of patients attending aTertiary Hospitals at Ile-Ife, Nigeria Methods: K. pneumoniae strains were identified by their morphology and biochemical characteristics according to the standards. Antibiotic sensitivity testing was done for all the isolates on Mueller–Hinton agar by modified Kirby–Bauer disc diffusion technique (Bauer, 1990). Results: 1144 clinical samples were cultured from various sites from patients at Obafemi Awolowo University Teaching Hospitals Complex, Ile-Ife. K. pneumoniae were most frequently isolated from urine 604 (42.5%), sputum 240 (29.9%) followed by blood 180 (42.9%), pus 86 (37.0%) and CSF with the least incidence of 34 (14.8%). All isolates were resistant to different antibiotics such as amoxycilin 64%, gentamicin 92.6%, erythromycin 82.3%, trimethoprim, Sulfamethoxazole 96.3% tetracycline 88.5%, ciprofloxacin 31.2% nitrofurantoin 31.2%, ceftazidime 69%, cefotaxime 74%, ceftriaxone 79.6% with all the organisms showing 100% sensitivity to imipenem. Conclusion: All of the strains isolated were sensitive to imipenem. A major increase in resistance and decrease in sensitivity was observed for all the drugs tested towards k. pneumoniae strains isolated from blood, sputum, urine, CSF and pus samples. This study suggested that there is also a need to emphasize on the rational use of antimicrobials and regular antimicrobial susceptibility surveillance is essential.
P101 Aeromonas species isolated from stool cultures and their susceptibilities to various antibiotics B. Ongen1 *, M. Ilktac1 , A. Aydın1 , H. Nazik1 . 1 Medical Microbiology Department, Istanbul University, Istanbul Medical Faculty, Istanbul, Turkey E-mail address : [email protected] Introduction: Aeromonas spp. are emerging agents of gastroenteritis. Since most of the species produce inducible type chromosomal betalactamase, resistance can develop during beta-lactam therapy [1].
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Posters / International Journal of Antimicrobial Agents 42S2 (2013) S41–S159
Objectives: It was aimed to investigate the frequency of Aeromonas spp. in stool samples of patients with gastroenteritis between January 2007 and June 2012 and to determine their antibiotic susceptibilities. Methods: Stool samples were inoculated onto 5% sheep blood agar, MacConkey agar, Hektoen enteric agar, selenite F and Gram negative broth. Media were incubated aerobically at 35–37°C. Oxidase positive Gram negative rods on blood agar were investigated for Aeromonas spp. by API 32 GN and VITEK 2 systems (bioMerieux). ´ Amoxicillin–clavulanic acid, ampicillin–sulbactam, piperacillin–tazobactam, cefoxitine, cefotaxime, ceftazidime, cefepime, imipenem, meropenem, ertapenem, aztreonam, gentamicin, amikacin, ciprofloxacin, levofloxacin, co-trimoxazole, tetracycline and chloramphenicol susceptibilities were determined by disc diffusion method according to CLSI M45-A2 criteria [2]. Results: 60 (0.6%) Aeromonas spp. were isolated from 10,666 stool samples. Between 2007–2012; Aeromonas spp. was isolated at the rates of 0.4%, 0.12%, 0.45%, 0.2%, 1.1% and 0.7% respectively. Fortythree (72%) isolates were identified as A. hydrophila/caviae, 8 (13%) as A. sobria , 3 (5%) as A. veronii and 6 (10%) as Aeromonas spp. Polymorphonuclear leukocytes were positive for 25% of the samples in which Aeromonas was isolated. Of the stool samples in which Aeromonas spp. was isolated, approximately ¾ were watery with mucus and 6% were watery with blood and mucus. Antibiotic susceptibility testing was carried out for 52 isolates and all isolates were found to be susceptible to imipenem, meropenem and cefepime. The highest resistance rate was for ampicillin– sulbactam (92%) followed by amoxicillin–clavulanic acid (63%) and co-trimoxazole (37%). Except for tetracycline (19.2%) and cefoxitin (13.5%), resistance rates of other antibiotics were found to be lower than 10%. Conclusion: As a result, in diarrheagenic patients, the presence of Aeromonas spp. and their antibiotic susceptiblities should be followed up. Reference(s) [1] Horneman AJ, Ali A. Aeromonas . In Versalovic J, Carroll KC, Funke, G, Jorgensen JH, Landry M, Warnock DW (eds): Manual of Clinical Microbiology, 10th ed. ASM Press, Washington (2011). [2] Clinical Laboratory Standards Institute (CLSI). Methods for antimicrobial dilution and disk susceptibility testing of infrequently isolated or fastidious bacteria; Approved guideline, 2nd ed. M45-A2. Wayne PA: CLSI (2010).
P102 Usefulness of measuring vancomycin MIC against MRSA between 1 and 2 mg/mL for making predictions of clinical effectiveness and outcome H. Shimizu1 *, T. Yamaguchi1 , I. Nakamura1 , S. Fukushima1 , Y. Mizuno1 , T. Matsumoto1 . 1 Department of Infection Control and Prevention, Tokyo Medical University, Tokyo, Japan E-mail address : [email protected] Objectives: Recently “VCM MIC creep” has been reported all over the world and treatment failure has been of concern in the patients infected with MRSA strains at MIC = 2 mg/mL. We sought to confirm the actual distribution of VCM MIC and verify the usefulness of measuring VCM MIC between 1 and 2 mg/mL in consideration of clinical effectiveness and outcome. Methods: We collected a total of 96 MRSA strains which were isolated from blood cultures (from 72 patients) at Tokyo Medical University Hospital from January 2009 to June 2012. The most frequent primary site of infection was central venous lines (n = 23, 31.9%), followed by iliopsoas muscle abscess (n = 5, 6.9%), osteomyelitis (n = 4, 5.6%), and skin and soft tissue infections (n = 4, 5.6%). The VCM MICs were evaluated by using a modified consecutive dilution (0.06, 0.12, 0.25, 0.5, 0.75, 1, 1.25, 1.5, 1.75, 2, 2.25, 2.5, 2.75, 3, 3.25, 3.5, 3.75, and 4 mg/mL) frozen panel prepared by Eiken Chemical (Tokyo, Japan). Each bacterial solution was produced by manual adjustment to 2 McFarland turbidity. The MICs were evaluated after a 24hour incubation period. The relationships between VCM MIC and clinical effectiveness and outcome were examined by retrospective analysis. Clinical effectiveness was ranked at 4 levels: “effective”, “ineffective”, “partially effective”, and “judgment impossible”. We defined “ineffective” as the case in which at least one of four criteria
(white blood cell count, C-reactive protein, body temperature, and blood pressure) worsened. Results: Among the 96 strains isolated from blood, the VCM MIC distribution ranged from 0.5 to 2.75 mg/mL. The most common MIC was 1 mg/mL (41/96 strains [42.7%]), followed by 24 (25.0%), 17 (17.7%), 6 (6.3%), 3 (3.1%), and 2 (2.1%) of 96 strains having MICs of 0.75, 1.25, 0.5, 2, and 1.5 mg/mL, respectively. Fifty eight of 72 patients received VCM as an initial drug. The rate of ineffective cases was 41.7% (5/12 cases) with the MRSA strain at MIC 1.25 mg/mL, and 28.2% (11/39 cases) with the stain at MIC < 1.25 mg/mL. The overall 30-day mortality rate was 66.7% (4/6 cases) with the strain at MIC 1.5 mg/mL and 21.2% (11/52 cases) with the strain at MIC < 1.5 mg/mL. Conclusion: We showed that the majority of MRSA strains at VCM MIC = 2 mg/mL, if evaluated by using commercial dilution panel (0.5, 1, 2, 4, 8, and 16 mg/mL), was shown to be MIC = 1.25 mg/mL. However, the rate of clinically ineffective cases and the mortality rate increase around the VCM MICs = 1.25 and 1.5 mg/mL, respectively. We suggest that measuring VCM MIC against MRSA between 1 and 2 mg/mL is critically useful for making predictions of clinical effectiveness and outcome. P103 Prevalence of constitutive and inducible resistance to clindamycin in staphylococci isolates in Aliebne Abitaleb Hospital in Rafsanjan, Iran M. Tashakori1 *, F. Mohseni Moghadam1 , H. Esmaeili1 , M. Karimi1 , E. Jafari1 , P. Jafarpour1 . 1 Rafsanjan University of Medical Science, rafsanjan, Iran, Islamic Republic of E-mail address : [email protected] Introduction: Macrolide resistance is the most widespread and clinically important mechanism of resistance encountered with Grampositive organisms. Resistance to clindamycin (CL) in staphylococci is both constitutive and inducible. Objectives: In this present study, we evaluated the prevalence of the constitutive and inducible resistance to CL among isolated staphylococci in Ali-Ebne Abitaleb Hospital in Rafsanjan, Iran 2011. Methods: This descriptive-analytical study was conducted on 100 staphylococci isolates. All collected isolates were identified based on conventional laboratory methods. Susceptibility to oxacillin, cefoxitin, erythrocyin and clindamycin (CL) was performed by agar disk diffusion method according to CLSI guidelines. D-test was carried out for all the isolates with resistant phenotype for erythromycin and susceptible phenotype for CL. Results: Of the 100 staphylococcus isolates, 66% were susceptible to CL, 27% had constitutive and 7% had inducible resistance to Cl. The frequencies of constitutive and inducible resistance for CL in methicillin resistant Staphylococcus aureus (MRSA) were 51.2% and 12.82% respectively. statistical analysis revealed the inducible resistance in MRSA isolates to be 3.92 times more frequent than that in MSSA isolates Conclusion: In conclusion, we found a high prevalence of inducible clindamycin resistance phenotype among MRSA isolates in our region. we recommended that whenever clindamycin is intended to be used for staphylococcal infections, D-Test should be performed to facilitated the appropriate treatment of patients. P104 MICs distribution of vancomycin and teicoplanin of Staphylococcus aureus recovered from patients with bacteraemia C.-Y. Tsai1 *, C.-H. Lee, J.-W. Liu. 1 Kaohsiung Chang Gung Memorial Hospital, Kaohsiung, Taiwan, Kaohsiung, Taiwan E-mail address : [email protected] Introduction: Both vancomycin and teicoplanin are glycopeptide to treat methicillin-resistant Staphylococcus aureus (MRSA). Over the past decade, more and more studies have reported the factors associated with therapeutic failure in patients with MRSA bacteraemia demonstrated the relationship between vancomycin treatment failure and higher vancomycin minimal inhibitory concentration (MIC, 2 mg/L) values. But there were limited clinical data to teicoplanin.