ABSTRACT
Schizophyllum commune is a mold in phylum Basidiomycota and is an uncommon human pathogen. Sinusitis and allergic bronchopulmonary mycosis are the two major diseases caused by S. commune. Although there have been several reports of invasive fungal diseases, most of them were invasive sinusitis. We present a case of invasive fungal pneumonia due to S. commune, developed in a patient with acute myeloid leukemia presenting neutropenic fever. The diagnosis was made by characteristic macroscopic and microscopic findings of fungal isolate and was confirmed via sequencing of internal transcribed spacer region. The patient was improved after 8 weeks of antifungal therapy based on the susceptibility result.We propose that S. commune should be considered as an emerging pathogen of invasive fungal pneumonia when a patient is under immunocompromised state. We also reviewed global literatures focused on the invasive fungal diseases caused by S. commune
ABSTRACT
Animal models are essential to studies of infectious diseases. The use of mice to test bacterial infection has been extensively reported. However, methods applied to clinical isolates, particularly for carbapenem-resistant bacteria, must be tailored according to the infection models and bacteria used. In this study, we infected 6-week-old female BALB/c mice intraperitoneally with different strains of resistant bacteria plus 3% hog gastric mucin. This method was found to be efficient and readily applicable for investigation of carbapenem-resisant Gram-negative pathogens (e.g., Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii) detected in Korea.
Subject(s)
Animals , Female , Humans , Mice , Acinetobacter , Bacteria , Bacterial Infections , Communicable Diseases , Escherichia coli , Gastric Mucins , Gram-Negative Bacteria , Klebsiella pneumoniae , Korea , Methods , Models, Animal , Peritonitis , Pseudomonas aeruginosaABSTRACT
BACKGROUND: Small colony variants (SCVs) of Staphylococcus aureus have emerged to be commonly associated with persistent and relapsing infections. Arbekacin (ABK) is one of a few alternatives to vancomycin in intractable case of methicillin resistant S. aureus (MRSA) infection. However, it has not yet been defined whethter ABK tends to be efficacious to the MRSA SCVs. In this study, we employed an in vitro pharmacodynamic infection model (IVPDIM) to define efficacies of ABK against MRSA SCVs. MATERIALS AND METHODS: Using four strains of clinically isolated MRSA (MRSA122, MRSA160, MRSA18, MRSA123), we adopted IVPDIM comprised of two-compartment in which effective surface-to-volume ratio of 5.34 cm(-1). Human pharmacokinetic regimen simulations of ABK were as follows: 100 mg every 12 h (q12h), 200 mg q24h, 200 mg q12h, and 400 mg q24h. Samples were taken from each model at 0, 1, 2, 4, 6, 12, 24, and 30 h, and the bacterial colony counts were determined. The experiments were repeated twice with ABK-administered groups and control group. RESULTS: MICs of ABK for MRSA122, MRSA160, MRSA18, and MRSA123 were 2, 2, 2, and 1 microgram/mL, respectively. In case of MRSA122, MRSA160, MRSA18, C(max)/MIC were less than 9.0 except for ABK 400 mg q24h regimen. In MRSA123, C(max)/MIC were 8.9 on average at ABK 100 mg q12h regimen. But, other regimen showed C(max)/MIC >9. Four regimens for 4 strains showed statistically different colony counts at 30 h (P=0.000). The more dosage or less frequent dosing interval, the more colonies tended to reduce in all strains. In 100 mg q12h groups, SCVs were observed in all strains within 24 h. With increment of dosage or changing dosing interval from q12h to 24h, SCVs were reduced (P=0.000). Regimen of 400 mg q24h did not let SCVs appear in all strains of MIC 2 microgram/mL during the experiments. CONCLUSION: SCVs were observed when MIC of ABK against MRSA were 1-2 microgram/mL, especially in most cases of C(max)/MIC <9. Those findings were also associated with re-growth of colony during the experiments. Once-daily dosing of ABK could reduce or eliminate the appearance of SCV.
Subject(s)
Humans , Linear Energy Transfer , Methicillin Resistance , Methicillin , Methicillin-Resistant Staphylococcus aureus , Staphylococcus aureus , Staphylococcus , VancomycinABSTRACT
BACKGROUND: During the era of increasing penicillin resistant Streptococcus pneumoniae, it is important to have knowledge about adequate dosage and dosing interval of ceftriaxone (CTR). We examined efficacies of once-daily CTR and compared results in an in vitro pharmacodynamic infection model (IVPDIM) supplemented with albumin and those without albumin. METHODS: Using three clinically isolated S. pneumoniae that were susceptible (SM24), intermediate (SM47) and resistant (SM60) against CTR, we utilized a two-compartment IVPDIM. CTR 2 g was administered intravenously every 24 h. Human albumin was added with concentration of 4 g/dL. Samples were removed at multiple time points over a 48-h period to determine the colony counts. RESULTS: In SM24 and SM60, bactericidal effects were observed within 6 hours in groups without albumin. The number of colonies during 1st 6 hours were more decreased in albumin-free groups than in albumin-supplemented groups (P<0.05). In SM47, similar results were found during 1st 6 hours (P=0.03). But, regrowth was observed in albumin supplemented group at 30 h. Irrespective of results of minimal inhibitory concentrations and albumin supplementation, bactericidal effects were shown at 24 h in all 3 strains. All groups were decreased below the detection limit at 48 h. Development of resistance was not detected throughout the entire study period in either strain. CONCLUSIONS: Although extents of killing in albumin supplemented broth of once-daily CTR dosing were delayed in all 3 strains compared with those of albumin free broth, final efficacies were not different between the two groups.
Subject(s)
Humans , Ceftriaxone , Homicide , Limit of Detection , Penicillins , Pneumonia , Streptococcus pneumoniae , StreptococcusABSTRACT
BACKGROUND: Small colony variants (SCVs) of Staphylococcus aureus have emerged to be commonly associated with persistent and relapsing infections. Arbekacin (ABK) is one of a few alternatives to vancomycin in intractable case of methicillin resistant S. aureus (MRSA) infection. However, it has not yet been defined whethter ABK tends to be efficacious to the MRSA SCVs. In this study, we employed an in vitro pharmacodynamic infection model (IVPDIM) to define efficacies of ABK against MRSA SCVs. MATERIALS AND METHODS: Using four strains of clinically isolated MRSA (MRSA122, MRSA160, MRSA18, MRSA123), we adopted IVPDIM comprised of two-compartment in which effective surface-to-volume ratio of 5.34 cm(-1). Human pharmacokinetic regimen simulations of ABK were as follows: 100 mg every 12 h (q12h), 200 mg q24h, 200 mg q12h, and 400 mg q24h. Samples were taken from each model at 0, 1, 2, 4, 6, 12, 24, and 30 h, and the bacterial colony counts were determined. The experiments were repeated twice with ABK-administered groups and control group. RESULTS: MICs of ABK for MRSA122, MRSA160, MRSA18, and MRSA123 were 2, 2, 2, and 1 microgram/mL, respectively. In case of MRSA122, MRSA160, MRSA18, C(max)/MIC were less than 9.0 except for ABK 400 mg q24h regimen. In MRSA123, C(max)/MIC were 8.9 on average at ABK 100 mg q12h regimen. But, other regimen showed C(max)/MIC >9. Four regimens for 4 strains showed statistically different colony counts at 30 h (P=0.000). The more dosage or less frequent dosing interval, the more colonies tended to reduce in all strains. In 100 mg q12h groups, SCVs were observed in all strains within 24 h. With increment of dosage or changing dosing interval from q12h to 24h, SCVs were reduced (P=0.000). Regimen of 400 mg q24h did not let SCVs appear in all strains of MIC 2 microgram/mL during the experiments. CONCLUSION: SCVs were observed when MIC of ABK against MRSA were 1-2 microgram/mL, especially in most cases of C(max)/MIC <9. Those findings were also associated with re-growth of colony during the experiments. Once-daily dosing of ABK could reduce or eliminate the appearance of SCV.
Subject(s)
Humans , Linear Energy Transfer , Methicillin Resistance , Methicillin , Methicillin-Resistant Staphylococcus aureus , Staphylococcus aureus , Staphylococcus , VancomycinABSTRACT
BACKGROUND: During the era of increasing penicillin resistant Streptococcus pneumoniae, it is important to have knowledge about adequate dosage and dosing interval of ceftriaxone (CTR). We examined efficacies of once-daily CTR and compared results in an in vitro pharmacodynamic infection model (IVPDIM) supplemented with albumin and those without albumin. METHODS: Using three clinically isolated S. pneumoniae that were susceptible (SM24), intermediate (SM47) and resistant (SM60) against CTR, we utilized a two-compartment IVPDIM. CTR 2 g was administered intravenously every 24 h. Human albumin was added with concentration of 4 g/dL. Samples were removed at multiple time points over a 48-h period to determine the colony counts. RESULTS: In SM24 and SM60, bactericidal effects were observed within 6 hours in groups without albumin. The number of colonies during 1st 6 hours were more decreased in albumin-free groups than in albumin-supplemented groups (P<0.05). In SM47, similar results were found during 1st 6 hours (P=0.03). But, regrowth was observed in albumin supplemented group at 30 h. Irrespective of results of minimal inhibitory concentrations and albumin supplementation, bactericidal effects were shown at 24 h in all 3 strains. All groups were decreased below the detection limit at 48 h. Development of resistance was not detected throughout the entire study period in either strain. CONCLUSIONS: Although extents of killing in albumin supplemented broth of once-daily CTR dosing were delayed in all 3 strains compared with those of albumin free broth, final efficacies were not different between the two groups.
Subject(s)
Humans , Ceftriaxone , Homicide , Limit of Detection , Penicillins , Pneumonia , Streptococcus pneumoniae , StreptococcusABSTRACT
BACKGROUND: We performed this stody to find out about antimicrobial effect of lidocaine which is commonly used local anesthetic, and thrombin and epinephrine used for hemostasis during bronchoscopic procedures. MATERIALS AND METHODS: The microorganisms that were cultured from specimens obtained during bronchoscopy were Staphylococcus aureus (n=42), Streptococcus pneumoniae (n=42), Klebsiella pneumoniae (n=42), and Pseudomonas aeruginosa (n=43) collected from St. Mary's Hospital, from March to Sep 2004 were used for susceptibity testing. Susceptibility to lidocaine, thrombin, and epinephrine were tested according to the National Committee for Clinical Laboratory Standards. RESULT: MIC50 and MIC90 of lidocaine for S. aureus, S. pneumoniae, P. aeruginosa were all 20,000 microgram/mL and that for K. pneumoniae were 10,000 microgram/mL. MIC50 and MIC90 of thrombin for both S. aureus and P. aeruginosa was 500 IU/mL and above 500 IU/mL, respectively; that for K. pneumoniae were all above 500 IU/mL and for S. pneumoniae they were 125 IU/mL, MIC50 and MIC90 of epinephrine for K. pneumoniae and S. pneumoniae were above 500 microgram/mL; that for S. aureus and P. aeruginosa were 500 microgram/mL. CONCLUSION: We observed possible antimicrobial effect of lidocaine, thrombin, and epinephrine in vitro against pathogens such as S. aureus, S. pneumoniae, K. pneumoniae, P. aeruginosa, which are common respiratory microorganisms. The use of these agants could affect the result of bacterial culture.
Subject(s)
Bronchoscopy , Epinephrine , Hemostasis , Klebsiella pneumoniae , Lidocaine , Pneumonia , Pseudomonas aeruginosa , Staphylococcus aureus , Streptococcus pneumoniae , ThrombinABSTRACT
BACKGROUND: We performed this stody to find out about antimicrobial effect of lidocaine which is commonly used local anesthetic, and thrombin and epinephrine used for hemostasis during bronchoscopic procedures. MATERIALS AND METHODS: The microorganisms that were cultured from specimens obtained during bronchoscopy were Staphylococcus aureus (n=42), Streptococcus pneumoniae (n=42), Klebsiella pneumoniae (n=42), and Pseudomonas aeruginosa (n=43) collected from St. Mary's Hospital, from March to Sep 2004 were used for susceptibity testing. Susceptibility to lidocaine, thrombin, and epinephrine were tested according to the National Committee for Clinical Laboratory Standards. RESULT: MIC50 and MIC90 of lidocaine for S. aureus, S. pneumoniae, P. aeruginosa were all 20,000 microgram/mL and that for K. pneumoniae were 10,000 microgram/mL. MIC50 and MIC90 of thrombin for both S. aureus and P. aeruginosa was 500 IU/mL and above 500 IU/mL, respectively; that for K. pneumoniae were all above 500 IU/mL and for S. pneumoniae they were 125 IU/mL, MIC50 and MIC90 of epinephrine for K. pneumoniae and S. pneumoniae were above 500 microgram/mL; that for S. aureus and P. aeruginosa were 500 microgram/mL. CONCLUSION: We observed possible antimicrobial effect of lidocaine, thrombin, and epinephrine in vitro against pathogens such as S. aureus, S. pneumoniae, K. pneumoniae, P. aeruginosa, which are common respiratory microorganisms. The use of these agants could affect the result of bacterial culture.
Subject(s)
Bronchoscopy , Epinephrine , Hemostasis , Klebsiella pneumoniae , Lidocaine , Pneumonia , Pseudomonas aeruginosa , Staphylococcus aureus , Streptococcus pneumoniae , ThrombinABSTRACT
BACKGROUND: Panipenem (PAPM) is a new carbapenem which has an enhanced broad spectrum activity against both gram-positive and negative organisms. However, its activities in vitro against Pseudomonas aeruginosa are still under controversy. The aim of this study was to compare the activity of PAPM with those of imipenem (IMPM) against clinical isolates of P. aeruginosa using in vitro kinetic model and to evaluate the differences according to the quantity of basic amino acid in media. MATERIALS AND METHODS: Using a clinical isolate of P. aeruginosa (SGP14) from blood, an in vitro 2-compartment artificial capillary model based on a dialyzer unit was prepared. Antibiotics were given as a bolus q12 hrs for 48 hrs. Simulated doses and frequencies of PAPM and IMPM were 500 mg q12 hrs as approved by Korea Food and Drug Administration. Muller-Hinton broth (MHB) and minimal broth Davis (MBD) were used as culture media and we divided the experiments into 4 groups [PAPM (MHB), PAPM (MBD), IMPM (MHB), IMPM (MBD)]. At 0, 1, 2, 4, 6, 8, 12, 24, 32, and 48 h, samples were removed from peripheral compartment and viable bacterial counts were measured. RESULTS: The susceptibility of PAPM and IMPM for SGP14 were 64 and 2 ug/mL in MHB and 4 and 2 ug/mL in MBD, respectively. Up until 12 hours, changes in bacterial colony counts were not significantly different (P=0.073) for each group. However among the four groups, PAPM (MHB) showed the least changes compared with PMPM (MBD), IMPM (MBD). The largest decrement of colony during 48 hours was observed with PMPM (MBD), followed by IMPM (MHB) or IMPM (MBD), and PAPM (MHB) in decreasing order (P=0.00). There were no differences between IMPM (MHB) and IMPM (MBD) as for the change in colony counts. CONCLUSIONS: The bactericidal activities of panipenem against the clinical isolate of P. aeruginosa was similar (at 12 h) or superior (at 48 h) to that of imipenem in an in vitro 2-compartment artificial capillary model using minimal broth to simulate human serum drug concentrations.
Subject(s)
Humans , Amino Acids, Basic , Anti-Bacterial Agents , Bacterial Load , Capillaries , Culture Media , Imipenem , Korea , Pseudomonas aeruginosa , Pseudomonas , United States Food and Drug AdministrationABSTRACT
BACKGROUND: Panipenem (PAPM) is a new carbapenem which has an enhanced broad spectrum activity against both gram-positive and negative organisms. However, its activities in vitro against Pseudomonas aeruginosa are still under controversy. The aim of this study was to compare the activity of PAPM with those of imipenem (IMPM) against clinical isolates of P. aeruginosa using in vitro kinetic model and to evaluate the differences according to the quantity of basic amino acid in media. MATERIALS AND METHODS: Using a clinical isolate of P. aeruginosa (SGP14) from blood, an in vitro 2-compartment artificial capillary model based on a dialyzer unit was prepared. Antibiotics were given as a bolus q12 hrs for 48 hrs. Simulated doses and frequencies of PAPM and IMPM were 500 mg q12 hrs as approved by Korea Food and Drug Administration. Muller-Hinton broth (MHB) and minimal broth Davis (MBD) were used as culture media and we divided the experiments into 4 groups [PAPM (MHB), PAPM (MBD), IMPM (MHB), IMPM (MBD)]. At 0, 1, 2, 4, 6, 8, 12, 24, 32, and 48 h, samples were removed from peripheral compartment and viable bacterial counts were measured. RESULTS: The susceptibility of PAPM and IMPM for SGP14 were 64 and 2 ug/mL in MHB and 4 and 2 ug/mL in MBD, respectively. Up until 12 hours, changes in bacterial colony counts were not significantly different (P=0.073) for each group. However among the four groups, PAPM (MHB) showed the least changes compared with PMPM (MBD), IMPM (MBD). The largest decrement of colony during 48 hours was observed with PMPM (MBD), followed by IMPM (MHB) or IMPM (MBD), and PAPM (MHB) in decreasing order (P=0.00). There were no differences between IMPM (MHB) and IMPM (MBD) as for the change in colony counts. CONCLUSIONS: The bactericidal activities of panipenem against the clinical isolate of P. aeruginosa was similar (at 12 h) or superior (at 48 h) to that of imipenem in an in vitro 2-compartment artificial capillary model using minimal broth to simulate human serum drug concentrations.
Subject(s)
Humans , Amino Acids, Basic , Anti-Bacterial Agents , Bacterial Load , Capillaries , Culture Media , Imipenem , Korea , Pseudomonas aeruginosa , Pseudomonas , United States Food and Drug AdministrationABSTRACT
OBJECTIVE:This study was performed to compare the in vitro antimicrobial activities of prepenem (PRPM) with those of imipenem (IMPM) and meropenem (MRPM) against several clinical isolates of Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Streptococcus pneumoniae. METHODS: We tested the in vitro antimicrobial activities of PRPM, IMPM, and MRPM against total 300 clinical isolates of E. coli, K. pneumoniae, and P. aeruginosa and 134 chinical isolated of S. pneumoniae (41 penicillin-susceptible, 93 penicillin-resistant strains) collected in 5 different university hospitals (March to June, 2002). According to NCCLS guidelines, MICs of PRPM, IMPM, MRPM, and/or ceftazidime were determined. RESULTS: MIC90s of E. coli to IMPM, PRPM, and MRPM were 1, 1, and 0.125 microgram/mL, respectively. Those of K. pneumoniae were 1, 0.5, and 0.125 microgram/mL, respectively. In case of P. aeruginosa, MIC90s to IMPM, PRPM, MRPM, and ceftazidime were 16, 32, 8, and 64 microgram/mL, respectively. In penicillin-susceptible S. pneumoniae, MIC90s to IMPM, PRPM, MRPM were 0.25, 0.25, 0.5 microgram/mL, while those of penicillin-nonsusceptible strains were 1, 1, and 2 microgram/mL, respectively. IMPM and PRPM showed similar pattern of distribution of MIC to various bacterial species. CONCLUSION: E. coli, K. pneumoniae, and S. pneumonia were susceptible to PRPM, which had a pattern similar to IMPM. The antimicrobial activity of PRPM to P. aeruginosa was also comparable to that of IMPM. PRPM could be potentially useful drugs for treatment of infections caused by E. coli, K. pneumoniae, P. aeruginosa and S. pneumoniae.
Subject(s)
Carbapenems , Ceftazidime , Escherichia coli , Hospitals, University , Imipenem , Klebsiella pneumoniae , Korea , Pneumonia , Pseudomonas aeruginosa , Streptococcus pneumoniaeABSTRACT
BACKGROUND: Glycopeptide has been used for the one-and-only treatment of choice in methicillin resistant Staphylococcus aureus (MRSA) infection, but its exclusive use for the MRSA infection has led to the increased risk of glycopeptide-resistance. To find an alternative (s), we employed an in vitro infective endocarditis model (IVIEM) to compare the efficacy of vancomycin (VCM), arbekacin (ABK), and gentamicin (GM) alone or in combination. METHODS: Using two strains of clinically isolated MRSA, one GM susceptible (GS171) and the other GM resistant (GR153), fibrin clots were prepared and suspended in IVIEM. Antibiotics were added as a bolus to simulate human pharmacokinetics of regimens, including q 6 h, q 12 h, q 24 h, or continuous infusion with VCM, q 12 h or q 24 h with ABK, and q 8 h or q 24 h with GM. In cases of combination, regimens were VCM q 12 h plus ABK q 24 h, and VCM q 12 h plus GM q 24 h. Fibrin clots were removed from each model at 0, 8, 24, 32, 48, and 72 h, and the bacterial densities (in CFU/g) were determined. RESULTS: At 8 hour, the colony counts of GS171 were lower than those of GR153 (P=0.02), and the lowest with the ABK q12h against GS171 (P=0.01). At 72 hour, monotherapy with ABK or VCM produced same degree of bacterial reductions in IVIEM, regardless of dosing frequency or GM-resistance. In the case of GM-resistance, combination of VCM and ABK did show additive effect until 24 hours, although VCM and GM showed no indifference during all the experiments. Development of resistance during experiment was not observed with any regimens. CONCLUSIONS: Our data suggest that ABK monotherapy could be used as an alternative to VCM even in the treatment of GM-resistant staphylococcal endocarditis. Further studies with clinical trials are warranted to evaluate the additive effect of VCM and ABK.
Subject(s)
Humans , Anti-Bacterial Agents , Endocarditis , Fibrin , Gentamicins , Methicillin Resistance , Methicillin-Resistant Staphylococcus aureus , Pharmacokinetics , Staphylococcus aureus , VancomycinABSTRACT
OBJECTIVE:This study was performed to compare the in vitro antimicrobial activities of prepenem (PRPM) with those of imipenem (IMPM) and meropenem (MRPM) against several clinical isolates of Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Streptococcus pneumoniae. METHODS: We tested the in vitro antimicrobial activities of PRPM, IMPM, and MRPM against total 300 clinical isolates of E. coli, K. pneumoniae, and P. aeruginosa and 134 chinical isolated of S. pneumoniae (41 penicillin-susceptible, 93 penicillin-resistant strains) collected in 5 different university hospitals (March to June, 2002). According to NCCLS guidelines, MICs of PRPM, IMPM, MRPM, and/or ceftazidime were determined. RESULTS: MIC90s of E. coli to IMPM, PRPM, and MRPM were 1, 1, and 0.125 microgram/mL, respectively. Those of K. pneumoniae were 1, 0.5, and 0.125 microgram/mL, respectively. In case of P. aeruginosa, MIC90s to IMPM, PRPM, MRPM, and ceftazidime were 16, 32, 8, and 64 microgram/mL, respectively. In penicillin-susceptible S. pneumoniae, MIC90s to IMPM, PRPM, MRPM were 0.25, 0.25, 0.5 microgram/mL, while those of penicillin-nonsusceptible strains were 1, 1, and 2 microgram/mL, respectively. IMPM and PRPM showed similar pattern of distribution of MIC to various bacterial species. CONCLUSION: E. coli, K. pneumoniae, and S. pneumonia were susceptible to PRPM, which had a pattern similar to IMPM. The antimicrobial activity of PRPM to P. aeruginosa was also comparable to that of IMPM. PRPM could be potentially useful drugs for treatment of infections caused by E. coli, K. pneumoniae, P. aeruginosa and S. pneumoniae.
Subject(s)
Carbapenems , Ceftazidime , Escherichia coli , Hospitals, University , Imipenem , Klebsiella pneumoniae , Korea , Pneumonia , Pseudomonas aeruginosa , Streptococcus pneumoniaeABSTRACT
BACKGROUND: Glycopeptide has been used for the one-and-only treatment of choice in methicillin resistant Staphylococcus aureus (MRSA) infection, but its exclusive use for the MRSA infection has led to the increased risk of glycopeptide-resistance. To find an alternative (s), we employed an in vitro infective endocarditis model (IVIEM) to compare the efficacy of vancomycin (VCM), arbekacin (ABK), and gentamicin (GM) alone or in combination. METHODS: Using two strains of clinically isolated MRSA, one GM susceptible (GS171) and the other GM resistant (GR153), fibrin clots were prepared and suspended in IVIEM. Antibiotics were added as a bolus to simulate human pharmacokinetics of regimens, including q 6 h, q 12 h, q 24 h, or continuous infusion with VCM, q 12 h or q 24 h with ABK, and q 8 h or q 24 h with GM. In cases of combination, regimens were VCM q 12 h plus ABK q 24 h, and VCM q 12 h plus GM q 24 h. Fibrin clots were removed from each model at 0, 8, 24, 32, 48, and 72 h, and the bacterial densities (in CFU/g) were determined. RESULTS: At 8 hour, the colony counts of GS171 were lower than those of GR153 (P=0.02), and the lowest with the ABK q12h against GS171 (P=0.01). At 72 hour, monotherapy with ABK or VCM produced same degree of bacterial reductions in IVIEM, regardless of dosing frequency or GM-resistance. In the case of GM-resistance, combination of VCM and ABK did show additive effect until 24 hours, although VCM and GM showed no indifference during all the experiments. Development of resistance during experiment was not observed with any regimens. CONCLUSIONS: Our data suggest that ABK monotherapy could be used as an alternative to VCM even in the treatment of GM-resistant staphylococcal endocarditis. Further studies with clinical trials are warranted to evaluate the additive effect of VCM and ABK.