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Query: UMLS:C0014118 (endocarditis)
 15,629 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We compared the pharmacodynamic activities of levofloxacin versus vancomycin, with or without rifampin, in an in vitro model with infected platelet-fibrin clots simulating vegetations. Infected platelet-fibrin clots were prepared with human cryoprecipitate, human platelets, calcium, thrombin, and approximately 10(9) CFU of organisms (MSSA 1199 and MRSA 494) per g and then were suspended via monofilament line into the in vitro model containing Mueller-Hinton growth medium. Antibiotics were administered by bolus injection into the model to simulate human pharmacokinetics; the regimens simulated included levofloxacin at dosages of 800 mg every 24 h (q24h) and 400 mg q12h, vancomycin at 1 g q12h, and rifampin at 600 mg q24h. Each model was run in duplicate over a 72-h period. Infected platelet-fibrin clots were removed in duplicate from each model, weighed, homogenized, serially diluted with sterile 0.9% saline, and plated on tryptic soy agar plates and plates containing antibiotics at 3, 6, and 12 times the MIC to evaluate the emergence of resistance. Time-kill curves were constructed by plotting the inoculum size versus time. Residual inoculum at 72 h was used to compare regimens. All levofloxacin regimens were significantly better than vancomycin monotherapy against both isolates (P < 0.002). Against MSSA 1199, levofloxacin q24h was significantly better than all other regimens, including levofloxacin q12h (P < 0.002); however, no difference between the levofloxacin monotherapy and combination therapy (with rifampin) regimens against MRSA 494 was seen. Killing activity for levofloxacin appeared to correlate better with the peak/MIC ratio than with the area under the curve/MIC ratio. The addition of rifampin significantly enhanced the activity of vancomycin but had little effect upon the activity of levofloxacin. For MRSA 494, vancomycin plus rifampin resulted in the greatest killing (P < 0.05). Development of resistance was not detected with any regimen. Levofloxacin may be a useful therapeutic alternative in the treatment of staphylococcal endocarditis, and further study with animal models of endocarditis or clinical trials are warranted.
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PMID:Pharmacodynamics of once- or twice-daily levofloxacin versus vancomycin, with or without rifampin, against Staphylococcus aureus in an in vitro model with infected platelet-fibrin clots. 885 96

Infective endocarditis is an uncommon disease but retains a high mortality. Glycopeptides are used for patients with resistant pathogens, those allergic to penicillins or for those outside the hospital. The once daily administration of teicoplanin and its low toxicity suggest that it would be suitable for use in the long courses required for endocarditis. However, the dosage and combinations to be used require further study. A retrospective review has been made of 104 episodes of endocarditis treated with teicoplanin in 101 patients seen over 7 years. Most patients had been referred to major London hospitals following failure of medical treatment. After three loading doses of 400 mg, teicoplanin was given at a dose of 400 mg/day in combination with other antibiotics such as gentamicin. Follow up was for one year. The most common pathogens were Streptococcus sanguis (15 cases), Staphylococcus aureus (13 cases) and Staphylococcus epidermidis (10 cases). Of 80 patients febrile at the start of treatment with teicoplanin, 63 (79%) lost their fever within a median of 2 days (1-35 days). Cure without surgery was effected in 50 (48%) and 75% of patients survived. Other antibiotics, usually gentamicin or rifampicin, were used in 92 (90%) of patients. Two strains of Streptococcus spp. were said to be resistant but there was no relationship between MIC of teicoplanin and outcome. Pathogens with a high MBC tended to be more likely to resist treatment. Adverse effects resulted in the withdrawal of teicoplanin in 20 cases (19%) but most events were mild and renal deterioration occurred in only five patients. Teicoplanin was effective in the treatment of endocarditis and appeared to be safe given the severity of disease in the patients treated.
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PMID:Treatment of endocarditis with teicoplanin: a retrospective analysis of 104 cases. 888 25

Two hundred microbiology laboratories in the UK took part in two separate experimental external quality assessment distributions related to the serum bactericidal test (SBT). In the first, Staphylococcus aureus NCTC 6571 (vancomycin MIC 1 mg/L), was tested against a human serum containing vancomycin 38 mg/L plus gentamicin 0.5 mg/L. In the second, Streptococcus oralis PAJ 112/4183 (penicillin MBC < or = 0.03 mg/L) and Streptococcus sanguis PAJ 107/4184 (penicillin MBC = 128 mg/L) were tested against human serum containing penicillin 15 mg/L. Respondents returned their laboratory results and a questionnaire on clinical interpretation and technical aspects. Most laboratories (194/199, 97.5%) recommend the use of the SBT in the management of infective endocarditis but only 48 (25.2%) often or always change therapy on the basis of the result. A wide range of interpretative criteria, definitions of bactericidal endpoints and methodologies are used. Performance in the first distribution was acceptable for 75% of laboratories but in the second only 34% could identify penicillin tolerance; 34 respondents reported an SBT result of < or = 2 for the tolerant strain, 81 laboratories reported one of > or = 16. Technical factors related to acceptable performance were: sonication of broth before counting the inoculum; knowing the inoculum size in cfu/mL; use of a 4-8 h broth culture to make the inoculum; incubation of recovery plates for > 36 h; use of a calibrated pipette to sample for surviving bacteria; use of measured volumes to add the inoculum. Use of uncalibrated pipettes or standard loops to recover survivors was related to poor performance. Microbiology departments in the UK should review the clinical need to perform the SBT in the light of their local circumstances and if they elect to continue to offer this test, revise their methodologies which could be producing misleading results when testing alpha-haemolytic streptococci.
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PMID:External quality assessment of the serum bactericidal test: results of a methodology/interpretation questionnaire. 906 54

Adaptive resistance following the first exposure to aminoglycosides is a recently described in vitro phenomenon in Pseudomonas aeruginosa and other aerobic gram-negative bacilli. We investigated the in vivo relevance of adaptive resistance in P. aeruginosa following a single dose of amikacin in the experimental rabbit endocarditis model. Rabbits with P. aeruginosa endocarditis received either no therapy (control) or a single intravenous (i.v.) dose of amikacin (80 mg/kg of body weight) at 24 h postinfection, after which they were sacrificed at 5, 8, 12, 16, or 24 h postdose. Excised aortic vegetations were subsequently exposed ex vivo to amikacin at 2.5, 5, 10 or 20 times the MIC for 90 min. In vivo adaptive resistance was identified when amikacin-induced pseudomonal killing within excised aortic vegetations was less in animals receiving single-dose amikacin in vivo than in vegetations from control animals not receiving amikacin in vivo. Maximal adaptive resistance occurred between 8 and 16 h after the in vivo amikacin dose, with complete refractoriness to ex vivo killing by amikacin seen at 12 h postdose. By 24 h postdose, bacteria within excised vegetations had partially recovered their initial amikacin susceptibility. In a parallel treatment study, we demonstrated that amikacin given once daily (but not twice daily) at a total dose of 80 mg/kg i.v. for 1-day treatment significantly reduced pseudomonal densities within aortic vegetations versus those in untreated controls. When therapy was continued for 3 days with the same total daily dose (80 mg/kg/day), amikacin given once or twice daily significantly reduced intravegetation pseudomonal densities versus those in controls. However, amikacin given once daily was still more effective than the twice-daily regimen. These data confirm the induction of aminoglycoside adaptive resistance in vivo and further support the advantages of once-daily aminoglycoside dosing regimens in the treatment of serious pseudomonal infections.
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PMID:Adaptive resistance of Pseudomonas aeruginosa induced by aminoglycosides and killing kinetics in a rabbit endocarditis model. 908 97

The influence of inducible cross-resistance to macrolides, lincosamides, and streptogramin B (MLS(B)) type antibiotics (inducible MLS(B) phenotype) on the activity of quinupristin-dalfopristin was investigated against Enterococcus faecium in vitro and in rabbits with experimental endocarditis. In vitro, quinupristin-dalfopristin displayed bacteriostatic and bactericidal activities against a MLS(B)-susceptible strain similar to those against two strains with the inducible MLS(B) phenotype. In addition, induction of the two MLS(B)-resistant strains with quinupristin (0.016 to 1 microg/ml) or quinupristin-dalfopristin (0.08 to 0.25 microg/ml) increased the MICs of quinupristin from 8 microg/ml to 32 to > 128 microg/ml, but did not modify the MIC of dalfopristin (2 microg/ml) or quinupristin-dalfopristin (0.5 microg/ml). In a rabbit endocarditis model, quinupristin-dalfopristin was as active as amoxicillin against the MLS(B)-susceptible E. faecium strain. In contrast, the activity of quinupristin-dalfopristin was significantly decreased in animals infected with either of the two inducible MLS(B)-resistant strains (P < 0.05), although no mutants resistant to quinupristin-dalfopristin were detected. Against the clinical strain with the inducible MLS(B) phenotype, quinupristin-dalfopristin was not effective and was less active than amoxicillin (P < 0.001); however, the activity of the combination of amoxicillin and dalfopristin-quinupristin was superior to that of amoxicillin (P < 0.01). The different impact of the inducible MLS(B) phenotype in E. faecium on the activity of quinupristin-dalfopristin in vitro and in experimental endocarditis may be related to the reduced diffusion of dalfopristin compared with that of quinupristin into cardiac vegetations that we previously reported. This result emphasizes the importance of the constant presence of dalfopristin at the site of infection to ensure synergism with quinupristin.
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PMID:Influence of inducible cross-resistance to macrolides, lincosamides, and streptogramin B-type antibiotics in Enterococcus faecium on activity of quinupristin-dalfopristin in vitro and in rabbits with experimental endocarditis. 914 47

The activity of methicillin, oxacillin, vancomycin, imipenem and FK037 against 106 isolates of staphylococci was assessed using a microbroth dilution method with low (10(5) cfu/mL) and high (10(7) cfu/mL) inoculum sizes. Overall, FK037, an oxime-type cephem antibiotic, was as active as imipenem, but less active than vancomycin (MIC90s 25, 25 and 6.25 mg/L, respectively) at the lower inoculum. Efficiency of plating experiments were also performed to characterize phenotypic expression of resistance to FK037, imipenem and methicillin. Five of 24 isolates and 18 of 24 isolates contained subpopulations resistant to FK037 and imipenem, respectively. In a rabbit model of endocarditis, FK037 was equally effective as other antibiotics tested in the treatment of methicillin-sensitive Staphylococcus aureus infection. In the treatment of endocarditis due to a homotypic methicillin-resistant S. aureus, FK037 and vancomycin were the most active antibiotics. The presence of subpopulations resistant to imipenem and FK037, as demonstrated by efficiency of plating and high inoculum MIC testing, did not correlate with antibiotic effectiveness in the rabbit model of endocarditis. Cultures of vegetation material following treatment with imipenem and FK037 demonstrated a lower frequency of organisms resistant to FK037 when compared with imipenem. Thus FK037 shows in-vitro and in-vivo activity against some methicillin-resistant staphylococcal species.
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PMID:Comparison of the in-vitro and in-vivo efficacy of FK037, vancomycin, imipenem and nafcillin against staphylococcal species. 924 5

In-vitro and in-vivo efficacies of quinupristin/dalfopristin and vancomycin against methicillin-resistant Staphylococcus aureus (MRSA) responsible for endocarditis have been compared. The following parameters were investigated: MIC, activity across a platelet-fibrin matrix simulating cardiac vegetations, killing of bacteria on the cardiac vegetations resulting from experimental aortic valve endocarditis in an animal model, and concentrations of antibiotics in the serum and vegetations of infected rabbits. The same bacterial strain was used for all experiments. The MICs of quinupristin/dalfopristin and vancomycin were 0.25 and 1 mg/L, respectively. When tested for their ability to penetrate platelet-fibrin matrices, both drugs were bactericidal against the MRSA strain (> or = 2 log10 cfu/mL decrease in 2 h). Both drugs significantly reduced the bacterial counts in vegetations in infected rabbits. Within 12 h of intravenous administration of 20 mg/kg, concentrations of quinupristin/dalfopristin decreased from 5.3 to < 0.10 mg/L in serum and from 12.9 to < 1 mg/kg in the valve vegetations. Although the concentrations of vancomycin in the serum and the infected tissue were higher than those of quinupristin/dalfopristin, the latter combination was equally effective, perhaps because its bactericidal activity is rapid and because it can more easily penetrate the cardiac vegetations.
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PMID:Antistaphylococcal activities of quinupristin/dalfopristin in vitro across platelet-fibrin matrices and in experimental endocarditis. 951 Oct 71

The emergence of antibiotic resistance in Streptococcus pneumoniae poses a particular threat to HIV-infected patients. These patients are at increased risk of invasive pneumococcal disease and may respond poorly to pneumococcal vaccination. We describe an HIV-infected patient with recurrent aortic valve endocarditis due to the same serotype of S. pneumoniae (19A) despite appropriate treatment with penicillin and immunoprophylaxis. The pneumococcus responsible for the second episode of endocarditis was susceptible to cefotaxime (MIC of 0.06 microg/ml), but was no longer susceptible to penicillin (MIC of 0.25 microg/ml). The patient was treated successfully with 4 weeks of intravenous ceftriaxone.
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PMID:Emergence of penicillin resistance in recurrent pneumococcal endocarditis in an HIV-infected patient. 953 27

Y-688 is a new fluoroquinolone with increased activity against ciprofloxacin-resistant staphylococci. The MICs of Y-688 and other quinolones were determined for 58 isolates of ciprofloxacin-resistant and methicillin-resistant Staphylococcus aureus (MRSA). The MICs at which 50% and 90% of bacteria were inhibited were >/=128 and >/=128 mg/liter, respectively, for ciprofloxacin, 16 and 32 mg/liter, respectively, for sparfloxacin, and 0.25 and 1 mg/liter, respectively, for Y-688. This new quinolone was further tested in rats with experimental endocarditis due to either of two isolates of ciprofloxacin-resistant MRSA (namely, P8/128 and CR1). Infected animals were treated for 3 days with ciprofloxacin, vancomycin, or Y-688. Antibiotics were administered through a computerized pump to simulate human-like pharmacokinetics in the serum of rats. The anticipated peak and trough levels of Y-688 were 4 and 1 mg/liter at 0.5 and 12 h, respectively. Treatment with ciprofloxacin was ineffective. Vancomycin significantly decreased vegetation bacterial counts for both organisms (P less, similar 0.05). In contrast, Y-688 only marginally decreased vegetation bacterial counts (P greater, similar 0.05). Moreover, several vegetation that failed Y-688 treatment grew staphylococci for which the MICs of the test antibiotic were increased two to eight times. Y-688 also selected for resistance in vitro, and isolates for which the MICs were increased eight times emerged at a frequency of ca. 10(-8). Thus, in spite of its low MIC for ciprofloxacin-resistant MRSA, Y-688 failed in vivo and its use carried the risk of resistance selection. The fact that ciprofloxacin-resistant staphylococci became rapidly resistant to this potent new drug suggests that the treatment of ciprofloxacin-resistant MRSA with new quinolones might be more problematic than expected.
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PMID:Y-688, a new quinolone active against quinolone-resistant Staphylococcus aureus: lack of in vivo efficacy in experimental endocarditis. 968 79

The effect of the type of sugar used as substrate on the susceptibility of Streptococcus mutans to antibiotics was evaluated. Thirty strains, grown in excess of sucrose (s-MIC) and in excess of glucose (g-MIC), were tested for susceptibility to four cephalosporins. About 21% of the strains were sensitive in the presence of sucrose and resistant in the presence of glucose, whereas only 3% of the strains showed the opposite situation. The mean values of the s-MICs of the four cephalosporins were significantly lower than those of the g-MICs. These findings may also be explained by the synthesis, in excess of sucrose, of insoluble glucan by Streptococcus mutans which increases the interbacterial distance and promotes antibiotic diffusion. Given the susceptibility of Streptococcus mutans grown in excess of sucrose to cefotaxime and cefepime, these antibiotics may be used in the primary prevention of infective endocarditis, when subjects predisposed to endocarditis need invasive dental therapy.
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PMID:Effect of sucrose and glucose on the susceptibility of Streptococcus mutans to cephalosporins. 969 12


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