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

Azlocillin is a semisynthetic acylureidopenicillin with increased activity against most strains of Pseudomonas aeruginosa. It was given as the sole antibacterial agent in the treatment of 21 patients with serious pulmonary, wound, bone or joint, or urinary tract infections, endocarditis, or malignant external otitis caused by Pseudomonas sp. In preliminary in vitro tests, azlocillin inhibited 90% of 36 clinical isolates, while carbenicillin and ticarcillin inhibited only 60% and 73%, respectively. Mean MIC of azlocillin against Ps. aeruginosa isolated from the 21 study patients was 9.8 mg/l; more than 50% of the strains were inhibited by a concentration of 6.25 mg/l. Intravenous administration of the antibiotic at a mean dosage of 17 g/day for 6 to 59 days resulted in an excellent or good clinical response in 90% (19) of the patients treated. Pseudomonas sp. was eliminated from the site of infection in 67% (14) of the patients. Azlocillin therapy was well tolerated; in only two patients, both of whom had penicillin-type rashes, was it necessary to discontinue therapy. Azlocillin was a safe and effective antimicrobial agent for the treatment of serious infections caused by strains of Pseudomonas sp., primarily Ps. aeruginosa.
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PMID:Treatment of serious Pseudomonas infections with azlocillin. 661 26

Rabbits with established staphylococcal endocarditis, injected twice at an interval of 2 h with either 0.5 mg of cloxacillin per kg or saline, were sacrificed 2.5 h after the second injection. Vegetations were excised, weighed, and cultured, and ultrathin sections were prepared and examined by light microscopy, transmission electron microscopy, and scanning electron microscopy. Several affected valves were examined histologically. Concentrations of cloxacillin in serum were determined 1 and 3 h after dosage. Staphylococci grown on membranes placed on agar containing 0.09 micrograms of cloxacillin per ml and in broth at the same cloxacillin concentration (one-third of the MIC) were examined by transmission electron microscopy. The mean numbers of CFU per gram of vegetations from control and treated rabbits were 2.28 X 10(10) and 1.31 X 10(10), respectively. Vegetations of treated rabbits contained staphylococci of normal size and form as well as organisms two to six times larger than normal with multiple cross walls. Larger bacterial cells were usually located in areas close to blood; cells of normal size were usually embedded in fibrin. The structures of these staphylococci and those grown on membranes in the presence of 0.09 micrograms of cloxacillin per ml were comparable but were different from those grown in broth containing this concentration of cloxacillin. Concentrations of cloxacillin in serum were 0.166 micrograms/ml at 1 h and 0.286 micrograms/ml at 3 h after dosage. The similarities in ultrastructure between staphylococci in vegetations of treated rabbits and staphylococci grown on membranes suggest that the vegetations contained approximately 0.09 micrograms of cloxacillin per g. Thus, antibiotic penetration from blood into vegetations and diffusion into fibrin were limited.
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PMID:Staphylococcal endocarditis in rabbits treated with a low dose of cloxacillin. 672 63

A previously described model of experimental Streptococcus faecalis endocarditis in rabbits without an indwelling catheter during the infectious processes was used to study the effect of long-term treatment with antibiotics. Groups of animals infected with six different strains were treated for four weeks and the following parameters were determined: survival rate, bacterial concentration in blood and vegetations, signs at autopsy indicating congestive heart failure. Before the therapeutic experiments, the tolerance of the rabbit to long-term exposure of the drugs penicillin and streptomycin was considered in a group of non-infected animals. Two out of 20 rabbits died with enteritis during the penicillin exposure, and a general weight reduction was observed. Streptomycin was apparently completely harmless. There was no therapeutic effect of streptomycin on S. faecalis endocarditis due to strains all designated resistant to streptomycin by MIC, except in rabbits infected with a strain, which showed partial susceptibility to the drug by IC50. Regardless of the therapeutic effect, evidence was obtained for rapid development of increased resistance of the infecting strains towards streptomycin. After long-term treatment with penicillin in either low or high dose some of the animals survived and the valves were sterilized in 37% of the animals after low-dose and in 39% after high-dose. It was observed that congestive heart failure occurred with the greatest frequency and intensity after infection with proteolytic strains.
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PMID:Experimental endocarditis in rabbits. 5. Results of long-term penicillin or streptomycin treatment of streptococcus faecalis endocarditis and the effect of long-term exposure of healthy rabbits to the same drugs. 680 49

The synergistic action of penicillin and streptomycin was investigated on animals with experimental endocarditis, using the previously described model and four different strains of Streptococcus faecalis. Two strains represented a moderate and two strains a high level of resistance to streptomycin. The purpose was to determine the effect of the combined penicillin and streptomycin treatment, since previous in vitro investigations showed that strains highly resistant to streptomycin were also resistant to combination of the drugs. Antibiotic treatment of the animals was carried out for 28 days, followed by a period of four weeks observation. The treatment resulted in a demonstrable effect against infection caused by the least streptomycin-resistant strain, but was completely ineffective in rabbits infected with the strain homogeneously resistant to 8000 micrograms/ml streptomycin. The synergistic effect of penicillin and streptomycin towards strains within a range of streptomycin resistance of 2000-8000 micrograms/ml could be predicted by the IC50 test, but not by MIC or the in vitro killing curve test for synergism. Besides the therapeutic results, this report also considers the following features: pathoanatomic and physiologic processes related to the number of viable bacteria in the endocardial vegetations; the influence of the proteolytic capacity of infecting strains; the development of congestive heart failure.
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PMID:Experimental endocarditis in rabbits. 6. Results of long-term combined therapy of Streptococcus faecalis endocarditis with penicillin and streptomycin. 680 50

The purpose of this study was to investigate the efficacy of long-term penicillin-gentamicin treatment on experimental S. faecalis endocarditis due to selected strains; one strain was homogeneously resistant to 8000 micrograms/ml streptomycin (IC50 and MIC greater than 8000 micrograms ml), the other strain heterogeneously resistant to 8000 micrograms/ml streptomycin (IC50: 3300 micrograms/ml, MIC: greater than 8000 micrograms/ml. Both strains showed low-grade resistance to gentamicin (MIC 10.5 and 25 micrograms/ml, respectively). The results showed that there was significant effect of the treatment in rabbits with endocarditis due to both strains, as measured by lowered mortality and by high bacteriologic cure rate. Despite effective antibiotic treatment, a high incidence (57%) of congestive heart failure was noted in rabbits late in the treatment period or after termination of antibiotic treatment, probably due to healing processes on the aortic valves. In human cases of S. faecalis endocarditis the antibiotic treatment should be either penicillin plus streptomycin or penicillin plus gentamicin. However, in cases where the infecting strain is homogeneously resistant to 8000 micrograms/ml streptomycin, the treatment with penicillin plus gentamicin is clearly the drug combination of choice.
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PMID:Experimental endocarditis in rabbits. 7. Results of long-term combined therapy of Streptococcus faecalis endocarditis with penicillin and gentamicin. 681 83

A patient was referred to our hospital with a tentative diagnosis of fungal endocarditis based upon clinical symptoms, suggestive travel history, and microscopic visualization in blood cultures of gram-negative bulbous filaments that appeared to be fungal elements. Subcultures of the blood culture bottles were unsuccessful on all media with the exception of blood agar plates, which had been cross-streaked with Staphylococcus aureus. These plates grew vitamin B6-dependent streptococci. This nutritionally variant organism was determined by biochemical tests to be Streptococcus mitis (mitior). It had a penicillin MIC and MBC of 0.015 micrograms/mL and 0.03 micrograms/mL, respectively and streptomycin MIC and MBC of 0.78 micrograms/mL and 1.56 micrograms/mL, respectively. The patient was treated with these two agents and recovered. We stress the importance of suspecting vitamin B6-dependent streptococci, even when gram stains may suggest presence of other microorganisms.
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PMID:Vitamin B6-dependent Streptococcus mimicking fungi in a patient with endocarditis. 685 59

Two cases of bacterial endocarditis in children, caused by viridans group Streptococcus which requires vitamin B6 or thiol compounds for growth are reported. It is important to recognize these organisms as a possible cause of endocarditis because supplemented media are needed for their isolation and sensitivity testing. These organisms may be penicillin-sensitive, -resistant, or -tolerant. An organism is considered tolerant to an antibiotic when the minimum bactericidal concentration of that antibiotic is greater than or equal to 32 times the minimum inhibitory concentration. One of our patients relapsed when treated with a single antibiotic to which the B6-dependent viridans group Streptococcus was tolerant. If a B6-dependent viridans group Streptococcus is isolated from a patient with endocarditis, therapy should be initiated with penicillin and an aminoglycoside until sensitivities are available. Sensitity testing should include both the MIC and MBC and adequate therapy can be confirmed by determing the serum bactericidal activity.
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PMID:Bacterial endocarditis caused by vitamin B6-dependent viridans group Streptococcus. 740 19

The efficacy of cefazolin or cefpirome alone or combined with rifampin was compared with that of vancomycin alone or combined with rifampin in an experimental model of methicillin-resistant, beta-lactamase-producing, coagulase-negative staphylococcal endocarditis. Phenotypically, the mecA gene-positive strain used in vivo did not exhibit methicillin resistance by the agar dilution or disk susceptibility method but was resistant in vitro (oxacillin MIC, 64 micrograms/ml) by the microtiter dilution method with 2% NaCl supplementation. Macrodilution broth susceptibilities of standard inocula failed to demonstrate cross-resistance of staphylococci to cefazolin (MIC, 8 micrograms/ml) or cefpirome (MIC, 4 micrograms/ml). In vivo, vancomycin and cefpirome had similar activities, and both regimens were more effective than was cefazolin alone. While the MIC of rifampin was low (0.031 micrograms/ml), monotherapy with rifampin resulted in a bimodal distribution of outcomes due to the expected emergence of resistant mutants. The results in vitro of time-kill synergy studies using rifampin in combination with cefazolin or cefpirome varied with the antimicrobial concentrations tested and did not reliably predict activities in vivo of rifampin-beta-lactam combination therapies. Cefpirome, but not cefazolin or vancomycin, in combination with rifampin was synergistic in vivo. Cefpirome in combination with rifampin was more effective than was cefazolin in combination with rifampin. Both cephalosporin-rifampin regimens were significantly more effective than was cephalosporin or vancomycin monotherapy and were as effective as vancomycin combined with rifampin. These data support further evaluation of rifampin-beta-lactam combinations as possible alternative therapies to vancomycin-containing regimens for selected methicillin-resistant coagulase-negative staphylococcal infections.
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PMID:Effective treatment of cephalosporin-rifampin combinations against cryptic methicillin-resistant beta-lactamase-producing coagulase-negative staphylococcal experimental endocarditis. 748 24

RP 59500 is a new injectable streptogramin composed of two synergistic components (quinupristin and dalfopristin) which are active against erythromycin-susceptible and -resistant gram-positive pathogens. The present experiments compared the therapeutic efficacy of RP 59500 with that of vancomycin against experimental endocarditis due to either of two erythromycin-susceptible or two constitutively erythromycin-resistant isolates of methicillin-resistant Staphylococcus aureus. RP 59500 had low MICs for the four test organisms as well as for 24 additional isolates (the MIC at which 90% of the isolates were inhibited was < 1 mg/liter) which were mostly inducibly (47%) or constitutively (39%) erythromycin resistant. Aortic endocarditis in rats was produced with catheter-induced vegetations. Three-day therapy was initiated 12 h after infection, and the drugs were delivered via a computerized pump, which permitted the mimicking of the drug kinetics produced in human serum by twice-daily intravenous injections of 7 mg of RP 59500 per kg of body weight or 1 g of vancomycin. Both antibiotics reduced vegetation bacterial titers to below detection levels in ca. 70% of animals infected with the erythromycin-susceptible isolates (P < 0.05 compared with titers in controls). Vancomycin was also effective against the constitutively resistant strains, but RP 59500 failed against these isolates. Further experiments proved that RP 59500 failures were related to the very short life span of dalfopristin in serum (< or = 2 h, compared with > or = 6 h for quinupristin), since successful treatment was restored by artificially prolonging the dalfopristin levels for 6 h. Thus, RP 59500 is a promising alternative to vancomycin against methicillin-resistant S. aureus infections, provided that pharmacokinetic parameters are adjusted to afford prolonged levels of both of its constituents in serum. This observation is also relevant to humans, in whom the life span of dalfopristin in serum is also shorter than that of quinupristin.
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PMID:Treatment of experimental endocarditis due to erythromycin-susceptible or -resistant methicillin-resistant Staphylococcus aureus with RP 59500. 749 78

We investigated the postantibiotic effects (PAEs) and the postantibiotic sub-MIC effects of benzylpenicillin on three strains of viridans streptococci isolated from infective endocarditis patients. The PAEs of benzylpenicillin on penicillin tolerant Streptococcus sanguis TW-70 (0.4-3.9 h), penicillin tolerant S. sanguis TW-80 (0.3-6.3 h) and nontolerant Streptococcus oralis TW-186 (0.5-3.1 h) were dependent on exposure time. The PAEs were not concentration dependent for S. sanguis TW-70 and S. sanguis TW-80 above the MIC, and for S. oralis TW-186 above 16 x MIC. The antimicrobial effects of benzylpenicillin at sub-MIC concentrations were examined in bacteria pretreated with benzylpenicillin (8 x MIC) for 2 h and compared with untreated bacteria. At the sub-MICs tested, the regrowth of pretreated S. oralis TW-186 cells was more prolonged than that of untreated cells and bactericidal action was seen only in pretreated cells. These effects (so-called 'postantibiotic' sub-MIC effects') were not observed in penicillin tolerant S. sanguis TW-70. The presence of the postantibiotic sub-MIC effect may be an important factor in determining the dosing regimen for infective endocarditis.
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PMID:Postantibiotic effects and postantibiotic sub-MIC effects of benzylpenicillin on viridans streptococci isolated from patients with infective endocarditis. 770 64


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