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IMBM: Institute for Microbial Biotechnology and …
Empirical antimicrobial therapy may mask the clinical manifestations of actinomycosis, since actinomycetes are extremely susceptible to penicillin and other broad-spectrum antibiotics, and is not recommended.
. Schaal KP, Pulverer G. Epidemiologic, etiologic, diagnostic, and therapeutic aspects of endogenous actinomycetes infections. In: Ortiz-Ortiz L, Bojalil LF, Yakoleff V, eds. Biological, biochemical, and biomedical aspects of actinomycetes. New York: Academic Press 1984:13-32.
Is the Cause of Cancer a Common Fungus? - Dr. Tullio Simoncini
After a sample is obtained, it should be examined by standard histologic methods, anaerobic culture for 2 weeks, and immunofluorescence if available. Culture is the least reliable method of verifying infection (in Fiorino's series only 35% of cultures were positive for fermentative actinomycetes () when standard aerobic and anaerobic culture techniques are used. However, an 86% success rate has been reported for samples cultured in the presence of metronidazole, which inhibits the growth of faster growing anaerobes (), and, as indicated by the overall number of culture-proven cases (, , ) and the percentage of culture-positive IUD specimens (, ), even better results may be obtained when transparent agar media, Fortner's () method for producing a semianaerobic atmosphere, and microscopic examination of the cultures for up to 14 days of incubation at 36 ± 1°C are used (). The last procedure also facilitates the detection of actinomycete colonies among a usually large amount of various colony types of concomitant microbes.
Because of the polymicrobial nature of the disease, culture and of abscess aspirates, sinus discharge, bronchial secretions or biopsy specimens may have important implications for the choice of adjunctive antibiotics. Microorganisms may be scarce in pathologic specimens, so detection may require diligent searching of multiple tissue sections (). The presence of sulfur granules is highly suggestive but not diagnostic of disease. These sulfur granules are visible with the unaided eye (diameter up to 1 mm) as yellowish to reddish to brownish particles that consist of spherical segments of filamentous actinomycete microcolonies, various concomitant bacteria and surrounding tissue reaction material, in particular polymorphonuclear granulocytes. Serodiagnosis of actinomycosis by detection of precipitating or other antibodies has not been a particularly useful diagnostic test (, ). Demonstration of pathogenic actinomycetes from smears of lesions by immunofluorescence is a more promising technique. More recently, molecular genotypic techniques have been utilized for identification of Actinomyces species. 16 S ribosomal RNA (rRNA) gene sequencing is now becoming the standard method of identification in most academic and reference laboratories ().
AcSIR – Academy of Scientific & Innovative Research – …
Matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry is a newer, promising technology that can accurately identify Actinomyces at the genus level, although precise species identification can sometimes be difficult ().
Some Actinomyces species (e.g. A. naeslundii, A. viscosus, A. odontolyticus) may be involved in the complex etiology of caries and periodontal disease. In addition, these and other species, in particular the recently described ones, may cause non-specific suppurative lesions such as wound infections, abscesses or empyemas, as well as infections of the urogenital tract, infections of root canals of teeth and even endocarditis and septicemia.
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Search Result - International Journal of Advanced …
In vitro antimicrobial susceptibility testing of fermentative actinomycetes is rarely required, as these results are quite predictable (, , , ). In addition, in vitro activity may not correlate with clinical outcome (e.g., streptomycin; see below). One study examined 74 strains (seven species); minimum inhibitory concentrations (MICs) for penicillin G were 0.03 to 0.5 mg/mL for all strains of A. israelii and 0.06 to 0.5 mg/mL for all other actinomycetes, except for one strain of A. naeslundii and three of four A. bovis strains (MIC, 1.0 mg/mL) (). Erythromycin was the most active antimicrobial agent in vitro (MIC, 0.12 mg/mL or less). Cephaloridine, minocycline, and clindamycin were also very active in vitro (MIC, 0.003 to 1.0 mg/mL), for a few strains other than A. israelii, the MIC for clindamycin ranged from 2.0 to 8.0 mg/mL. The MIC for cephalothin, ampicillin, lincomycin, tetracycline, doxycycline, and chloramphenicol was within the therapeutic range for all strains of A. israelii and most other species. Metronidazole displayed conspicuously unimpressive in vitro activity, as did the aminoglycosides (49, 59). Lerner found that bothActinomyces and P. propionicum are highly susceptible to penicillin G, erythromycin, clindamycin, and minocycline, and that cephalothin, ampicillin, lincomycin, tetracycline, and chloramphenicol are also active at therapeutic concentrations (). Peabody and Seabury () reviewed in vitro and clinical data up to 1960 for sulfadiazine, streptomycin, erythromycin, chloramphenicol, and the tetracyclines. Cures had been achieved with each alone, or in combinations; in vitro data suggest that Actinomyces are inhibited by chloramphenicol (0.005 to 0.01 mg/mL), erythromycin (0.005 to 0.1 mg/mL), and several tetracyclines. Even streptomycin, considerably less active in vitro, produced excellent clinical results in some cases. Cures have been reported with isoniazid and even stilbamidine (). In addition, rifampin therapy for suspected tuberculosis may mask undiagnosed pulmonary actinomycosis (). Fluoroquinolones, aztreonam, fosfomycin, and other aminoglyocosides generally have poor activity against Actinomyces species and P. propionicum (, ).
Phosphine and selected metal phosphides (EHC 73, 1988)
From the short review of the literature given above and numerous additional reports published during the past 40 years, it must be concluded that many details concerning both the in vitro susceptibility of fermentative actinomycetes to antibacterial drugs and the clinical efficacy of these drugs are still controversial. Schaal and Pape () demonstrated convincingly that the results of in vitro susceptibility tests of fermentative actinomycetes are highly dependent on the individual test procedures used. For instance, with the agar dilution test, the use of different commercial agar media changed the MICs of P. propionicum for ampicillin, tetracycline, and gentamicin by two to three dilutions. Such discrepancies may even be more pronounced when the results of agar dilution and broth dilution techniques are compared. Disk-diffusion methods are in general not suitable for testing fermentative actinomycetes, at least as far as the slow-growing anaerobic strains are concerned ().
Senior Chemistry - Extended Experimental Investigations
Different results concerning the clinical efficacy of certain antibacterial drugs may be related to differences in the definition of clinical cure, difficulties in diagnosing human actinomycoses unambiguously, and insufficient characterization of the concomitant actinomycotic flora. The last factor is of particular clinical importance () because several characteristic companions of the pathogenic fermentative actinomycetes differ greatly in their antibiotic susceptibility patterns from the actinomycetes themselves. This is especially true for certain black pigmented Bacteroidaceae,Bacteroides species sensu stricto and A. actinomycetemcomitans, but also for aerobically growing members of the synergistic flora such as Staphylococcus aureus or Enterobacteriaceae. Thus, at least 5% of the black pigmented Bacteroidaceae, 10% of the A. actinomycetemcomitans strains and more than 30% of the members of the genus Bacteroides sensu stricto are highly resistant to benzyl penicillin. Therapeutically sufficient susceptibility is only exhibited by 80% of the black-pigmented Bacteroidaceae, 60% of the A. actinomycetemcomitans strains and a few percent of theBacteroides species (). A detailed description of the in vitro susceptibility of the common concomitant bacteria species to antibiotics would be beyond the scope of this chapter. However, it is well known that strict anaerobes are usually susceptible to nitroimidazoles (e.g., metronidazole) or clindamycin and also to aminopenicillins combined with β-lactamase inhibitors, and carbapenems (e.g., imipenem). A. actinomycetemcomitans, although often resistant or only moderately susceptible to penicillin G, is nearly always susceptible to aminopenicillins such as ampicillin or amoxicillin. The susceptibility patterns of staphylococci and Enterobacteriaceae cannot be predicted and therefore require individual susceptibility test results for optimal treatment. Moreover, it should be noted that all of the fermentative actinomycetes are resistant to metronidazole and that A. actinomycetemcomitans is usually resistant to lincomycins including clindamycin (). As aminoglycosides (e.g., gentamicin, tobramycin, amikacin) are not active against anaerobes both in vitro and in vivo, these drugs may only be considered when the concomitant flora contains Enterobacteriaceae or other gram-negative aerobically growing rods that are resistant to combinations of aminopenicillins with β-lactamase inhibitors.
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