- Mar 30, 2007
Actinomycosis is a subacute-to-chronic bacterial infection caused by filamentous, gram-positive, anaerobic-to-microaerophilic bacteria that are not acid fast. It is characterized by contiguous spread, suppurative and granulomatous inflammation, and formation of multiple abscesses and sinus tracts that may discharge sulfur granules. The most common clinical forms of actinomycosis are cervicofacial (ie, lumpy jaw), thoracic, and abdominal. In women, pelvic actinomycosis is possible.
Causes: Actinomycosis is caused by gram-positive filamentous bacteria that do not form spores and are not acid-fast. They belong to the order of Actinomycetales, family Actinomycetaceae, genus Actinomyces. Members of the genera Propionibacterium, Actinobaculum, and Bifidobacterium may cause similar clinical syndromes. These bacteria grow slowly in anaerobic-to-microaerophilic conditions, forming colonies with a characteristic molar tooth appearance. The most common isolated species are Actinomyces israeli and Actinomyces gerencseriae, Actinomyces turicensis, Actinomyces radingae, Actinomyces europaeus, followed by Actinomyces naeslundii, Actinomyces odontolyticus, Actinomyces viscosus, Actinomyces meyeri, and Propionibacterium propionicum.
In addition to these microorganisms, almost all actinomycotic lesions contain so-called companion bacteria. The most important of these bacteria is Actinobacillus actinomycetemcomitans, followed by Peptostreptococcus, Prevotella, Fusobacterium, Bacteroides, Staphylococcus, and Streptococcus species, and Enterobacteriaceae, depending on the location of actinomycotic lesions. These companion bacteria appear to magnify the low pathogenic potential of actinomycetes.
[FONT="]Treatment:[/FONT][FONT="] High-dose penicillin, administered over a prolonged period, is the cornerstone of therapy for actinomycosis. The risk of actinomycetes developing penicillin resistance appears to be minimal. Lack of a clinical response to penicillin usually indicates the presence of resistant companion bacteria, which may require modification of the antibiotic regimen (ie, addition of an agent that is active against these copathogens).[/FONT]
Antibiotics that possess no activity against [FONT="]Actinomyces[/FONT] species include metronidazole, aminoglycosides, aztreonam, co-trimoxazole (TMP-SMX), and penicillinase-resistant penicillins (eg, methicillin, nafcillin, oxacillin, cloxacillin) and cephalexin. The data concerning the fluoroquinolones (ciprofloxacin, gatifloxacin and moxifloxacin) are insufficient. Following treatment can be used preferably, Penicillin G (Pfizerpen, Bicillin), Penicillin VK (Pen-Vee K, V-Cillin-K), Doxycycline (Bio-Tab, Doryx, Vibramycin), Clindamycin (Cleocin), Amoxicillin/clavulanic acid (Augmentin),