Anaerobic, Non-Spore-Forming, Gram-Positive Bacteria

Table 41-1. New Classification of Selected Anaerobic Cocci Formerly in the Genus Peptostreptococcus Organism Historical Derivation Anaerobic Cocci Anaerococcus an, without; aer, air; coccus, berry or coccus (anaerobic coccus) Finegoldia Named after the American microbiologist S. Finegold Micromonas Peptostreptococcus micro, tiny; monas, cell (tiny cell) pepto, cook or digest (the digesting streptococcus) Schleiferella Named after the German microbiologist K.H. Schleifer Anaerobic Rods Actinomyces aktinos, ray; mykes, fungus (ray fungus referring to the radial arrangement of filaments in granules) Bifidobacterium bifidus, cleft; bakterion, small rod (a small clefted or bifurcated rod) Eubacterium eu, good or beneficial (a beneficial rod; that is, a rod normally present) Lactobacillus lacto, milk (milk bacillus; organism originally recovered in milk; also, lactic acid     is the primary metabolic product of fermentation) Mobiluncus mobilis, capable of movement or being active; uncus, hook (motile, curved rod) Propionibacterium propionicum propionic acid (propionic acid is the primary metabolic product of fermentation)

Table 41-1. New Classification of Selected Anaerobic Cocci Formerly in the Genus Peptostreptococcus Former Classification New Classification P. anaerobius Unchanged P. asaccharolyticus Schleiferella asaccharolytica P. magnus Finegoldia magna P. micros Micromonas micros P. prevotii Anaerococcus prevotii

Anaerobic, Non-Spore-Forming, Gram-Positive Rods facultatively anaerobic or strictly anaerobic bacteria colonize the skin and mucosal surfaces. Actinomyces, Mobiluncus, Lactobacillus, and Propionibacterium Bifidobacterium and Eubacterium Table 41-2. Anaerobic, Non-Spore-Forming, Gram-Positive Rods Anaerobic Rods Human Disease Actinomyces spp. Actinomycosis (cervicofacial, thoracic, abdominal, pelvic, central nervous system) Propionibacterium spp. Acne, lacrimal canaliculitis, opportunistic infections Mobiluncus spp. Bacterial vaginosis, opportunistic infections Lactobacillus spp. Endocarditis, opportunistic infections Eubacterium spp. Opportunistic infections Bifidobacterium spp.

Actinomyces PHYSIOLOGY AND STRUCTURE facultatively anaerobic or strictly anaerobic, gram-positive rods. no acid-fast grow slowly in culture filamentous forms or hyphae (균사) (resembling fungi) true bacteria : lack mitochondria, nuclear membrane, reproduce by fission, inhibited by penicillin but not antifungal antibiotics. - Human infection : Actinomyces israelii, Actinomyces meyeri, Actinomyces naeslundii, Actinomyces odontolyticus, and Actinomyces viscosus Microscopic colony, Gram stain

PATHOGENESIS AND IMMUNITY upper respiratory, gastrointestinal, and female genital tracts. not normally present on the skin surface. low virulence potential, cause disease only when the normal mucosal barriers are disrupted by trauma, surgery, or infection actinomycosis (방선균증) - in keeping with the original idea that these organisms were fungi or "mycoses" development of chronic granulomatous lesions  suppurative, form abscesses connected by sinus tracts. sulfur granules in the abscesses and sinus tracts : yellow or orange, are masses of filamentous organisms bound together by calcium phosphate The areas of suppuration are surrounded by fibrosing granulation tissue Figure 41-3 Sulfur granule collected from the sinus tract in a patient with actinomycosis. Delicate filamentous rods (arrow) are seen at the periphery of the crushed granule

EPIDEMIOLOGY - Actinomycosis - endogenous infection - Disease is classified according to the organ systems involved. : Cervicofacial infections : have poor oral hygiene or have undergone an invasive dental procedure or oral trauma. In the mouth, invade into the diseased tissue and initiate the infectious process. : Thoracic infections generally have a history of aspiration, in the lungs and then spreading to adjoining tissues. : Abdominal infections : gastrointestinal surgery or have suffered trauma to the bowel : Pelvic infection : secondary manifestation of abdominal actinomycosis or primary infection in a woman with an intrauterine device : Central nervous system infections : represent hematogenous spread from another infected tissue, such as the lungs.

CLINICAL DISEASES - cervicofacial type :most cases of actinomycosis : acute, pyogenic infection, slowly evolving, relatively painless process : tissue swelling with fibrosis and scarring, as well as draining sinus tracts along the angle of the jaw and neck - thoracic actinomycosis : nonspecific. Abscesses form in the lung tissue early in the disease and then spread into adjoining tissues as the disease progresses. - Abdominal actinomycosis : abdomen, potentially involving virtually every organ system. - Pelvic actinomycosis : benign form of vaginitis or, more commonly, there can be extensive tissue destruction, including the development of tuboovarian abscesses or ureteral obstruction. - central nervous system actinomycosis : solitary brain abscess, but meningitis, subdural empyema, and epidural abscess are also seen.

LABORATORY DIAGNOSIS - Laboratory confirmation of actinomycosis is often difficult - the organisms are concentrated in sulfur granules and are sparse in involved tissues, a large amount of tissue or pus should be collected. - If sulfur granules are detected in a sinus tract or in tissue, the granule should be crushed between two glass slides, stained, and examined microscopically. fastidious and grow slowly under anaerobic conditions Figure 41-6 Molar tooth appearance of Actinomyces israelii after incubation for 1 week. This colonial morphology serves as a reminder that the bacteria are normally found in the mouth.

TREATMENT, PREVENTION, AND CONTROL Treatment for actinomycosis : combination of surgical débridement of the involved tissues and the prolonged administration of antibiotics. susceptible to penicillin, erythromycin, clindamycin Most species are resistant to metronidazole tetracyclines have variable activity.

Propionibacterium small gram-positive rods often arranged in short chains or clumps. found on the skin (in contrast with the actinomyces), conjunctiva, external ear, and in the oropharynx and female genital tract. anaerobic or aerotolerant, nonmotile, catalase positive, and capable of fermenting carbohydrates, producing propionic acid as their major by-product. - Propionibacterium acnes and Propionibacterium propionicus stimulate an inflammatory response Production of a low-molecular-weight peptide  attracts leukocytes  bacteria are phagocytized  release of bacterial hydrolytic enzymes (lipases, proteases, neuraminidase, and hyaluronidase  )  stimulate a localized inflammatory response. - When injected into experimental animals, P. propionicus causes lacrimal canaliculitis (inflammation of the tear duct) and abscesses. - Acne(duemfma) : Benzoyl peroxide, antibiotics- erythromycin, clindamycin

Mobiluncus obligate anaerobic, gram-variable or gram-negative, curved rods with tapered ends. gram-positive rods (1) have a gram-positive cell wall, (2) lack endotoxin, (3) are susceptible to vancomycin, clindamycin, erythromycin, ampicillin  but resistant to colistin. - Two species, Mobiluncus curtisii and Mobiluncus mulieris, - genital tract in low numbers but are abundant in women with bacterial vaginosis (vaginitis).

Bifidobacterium and Eubacterium Lactobacillus facultatively anaerobic or strictly anaerobic rods. the normal flora of the mouth, stomach, intestines, and genitourinary tract isolated in urine specimens and blood cultures. Invasion into blood (1) transient bacteremia from a genitourinary source (e.g., after childbirth or a gynecologic procedure), (2) endocarditis, and (3) opportunistic septicemia in an immunocompromised patient. lactobacilli are resistant to vancomycin (an antibiotic commonly active against gram-positive bacteria) A combination of penicillin with an aminoglycoside is required for bactericidal activity. Bifidobacterium and Eubacterium commonly found in the oropharynx, large intestine, and vagina clinically insignificant contaminants.