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

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

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

- 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. Opportunistic infections

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 invasi

ve 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 anoth

er 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 an

gle 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 ti

ssue 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

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.

- 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

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).

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.