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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
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)
is
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,
Microscopic colony, Gram stain
reproduce by fission,
inhibited by penicillin but not antifungal antibiotics.
- Human infection : Actinomyces israelii, Actinomyces meyeri,
Actinomyces naeslundii, Actinomyces odontolyticus, and Actinomyces
viscosus
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).
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.