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Bacteroides Species, Anaerobic Streptococci, Fusobacterium Fusiforme

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Bacteroides species, anaerobic streptococci, Fusobacterium fusiforme, and a variety of spirochetes. are members of the indigenous microbial flora of the mouth, intestinal tract, vagina, and mucous membranes of the external genitalia. F. fusiform and' the indigenous spirochetes are often present in large numbers in the gingival areas of the mouth, and Bacteroides usually outnumber Escherichia coli in the feces of man. The Bacteroides are a group of gram-negative, non-spore-forming, nonmotile, strictly anaerobic bacilli. Bacteroides fund uniforms (B. necrophorus), B. fragilis, and B. nigrescens (B. melaninogenicum) is the most common species associated with clinical infections of man. Anaerobic streptococci are gram-positive, grow in short or long chains, and, although varying considerably in size, are usually smaller than the common aerobic strepto-cocci.

These organisms comprise many different groups of species, but available information is too scant to permit systematic classification. Many, but not all, species of Bacteroides or strains of anaerobic streptococci from abundant gas and produce an extremely foul odor. F. fusiforme is a gram-negative, anaerobic, non-motile bacillus. The bacterial cells are small with tapered ends, maybe evenly stained or granular, and often occur in roughly parallel bundles. F. fusiforme is closely related to Bacteroides but can be distinguished by certain biological and biochemical reactions. Spirochetes are often found in association with F. fusiforme. Although “specific” designations, such as Treponema microdontia, Borrelia Vincenti, or Borrelia buccale, have been applied to these spirochetes on the basis of differences in morphology, it is not certain whether these organisms belong to a single variable species or many separate groups.

Pathogenesis. Anaerobic streptococci and Bacteroides are not highly invasive organisms and usually initiate infection at sites of trauma or – tissue necrosis where these organisms exist in large numbers. Local lesions are characterized by suppuration, abscess formation, and often a foul odor. Infection usually remains limited to one area, but blood invasion may occur and may lead to metastatic abscess formation at distant sites. The incidence of severe Bacteroides infections appears to be increased in patients with serious underlying diseases such as malignancy or diabetes mellitus, or in patients receiving therapy with multiple antimicrobials or corticosteroids.

Thrombophlebitis occasionally develops adjacent to the site of initial infection and may result in septic emboli. Thrombophlebitis is considered characteristic of Bacteroides infection but is also observed occasionally in anaerobic streptococcal infections. Although Bacteroides or anaerobic streptococci may be isolated in pure culture from local suppurative infections, an additional organism is present in most cases. F. fusiform and the indigenous spirochetes apparently act in concert to produce superficial inflammatory and ulceromem branous legions of the gums, pharynx, and external genitalia. Local tissue damage, malnutrition, and a variety of debilitating diseases predispose to fusospirochetal infections. Clinical Manifestations. Bacteroides and Anaerobic Streptococcal Infections. Bacteroides and anaerobic streptococci produce localized suppurative infections in many locations but most often in tissues liable to contamination with the flora of the intestinal tract or vagina.

These organisms have been isolated from infected human bites, contaminated wounds, peritonsillar, appendiceal, ischio-rectal, and pelvic abscesses, exudate' in localized or generalized peritonitis, and purulent discharges from patients with endometritis. The manifestations, course, and outcome of localized infection obviously depend on the size and extent of involvement. Invasion of the blood by Bacteroides or anaerobic streptococci is usually secondary to infection of the peritoneum, female genital tract, or tonsils, but may be related to a local infection at any site. The initial manifestations are determined by the portal of entry and, may be symptoms of peritonsillar abscess, endometritis, appendicitis, etc. Gastrointestinal surgery is a frequent predisposing event. Patients with blood invasion are extremely ill and frequently have chills, hectic fever, and severe diaphoresis.

The clinical picture of septic shock may be observed. A leukocytosis of 12,000 to 35,000 cells per cubic millimeter of blood is usually present. Septic thrombophlebitis, especially characteristic of Bacteroides infection, may extend from the area of the initial lesion and may lead to multiple septic pulmonary infarcts that are manifested by rales, dyspnea, cough, hemoptysis, pleurisy, lung abscess, or empyema. Metastatic infection may also occur in the brain, meninges, liver, bones, endocardium, or joints. A

A Suitable Dosage Regimen, Including Subcutaneous, Intramuscular

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