The Role of Enteric Bacteria in Pyogenic Infections
The mixed flora of the intestinal tract participates in infections that originate from lesions of the bowel, such as appendicitis, cholangitis, Pyogenic Infections, diverticulitis, and perforation (from ulcerative colitis, ileitis, or carcinoma). These may lead to subdiaphragmatic hepatic, and pelvic abscesses, which are frequent causes of fever of unknown origin in the patient recovering from abdominal surgery or trauma to this region.
Pyogenic Infections Because enteric bacteria grow luxuriantly in both aerobic and anaerobic media and therefore are likely to predominate in cultures, their relative importance tends to ‘be exaggerated There is good reason to believe that anaerobic bacteria Bacteroides, Clostridia, and anaerobic streptococci— play more important roles in this kind of process. It should be pointed out here that a “fecal” odor of pus, though often ascribed to coliforms is doubtless caused by associated anaerobic bacteria'. Anaerobic bacteria are usually present as mixtures of two or more species. They should be suspected when there is foul pus and when organisms can be visualized microscopically bait fail to grow under routine conditions.
OTHER INFECTIONS CAUSED BY THE ENTERIC BACTERIA
Gastroenteritis. A significant proportion of cases of gastroenteritis occurring in the neonatal period of life appear to be caused by enteric bacteria. About ten serologic strains of E. coli have been identified with this capability; they are spoken of as enteropathogenic strains. Certain strains of Proteus and Pseudomonas have at times also been held responsible for similar illnesses. Meningitis and Brain Abscess. Such cases are sporadically in nurseries and may be associated with infection of any other tissue of the body. lymphoma (see Meningitis Caused by Bacteria Other Than Meningococci.). Nontraumatic brain abscess is frequently due to infection by multiple species of anaerobic organisms similar to those found in the gastrointestinal tract.
The sites of origin include chronically infected ears, sinuses, lungs, abdomen, and pelvis. Bacteremia in Hepatic Cirrhosis. Occasionally persons with cirrhosis of the liver develop an acute febrile illness and are found to lame ber-viremia caused by one of the enteric organisms. usually E. coli. Occasionally these patients saw signs of peritonitis, but in most of them, the event comes “out of the blue” without evidence of localized sepsis anywhere. The illness is short and self-limited or responds to appropriate chemotherapy. Speculation as to its pathogenesis has included the possibility of shunting bacteria away from-the filtering action of the liver, impairment of humoral or cellular defense mechanisms, or complement inactivation owing to high blood ammonia. In actuality, a satisfactory explanation is lacking at present. – Surface Infection.
Enteric bacteria, particularly Proteus and Pseudomonas, are commonly recovered from the surfaces of burns, varicose. ulcers; decubitus ulcers, tracheostomy sites, and the like. Generally, these organisms appear to play no pathogenic role, and satisfactory healing may proceed regardless of their presence. They can, at times result in fulminant gram-negative sepsis, particularly in the patient with severe burns. The exudate from the sinus of chronic osteomyelitis or chronic otitis media often contains Proteus as the dominant ‘ organism: Otitis of the external auditory canal owing to Pseudomonas may give troublesome local symptoms, especially in swimmers. Perirectal Abscess.
This is an important complication in patients with marked granulocytopenia. Abscesses at Sites of Subcutaneous Injections. Rarely, enteric bacilli cause abscesses in subcutaneous tissue at sites of hypodermic injections, notably in diabetic subjects who inject their own insulin. These are sometimes characterized by gas formation, and they thus arouse fear of more serious clostridia infection, whereas, in fact, they are usually of minor clinical importance. Metastatic Infections. Despite the frequency with which enteric bacteria succeed in invading the blood, metastatic localization of infection is rare.
There are, .however, occasional instances of such suppurative lesions as arthritis and panophthalmitis in patients with bacteremia originating in acute pyelonephritis. This is usually seen in men with the prostatic disease, chronic cystitis, and posterior urethritis. In most instances, this is not of significance and simply represents the emergence of unaffected bacterial strains following the suppression of the primary pathogens. It is not an indication for cessation or Change in antimicrobial therapy unless there is clinical evidence of tissue invasion by the newly emergent organism. Primary gram-negative bac-