INFECTIONS CAUSED BY THE ENTERIC BACTERIA 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 the similar illness. Meningitis and Brain Abscess. During the first four weeks of life, purulent meningitis is frequently caused by members of the enteric group of bacteria. Such cases our sporadically in nurseries, and may be associated with infection of any other tissue of the body. Infants with meningoceles are especially liable to enteric bacterial meningitis.
INFECTIONS CAUSED BY THE ENTERIC BACTERIA In adults, such infections are rare, but may occasionally be seen as complications of gram-negative bacteremia or in association with other diseases affecting host resistance, e.g.., diabetes mellitus or 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, lung, 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 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 defence 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. Rectal examination should be carefully performed in such patients, particularly when they develop a fever and perianal pain. 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 panoph-thalmitis in patients with bacteremia originating in acute pyelonephritis. Of special interest in this regard is osteomyelitis of the spine.
This is usually seen in men with prostatic disease, chronic cystitis, and posterior urethritis. Possibly the method of the spread here is by way of septic emboli to the spine through the vertebral venous plexus. Superinfection. Enteric bacteria frequently predominate in the bronchial secretions of patients under treatment with large doses of penicillin or broad-spectrum antimicrobial agents. 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 bacterial pneumonia often superimposed on viral influenza, however, does occur and may be exceedingly difficult to manage.