ENTERIC BACTERIAL INFECTIONS
BACTERIAL INFECTIONS and should be administered in divided doses of about 50 mg. per kilogram per day for at least two weeks. Four to six days may be required for deferring -. science in favorable cases and even longer in patients with localized infection. In patients with localized infections, it may be necessary to continue antimicrobial therapy for four to six weeks, and surgical drainage of collections of pus maybe Musaceae persisting in tissues during chloramphenicol therapy may be responsible for relapse after the antimicrobial is discontinued.
Relapse is not related to the emergence of chloramphenicol-resistant strains during therapy, and clinical response to a second or third course of therapy usually differs in no way from the first. Ampicillin has also been shown to be effective in treating paratyphoid fever, but the response to ampicillin is slower than the response to chloramphenicol. Ampicillin is also often effective in the. treatment of other systemic Salmonella infections if the causative organism is susceptible to this drug. Ampicillin is preferred over chloramphenicol for patients requiring prolonged therapy. Approximately 10 to 20 percent of the S. Typhimurium strains isolated in the United States and a somewhat higher proportion in England are resistant to ampicillin. Ampicillin resistance i.8 mediated by transferable resistance determinants or R factors and is uncommon among serologic types other than S. Typhimurium.
Very few strains of Salmonella are resistant to chloramphenicol in vitro. Excretion of salmonellae in stool after clinical or subclinical infection ceases spontaneously in almost all patients; the convalescent carrier state is not an indication for antimicrobial therapy. Chronic enteric carriers of salmonellae other than S. typhosa are managed as are typhoid carriers. Prognosis. The case fatality rate in Salmonella gastroenteritis rarely exceeds 1 or 2 percent and probable averages about 0.3 percent. Fatalities occur almost entirely in infants, the aged, and persons with major underlying disease: The case. the fatality rate in the more serious systemic infections is high; it approaches 20 per, cent in. S. choleraesuis bacteremia.
Prevention. Patients with acute illness should be isolated, and convalescent or chronic' carriers should not be employed as food handlers and should practice strictly. personal hygiene. The control of salmonellosis among animals and the prevention of the spread of infection to man present many problems. Progress is being made in developing methods of detection and control of salmonellosis in domestic animals and in improving hygienic conditions in food-processing and food-dispensing establishments. An Evaluation of the Salmonella Problem. National Academy of Sciences Publication No. 1683. Washington, D.C., Printing and Publishing Office, National Academy of Sciences, 1969.
Aserkoff, B., and Bennett, J. V.: Effect of therapy in acute salmonellosis on salmonellae in feces. New Eng. J. Med., 281: 636, 1969. Bennett, I. L., Jr., and Hook, E. W.: Infectious diseases (some aspects of salmonellosis). Ann. Rev. Med., 10:1, 1959. Black, P. H., Kunz, L. J., and Swartz, M. N.: Salmonellosis— A review of some unusual aspects. New Eng. J. Med., 262:811, 864, 921, 1960. : Gezon, H. M.: Salmonellosis. D. M., July 1959, 4-toteestIgs %e National Conference on Salmonellosis, March 11-13, 1964. Public Health Service Publication No. 1262, Washington, D.C., U.S. Government Printing Office, 1965. Van Oye, E. (ed.): The World Problem of Salmonellosis. The Hague, Dr. W. Junk Publishers, 1964. Wahab, M. F. A., Robertson, R. P.; and Raasch, F. 0.: Paraty-phoid A fever. Ann. Intern. Med., 70:913, 1969.
ENTERIC BACTERIAL INFECTIONS (INCLUDING URINARY TRACT INFECTIONS) Calvin M. Kunin
Definition. The wide variety of micro-organisms commonly found in the gastrointestinal' tract, particularly the gram-negative, nonsporulating bacilli, have become increasingly important in clinical medicine. They are the principal organ: isms found in, infections of the abdominal viscera, peritoneum, and urinary tract, as well as being • frequent secondary ‘invaders of the respiratory tract, burned' or traumatized skin, and sites of decreased host resistance and instrumentation. Currently, they are the most frequent cause of life-threatening bacteremia.
Infections with these organisms will be considered together because of their common habitat in the gut and on mucous surfaces, the similarity of epidemiologic and pathogenic characteristics, and the common approach used in diagnosis, treatment, and prevention. Bacteriology. The gastrointestinal flora is exceedingly complex, The large intestine contains about 1010 to 10″ organisms per gram of contents. Of these, 90 to 95 percent are obligate anaerobes. Most, common are the gram-negative bacilli, Bacteroides, and Fusobacterium, gram-positive bacilli including Bifidobacterium, -Eu-bacterium, Corynebacterium ‘species, and a wide variety of anaerobic streptococci.
Other anaerobes include the gram-positive spore-forming rods *of the Clostridia species and gram-negative cocci, Veillonella. Lactobacilli and enterococci are also present. The well-known aerobic gram-negative rods, which are members of the family Enterobacteriaceae account for only 5 to 10 percent of the total flora. These include the most common, E. coli, as well as the Klebsiella-Enterobacter group, Proteus, Providencia, Edwardsiella, Serratia, and, under pathologic conditions, Salmonella and Shigella. Pseudomonas is entirely unrelated.