Enteric Infection Treatment is being explored in this article.The major clinical problems in management of enteric bacterial infections are (1) differentiation of superficial contamination that often requires no treatment from true or potential tissue invasion, (2) early recognition and drainage of abscesses, (3) anticipation of the role of anaerobic bacteria that cannot be readily cultured, and (4) early recognition of bacteremic shock. Many of these infections are preventable, particularly those arising from instrumentation of the urinary tract, intravenous catheters and contaminated fluids, suction, and ventilation equipment. Every physician must consider Elimination of such sources of contamination as one of his prime responsibilities.
The presence of gram-negative organisms in the blood should alert , the physician to search for a site of origin such as intravenous or urinary catheters and abdominal or perirectal abscesses. Removal of devices and drainage of abscesses should be done as soon as possible. Antimicrobial therapy should be guided as often as possible by in. vitro drug- susceptibility tests because of the remarkable ability of enteric bacteria to develop resistant strains. Among the aminoglycoside antimicrobials, gentamicin and kanamycin are most reliable,followed by streptomycin.
The so-called broad- spectrum drugs such as tetracycline and chloramphenicol are also useful against the Enterobac- teriaceae. Large doses of penicillin G are effective against many of the gram-positive and some gram- negative anaerobes. Tetracycline and chloramphenicol are useful for Bacteroides, whereas Pseudomonas will generally respond only to drugs such as polymyxin B or colistin methane sulfonate (polymyxin E) and gentamicin. Carbenicillin is a new semisynthetic penicillin that may be of considerable value in treatment of Pseudomonas, Enterobacter and Proteus infections. The problems are the large doses required, development of resistance, tendency for sodium overload, and high cost.
It should be reserved for clearly established infection caused by a susceptible organism. It is generally advisable to use two and sometimes more agents in severe gram-negative sepsis, particularly when bacteriologic identification is delayed. In general, this treatment would include an aminoglycoside drug, a broad-spectrum drug, and penicillin G. Ampicillin and cephalothin (or cephaloridine are considered to have generally similar properties to penicillin G, and usually would not be used simultaneously.
At times, they offer special advantages over penicillin,, because both ampicillin and the cephalosporins are active agair.s: mar- gram-negative bacteria as well as gram-posit:ve cocci. The cephalosporins are generally more active against Klebsiella than is ampicillin, but ampicillin is much more effective against enterococc:. The cephalosporins are also useful in patients allergic to penicillin. The inherent toxicity of the polymyxins should restrict their use mainly to treatment of Pseudomonas. Satisfactory results have been achieved by combinations of large doses of penicillin-like drugs with tetracycline in mixed anaerobic infections such as peritonitis or brain abscess, but many other combinations appear to be good.
Management of bacteren-<.:c shock is complex, requiring corrective measures designed to improve cardiac function,, tissue perfusion, and electrolyte imbalance, particularly acidosis This requires monitoring of the central venous pressure by a well-placed catheter- in the superior vena cava or right atrium in an attempt to achieve a pressure of about 8 to 12 cm. of water, and following the dynamics of pressure changes as fluid replacement is given. Replacement fluids include blood, dex- tran, and saline solutions. Drugs such as isoproterenol may be used to increase cardiac output and improve tissue perfusion; vasopressors such as metaraminol should be used sparingly except in severe shock. High doses of corticosteroids are widely used, but their efficacy has not been established by controlled studies.
Urinary Tract Infection. The therapeutic principles are similar for all urinary infections, including bacteriuria, cystitis, or pyelonephritis. Recognition and relief of obstruction are essential. Therapy is then directed to sterilization of the urine and careful follow-up to detect recurrence, using significant bacteriuria as a guide. Infections uncomplicated by obstruction or many previous will generally respond to oral therapy vr.tr. sulfonamides, tetracycline, ampicillin, chloramphenicol, nalidixic acid, or nitrofurantoin.
The last-named drug is particularly useful in recurrent infections because of relatively less frequency of emergence of resistant strains. Drugs are selected on the basis of relative cost, side effects, and antimicrobial sensitivity, all of which may be highly variable. Bacteria should disappear within 24 to 48 hours even if pyuria and symptoms continue. It is important to recognize bacteriologic failure early and change to another drug. Generally, short courses of treatment, from 10 to 14 days, are quite adequate; short-term high-dose therapy, sometimes with the parenteral agents described above, may be required in some instances of failure with lower doses. Recurrence within a few weeks after treatment is usually due to persistence of the same focus, whereas later recurrence, particularly in females, is more often the result of reinfection.
Highly recurrent infections may be managed by either very close follow-up and treatment of each episode or by prophylaxis with nitrofurantoin or urinary antiseptics such as methenamine mandelate or hippuric acid. These agents require an acid urine, preferably at pH 5.5. This may be achieved by addition of a high protein diet, ammonium chloride,’ or methionine. Methionine is a particularly effective acidifier, but it may have to be given in doses as high as 10 grams per day. The dose can be titrated downward by measuring urinary pH. Prophylaxis should not be given for more than three to six months if at all possible, and should be abandoned, if bacteriuria persists or recurs.
Complex urinary infections, that is, those in the presence of obstructive uropathy, neurogenic bladders, or catheters, are exceedingly difficult to eradicate and may be managed by suppressive therapy with urinary antiseptics if shown effective, or simply left alone unless systemic complications develop. Sepsis in these cases is Usually due to- obstruction’ and should be promptly relieved. Bacteriuria in the aged is frequent, usually uncomplicated, and highly recurrent. It should not be overzealously treated if simple measures fail, because toxicity and expense of therapy may outweigh the risk of disease.