MICROBIAL DISEASES PROGNOSIS Untreated meningitis is almost always fatal. Antimicrobial therapy has dramatically improved the outlook for patients with meningeal infections. Despite this, the mortality inadequately treated pneumococcal meningitis remains between 10 and70 percent, and 50 percent of infections with staphylococci and gram-negative enteric bacilli are lethal. On the other hand, the mortality rate associated with meningococcal and H. influenzae meningitis is less than 10 percent. In addition to the difference in prognosis engendered by different microorganisms, factors that adversely influence outcome include
(1) improper or delayed diagnosis, usually a consequence of falsely attributing con-fusion or delirium to “toxemic” depression of the central nervous system or hepatic encephalopathy;
(2) fulminating infection with rapid loss of consciousness;
(3) bacteremia; MICROBIAL DISEASES PROGNOSIS
(4) old age or the neonatal period;
(5) certain underlying and complicating illnesses, including bacterial endocarditis, brain abscess, diabetes mellitus, and pneumonia;
(6) development of coma, localizing neurologic signs, and convulsions.
MICROBIAL DISEASES PROGNOSIS Antimicrobials are the mainstay of therapy in bacterial meningitis and should be administered parenterally at the earliest possible moment. If the Gram stain of the Cerebro-spinal fluid reveals the causative micro-organism, specific treatment may be instituted from the beginning. However, if microscopy of the stained Smear has been inconclusive, the initial therapy must be sufficiently broad to be fully effective against the most reasonable possibilities. For example, purulent meningitis in an adult without evidence of an overt portal of entry is most apt to be pneumococcal or meningococcal; in a young child, H. influenzae must also be considered. Pri-mary staphylococcal meningitis would be rare in a previously healthy adult, but should he consider-ea-c2 )..g-ho.capitalized patient, particularly if neurosurgery has been performed. Penicillin is the drug of choice for pneumococcal and meningococcal meningitis and should be administered parenterally in a dosage of 10 to 20 million units a day. For patients who are sensitive to penicillin, chloramphenicol in dosage of 4.0 to 6.0 grams per day should be used if Neisseria is the causative pathogen, although cephalothin, in dosage of 6.0 to 12.0 grams per day, or cephaloridine, in dosage of 4.0 grams per day, can be substituted for penicillin in pneumococcal meningitis.
Chloramphenicol (2.0 to 4.0 grams a day) may be given in H. influenzae meningitis, but ampicillin in a dosage of 6.0 to 12 grams a day is at least as effective and has the additional advantage of being bactericidal for pneumococci and meningococci. MICROBIAL DISEASES PROGNOSIS Use of this agent should, for all practical purposes, eliminate multiple drug therapy in “undiagnosed meningitis.” A few “ampicillin failures” have been reported in children with H. influenzae meningitis.
These were probably related to inadequate dosage or poor absorption of the drug. Staphylococcal meningitis should always be treated with one of the penicillinase-resistant penicillins, e.g., methicillin, oxacillin, or nafcillin in the dosage of 6.0 to 12.0 grams parenterally, or with cephalothin in similar dosage. For the rare cases of meningitis caused by the Enterobacteriaceae, kanamycin in a dosage of 2.0 grams a day is probably the agent of choice until drug-susceptibility tests have been performed. If Pseudomonas meningitis is suspected, polymyxin B .or colistin should be employed both parenterally and intrathecally. Only the preparation free of dibucaine should be used for intrathecal therapy. MICROBIAL DISEASES PROGNOSIS
The dosage of colistin is 5 mg. per kilogram per day parenterally and 5 mg. daily intrathecally. Polymyxin B should be given in approximately half the dose of colistin. Gentamicin, in a dosage of 5 mg. per kilogram daily in divided dosage may become the drug of choice in Pseudomonas meningitis, and its use may obviate intra-thecal therapy.
In patients with mastoiditis, an infected venturi-culomastoid shunt, or cranial osteomyelitis, surgical attack on these primary foci while the patient is receiving appropriate antimicrobial therapy is indicated but may be postponed until the acute meningeal episode is over.
Duration of Therapy. The duration, of antimicrobial therapy in meningitis cannot be pre-scribed categorically. The cerebrospinal fluid should be examined every 24 to 48 hours during the early days of therapy, but once the patient is recovering, the intervals between lumbar puncture may be as long as a week, and numerous examinations of the CSF are rarely necessary. In the absence of extrameningeal foci, a seven- to ten-day course of antimicrobial therapy should suffice. Other Measures. If there is evidence. of in-creased intracranial pressure, and supratentorial or cerebellar herniation, therapy with mannitol, urea, or dexamethasone should be instituted. Adrenal cortical hormones also have been used as an adjunct to antimicrobial therapy, but have not resulted in noteworthy improvement They should never be used unless the etiologic °maids: es has been clearly identified and the appropriate areg is being administered- The lime hem mime tea, enthusiastic reports about proteolytic enzymes in the treatment of pneumococcal meningitis, but these agents have not been evaluated in sufficient detail to recommend their general use.
Other supportive therapy inehides administration of adequate but not excessive parenteral fluids and anticonvulsants when indicated. Sedation should be employed with caution, even for delivery-ous patients; of the many agents available, panel 4, ZBeaty, H. N… and Offeabeiuter. CSF lactic dehydrogenase and its litoetaymes in lifetimes of the central nervous system New! meJ. 279:1197. 1968.
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Snyder; S. N., and Brunjes, influence meningitis in adults. Amer. J. Med. Sci., 250:658. /965.• Swartz, M. N., and Dodge, P. IL: Bacterial meningitis— A review of selected aspects. New Eng. J. Med., 272:725, 779, 842JH 898, 954, 1003, 1965.Welshimer, H. J., and Winglewish, Listeriosis Summary of seven cases of listeria meningitis. J.A.M.A., 171:1319,1959.