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The discovery that aminosugars found in nature kill common bacteria initiated use of a new class of antibiotics that have played a key role in the management of several major medical problems over the past 40 years. The rapid bactericidal effect of the aminoglycosides on aerobic Gram-negative bacilli has expanded their use to approximately 6% of all our general hospital patients. These agents have many desirable properties, but also have the potential for producing ototoxicity and nephrotoxicity that imposes pharmacological limitations on their optimum use. The experience of earlier investigations demonstrated the need for quantitative measurements and individual patient dosing which has reduced the risk of toxicity many fold. Using sensitive measurements, toxic manifestations can be classified as detectable by laboratory means only, some that have clinical expression and rarely a lasting handicap. Semisynthetic modification of kanamycin (amikacin) and sissomicin (netilmicin) protects these compounds against inactivation by most bacterial enzymes and preserves their effectiveness. Netilmicin seems to have less potential for causing toxicity, especially ototoxicity that is irreversible, and offers the possibility of further gains through pharmacological flexibility without crippling toxicity.

Fungal and mycobacterial infections are among the most common opportunistic infections in patients infected with human immunodeficiency virus (HIV). Candida infections are the bell-wether of progression to symptomatic HIV infection and candida oesophagitis often marks the onset of the acquired immunodeficiency syndrome (AIDS). More than 80% of AIDS patients have candida disease. Candida infections remain local and respond to treatment but tend to recur. Cryptococcal infections initially affect few HIV positive patients but involve 10-30% with AIDS. Meningitis is the usual presentation and dissemination is common. Amphotericin usually produces improvement but cure is infrequent, and maintenance therapy is advisable. Mycobacteria cause intracellular infections increasing in parallel with immunodeficiency. Mycobacterium avium-intracellulare is predominant, occurring with other opportunistic pathogens causing systemic and local symptoms with high bacterial density in infected cells. Multidrug treatment is best, but the results are disappointing. Tuberculosis is prevalent in certain groups of patients. It often presents with atypical clinical and pathological features. Anti-tuberculous treatment is effective and prophylaxis should be considered. Endemic fungi with mycobacteria cause sporadic infections. Opportunistic infections are the lethal arm of HIV infection. Diligent diagnosis and persistent treatment offer benefit to HIV-infected patients.

The value of netilmicin, like that of other antibiotics, is influenced by its antimicrobial specificity, dosage and ease of administration, activity in pus and the underlying condition of the host. Different classes of antibiotics and different members among a group of antibiotics have relative strengths and weaknesses among these clinical factors that affect the results of antibacterial therapy and must be determined by careful clinical investigation.