BACKGROUND:The nontuberculous mycobacteria (NTM) have been found in different environmental sources. They tend to colonize different body surfaces and secretions. The purpose of this study is to evaluate the presence of NTM in the oral cavity of healthy individuals and its relationship to tap water or oral hygiene.MATERIALS AND METHODS:One hundred sixty-seven healthy subjects were recruited. Three consecutive early morning mouthwashes using tap water were performed and examined for the presence of Mycobacterium tuberculosis (MTB) and NTM. In addition we obtained mouthwashes from 30 control healthy individuals with good oral hygiene using sterile water and examined these for the presence of MTB and NTM.RESULTS:NTM was isolated from the mouthwash of 44 (26.3%) subjects that used tap water. On the other hand, NTM was isolated from the mouthwash of 10 (33%) subjects that used sterile water. Age, gender, social class oral hygiene and the regular use of toothbrush made no statistically significant differences in the isolation rate of NTM.CONCLUSION:The rate of isolation of NTM from mouthwash is high in normal subjects. It is independent of oral hygiene, the use of tap water or teeth brushing. Smear-positive sputum could be NTM rather than M. tuberculosis. Tuberculosis polymerase chain reaction or culture confirmation is essential in developing countries to avoid the unnecessary use of antituberculosis therapy when the clinical suspicion is very low.

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Despite the well-recognized renal toxicity and ototoxicity of aminoglycosides, they are still commonly used in the treatment of gram-negative infections, alone or in combination with beta lactam antibiotics. Various approaches have been proposed to reduce aminoglycoside toxicity. These rely on manipulating and correcting for either patient-related factors or drug-related factors. Drug-related risk factors can be corrected for by choosing the appropriate aminoglycoside, adapting the dose and duration of treatment or by co-administration of nephroprotectants.Aminoglycosides have two virtues: 1) concentration-dependent killing and 2) post-antibiotic effect. Aminoglycosides demonstrate dose-dependent killing, i.e., the higher the level, the more rapid the killing of bacteria. The other property of aminoglycosides is the so-called postantibiotic effect. This effect is defined as the delay in regrowth of antibiotic-treated organisms following antibiotic removal. In practice, the effect of postantibiotic effect is the suppression of bacterial growth after cessation of exposure to aminoglycoside concentrations above the minimal inhibitory concentrations (MIC). The duration of this effect is dependent on the aminoglycoside serum concentration achieved and the duration of exposure. It has therefore been suggested that the administration of a large dose once daily could maximize the rate of bacterial killing, and the post-antibiotic effect, preventing regrowth of bacteria during the period of low antibiotic concentration in the serum. 1A narrow therapeutic margin and low predictability of plasma concentrations are the main reasons for drug monitoring during aminoglycoside treatment. Gentamicin, tobramycin, amikacin and netilmicin can now be accurately and rapidly measured by radioenzymatic and radio and enzyme immunoassays. Routine determinations of peak (one to two hours post dose) and trough levels are recommended to ensure adequate dosage in all patients with serious gram-negative infections, especially when renal function is impaired. However, maintaining aminoglycoside concentration within a given range is frequently difficult and will reduce but not entirely eliminate the risk of toxicity. The pharmacokinetic behavior of the aminoglycosides leads to a progressive drug accumulation in the renal tissue and the inner ear, which depends on both dosage and duration of treatment. Nephrotoxicity to aminoglycosides has been estimated to occur in up to 5% to 25% of patients, while hearing loss (cochlear) is observed in about 3% to 14% and vestibular toxicity affecting about 4% to 6% of patients when multiple daily doses of the aminoglycosides are used for therapy. In vitro and animal studies suggest that a oncedaily regimen could reduce the risk of side effects with equal or even improved efficacy of the aminoglycosides in bacterial eradication. 1,2A large number of animal data have demonstrated that the single daily administration of an aminoglycoside is less toxic than administration twice, thrice or by continuous infusion ...