An account is given of the first hundred consecutive proven cases of sulphone resistance in leprosy, detected in Malaysia between 1963 and 1974. Proof of resistance was clinical in eighty patients and was obtained by drug-sensitivity testing in mice in ninety-six patients; 76 cases were proved both clinically and experimentally, and there was no discrepancy between the two methods. Sulphone resistance was confined to patients with lepromatous-type leprosy--i.e., patients with a large bacterial population. Clinical evidence of relapse due to drug resistance appeared 5-24 years after the start of sulphone treatment. Low dosage favoured the appearance of resistance; therefore regular treatment of lepromatous leprosy with dapsone in full dosage is recommended. The attainment of "skin smears negative for leprosy bacilli" is no test of cure of lepromatous leprosy.
Proof that a patient is suffering from sulfone-resistant leprosy depends on demonstrating that his bacilli can multiply in the mouse foot pad even when the mice are fed sulfone in the diet. Hitherto the maximal dose of DDS tolerated by the mouse has been used in such tests. This paper concerns a patient whose bacilli multiplied in mice fed lower doses of DDS, but were inhibited when the maximal dose was used . His clinical features are distinctive and probably characteristic of this type of "partial" resistance. It is likely that more cases of this type will be found . Recommendations are made concerning the investigation of possible DDS-resistant leprosy patients and their treatment.
Kveim tests using a validated material have been undertaken in Malaysia on 39 patients (32 Chinese; 4 Malay and 3 Aboriginal) with lepromatous or tuberculoid leprosy. All the patients had been treated for leprosy, most for two or more years. The tests were read microscopically. Of the 21 lepromatous patients one gave a weak positive and two an equivocal Kveim test whereas four of the nine tuberculoid patients gave equivocal or weak Kveim positivity. Only the tuberculoid form elicits a higher proportion of granulomas than might be expected in a comparable normal population. Of nine patients (8 lepromatous; 1 tuberculoid ) who failed to sensitize well to tuberculin
following two BCG vaccinations, two gave equivocal Kveim tests similar in appearance to those in the other groups.
A multitude of factors can affect drug response in individuals. It is now well established that variations in genes, especially those coding for drug metabolising enzymes, can alter the pharmacokinetic and/or pharmacodynamic profile of a drug, impacting on efficacy and often resulting in drug-induced toxicity. The UDRUGS study is an initiative from the Carney Centre for Pharmacogenomics to biobank DNA and store associated clinical data from patients who have suffered rare and/or serious adverse drug reactions (ADRs). The aim is to provide a genetic explanation of drug-induced ADRs using methods ranging from Sanger sequencing to whole exome and whole genome sequencing. Participants for the UDRUGS study are recruited from various sources, mainly via referral through clinicians working in Canterbury District Health Board, but also from district health boards across New Zealand. Participants have also self-referred to us from word-of-mouth communication between participants. We have recruited various ADRs across most drug classes. Where possible, we have conducted genetic analyses in single or a cohort of cases to identify known and novel genetic association(s) to offer an explanation to why the ADR occurred. Any genetic results relevant to the ADR are communicated back to the referring clinician and/or participant. In conclusion, we have developed a programme for studying the genetic basis of severe, rare or unusual ADR cases resulting from pharmacological treatment. Genomic analyses could eventually identify most genetic variants that predispose to ADRs, enabling a priori detection of such variants with high throughput DNA tests.