Biomedical subjects
Publications and source records attributed to S Gamage.
Since the first autochthonous case of cutaneous leishmaniasis in Sri Lanka was reported in 1992 (1) attempts to culture the causative organisms have been unsuccessful. We report the first successful isolation of the local Leishmania sp. by in vitro culture, which would pave the way for species and strain indentification.
OBJECTIVE: To determine the drug sensitivity of Mycobacterium tuberculosis strains isolated from pretreatment (primary) cases of pulmonary tuberculosis. DESIGN: A descriptive study. SETTING: The Central Chest Clinic, Colombo. PATIENTS: 103 patients with pulmonary tuberculosis who have not taken anti-tuberculosis drugs previously. MEASUREMENTS: Antibiotic sensitivity pattern of M tuberculosis isolates for isoniazid (INAH), ethambutol (EMB), rifampicin (RMP) and streptomycin (SM) tested in drug incorporated Lowenstein Jenson (LJ) medium using resistance ratio method. RESULTS: 15.5% isolates of M tuberculosis were resistant to at least one drug. Resistance to a single drug was found to be most prevalent (69%) among the resistant isolates and among these INAH resistance was most prevalent followed by streptomycin. None of the isolates were resistant to all four drugs. Resistance rates to individual drugs were INAH 9.7%. SM 6.7% EMB 2.9% and RMP 2.9%. CONCLUSIONS: Since the introduction of RMP and EMB in the treatment regimens from mid-1970s the incidence of tuberculosis and rate of primary drug resistance to anti-tuberculosis drugs has not changed significantly (p > 0.05) when compared with the results of studies conducted previously (2, 3). However, it is recommended that regular surveillance of drug sensitivity pattern should be maintained to determine alternate drug regimes and to detect the spread of resistant strains in the community.
An in vitro investigation of the structure-activity profiles for a range of 9-anilinoacridines on drug-resistant Plasmodium falciparum is reported. C-3, 6-diamino substitution, low lipophilicity, and high pKa values substantially increased the activities of the 9-anilinoacridines tested. There appeared to be no correlation between DNA binding and antimalarial activity. 3,6-Diamino-1'-amino-9-anilinoacridine (compound 13) was the most active compound tested; it had a 50% inhibitory concentration of 25 nM. In vitro mammalian cell growth assays showed compound 13 to be one of the least cytotoxic 9-anilinoacridines (50% inhibitory concentration, 15 microM). Both compound 13 and the antimalarial drug pyronaridine inhibited the decatenation activity of P. falciparum DNA topoisomerase II at concentrations of 10 and 11 microM, respectively.
A number of 1'-substituted 9-anilinoacridines were evaluated for their activities against promastigote and amastigote forms of Leishmania major and for their toxicities to human Jurkat leukemia cells. Several compounds possessing 1'-NH-alkyl substituents produced more than 80% growth inhibition of macrophage-infected L. major amastigotes at or below a concentration of 1 microM. 1'-Hexylamino-9-anilinoacridine (compound 14) was the least toxic compound to human Jurkat cells, while it retained strong antileishmanial activity. There was a general trend for the more lipophilic compounds to show the greatest antileishmanial activity, whereas 3,6-di-NH2 substitution of the acridine nucleus reduced or eliminated activity. Some structure-activity relationships of the various compounds are discussed.
Out of 308 isolates of Staphylococcus aureus isolated from specimens processed at the Department of Microbiology, Faculty of Medicine, Colombo 66 (21.5%) were resistant to methicillin. A significantly higher proportion of methicillin resistant Staphylococcus aureus (MRSA) were isolated from special care units, namely the Premature Baby Unit (PBU) and the Plastic Surgery Unit (PSU) when compared with other general medical and surgical units. Most of these strains were also resistant to many other antibiotics. The patients with MRSA infections had a longer mean hospital stay when compared to patients with methicillin sensitive Staphylococcus aureus (MSSA) infections. MRSA strains are as virulent as MSSA strains and these infections are mainly nosocomial.