Microbial colonization of Provox voice prosthesis in the Indian scenario.

INTRODUCTION: Tracheoesophageal speech using the voice prosthesis is considered to be the “gold standard” with success rates as high as 90%. Despite significant developments, majority eventually develop dysfunction due to microbial deterioration. We did a pilot study of 58 laryngectomy patients who developed prosthesis dysfunction. MATERIALS AND METHODS: A total of 58 laryngectomy patients who had their dysfunctional prosthesis removed were included in this study. Dysfunctional prostheses were removed and examined. Esophageal and tracheal flanges were examined separately. After obtaining pure fungal and bacterial cultures, the yeast strains were identified. Bacteria were identified with the light microscope and gram staining. We analyzed prosthesis lifespan and probable factors affecting it. RESULTS: Central leak was found in 43% cases while in 57% peri‑prosthetic leakage was the most common reason for prosthesis replacement. Microbial analysis revealed a combination of yeast and bacteria in approximately 55% culture samples. Out of these, almost 90% had the presence of single yeast species with bacteria. Pure fungal culture was identified in rest of the 45% cultures while none detected pure bacterial forms. Candida tropicalis was the solitary yeast in 81% while Candida albicans was seen in 10% as the solitary yeast. Bacterial isolates revealed Klebsiella pneumonia in 19%, Escherichia coli in 8% while Staphylococcus aureus was grown in 1% cultures. The consumption of curd (P = 0.036, 95% confidence intervals [CI]: 2.292‑64.285) to have a significant correlation of the mean prosthesis lifespan. Consumption of curd (P = 0.001, 95% CI: 0.564‑2.008) and history of prior radiotherapy (P = 0.015, 95% CI: 0.104‑0.909) had a significant bearing on the Provox prosthesis lifespan. CONCLUSIONS: Candida is the most common organism grown on voice prosthesis in Indian scenario. Consumption of curd and history of prior radiotherapy significantly affect Provox prosthesis lifespan.

Effect of some new insect growth regulators on metamorphosis & reproduction of Aedes aegypti.

Fourth instar larvae and pupae of Ae. aegypti were treated with four most active insect growth regulators from a new series of mixed alkyl and aryl diethers based on geraniol. Considerable reduction in fecundity and fertility of adults was obtained. Treatment of pupae or pharate adults did not affect adult emergence. Topical treatment of adult females caused great reduction in fertility and fecundity in older as compared to younger females. In addition to the effects on reproduction, adult survival was also reduced in the treated younger females.

Action of some new insect growth regulators on mosquito vectors. Part II: Geraniol based diethers.

Biological activity of saturated diethers viz. 1-benzyloxy/phenoxy-8-alkoxy and 1-alkoxy-8-benzyloxy-3,7-dimethyl-1, 8-octanes (IIa-IIq) prepared from Geraniol, were studied on three mosquito species and the bug Dysdercus koenigii. These diethers exhibited oviposition deterrent and developmental inhibition activities of greater magnitudes than the compounds based on citronellol reported in Part I of this paper. Some of these new compounds inhibit development of mosquitoes at 0.05 ppm and deter oviposition at 0.05 per cent doses. Tests were extended to field simulated conditions in selected cases.

Action of some insect growth regulators on mosquito vectors: Part I--Citronellol based diethers.

New series of compounds starting from common terpenoids (Geraniol, citronellol) have been examined for biological activity on mosquito larvae. Many of these exhibited development disruption on eggs as well larvae. Some also affected adult oviposition behaviour. Developmental disturbances were classified as JH type by inducing typical metamorphosis inhibition in Dysdercus koenigii in the standard Hemipteran JH bioassay. Where indicated simulated field trials were also undertaken. This report describes results of bioevaluation of the citronellol based compounds. The results indicate that these show multifarious activity against mosquitoes but at relatively high doses, suggesting that exploration of further structural variety is needed before truly promising analogues can be obtained.