Comparison of the boronic acid disk potentiation test and cefepime-clavulanic acid method for the detection of ESBL among AmpC-producing Enterobacteriaceae.

Purpose: Extended spectrum β-lactamase (ESBL) and AmpC β-lactamase are important mechanisms of betalactam resistance among Enterobacteriaceae . The ESBL confirmation test described by Clinical Laboratory Standards Institute (CLSI) is in routine use. This method fails to detect ESBL in the presence of AmpC. Therefore, we compared two different ESBL detection methods against the CLSI confirmatory test. Materials and Methods: A total 200 consecutive clinical isolates of Enterobacteriaceae from various clinical samples were tested for ESBL production using (i) CLSI described phenotypic confirmatory test (PCT), (ii) boronic acid disk potentiation test and (iii) cefepime-CA disk potentiation method. AmpC confirmation was done by a modified three-dimensional test. Results: Among total 200 Enterobacteriaceae isolates, 82 were only ESBL producers, 12 were only AmpC producers, 55 were combined ESBL and AmpC producers, 14 were inducible AmpC producers and 37 isolates did not harboured any enzymes. The CLSI described PCT detected ESBL-producing organisms correctly but failed to detect 36.3% of ESBLs among combined enzyme producers. The boronic acid disk potentiation test reliably detected all ESBL, AmpC, and combined enzyme producers correctly. The cefepime-CA method detected all ESBLs correctly but another method of AmpC detection has to be adopted. Conclusion: The use of boronic acid in disk diffusion testing along with the CLSI described PCT enhances ESBL detection in the presence of AmpC betalactamases.

Efficacy of diethylcarbamazine-medicated salt for microfilaraemia of Brugia malayi.

BACKGROUND: Pilot studies in India and abroad have demonstrated the benefit of cooking salt fortified with diethylcarbamazine citrate (DEC) for the control of lymphatic filariasis. In India, DEC-medicated salt has been introduced on a commercial basis in the Cherthala region of Kerala, which is endemic for Brugia malayi (B. malayi). We studied the efficacy of DEC-medicated salt in the clearance of microfilaraemia of B. malayi. METHODS: Eighteen cases of microfilaraemia (11 men; 7 women) were selected; 14 in the experimental group (i.e. treated with 0.2% w/w DEC-medicated salt) and the rest as the control group who were given a placebo. The consumption of salt and the status of parasitaemia were monitored till all the microfilaria carriers became negative. RESULTS: There was a significant reduction in the density of microfilariae (intensity) among the treated individuals over a period of time. The duration required for the clearance of microfilariae ranged from 9 to 30 [mean (SD) 19.4 (1.7)] weeks. All microfilaraemics except one reported side-effects which were mild-to-moderate and persisted for a maximum period of one month. CONCLUSION: DEC-medicated salt effectively clears microfilariae within 30 weeks in parasitaemic individuals. No 'endemic normals' reported any side-effects, though these were common among the microfilaria carriers.