Decrease of antibiotic resistance in Salmonella typhi isolated from patients attending hospitals of Dhaka City over a 3 year period.

Salmonella typhi is an important cause of enteric fever in Bangladesh. Resistance to commonly used antibiotics like cotrimoxazole and ampicillin has led to the introduction of third generation cephalosporins and fluoroquinolones for the treatment of enteric fever. Prescription patterns for enteric fevers and for other infections have been changing and so we looked at the antibiotic resistance of S. typhi isolated from patients in and around Dhaka City from 1996-1998. The study showed a gradual change in resistance to ampicillin and cotrimoxazole among S. typhi in our area. The rate of resistance to cotrimoxazole, ampicillin and chloramphenicol decreased from 59.6 to 5.6% in S. typhi over a 3 year period. The extensive use of third generation cephalosporins and fluoroquinolones, in place of conventional antibiotics, has probably influenced the change in resistance pattern in S. typhi.

Comparative studies on IFAT, ELISA & DAT for serodiagnosis of visceral leishmaniasis in Bangladesh.

The purpose of the study was to estimate the specificity and sensitivity of different serological methods for the diagnosis of visceral leishmaniasis in Bangladesh. Blood samples from 155 suspected kala-azar patients together with 80 sick subjects and 50 healthy subjects from the endemic areas were collected. Out of the 155 suspected kala-azar patients, bone marrow were collected from 126 patients. All bone marrow samples were examined by direct microscopy. 92 bone marrow samples were also examined by culture method. Blood samples were examined by various serological tests. Out of 126 marrow samples, LD bodies were present by microscopy in 77 (61.1%) cases and out of 92 marrow samples, cultures for LD bodies were positive in 33 (35.9%) cases. All the three serological tests (IFAT, ELISA & DAT) were positive in all parasitologically positive kala-azar patients. They were also positive in seven (15.5%) out of 45 parasitologically negative cases and 10 (34.4%) out of remaining 29 cases in whom bone marrow samples were not available. Thus the serological tests proved to be simple, non-invasive, highly sensitive and specific methods for the diagnosis of visceral leishmaniasis. DAT is the simplest of these serological tests, although these tests did not differ in sensitivity and specificity.

Incidence of Aeromonas isolated from diarrhoeal children and study of some virulence factors in the isolates.

Stool samples from 305 children with diarrhoea and equal number of age and sex matched non-diarrhoeal control children, less than 5 years of age, were examined during the period from Sept 1988 to April 1989. Aeromonas spp. were isolated from 37 (12.1%) diarrhoeal and 05 (1.6%) control cases. Out of 37 diarrhoeal isolates 13 (35.1%) were A. hydrophila, 19 (51.1%) A. sobria and 05 (13.5%) A. caviae. All the isolated strains were tested for haem agglutination property and haemolysin production. Seventeen diarrhoeal and 05 control isolates were tested for cytotoxin production in He La cell line and enterotoxin production in rat ileal loop model and suckling mouse model. Chinese hamster ovary cell (CHO) assay and Gm-1 ELISA methods were also employed. Cytotoxin production was found in 82.5% of diarrhoeal and 40% of control isolates. Haemagglutination was found in 62.1% of Aeromonas isolated from diarrhoeal children and 20% from control children. Enterotoxin production was detected in 58.8% diarrhoeal and none of the control isolates by either of the methods. Of the virulence factors enterotoxin production was found to correlate well with enteropathogenicity but haemolysin, cytotoxin and haemagglutinin did not.

Indirect fluorescent antibody test in the serodiagnosis of visceral leishmaniasis in Bangladesh.

Indirect fluorescent antibody test (IFAT) was found to be 100% sensitive and 100% specific when tested with sera from 125 parasitologically proven kala-azar patients, 100 healthy controls and 50 sick control cases. Promastigotes of both L. enriettii and L. donovani as well as amastigotes of L. enriettii were found equally satisfactory as antigen for IFAT. From the results of the present study, it is concluded that IFAT is a highly sensitive as well as specific serological test for the diagnosis of kala-azar.