Primary drug resistance pattern of mycobacterium tuberculosis in Dhaka, Bangladesh.

One thousand two hundred and eighty one clinically suspected untreated patients with pulmonary tuberculosis were studied from an urban tuberculosis clinic in Dhaka. Majority of the 1281 patients (77.6%) were from the age group of 14 to 44 years. Sputum, 106 (8.3%) were found positive for mycobacteria (both by Ziehl-Neelsen smear staining and culture to consider those as confirmed cases of mycobacterial infection. Out of these 106 cases, 101 (95.3%) were identified as M. tuberculosis and the rest 5 (4.7%) as Non-tuberculous Mycobacteria (NTM). Among the 101 M. tuberculosis strains, 30 (29.7%) were resistant to at least one drug; 16 (15.8%); to isoniazid, 11 (10.9%) to rifampicin, 07 (6.9%) to streptomycin, 03 (2.9%) to ethambutol and 04 (3.9%) to pyrazinamide. Multi-drug resistant tuberculosis (MDR-TB) was found in 5 (4.95%) cases. 5 (4.95%) cases were resistant to two drugs and 3 (2.97%) cases to three drugs. Ciprofloxacin was tested against 30 strains of M. tuberculosis; 2 (6.67%) of which were resistant. This is the first report of ciprofloxacin resistant Mycobacterium tuberculosis from Bangladesh. All the 5 strains of NTM tested for said 5 anti-tuberculous drugs, were found resistant to more than one.

Isolation and characterization of Helicobacter pylori strains from peptic ulcer patients in Dhaka, Bangladesh.

To study the association of Helicobacter pylori with peptic ulcer and the associated histopathological changes, to characterize the isolated strains in terms of their protein profile, 83 peptic ulcer cases were studied. A high association of H pylori with peptic ulcer (duodenal ulcer 77%, gastric ulcer 75%) and gastritis (74%) was observed. Age and smoking did not have any relationship with H pylori infection. The infection was predominantly associated with the 'quiescent' form of chronic gastritis. Comparative sodium dodecyl sulfate polyacrylamide gel electrophoresis of whole cell extracts of the local isolates and a reference strain from Australia showed a general homogeneity between the strains with obvious interstrain differences. However, the difference between the local isolates and the reference strain was more marked. Significant association of H. pylori with peptic ulcer along with strain variations were observed.

Antigen profile of Helicobacter pylori strains isolated from peptic ulcer patients in Dhaka, Bangladesh.

The whole-cell-extract and the acid-extract preparations of Helicobacter pylori strains isolated from peptic ulcer patients and the NCTC 11638 control strain were studied to compare their antigen profiles. Besides, the anti-H. pylori-antibody profile in serum from H. pylori-infected peptic ulcer patients were also studied to define the antigen stimulating specific anti-H. pylori-antibody response in the infected patients. The whole-cell extract (WCE) and the acid-extract (AE) preparations showed a general antigenic homogeneity among the H. pylori strains isolated from the patients and the NCTC 11638 control strain. A humoral immune response against the infecting organism was observed and three antigenic bands of approximate molecular masses of 61 kDa, 58 kDa and 24 kDa were recognized by all the tested sera. Those bands were found to be unique for H. pylori and did not show any cross reaction with the Campylobacter jejuni antigenic bands. This makes them a candidate for the specific antigens required to develop a specific serological diagnostic test. Further purification and characterization of the protein bands may be carried out to define their probable diagnostic or immuno-pathogenic role.

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.

Studies on virulence determinants of Plesiomonas shigelloides.

Virulence determinants of nineteen strains of Plesiomonas shigelloides isolated from stool samples of diarrhoeal children were studied. Heat-labile toxin was detected in seven strains using rat ileal loop model and in none of the strains using Chinese hamster ovary cell assay system and by Enzyme-linked immunosorbent assay. Rat ileal loop model was used for the first time to assay toxin in P. shigelloides and is suggested to be a cheap and effective method of detecting labile toxin in the organism. Heat stable toxin, cytotoxin, hemolysin and hemagglutinin were not detected in the strains tested. Invasiveness could not be established by using HEp-2 cell assay system. The results of this study provide some experimental support for an etiological role for P. shigelloides in the production of diarrhoea.

Special properties associated with virulence of urinary Escherichia coli.

Escherichia coli (E. coli) isolated from 53 urine and 26 stool samples of patients with urinary tract infection (UTI) and 50 stool samples of normal individuals were studied to see their hemolytic, hemagglutinating and 'O' antigenic properties which might be related to virulence of the organism. Significantly higher number of E. coli isolated from urine of UTI patients were found to possess hemolytic, hemagglutinating properties and more frequently belonged to certain "O" antigenic groups either singly or in combination as compared to those isolated from stool of both UTI patients and normal individuals. Hemagglutinating property appeared to be most frequently associated with UTI.

Penicillinase-producing Neisseria gonorrhoeae in Dhaka, Bangladesh.

Among the 52 strains of Neisseria gonorrhoeae isolated from cases of acute urethritis attending the dermatovenerology department of different hospitals of Dhaka city, 5(9.6%) strains were identified as penicillinase-producing (PPNG) and had minimum inhibitory concentration (MIC) of penicillin 4.0 micrograms/ml or more. Of the rest 47 (90.4%) non-penicillinase-producing strains (non-PPNG), 18(38.3%) were fully sensitive to penicillin (MIC = 0.06 micrograms/ml or less), 25(53.2%) had diminished sensitivity (MIC = 0.125 to 0.5 micrograms/ml) and 4(8.5%) were resistant to penicillin (3 had MIC 1 micrograms/ml and 1 had MIC 2 micrograms/ml).