Biomedical subjects

S D Puthucheary

Publications and source records attributed to S D Puthucheary.

At least 55 records · Page 3Linked to original sources

PubMed1996

Short report: Electron microscopic demonstration of extracellular structure of Burkholderia pseudomallei.

The occurrence of latency and relapse in human melioidosis suggests adaptations by Burkholderia pseudomallei that help to avoid the human immune response. Ruthenium red-stained preparations of bacterial cultures viewed by electron microscopy revealed three morphologically distinct variants; one with a very marked and another with a less electron-dense layer surrounding the cell wall, and a third variety devoid of such a structure. This structure may be attributable to a layer of polysaccharide, suggesting the presence of a glycocalyx that may aid in the survival of the organism during latency.

Burkholderia pseudomallei↗

PubMed1996

Hemolysins and plasmid profiles of Vibrio parahaemolyticus.

Forty clinical isolates of Vibrio parahaemolyticus were studied for the production of the thermostable direct hemolysin (TDH), and the TDH-related hemolysin (TRH) including the respective encoding genes, tdh and trh. The presence of TDH and its encoding genes were found amongst 95% of the strains, whereas the TRH was absent amongst these isolates. Thirty-two isolates were found to be plasmid-free, whereas eight isolates possessed plasmids with sizes ranging from 2.4 > or = 23 kb. Using a DNA probe coding for the homologous region of the tdh and trh, it was found that the tdh genes were present on the chromosomal DNA.

Bacteriological Techniques↗

PubMed1995

Possible virulence factors involved in bacteraemia caused by Aeromonas hydrophila.

Eighteen strains of Aeromonas hydrophila from patients with bacteraemia were investigated for possible virulence factors. Cytotoxin and haemolysin were produced by all strains, whereas cholera toxin-like factor was produced by 33% of strains only. Enterotoxin production was not detected. Haemagglutination of guinea-pig, fowl and rabbit erythrocytes was demonstrated by 83%, 67% and 61% of strains, respectively. Fucose- and mannose-sensitive haemagglutinins were predominant. None of the strains agglutinated sheep erythrocytes. Extrachromosomal DNA was detected in 17 strains, 16 of which had a plasmid (3.6-5.1 MDa), the majority being between 4.6 and 5.1 MDa.

Adolescent↗

PubMed1995

Detection of haemolytic activity of campylobacters by agarose haemolysis and microplate assay.

There are several methods for the detection of haemolytic activity in campylobacters. However, we found the haemolytic effect of campylobacters on conventional blood agar plates to be variable, inconsistent and difficult to interpret. Blood agarose plates showed campylobacter haemolytic activity more clearly. The incubation conditions (temperature and gaseous) appear to be important for the expression of this activity. Ninety four percent of the Campylobacter isolates examined were found to be haemolytic by the microplate assay with minimal haemolytic units that ranged from 1 to 64. Haemolytic activity was detected only from live bacterial cultures and not from any of the 50 bacterial culture supernates, which suggests that campylobacters may possess a cell-associated haemolysin. The identification of such haemolytic activity in a large number of campylobacters (94%) suggests its potential role as a virulence factor in campylobacter gastroenteritis.

Animals↗

PubMed1995

The histopathology of human melioidosis.

We examined human tissues infected by Burkholderia (Pseudomonas) pseudomallei which is endemic in Malaysia to study the types of inflammation invoked, and to look for histopathological clues to its diagnosis. The lesions which varied from acute to chronic granulomatous inflammation were not tissue-specific. In five autopsy cases, the inflammation was usually a focal or diffuse, acute necrotising inflammation with varying numbers of neutrophils, macrophages, lymphocytes and 'giant cells'. The 'giant cells' probably represent giant macrophages with phagocytosed leukocytes. There were numerous gram-negative, non-acid-fast, intra- and extracellular bacilli, occurring either singly or in chains. Intracellular bacteria within macrophages and 'giant cells' were so numerous as to resemble globi. This feature has not been previously reported and may be a useful diagnostic clue in melioidosis. In 14 surgical cases biopsies showed acute inflammatory lesions that appeared no different from acute inflammation due to other causes. In many biopsies, however, the inflammation was either an acute-on-chronic inflammation with a focal granulomatous component, or was purely granulomatous in character. Bacilli were difficult to demonstrate in surgical biopsies even with the gram strain.

Abscess↗

PubMed1995

Characterisation of Campylobacters from Malaysia.

Eight-five clinical and 15 poultry isolates of Campylobacter species were characterised by biotyping, serotyping and by using a radiolabelled DNA probe. A total of 80% of the isolates from both sources were identified as C. jejuni. Also amongst the clinical strains were 5 c. jejuni subsp. doylei, 7 C. coli, 3 C. lari and 8 were untypable. The similarity in the distribution of C. jejuni in the clinical and poultry isolates adds credibility to published reports of chickens being the most common source of Campylobacter infections. Although the gold standard for identification of C. jejuni is the DNA probe, serotyping is more discriminating while biotyping is the most feasible method in most laboratories.

Animals↗

PubMed1995

Serodiagnosis of melioidosis in Malaysia.

Current diagnosis of melioidosis is based on bacterial culture and/or serology which is becoming increasingly useful. An IgM-ELISA using heat-killed whole cells of Pseudomonas pseudomallei was developed and compared with an indirect haemagglutination technique (IHAT) and an indirect immunofluorescent technique(IFAT). The IgM-ELISA using a P:N ratio of > or = 2 had a sensitivity of 91% and a specificity of 96%. All 3 assays were further used in a seroepidemiological survey amongst different groups of patients and healthy individuals. It was found that the IFAT performed better than the IHAT, detecting antibodies to P. pseudomallei in 6% of diabetics, 5% of pyrexics, 8% of pregnant women and 3% of farmers. For the same groups the IgM-ELISA detected antibodies in 1% of pyrexics, 8% of pregnant women and a further 14% of farmers. The IgM-ELISA was found to be sensitive and useful for the serological diagnosis of acute melioidosis.

Adult↗

PubMed1994

Campylobacter enteritis in children: clinical and laboratory findings in 137 cases.

One hundred and thirty-seven children with Campylobacter diarrhoea were reviewed. The predominant species was C. jejuni. Ninety-five percent of the children were below 5 years of age with 61% of these being 2-12 months old. A slight male preponderance was noted. About half the cases presented with fever and bloody diarrhoea; vomiting was seen in 28% and abdominal colic in only 8%. Moderate to severe diarrhoea was present in 48% of the children. Thirty-seven percent had a history of recent or concurrent illness. Other bacterial enteropathogens together with Campylobacter were isolated in 15% of the children. Erythromycin, the most useful drug, when indicated for Campylobacter infections, had an MIC90 of 2 mg/l with 96.2% of the strains being sensitive.

Age Distribution↗

PubMed1994

Exotoxin profiles of Campylobacters isolated in Malaysia.

Approximately 57% of clinical and 33% of poultry isolates examined produced a cytotoxin. Cytotoxic activity was detected in 25 (50%) isolates of Campylobacter of which 12 were isolated from bloody diarrhea and 9 from watery stools. The cytotoxin titers were low, ranging from 2 to 16. The crude filtrates from 50 Campylobacter isolates showed no cytotoxic effect in Vero cells, no fluid accumulation in suckling mice and no hemolytic activity.

Animals↗

PubMed1994

The rapid urease test in the diagnosis of Helicobacter pylori infection.

With the increasing recognition of the importance of H. pylori in gastrointestinal disease, there is a need for a reliable, efficient and yet inexpensive diagnostic test. The performance of the rapid urease test (RUT) as an endoscopy suite diagnostic test was compared to the established methods of culture, histology and Gram stain of tissue smear, in 274 gastric biopsy samples. Histology had the highest sensitivity of 99.3% followed by the RUT (96.6%). Culture and Gram stain of tissue smear had 100% specificity, while the rapid urease test had 99.2% specificity. The RUT had a positive predictive value of 99.3% and a negative predictive value of 96.2%. The RUT is an inexpensive, rapid and reliable diagnostic test of H. pylori infection.

Biopsy↗

PubMed1994

Neonatal meningitis due to non-encapsulated Haemophilus influenzae in a set of twins--a case report.

A set of twins born to a 24-year-old primigravida had evidence of sepsis 24 to 60 hours after birth and were treated empirically with penicillin and gentamicin. A non-encapsulated H. influenzae biotype IV strain was isolated from the blood cultures of both and from the CSF of twin II. The isolates were beta-lactamase positive and hence showed resistance to ampicillin and therapy was changed to chloramphenicol only. Twin II recovered but Twin I developed a brain abscess in the left occipital region which resolved with extended antibiotic treatment. Although ampicillin-resistant H. influenzae have been reported in Malaysia, invasive disease by such strains are rare.

Adult↗

PubMed1993

Detection of antibodies against Salmonella typhi outer membrane protein (OMP) preparation in typhoid fever patients.

An indirect ELISA was used to detect antibodies against outer membrane protein preparations (OMPs) from Salmonella typhi. Sera from patients with a definitive diagnosis of typhoid fever (TF) gave a mean absorbance reading, at 414 nm, of 1.52 +/- 0.23 as compared to 0.30 +/- 0.11 for sera from healthy individuals. This gave a positive to negative ratio of absorbance readings of approximately 5.1. Suspected TF patients (no isolation of S. typhi), with positive and negative Widal titers had mean absorbance readings of 1.282 +/00.46 and 0.25 +/- 0.19, respectively. Sera from patients with leptospirosis, rickettsial typhus, dengue fever, and other infections gave mean absorbances of 0.20 +/- 0.08, 0.24 +/- 0.08, 0.27 +/- 0.08, and 0.31 +/- 0.16, respectively. The sensitivity, specificity, positive and negative predictive values were 100%, 94%, 80% and 100%, respectively. The antibody response detected in the definitive TF cases was predominantly IgG in nature and no cross-reactivity was seen with OMP preparations extracted from E. coli. Variable reactivity was noted with OMP preparations obtained from other Salmonella spp. Three major OMPs are presented in the antigen preparation and strong binding of positive sera was detected to all three bands.

Antibodies, Bacterial↗

PubMed1992

Comparison of two assays for the detection of haemolysins of Aeromonas species.

The haemolysins produced by Aeromonas species were detected and compared by two assay methods--a modified blood agar plate assay and the rabbit erythrocyte haemolysin method. Both assays showed a high level of agreement (86%). The titres of the rabbit erythrocyte haemolysin assay correlated with the haemolytic zone diameter of the ox blood agar assay. In addition the agar haemolysin assay had simple media requirements, was easy to perform and results were well defined.

Aeromonas↗

PubMed1991

Exotoxin profiles of clinical isolates of Aeromonas hydrophila.

Eighty-six clinical isolates of Aeromonas hydrophila were studied for their ability to produce four exotoxins: a haemolysin active against rabbit erythrocytes, cytotoxin and enterotoxin detectable with Vero cell cultures, and the cholera toxin-like factor detected by an enzyme-linked immunosorbent assay. At least one exotoxin was produced by 80% of enteric and 96% of non-enteric isolates. The exotoxin profiles of non-enteric isolates were more restricted than those of enteric isolates, with haemolysin and cytotoxin producers preponderant. Although haemolysin and cytotoxin were produced by isolates from all sources, the enterotoxin and cholera toxin-like factor were more common amongst enteric isolates. The production of haemolysin and cytotoxin were closely related but the association between the enterotoxin and the cholera toxin-like factor was not significant.

Aeromonas↗

PubMed1991

Helicobacter pylori infection and non-ulcer dyspepsia: the effect of treatment with colloidal bismuth subcitrate.

A study was undertaken to determine the role of Helicobacter pylori in non-ulcer dyspepsia (NUD) and to determine the efficacy of colloidal bismuth subcitrate (CBS) in the treatment of NUD. Seventy-one patients were randomly allocated (double blind) to CBS or placebo, two tablets twice daily for 4 weeks. The severity of dyspepsia was scored and endoscopies performed before and after treatment, and antral biopsy specimens were taken for bacteriologic and histologic examination. Forty patients had H. pylori infection, and all had changes of chronic active gastritis. H. pylori was cleared from 17 to 21 patients (81%) treated with CBS, whereas none of the 19 patients treated with placebo cleared the bacteria. Improvement in histology was noted in 15 of 21 patients (71.4%) treated with CBS, whereas no improvement was noted in any of the placebo controls. Thirty-one patients were negative for H. pylori. All had either normal gastric histology or minor degrees of inflammation. Seventeen of these patients received CBS, and 14 received placebo. All groups reported improvement in the symptom score; however, the H. pylori-positive, CBS-treated group recorded a significantly higher improvement than the other groups (p less than 0.001). Relapse of H. pylori infection after initial clearance of the bacteria was high. Twelve of 16 patients evaluated relapsed 1 month after withdrawal of CBS.

Adult↗

PubMed1990

Culture-positive thoracic empyema in adults.

Twenty-nine adult patients with culture-positive thoracic empyema were seen at the University Hospital Kuala Lumpur from 1984 to 1988. Cough, fever, chest pain, dyspnoea and weight loss were the common presenting symptoms. The empyema in 16 patients was associated with primary bronchopulmonary infections, nine occurred following thoracentesis of culture-sterile pleural effusions, two occurred as post-thoracic surgery complications, one following a subdiaphragmatic abscess and one as a result of a stab wound. The most common culture isolates were Streptococcus milleri, Pseudomonas aeruginosa and Klebsiella pneumoniae. Closed tube thoracostomy, the most common form of drainage procedure employed, was able to effect a cure or control of the empyema in 11 out of 19 patients in whom it was used.

Adolescent↗

PubMed1989

Enterotoxigenic Escherichia coli in the domestic environment of a Malaysian village.

The membrane-filter assay, GM1-ELISA, and DNA-DNA hybridization assay, were used to detect enterotoxigenic Escherichia coli (ETEC) in samples of water, weaning food, food preparation surface swabs, fingerprints of mothers, and the fingerprints and stools of children under 5 years of age, in 20 households in a Malaysian village. Weaning food and environmental samples were frequently contaminated by faecal coliforms, including ETEC. The membrane-filter assay detected and enumerated faecal coliforms and LT-ETEC in all types of water and weaning food samples. Highest concentrations of faecal coliforms and LT-ETEC were found in weaning food, followed by well-water, stored water and stored drinking water. The GM1-ELISA detected LT-ETEC in weaning food, food preparation surfaces, fingerprints and stool samples. The DNA-DNA hybridization assay detected a larger proportion of STa2-ETEC than the other toxotypes, either singly or in combination. All the assays in combination detected the presence of ETEC in all types of samples on at least one occasion in each household. It was not possible to classify households as consistently more or less contaminated with ETEC. On individual occasions it was possible to show a significant association of the presence of LT-ETEC between the fingerprints of children and their stools, fingerprints of mothers and children, and weaning food and the stools of the child consuming the food.

Child, Preschool↗

PubMed1989

A simple adherence test for detection of IgM antibodies in typhoid.

A simple adherence test to detect IgM antibodies in patients with typhoid is described. The test utilises the IgM-"capture" approach, in which the test serum is applied to microtitration plate wells previously coated with anti-human IgM, followed by application of a stained Salmonella typhi antigen suspension which shows adherence in positive cases. By this test, 58 (95%) of 61 sera from confirmed cases of typhoid possessed IgM antibodies to the H or O or both antigens of S. typhi. In patients for whom a diagnosis of typhoid was based only on a significant Widal-test titre, 31 (41%) of 76 sera had IgM antibodies to the H or O or both antigens of S. typhi. Some cross-reactivity of the IgM antibodies was detected, especially with the O antigens of S. paratyphi A and B. A total of 82 sera from non-typhoidal fevers (leptospirosis, typhus, dengue fever) showed no reactivity in this test. In normal sera there was no detectable IgM to the O antigen of S. typhi and only a small number (3.9%) had low levels of IgM to the H antigen. The significance and potential importance of this simple, sensitive, specific and economical test is discussed.

Antibodies, Bacterial↗