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Biomedical subjects

A H Chagla

Publications and source records attributed to A H Chagla.

At least 19 recordsLinked to original sources
PubMed2000

Hospital- and community-based surveillance of methicillin-resistant Staphylococcus aureus: previous hospitalization is the major risk factor.

OBJECTIVE: The purpose of the study was to determine the incidence and risk factors for the acquisition of methicillin-resistant Staphylococcus aureus (MRSA) in our community. DESIGN: This study used a cross-sectional design to assess patients colonized or infected with MRSA. PATIENTS: The study population consisted of residents of London, Ontario, Canada, who were identified as MRSA-positive for the first time in 1997. SETTING: All acute- and chronic-care hospitals, long-term healthcare facilities, and community physicians' offices in the city of London participated in the study. MAIN OUTCOME MEASURE: Incidence of MRSA in the community, risk factors for acquisition, especially previous hospitalization over a defined period, and strain type were evaluated. RESULTS: In 1997, 331 residents of London were newly identified as MRSA-positive, representing an annual incidence of 100/100,000 persons (95% confidence interval, 88.8-110.7). Thirty-one (9.4%) individuals were not healthcare-facility patients in the previous month, and 11 (3.3%), 10 (3.0%), and 6 (1.8%) individuals had no such contact in the previous 3, 6, and 12 months, respectively. One hundred seventy-seven strains, including five of the isolates from patients with no healthcare-facility contact in the previous year, were typed. One hundred sixty (90.3%) of these isolates, including all typed strains from patients with no healthcare facility contact, belonged to a single clone. CONCLUSION: These findings demonstrate that the incidence of MRSA is higher than previously reported and that hospital contact is the single most important risk factor for the acquisition of MRSA in our community. Screening for MRSA in previously hospitalized patients at the time of hospitalization may reduce nosocomial spread and indirectly reduce the incidence of MRSA in the community.

Adult↗
PubMed1999

Three sample preparation protocols for polymerase chain reaction based detection of Cryptosporidium parvum in environmental samples.

Cryptosporidium parvum is a protozoan parasite responsible for an increasing number of outbreaks of gastrointestinal illness worldwide. In this report, we describe development of sample preparation protocols for polymerase chain reaction (PCR)-based detection of C. parvum in fecal material and environmental water samples. Two of these methods were found adequate for isolation of Cryptosporidium DNA from filtered water pellet suspensions. The first involved several filtration steps, immunomagnetic separation and freeze-thaw cycles. The second method involved filtration, addition of EnviroAmp lysis reagent, freeze-thaw cycles and precipitation of the DNA with isopropanol. Using nested PCR, we detected 100 oocysts/ml of filtered water pellet suspension, with either of the above sample preparation procedures. Nested PCR increased sensitivity of the assay by two to three orders of magnitude as compared to the primary PCR. The detection limit for seeded fecal samples was 10-fold higher than for filtered environmental water pellet suspension. Nested PCR results showed 62.4 and 91.1% correlation with immunofluorescence assay (IFA) for fecal samples and filtered environmental water pellet suspensions, respectively. This correlation decreased to 47.2% and 44.4%, respectively, when only IFA positive samples were analyzed. However, in fecal samples contaminated with a high number (> 10(5)/g) of C. parvum oocysts, this correlation was 100%.

2-Propanol↗
PubMed1999

PCR-based quantitation of Cryptosporidium parvum in municipal water samples.

A PCR method for the quantitation of Cryptosporidium parvum oocysts in municipal drinking water samples was investigated. Quantitative PCR uses an internal standard (IS) template with unknown target numbers to compare to standards of known concentrations in a standard curve. The IS template was amplified using the same primers used to amplify a portion of a 358 bp gene fragment that encodes a repetitive oocyst wall protein in C. parvum. Municipal water samples spiked with known numbers of C. parvum oocysts were tested by quantitative PCR using the IS and the Digene SHARP Signal System Assay for PCR product detection. The absorbance readings for target DNA and IS templates versus the number of molecules of the target DNA were plotted to generate standard curves for estimating oocyst numbers. The method allowed the quantitation of oocysts from log 3 to log 5 spiked into municipal water samples.

Animals↗
PubMed1998

Breast abscess associated with Helcococcus kunzii.

Helcococcus kunzii, a nonvirulent member of the human skin flora, has recently been implicated in causing infections in immunosuppressed patients. We report a case of breast abscess associated with H. kunzii in an immunocompetant patient and discuss the criteria used in its identification and our observations of susceptibility testing for this species.

Abscess↗
PubMed1993

Evaluation of the L-pyrrolidonyl-beta-naphthylamide hydrolysis test for the differentiation of members of the families Enterobacteriaceae and Vibrionaceae.

A simple, rapid, and inexpensive spot test incorporating the substrate pyrrolidonyl naphthylamide was used to examine pyrrolidonyl peptidase activity among 800 bacterial strains belonging to the families Enterobacteriaceae and Vibrionaceae. The pyrrolidonyl naphthylamide test was found to be particularly useful in separating Citrobacter spp. (100% positive) from Salmonella spp. (0.4% positive) and Escherichia coli (0% positive). Furthermore, it would appear to offer a safer alternative to the traditional potassium cyanide test for differentiating citrobacters from salmonellae.

Bacterial Typing Techniques↗
PubMed1989

Do gowns prevent infection in neonatal intensive care units?

In a prospective study we found that gowns had no effect when used by medical and paramedical staff, in reducing infection in a tertiary care neonatal unit. We conclude that the use of gowns in this area is an ineffective and expensive method of preventing nosocomial infection.

Clothing↗
PubMed1989

Laboratory-acquired brucellosis.

Brucellosis is endemic in Saudi Arabia and hospital laboratories are handling increasing numbers of specimens for diagnosis. We report four cases of laboratory-acquired brucellosis.

Accident Prevention↗
PubMed1988

Fatal brain abscesses caused by Ramichloridium obovoideum: report of three cases.

Three cases of brain abscesses caused by Ramichloridium obovoideum are reported. Inspite of adequate antifungal chemotherapy and multiple surgical procedures, all the three patients died of the rupture of a recurrant abscess into the ventricles. Ramichloridium obovoideum was identified as the causative fungus of these brain abscesses. Clinical, histological and mycological features of these cases are described. To our knowledge this is the first time that this fungus is isolated from a brain abscess in Saudi Arabia. The possibility that this life threatening cerebral mycosis may be endemic in this part of the world is considered.

Aged↗
PubMed1988

Septicaemia caused by Vibrio vulnificus.

Vibrio vulnificus is an uncommon cause of septicaemia. A few reports suggest that patients with chronic liver disease are more susceptible. We report two cases of septicaemia caused by this organism and emphasise the need for early empirical therapy.

Adult↗
PubMed1988

Bacterial, parasitic and viral enteropathogens associated with diarrhoea in Saudi children.

In a 2-year study of stools from Saudi children with gastro-enteritis and from controls, rotavirus was the pathogen most frequently detected, either alone (44.3%) or in combination with other enteropathogens (7%). There were two peaks for rotavirus isolates, one during the cold months and the other during the dry, hot season. Salmonella spp. and Campylobacter jejuni were the second and third most frequently isolated enteropathogens. Enteropathogenic Escherichia coli did not contribute significantly to diarrhoea. Detection of enterotoxigenic E. coli was not attempted and its role in diarrhoea remains obscure. Giardia lamblia was detected more frequently in controls than in cases of diarrhoea. Neither Entamoeba histolytica nor Schistosoma mansoni was detected in any of the children studied.

Campylobacter fetus↗
PubMed1987

Cerebral phaeohyphomycosis.

Multiple phaeohyphomycotic brain abscesses caused by Cladosporium species occurred in a 55 year old woman. No immunological abnormality could be detected. The disease ran a protracted course for a total of 20 months before she died from sudden rupture of an abscess loculus into the ventricular system. Course was characterised by spontaneous remissions and relapses totally independent of adequate doses and prolonged regimes of all the three available anti-fungal chemotherapeutic agents, namely amphotericin B, flucytosine and ketoconazole. Three surgical procedures were carried out; and surgical intervention appeared to be the only modality of treatment capable of prolonging the life or altering the course of the disease. An interesting transitory pulmonary phase of phaeohyphomycosis resembling miliary tuberculosis was noticed. This may help to explain the portal of entry and mole of spread of the fungus to the brain. A dematiaceous fungus was isolated from these abscesses. Mycologic features and histology of brain lesions are described.

Amphotericin B↗
PubMed1986

Lower respiratory tract infection due to Branhamella catarrhalis, two case reports.

We describe two cases of lower respiratory tract infection due to Branhamella catarrhalis in elderly patients. The diagnosis was confirmed by isolation of the organism from the sputa in pure growth and also by response to treatment with appropriate antibiotics. Both patients had predisposing factors: one had chronic bronchial asthma and was also on corticosteroids during the illness and the other had chronic obstructive lung disease. Previously reported cases are reviewed.

Asthma↗
PubMed1985

Shigella flexneri bacteraemia.

Shigellosis is usually a non-invasive enteric disease, rarely accompanied by extra-intestinal manifestations. Shigella septicaemia is therefore reported in a child aged 10 months. In the laboratory the organism was resistant to ampicillin and only moderately susceptible to chloramphenicol. The patient responded well to cotrimoxazole to which the organism isolated was susceptible in vitro. We recommend that blood as well as faeces should be cultured in exceptionally ill patients with suspected or otherwise confirmed shigella infection.

Drug Combinations↗
PubMed1985

Diagnostic value of phase contrast microscopy in haematuria.

Phase contrast microscopic examination of 105 urine specimens was carried out in a study to differentiate glomerular from nonglomerular haematuria. Urine was obtained from patients with proven glomerular disease, healthy subjects, and healthy subjects to whose urine blood had been added. Phase contrast microscopy identified correctly glomerular haematuria in 74 out of 80 samples, and nonglomerular erythrocyturia in all the 25 samples tested. These results give a sensitivity rate of 93% and specificity of 100%. Phase contrast microscopy was found to be a useful screening test in the investigation of haematuria.

False Negative Reactions↗