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Biomedical subjects

A L Walsh

Publications and source records attributed to A L Walsh.

At least 37 records · Page 2Linked to original sources
PubMed1997

Polymerase chain reaction for the detection of Burkholderia pseudomallei.

Melioidosis is a potentially lethal infection of humans and animals in Southeast Asia and northern Australia. Current methods for detection of the causative organism, Burkholderia pseudomallei, lack both speed and sensitivity. We report the development of a highly sensitive polymerase chain reaction-based method that can detect as few as 35 colony-forming units of B. pseudomallei/mL in saline suspensions. This polymerase chain reaction test also detected the presence of B. pseudomallei DNA in culture-negative splenic tissue obtained from mice infected with the organism, but without clinical evidence of disease. Specificity has been confirmed using a variety of pathogenic and nonpathogenic organisms, including B. mallei, B. cepacia, and Pseudomonas species. The clinical usefulness of this test should be assessed prospectively and compared with conventional diagnostic techniques.

Animals↗
PubMed1996

In-vitro activity of carbapenem antibiotics against beta-lactam susceptible and resistant strains of Burkholderia pseudomallei.

Four carbapenem antibiotics were tested for their in-vitro activities (MICs, MBCs and time-kill studies) against Burkholderia pseudomallei. The carbapenems were all more active than either ceftazidime or co-amoxiclav against strains of B. pseudomallei with a normal susceptibility pattern. Biapenem was the most active antibiotic tested. All four carbapenems retained bactericidal activity against 24 strains of B. pseudomallei with reduced susceptibility to ceftazidime and/or co-amoxiclav.

Anti-Bacterial Agents↗
PubMed1996

Biochemical characteristics of clinical and environmental isolates of Burkholderia pseudomallei.

The biochemical characteristics of 213 isolates of Burkholderia pseudomallei from patients with melioidosis and 140 isolates from the soil in central and northeastern Thailand were compared. Whereas the biochemical profiles of all the clinical isolates were similar, all soil isolates from the central area and 25% of isolates from northeastern Thailand comprised a different phenotype. This was characterised by the ability to assimilate L-arabinose (100%), adonitol (100%), 5-keto-gluconate (90%) and D-xylose (84%), but failure to assimilate dulcitol (0%), erythritol (0%) and trehalose (10%). Compared with clinical isolates, these organisms had similar antibiotic susceptibility profiles and were also recognised by a specific polyclonal antibody against B. pseudomallei. As melioidosis is rare in central Thailand, but common in the northeast, this raises the possibility that this biochemical phenotype may be less virulent, or may even represent a different species.

Anti-Bacterial Agents↗
PubMed1996

The laboratory diagnosis of melioidosis.

The recognition of unusual, but important, pathogens such as Burkholderia pseudomallei is essential for the rapid implementation of appropriate antimicrobial therapy--delays can be fatal. Melioidosis should be considered as a potential diagnosis for any patient with exposure to areas of endemicity, and thus laboratories should be aware of the differential features of the disease and the causative organism. Isolation of B. pseudomallei is readily achieved using standard culture media such as blood, MacConkey or cystine-lactose-electrolyte-deficient (CLED) agars, and routine blood culture broths. Selective media, Ashdown's agar and selective broth, are required for respiratory tract specimens to ensure reliable isolation from amongst the normal or contaminating flora. These media are easily prepared from common media constituents. Colonial morphology and simple biochemical tests will suggest the identity of the organism, which can then be confirmed by additional tests for 'non-fermenters', such as the API 20NE.

Bacteriological Techniques↗
PubMed1995

Prognostic significance of quantitative bacteremia in septicemic melioidosis.

Pour-plate blood cultures were performed for 418 adult patients with suspected septicemic melioidosis in order to determine the relationship between quantitative bacterial counts in blood and mortality. Of 108 patients whose hemocultures yielded Burkholderia pseudomallei, 53% had < 10 cfu/mL and 24% had > 100 cfu/mL. High blood bacterial counts were more common than reported previously with regard to other gram-negative septicemias and were significantly associated with the development of hypotension (P = .008) and a fatal outcome (P = .0001). The overall mortality was 63% (95% CI, 53%-72%); however, counts of < or = 1 cfu/mL were associated with a mortality of 42% (95% CI, 28%-58%), compared with 96% (95% CI, 80%-100%) with counts of > 100 cfu/mL. Heavy bacteremia (> 50 cfu/mL) is common in septicemic melioidosis and is usually fatal.

Adolescent↗
PubMed1995

Postantibiotic effects and Burkholderia (Pseudomonas) pseudomallei: evaluation of current treatment.

The postantibiotic effects (PAEs) OF 16 antibiotics or antibiotic combinations currently used against Burkholderia (Pseudomonas) pseudomallei were determined. The beta-lactams had zero PAEs, while the carbapenems and ciprofloxacin induced median PAEs of 1 and 5 h, respectively. These results emphasize the need to maintain antibiotic levels above inhibitory concentrations in blood throughout the dosing interval in cases of severe melioidosis.

Anti-Bacterial Agents↗
PubMed1995

Latex agglutination for rapid detection of Pseudomonas pseudomallei antigen in urine of patients with melioidosis.

A latex agglutination test for the detection of Pseudomonas pseudomallei antigen in urine was evaluated for the rapid diagnosis of melioidosis. With unconcentrated urine, antigen was detected in only 18% of patients with melioidosis overall. However, when urine was concentrated 100-fold, antigen was detected in 47% overall and in 67% of patients with septicaemia or disseminated infection, in whom a rapid diagnosis is most important. The specificity of the test was 100%. These results compared favourably with an enzyme immunoassay. This latex agglutination test is a simple, rapid and highly specific method of diagnosing melioidosis, and will be particularly useful in areas with limited laboratory facilities.

Antigens, Bacterial↗
PubMed1995

Short course of ofloxacin for treatment of multidrug-resistant typhoid.

In recent years, multiresistant strains of Salmonella typhi have emerged in many tropical countries. These strains remain highly sensitive to the fluoroquinolone antibiotics, although use of these drugs by children is considered contraindicated because of their reported toxicity in the cartilage of experimental animals. In a paired, open, randomized study during an epidemic of multidrug-resistant typhoid in southern Vietnam, two short-course ofloxacin regimens (15 mg/kg daily for 3 days and 10 mg/kg daily for 5 days) were compared for the treatment of uncomplicated typhoid fever. Of 438 patients enrolled (of whom 286 were < or = 14 years old), 228 had blood cultures positive for Salmonella species (S. typhi, 207; S. paratyphi A, 19; and S. choleraesuis, 2). There was one treatment failure in a patient who took only one dose of ofloxacin. Otherwise, both regimens were completely effective; there were no proven carriers, and there was no evidence of toxicity, particularly in children. A 3-day course of ofloxacin proved to be safe and highly effective in the treatment of uncomplicated, multidrug-resistant typhoid fever.

Adolescent↗
PubMed1994

Ceftazidime vs. amoxicillin/clavulanate in the treatment of severe melioidosis.

An open, paired, randomized, controlled trial of high-dose parenteral ceftazidime (120 mg/[kg.d]) vs. amoxicillin/clavulanate (160 mg/[kg.d]) for the treatment of severe melioidosis was conducted in Ubon Ratchatani in northeastern Thailand. Of 379 patients enrolled in the study, 212 (56%) had culture-proven melioidosis; 106 patients were in each treatment group. The overall mortality rate (47%) was similar for both treatment groups. However, 4 of 75 surviving patients in the ceftazidime group compared with 16 of 69 surviving patients in the amoxicillin/clavulanate group were switched to the alternate regimen because of an unsatisfactory clinical response after > or = 72 hours of treatment (P = .004). The overall therapeutic failure rate (i.e., treatment failure or death due to uncontrolled melioidosis) was significantly higher for the amoxicillin/clavulanate group than for the ceftazidime group (P = .02). Clinical and bacteriologic responses for successfully treated patients were similar in both groups, and both treatments were well tolerated. Parenteral amoxicillin/clavulanate is a safe and effective initial treatment, but parenteral ceftazidime remains the treatment of choice for severe melioidosis.

Adolescent↗
PubMed1994

Immunofluorescence microscopy for the rapid diagnosis of melioidosis.

A direct immunofluorescent antibody test (DIF) was developed for the rapid diagnosis of melioidosis, a potentially fatal infection caused by Pseudomonas pseudomallei. In a clinical evaluation of 369 sputum, pus, or urine specimens from 272 patients with suspected melioidosis, the DIF had a sensitivity of 73% and a specificity of 99% compared with culture. Using this DIF, a confident diagnosis of melioidosis can now be made within two hours of admission to hospital, compared with the delay of two to four days required for culture results. Consequent early institution of specific antimicrobial therapy may help to save lives.

Fluorescent Antibody Technique↗
PubMed1993

Latex agglutination test for identification of Pseudomonas pseudomallei.

A latex agglutination test was developed and evaluated for the rapid presumptive identification of Pseudomonas pseudomallei, the causative organism of melioidosis. The test was 100% sensitive for 52 isolates of Ps pseudomallei and 100% specific when tested with other medically important Pseudomonas species and Enterobacteriaceae. A subsequent field trial, with clinical specimens from patients with suspected melioidosis, confirmed the sensitivity and specificity of the test.

Burkholderia pseudomallei↗
PubMed1989

Growth factor activity in luminal fluids from the male reproductive tract of the ram, rat, tammar wallaby (Macropus eugenii) and Japanese quail (Coturnix coturnix japonica).

Growth factor activity in luminal fluids from the male reproductive tract was assayed by measuring the stimulation of [3H]thymidine incorporation into BALB/c 3T3 fibroblasts. The potency of fluids from the rete testis of the rat, ram, tammar wallaby and Japanese quail was much the same. However, about 90% of the activity in fluid from the rete testis of the rat and tammar was lost during its passage through the epididymis.

Animals↗
PubMedDate not supplied

Quantitative recovery of Burkholderia pseudomallei from soil in Thailand.

Melioidosis is common in north-eastern Thailand, but is reported rarely from the adjacent areas of central Thailand, although rice farming is common to both regions. Quantitative soil cultures for Burkholderia pseudomallei were therefore prepared on 12 rice farms in both regions. B. pseudomallei was isolated from a similar proportion of rice fields in the central region (6/12) and in the north-east (7/12). Within the culture-positive sites, the number of B. pseudomallei colony-forming units (cfu) per mL of soil/water supernatant was significantly higher in the north-east (median 230 cfu/mL; range 1-17,000) than in the central region (median 10 cfu/mL; range 1-600). As bacterial counts in the soil are probably related to the risk of developing melioidosis, differences in exposure to B. pseudomallei probably contribute to the considerable differences in the incidence of this disease between these 2 adjacent regions.

Burkholderia pseudomallei↗
PubMedDate not supplied

Clinical presentation of non-typhoidal Salmonella bacteraemia in Malawian children.

We report the clinical presentation and outcome of 299 Malawian children with non-typhoidal Salmonella (NTS) bacteraemia and no evidence of focal sepsis, admitted to Queen Elizabeth Central Hospital (QECH), Blantyre, over a 26-month period (February 1996-April 1998). A peak incidence during the rainy season was noted. Salmonella typhimurium (79%) and S. enteritidis (13%) were the commonest isolates. For children aged > 6 months, NTS bacteraemia was significantly associated with malarial parasitaemia (RR 1.5 [1.2, 2.2], P < 0.01) and with severe anaemia (RR 7.2 [3.4, 15.3], P < 0.0001), when compared to other common pathogens causing childhood bacteraemia. Clinical overlap with malaria and anaemia, and the presence of malarial parasitaemia on admission, may delay diagnosis. NTS bacteraemia was commonly diagnosed following blood transfusion. Resistance in vitro to ampicillin (79%), co-trimoxazole (72%) and gentamicin (55%) was very common, and was rare to chloramphenicol (0.3%) which is the antibiotic of choice for NTS sepsis at QECH. Overall mortality was high (23%). Young age and clinical HIV infection were risk factors for mortality. Recurrences of NTS bacteraemia following antibiotic therapy were common among children with clinical HIV infection.

AIDS-Related Opportunistic Infections↗