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P T Davidson

Publications and source records attributed to P T Davidson.

At least 19 recordsLinked to original sources
PubMed1996

Misdiagnosis of multidrug-resistant tuberculosis possibly due to laboratory-related errors.

OBJECTIVE: To describe 9 cases where a misdiagnosis of multidrug-resistant tuberculosis (MDR TB) was made, possibly due to laboratory-related errors. DESIGN: Case series. SETTING: Public and private hospitals, outpatient clinics, and mycobacteriology laboratories serving those institutions in Los Angeles County, Calif. PATIENTS: Consecutive sample of 70 patients diagnosed with MDR TB who were identified between August 1993 and August 1994 by the Multidrug-Resistant Unit within TB Control in Los Angeles County. OUTCOME MEASURE: Detection of laboratory-related diagnostic errors. RESULTS: Pulmonary MDR TB was misdiagnosed in 9 (13%) of 70 patients. Reasons why the diagnoses appeared to be erroneous are as follows: growth of MDR TB from an old tuberculous lesion in a patient who was never treated for TB and whose diagnosis predated anti-TB drugs (1 case), documented contamination with Mycobacterium avium complex (1 case), suspected cross-contamination (1 case), suspected specimen mislabeling (1 case), successful treatment using drugs to which the isolate was reportedly resistant (4 cases), discrepant susceptibility test results on additional sputum specimens submitted by the patient (2 cases), and no clinical evidence of TB (3 cases). CONCLUSIONS: These cases emphasize the diagnostic errors that can occur if mycobacterial susceptibility results are not correlated with all clinical data including other laboratory results for a given patient. We conclude that susceptibility results alone are not enough to dictate treatment, and that careful clinical correlation is necessary in making the diagnosis of MDR TB.

Adult↗
PubMed1996

Tuberculosis among foreign-born persons in Los Angeles County, 1992-1994.

OBJECTIVES: To describe the epidemiology of foreign-born tuberculosis (TB) cases in Los Angeles County and to evaluate current TB screening and follow-up of immigrants and refugees (I&R) to the USA. DESIGN: Retrospective analysis of the Los Angeles County TB registry between October 1992 and December 1994. We matched all cases who entered the USA during fiscal year 1993 (FY93) with a database from the tracking system of I&R with suspected TB. RESULTS: Foreign-born persons accounted for 64% of all reported TB cases. Half were born in Mexico or Central America. Standardized incidence rates were 3-5 times higher than those of US-born persons for Mexicans and Central Americans, 6-7 times higher for North-east Asians, and 10-15 times higher for South-east Asians. Among foreign-born cases who arrived during FY93, 5% of the Mexicans and Central Americans, 48% of the North-east Asians and 67% of the South-east Asians were registered by the tracking system. CONCLUSION: Mexicans and Central Americans accounted for the majority of cases but had a lower incidence of TB than Asians. The current screening procedures identify a large proportion of cases among recently arrived South-east Asians, but contribute little to the control of TB among Mexicans and Central Americans.

Adolescent↗
PubMed1994

A prospective evaluation of antituberculosis therapy in patients with human immunodeficiency virus infection.

The purpose of this study was to determine the efficacy and toxicity of a standard antituberculosis regimen in patients with human immunodeficiency virus (HIV) infection. We prospectively evaluated 89 patients with tuberculosis and HIV infection at an urban medical center. Eighty-two patients received isoniazid, rifampin, and pyrazinamide, with or without ethambutol, for 2 mo, followed by isoniazid and rifampin for 7 mo. Seven patients received other regimens because of drug resistance or intolerance. Therapy was self-administered in 57 patients and directly observed in 32 cases. All patients showed rapid clinical improvement during the first month of therapy, and sputum cultures reverted to negative after 3 mo in 52 of 54 patients from whom specimens were obtained. Adverse reactions to isoniazid or rifampin prompted alterations in antituberculosis regimens in five patients (6%). Forty patients (45%) died during follow-up, and tuberculosis was a potential contributory cause of death in three cases. Treatment failure occurred in five patients (6%), four of whom were noncompliant with therapy. The fifty patient had an isoniazid-resistant organism. No relapses occurred in 916 patient-months of follow-up posttreatment. We thus conclude that the 9-mo regimen used for treatment of drug-susceptible tuberculosis in HIV-infected patients is effective and well tolerated.

AIDS-Related Opportunistic Infections↗
PubMed1993

Tuberculosis in patients with HIV infection.

Tuberculosis is the most common opportunistic infection in patients with HIV infection worldwide and is the only one that is transmissible to others by the respiratory route. Tuberculosis is curable and preventable. Early detection of tuberculosis disease and infection in individuals with or at risk for HIV infection is paramount. This approach can minimize the devastating interaction between these two diseases.

AIDS-Related Opportunistic Infections↗
PubMed1993

Relationship of the manifestations of tuberculosis to CD4 cell counts in patients with human immunodeficiency virus infection.

To evaluate the relationship between the clinical presentation of tuberculosis and the CD4 cell count in patients with human immunodeficiency virus (HIV) infection, we evaluated clinical and laboratory features of 97 HIV-infected patients with tuberculosis in whom CD4 cell counts were available. Extrapulmonary tuberculosis was found in 30 (70%) of 43 patients with < or = 100 CD4 cells/microL, 10 (50%) of 20 patients with 101 to 200 CD4 cells/microL, seven (44%) of 16 patients with 201 to 300 CD4 cells/microL, and five (28%) of 18 patients with > 300 CD4 cells/microL (p = 0.02). Mycobacteremia was found in 18 (49%) of 37 patients with < or = 100 CD4 cells/microL, three (20%) of 15 patients with 101 to 200 CD4 cells/microL, one (7%) of 15 patients with 201 to 300 CD4 cells/microL, and none of eight patients with > 300 CD4 cells/microL (p = 0.002). Acid-fast smears were more often positive in patients with low CD4 cell counts. Positive tuberculin skin tests were more common in patients with high CD4 counts. On chest roentgenograms, mediastinal adenopathy was noted in 20 (34%) of 58 patients with < or = 200 CD4 cells/microL and four (14%) of 29 patients with > 200 CD4 cells/microL (p = 0.04). Pleural effusions were noted in six (10%) of 58 patients with < or = 200 CD4 cells/microL and eight (28%) of 29 patients with > 200 CD4 cells/microL (p = 0.04). The CD8 cell counts did not correlate with the manifestations of tuberculosis.(ABSTRACT TRUNCATED AT 250 WORDS)

AIDS-Related Opportunistic Infections↗
PubMed1992

Combined toxicity of zidovudine and antituberculosis chemotherapy.

Because antituberculosis agents and zidovudine are commonly used in HIV-infected patients, we performed a cohort study to determine the toxicity of such combined therapy. A group of 24 consecutive human immunodeficiency virus (HIV)-infected patients with tuberculosis who received concomitant antituberculosis therapy and zidovudine (tuberculosis group) were compared with 24 patients who received zidovudine but not antituberculosis medications (comparison group). Comparison patients were matched to tuberculosis patients by age, sex, ethnic group, month of starting zidovudine, and CD4 cell count. Most tuberculosis patients received isoniazid, rifampin, pyrazinamide, and ethambutol initially, followed by isoniazid and rifampin for a mean total duration of 8.4 months. Baseline clinical and laboratory parameters in tuberculosis and comparison patients were similar, except for the mean hemoglobin (11.2 g/dl in tuberculosis patients versus 12.9 g/dl in comparison patients, p = 0.03). The mean zidovudine dose in tuberculosis and comparison patients was approximately 500 mg/day, and the mean duration of zidovudine therapy was 10.3 and 9.6 months, respectively. Symptoms occurred during therapy with similar frequency in both groups. The frequency and severity of leukopenia and granulocytopenia were similar in tuberculosis and comparison patients, but marked anemia (hemoglobin less than 9.5 g/dl) developed in 50% of tuberculosis patients and 17% of comparison patients (p = 0.03). The maximum decrease in hemoglobin during therapy was similar in both groups (mean of 2.0 versus 1.6 g/dl, respectively), suggesting that the higher frequency of marked anemia in tuberculosis patients was due to their lower baseline hemoglobin values. Although transfusions were required in five tuberculosis patients and one comparison patient, zidovudine was not permanently discontinued in any patient because of anemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Drug treatment of tuberculosis--1992.

The impact of the acquired immunodeficiency syndrome (AIDS) pandemic has made tuberculosis an increasing worldwide problem, and the effectiveness of modern chemotherapy has been blunted by the high incidence of primary drug resistance, especially in developing countries. The prospect of finding new and highly effective drugs similar to isoniazid or rifampicin is dim, yet the maximum benefits from the existing drugs which are highly effective have not been received. A 6-month regimen of isoniazid plus rifampicin, supplemented by pyrazinamide during the first 2 months, for treatment of uncomplicated tuberculosis is highly effective and the regimen of choice. Ethambutol should be added if the risk of isoniazid resistance is increased. A regimen of isoniazid, rifampicin, pyrazinamide and streptomycin for 4 months provides effective defence against smear-negative pulmonary tuberculosis. Re-treatment of multiple drug-resistant tuberculosis remains a difficult therapeutic problem. At least 3 drugs that the patient has never previously received, and that are effective according to laboratory susceptibility testing, must be used. Preventive therapy against tuberculosis is accomplished with isoniazid for 6 to 12 months, although rifampicin plus isoniazid for 3 months has been used in the United Kingdom with success. In a mouse model, rifampicin plus pyrazinamide for 2 months is more effective than isoniazid for 6 months as preventive treatment. Patient noncompliance with medication remains the biggest problem in tuberculosis control, and is a complex issue. It can only be resolved by multiple approaches. Intermittent directly observed short course chemotherapy is a major, but not the only, possible solution.

Animals↗
PubMed1989

The diagnosis and management of disease caused by M. avium complex, M. kansasii, and other mycobacteria.

Because mycobacteria other than Mycobacterium tuberculosis are common in the environment and yet are infrequent causes of disease in humans, their isolation from a clinical specimen must be carefully evaluated before concluding that disease exists. It is often necessary to accumulate and weigh a cascade of various clinical factors before a diagnosis can be made. Mycobacterium avium complex has emerged as an increasingly important pathogen, particularly in patients with the acquired immunodeficiency syndrome. Even after the diagnosis of disease has been established, its management must be carefully individualized because highly effective treatment regimens are not available except for Mycobacterium kansasii. A scheme to categorize patients with M. avium complex according to the nature of their disease, together with subsequent management strategies, is presented.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Respiratory pharmacology. Antituberculosis drugs.

Tuberculosis remains a significant health problem. Its control and treatment depend on a thorough understanding of the basic principles and application of antituberculosis chemotherapy. The pharmacology of the major antituberculosis drugs is presented, including the management of adverse and allergic reactions.

Aminosalicylic Acids↗