Biomedical subjects
Publications and source records attributed to E Desmond.
This study assessed the extent to which laboratory methods recommended by the Centers for Disease Control and Prevention were used in tuberculosis testing of patients in California in 1998. While recommended methods were used for most patients, there was room for improvement by hospital and independent non-health maintenance organization laboratories.
CONTEXT: Despite improvements in tuberculosis (TB) control during the past decade, Mycobacterium tuberculosis transmission and resulting disease continue to occur in the United States. OBJECTIVE: To determine the primary reasons for disease development from a particular strain of M tuberculosis. DESIGN: Population-based, molecular epidemiological study. SETTING: Urban community in the San Francisco Bay area of California with recommended elements of TB control in place. PATIENTS: Seventy-three TB cases were reported in 1996-1997 that resulted from 1 strain of M tuberculosis as identified by TB genotyping and epidemiological linkage. MAIN OUTCOME MEASURES: Transmission patterns involving source and secondary case-patients; primary reasons for disease development. RESULTS: Seventy-three (33%) of 221 TB case-patients in this community resulted from this strain of M tuberculosis. Thirty-nine (53%) of the 73 case-patients developed TB because they were not identified as contacts of source case-patients; 20 case-patients (27%) developed TB because of delayed diagnosis of their sources; and 13 case-patients (18%) developed TB because of problems associated with the evaluation or treatment of contacts; and 1 case-patient (1%) developed TB because of delay in being elicited as a contact. Of the 51 TB cases identified with sources, 49 (96%) were infected within the 2 years prior to diagnosis. CONCLUSIONS: Our results indicate that in a community that has implemented the essential elements of TB control, TB from ongoing transmission of M tuberculosis will continue to develop unless patients are diagnosed earlier and contacts are more completely identified. JAMA. 2000.
The importance of hunger state for the acquisition and expression of chocolate craving was investigated. Seventeen chocolate cravers and 12 non-cravers were supplied with chocolate and instructed to eat some twice a day for 14 days. Within each group, subjects were allocated to one of two conditions, hungry- or full-trained. Hungry-trained subjects were asked to eat the chocolate exclusively at least 2 h after last eating; full-trained subjects were asked only to eat the chocolate 15-30 min after eating a meal. A diary was kept to encourage and allow assessment of compliance. At the start and end of the 2 weeks, subjects rated their craving for and anticipated intake of chocolate prior to eating it; then, on initial tasting, pleasantness of the taste was rated. All subjects made these ratings on one day when hungry and on another when full, as defined above. For cravers and non-cravers who ate chocolate exclusively when hungry, chocolate craving increased post-training, but, at least for cravers, only when ratings were made while hungry. For full-trained subjects, chocolate craving decreased post-training, but this decrease did not depend on whether subjects were currently hungry or full. A similar pattern of results was found for anticipated intake and pleasantness of taste, except that pleasantness did not increase in hungry-trained subjects. The results are interpreted with reference to learned control of appetite and in particular to recent findings on incentive learning processes. Craving for chocolate or other foods may be an expression of a strong appetite elicited by hunger that has been acquired by repeated experience of eating the craved food when hungry.
Microscopic examination of respiratory specimens for acid-fast bacilli (AFB) plays a key role in the initial diagnosis of tuberculosis, monitoring of treatment, and determination of eligibility for release from isolation. The objective of this study was to compare the sensitivity obtained with smears for detection of AFB (AFB smears) made directly from respiratory specimens (direct AFB smears) to that obtained with parallel smears made from concentrates of the specimens (concentrated AFB smears). A total of 2,693 specimens were evaluated; 1,806 were from the University of California Irvine Medical Center Medical Microbiology Laboratory (UCIMC), which serves a tertiary-care hospital with outpatient clinics, and 887 were from the Microbial Disease Laboratory at the California Department of Public Health (MDL), which receives specimens from outpatient facilities and clinics on Pacific islands. Of the 353 AFB culture-positive specimens at UCIMC, there was a statistically significant difference in the sensitivity of the direct AFB smear (34%) and that of the smear made from the concentrated specimen (58%) (P < 0.05). This was also true for the 208 specimens positive for Mycobacterium tuberculosis, for which the sensitivity of the direct smear was 42% (87 of 208) and that for the smear made from the concentrated specimen was 74% (154 of 208). At MDL, where all but 1 of the 45 culture-positive specimens grew M. tuberculosis, the sensitivity of the smear made from the concentrated specimen was 93% (42 of 45) and was not significantly higher than the sensitivity of the direct smear, which was 82% (37 of 45). By combining the results from both laboratories, 42 patients from whom at least three specimens were received were culture positive for M. tuberculosis. The cumulative results for the initial three specimens from these patients showed that the direct smear detected M. tuberculosis in 81% of these patients, whereas the smear made from the concentrate detected M. tuberculosis in 91% of these patients. In summary, when all culture-positive specimens are considered, the sensitivity of the direct smear compared to that of a smear made from the concentrated specimen was significantly different overall in the two different laboratory settings. However, this difference was reduced only if the cumulative results for the initial three specimens received from patients who were culture positive for M. tuberculosis were evaluated.
High-density oligonucleotide arrays can be used to rapidly examine large amounts of DNA sequence in a high throughput manner. An array designed to determine the specific nucleotide sequence of 705 bp of the rpoB gene of Mycobacterium tuberculosis accurately detected rifampin resistance associated with mutations of 44 clinical isolates of M. tuberculosis. The nucleotide sequence diversity in 121 Mycobacterial isolates (comprised of 10 species) was examined by both conventional dideoxynucleotide sequencing of the rpoB and 16S genes and by analysis of the rpoB oligonucleotide array hybridization patterns. Species identification for each of the isolates was similar irrespective of whether 16S sequence, rpoB sequence, or the pattern of rpoB hybridization was used. However, for several species, the number of alleles in the 16S and rpoB gene sequences provided discordant estimates of the genetic diversity within a species. In addition to confirming the array's intended utility for sequencing the region of M. tuberculosis that confers rifampin resistance, this work demonstrates that this array can identify the species of nontuberculous Mycobacteria. This demonstrates the general point that DNA microarrays that sequence important genomic regions (such as drug resistance or pathogenicity islands) can simultaneously identify species and provide some insight into the organism's population structure.
BACKGROUND: In the United States there have been recent outbreaks of multidrug-resistant tuberculosis. These outbreaks have primarily involved persons infected with the human immunodeficiency virus (HIV). METHODS: We collected clinical information on 17 patients seen at a New York City hospital who had repeatedly positive cultures for Mycobacterium tuberculosis. Analysis of restriction-fragment--length polymorphisms (RFLPs) was performed on serial isolates of M. tuberculosis obtained from these patients. RESULTS: Six patients had isolates that remained drug-susceptible, and the RFLP patterns of these isolates did not change over time. Eleven patients had isolates that became resistant to antimicrobial agents. The RFLP patterns of the isolates from six of these patients remained essentially unchanged (two strains showed one additional band) despite the development of drug resistance. In five other patients, however, the RFLP patterns of the isolates changed dramatically at the time that drug resistance was detected. The change in the RFLP pattern of the isolate from one patient appeared to be the result of contamination during processing in the laboratory. In the remaining four patients, all of whom had advanced HIV disease, the clinical and microbiologic evidence was consistent with the presence of active tuberculosis caused by a new strain of M. tuberculosis. CONCLUSIONS: Resistance to antituberculous drugs can develop not only in the strain that caused the initial disease, but also as a result of reinfection with a new strain of M. tuberculosis that is drug-resistant. Exogenous reinfection with multidrug-resistant M. tuberculosis can occur either during therapy for the original infection or after therapy has been completed.
One hundred twenty seven human isolates of Nocardia asteroides complex were identified to the species level by drug susceptibility testing, acetamide utilization, thermotolerance studies, studies of arylsulfatase activity, and studies of acid production from rhamnose. N. asteroides complex organisms which were not identifiable as N. farcinica or N. nova were designated N. asteroides sensu stricto. All of the N. farcinica isolates and none of the other isolates produced a milky-white opacity surrounding colonies on Middlebrook 7H10 agar. This finding may facilitate the identification of N. farcinica.
Over a 30-month period, we evaluated 74 patients with acquired immunodeficiency syndrome (AIDS) for suspected opportunistic pulmonary infection. All had abnormal findings on chest roentgenogram. Sixty patients (81%) were found to have Pneumocystis carinii pneumonia (PCP). We assessed the yield of various diagnostic methods, and found that bronchoalveolar lavage samples obtained by the instillation of 20 to 50 ml of normal saline (minilavage) contained detectable organisms in 51 of 53 patients (sensitivity of 96%) when the samples were embedded in plastic, cut in thick sections (1 micron), stained with toluidine blue O, and evaluated by light microscopy. In comparison, the diagnostic yield was 94% for lung biopsy, 85% for touch preparation of lung tissue, 32% for bronchial washing, and 14% for brush biopsy. It is significant that minilavage samples embedded in plastic were positive in all seven patients who did not have transbronchial lung biopsy because they were at high risk for complications. We conclude that the process of embedding minilavage samples in plastic and evaluating thick sections stained with toluidine blue O is a sensitive method of diagnosing PCP in patients with AIDS.
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The efficacy of eight routine enteric agars for supporting the growth of 32 strains of Aeromonas spp. (17 A. hydrophila strains, 8 A. sobria strains, and 7 A. caviae strains) was investigated. The plating efficiency of Aeromonas spp. on these media varied greatly (range, 0 to 100%), as did their colony size when compared with that on noninhibitory medium (5% sheep blood agar). Plating efficiency on seven of these eight media appeared to be strain- and not species dependent. Overall, eosin-methylene blue and Hektoen enteric agars showed low plating efficiencies for A. hydrophila, whereas both A. sobria and A. caviae were severely inhibited on brilliant green agar. When all these species are considered collectively, deoxycholate, MacConkey, and xylose lysine deoxycholate appeared to be the most satisfactory routine agars for Aeromonas spp. recovery when used in conjunction with blood agar.
In a prospective study of an obstetric population, 28 of 488 (4%) routine asymptomatic patients had positive cultures for herpes simplex virus from their genital tract. Cesarean section was carried out if the virus was present in the genital tract at the time of delivery. In one instance, a culture which had reverted to negative became positive again. No cases of neonatal herpes were reported in the time of the study. As yet, the infectivity of these subclinical cases is unclear, and the incidence of neonatal herpes is not as high as would be expected from the study. Further studies need to be carried out to evaluate the exact risk of the asymptomatic herpesvirus shedder to the infant at birth.
Clostridium difficile toxin, the presumed mechanism of antibiotic-associated pseudomembranous colitis, has been suggested as a contributory factor to mucosal injury in inflammatory bowel disease. We evaluated its incidence and apparent role in 65 consecutive patients with diarrheal and inflammatory bowel diseases. Toxin was demonstrated in 3 of 18 patients with ulcerative colitis (17%), 1 of 26 with Crohn's colitis (4%), and 5 of 21 with a variety of diarrheal illnesses (24%). Toxin appeared only in those who had been exposed to antimicrobials within 2 mo. In inflammatory bowel disease, presence of toxin was not correlated with disease severity. We conclude that Clostridium difficile toxin appears only in patients exposed to antimicrobials and is unlikely to be a significant contributory factor in inflammatory bowel disease.
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