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Biomedical subjects

Clinton K Murray

Publications and source records attributed to Clinton K Murray.

At least 37 records · Page 2Linked to original sources

Medical problems of detainees after the conclusion of major ground combat during Operation Iraqi Freedom.

After the conclusion of major ground combat operations during Operation Iraqi Freedom, the focus of the mission changed, although intense armed conflict continued. Included in this mission was management of security detainees, including provision of their medical care. We retrospectively reviewed the admission records identified at a short-term holding facility over 2 months and diagnoses of detainees admitted to a combat support hospital over 4 months as a health care service utilization statistics review. Six thousand six hundred thirty-one detainee encounters occurred at the short-term facility with approximately 45% of detainees reporting medical problems during each daily evaluation. Most frequent complaints were neurological (11%), gastrointestinal (10%), and respiratory (8%). Two hundred nineteen detainees' admission diagnoses were retrospectively reviewed from the combat support hospital, 98 (45%) due to gunshot or fragmentary injuries and 121 (55%) to other medical problems. Medical problems included cardiac (29%), gastrointestinal (17%), neurological (14%), musculoskeletal (11%), and pulmonary (6%) disease. Medical problems not traditionally dealt with in a combat theater, including management of transplant recipients, patients with cardiac valve replacement, and cancer patient, were also seen.

Delivery of Health Care↗

Spectrum of care provided at an echelon II Medical Unit during Operation Iraqi Freedom.

We describe the types of medical problems encountered at a U.S. Army echelon II medical facility during Operation Iraqi Freedom in the period after completion of major ground combat operations, a time of nation restructuring and intermittent, intense, armed conflict. A total of 4,831 patients were assessed between October 1, 2003 and June 30, 2004, 74% with disease and nonbattle injury presentations, 19% with dental complaints, and 7% wounded in action (WIA). Disease and nonbattle injury evaluations were predominantly musculoskeletal. Improvised explosive devices or mortars caused 78% of the WIA casualties. The most frequent dental evaluations were for restorations (47%). Thirty-eight individuals were admitted to holding beds, most commonly to receive intravenous antibiotic treatment for cellulitis (29%). Three hundred forty-one individuals were evacuated, including 150 WIA. Determining the types of casualties seen at forward echelons of medical care during different phases of conflict can aid medical planning and help predict the type of medical resources required.

Delivery of Health Care↗

Enumerating leptospires using the coulter counter.

The currently accepted gold standard for enumeration of leptospires is tabulation of organisms using a Petroff-Hausser counting chamber and dark-field microscopy, a technically demanding, time-consuming technique. Quantification of leptospires with a Coulter counter produced reliable and reproducible counts, comparable to the counting chamber. This experiment demonstrates that the faster, less technically demanding Coulter counter may be an alternative to determine numbers of leptospires.

Bacteriological Techniques↗

Natural history of community-acquired methicillin-resistant Staphylococcus aureus colonization and infection in soldiers.

BACKGROUND: Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) is an emerging pathogen for which the prevalence, risk factors, and natural history are incompletely understood. METHODS: In this prospective observational study, we evaluated 812 US Army soldiers to determine the prevalence of and risk factors for CA-MRSA colonization and the changes in colonization rate over time, as well as to determine the clinical significance of CA-MRSA colonization. Demographic data and swab samples from the nares for S. aureus cultures were obtained from participants at the start of their training and 8-10 weeks later. Over this time period, participants were observed prospectively to monitor for soft-tissue infections. S. aureus isolates were characterized by in vitro examination of antibiotic susceptibilities, mecA confirmation, pulsed-field gel electrophoresis, and Panton-Valentine leukocidin (PVL) gene testing. RESULTS: At the initial sampling, 24 of the participants (3%) were colonized with CA-MRSA, 9 of whom (38%) developed soft-tissue infections during the study period. In contrast, 229 participants (28%) were colonized with methicillin-susceptible S. aureus (MSSA), 8 (3%) of whom developed clinical infections during the same period (relative risk, 10.7; 95% confidence interval, 4.6-25.2; P<.001). At follow-up culture, the CA-MRSA colonization rate dropped to 1.6% without eradication efforts. Previous antibiotic use was a risk factor for CA-MRSA colonization at the initial sampling (P=.03). PVL genes were detected in 66% of 45 recovered CA-MRSA isolates, including all 9 clinical isolates available for analysis. Of subjects hospitalized, 5 of 6 had PVL-positive CA-MRSA infections. CONCLUSIONS: CA-MRSA colonization with PVL-positive strains was associated with a significant risk of soft-tissue infection, suggesting that CA-MRSA may be more virulent than MSSA. Previous antibiotic use may play a role in CA-MRSA colonization.

Abscess↗

Frequency of vaccinia virus isolation on semipermeable versus nonocclusive dressings covering smallpox vaccination sites in hospital personnel.

BACKGROUND: The Centers for Disease Control and Prevention recommends a semipermeable occlusive dressing for hospital workers who receive smallpox vaccination. OBJECTIVE: The study was designed to determine the frequency of vaccinia virus isolation from the outer surface of semipermeable dressings and to compare the prevalence of vaccinia virus on the outer surface of semipermeable dressings with its prevalence on the outer surface of nonocclusive dressings. METHODS: A prospective, observational study was conducted on hospital employees who received smallpox vaccination at a military academic medical center. Subjects were instructed to wear a semipermeable dressing if they had direct patient contact. Employees without direct patient care had the option of wearing a semipermeable dressing or a nonocclusive dressing. Prior to a programmed dressing change, the outer surface of the bandage site was swabbed and cultured for virus. Samples were considered positive when cytopathic effects were observed, with results confirmed as vaccinia by polymerase chain reaction. RESULTS: A total of 212 cultures were obtained from 93 subjects. All cultures directly obtained from active lesions were positive (13/13). Positive cultures were obtained from 7% (10/135) of the semipermeable dressings and 23% (15/64) of the nonocclusive dressings (P <.05). Ten percent (8/79) of the semipermeable dressings with purulent exudate observed underneath the bandage were culture positive, compared with 4% (2/56) of semipermeable dressings with no purulent exudate observed underneath the bandage (P=.19). CONCLUSIONS: Compared with nonocclusive dressings, the semipermeable dressing reduced, but did not eliminate, the frequency with which vaccinia virus was cultured from the surface of the dressing. Virus was present, but only rarely, on the dressing surface in the absence of purulent exudate under the semipermeable dressings.

Bandages↗

The effect of semipermeable dressings on smallpox vaccine site evolution.

BACKGROUND: Many hospital systems in the United States are contemplating the implementation of a smallpox vaccination program. The Centers for Disease Control and Prevention and other organizations recommend use of occlusive dressings over the vaccination site of health care workers in contact with patients. Minimal data are available on the impact of an occlusive dressing on the evolution of the vaccinia inoculation site. METHODS: We conducted a prospective observational study in which subjects were instructed to cover their vaccination site with either a semipermeable dressing over gauze or gauze alone. We recorded the duration of semipermeable dressing use and parameters pertaining to vaccination site evolution, to include time until scab separation. RESULTS: The increased use of a semipermeable dressing is associated with increased time until scab separation (n = 41, r =.48, P =.001 by regression analysis). This analysis predicts a 9-day difference in time until scab separation between patients that wore semipermeable dressings 100% of the time versus not at all. No significant correlation was observed between semipermeable dressing use and size of maximum erythema, time until maximum erythema, size of erythema on day 6 or 8, nor time until pustule formation. CONCLUSION: Semipermeable dressing use appears to prolong the time until scab separation and possibly the duration of infectivity and risk of secondary transmission. Health care organizations may wish to consider this information when instituting a smallpox vaccination program.

Adult↗

The role of antifungal susceptibility testing in the therapy of candidiasis.

Prior to the introduction of azoles, no real need for antifungal susceptibility testing (AFST) existed, as amphotericin B was the only agent available to treat systemic candidiasis. Introduction of fluconazole and itraconazole provided alternate, less toxic antifungal therapies. Intrinsic resistance of Candida krusei, decreased susceptibility of Candida glabrata, and development of resistance by Candida albicans (in mucosal disease in AIDS) to azoles led to development of our current AFST methodologies. The goal of AFST, like that of antibacterial susceptibility testing, is to predict clinical response, or at least to forecast failure. Although the ability of AFST to predict clinical outcome (clinical correlation) is still being fully elucidated, current methodologies do appear to reliably predict clinical resistance to azoles. Ready access to AFST is currently limited, affecting its timely use, but even with this lack of timeliness, AFST can still play an important role in patient care. Important potential roles include: 1) use in the development of local antibiograms to aid empiric selection of antifungals; 2) testing of isolates from candidemia or deep infection to aid in selection of long-term therapies; and, 3) the testing of isolates from recurrent mucosal disease to aid in selection of alternative regimens.

Antifungal Agents↗

Determination of susceptibilities of 26 Leptospira sp. serovars to 24 antimicrobial agents by a broth microdilution technique.

The MICs of 24 antimicrobials for 26 Leptospira spp. serovars were determined using a broth microdilution technique. The MICs at which 90% of isolates tested were inhibited (MIC(90)s) of cefepime, imipenem-cilastatin, erythromycin, clarithromycin, and telithromycin were all </=0.01 microg/ml. The MIC(90)s of amoxicillin, aztreonam, cefdinir, chloramphenicol, and penicillin G were >/=3.13 microg/ml. Many antimicrobials have excellent in vitro activity against Leptospira.

Anti-Bacterial Agents↗

Broth microdilution susceptibility testing for Leptospira spp.

Leptospirosis in humans has traditionally been treated with penicillin or doxycycline. The choice of therapy offered at the time of initial patient presentation is often empirical, as definitive diagnosis can take weeks. Determining the activity of numerous antimicrobial agents against a wide range of Leptospira serovars may broaden empirical therapeutic options. Various antimicrobials have been shown to be active against a limited number of serovars in in vitro studies, chiefly by the use of broth macrodilution techniques. We developed a broth microdilution technique using the commercially available growth indicator alamarBlue. MICs produced by this technique were compared to MICs and minimal bactericidal concentrations produced by the traditional broth macrodilution technique. The internal validity of our methods was assessed with 11 runs over numerous days with a single isolate of Leptospira interrogans serovar Icterohaemorrhagiae. By either method, the MICs for these internal-validity runs fell within 2 dilutions of each other for more than 90% of antimicrobials. A broader application of these two techniques included 12 serovars (including seven species) of Leptospira and six antimicrobials (penicillin G, doxycycline, chloramphenicol, erythromycin, cefotaxime, and ciprofloxacin). Observed reproducibility fell within 2 dilutions for 99% of the duplicate result sets for the MIC microdilution method, compared to 89% for the MIC macrodilution method. The macrodilution method tended to have a higher MIC at which 90% of the isolates were inhibited (MIC(90)) than did the microdilution method, but the MIC(90)s of both methods were within 2 dilutions of each other for all six drugs. The macrodilution and microdilution techniques produced similar results, with microdilution allowing a faster, more streamlined method of producing MIC results.

Anti-Bacterial Agents↗

Direct comparison of the BACTEC 9240 and BacT/ALERT 3D automated blood culture systems for candida growth detection.

A direct comparison of two automated blood culture systems was conducted to compare their ability to detect Candida growth. The systems evaluated were the BACTEC 9240 (Bactec) and BacT/ALERT 3D (BacT). The aerobic, anaerobic, and mycology media for each system were evaluated: Bactec Plus Aerobic/F, Plus Anaerobic/F, and Myco/F Lytic bottles, respectively, and BacT FA, SN, and MB bottles, respectively. Each blood culture bottle was inoculated with fresh blood from healthy donors. Fifty isolates of Candida spp. were used. The six different blood culture bottles were each inoculated with 1000 yeasts per bottle and then incubated in the corresponding automated system. The BacT detected growth of 90% (135 of 150) of Candida pathogens, while Bactec detected 66% (100 of 150). Growth was detected in all BacT and Bactec mycology bottles, all BacT aerobic bottles, and by terminal subculture of all bottles. Sixty-five of 300 (22%) bottles had no growth detected; 50 from the Bactec (5 aerobic and 45 anaerobic) and 15 from the BacT (all anaerobic). Terminal subculture of "negative" bottles demonstrated viable yeast growth from all 65 bottles, representing 65 false-negatives. The mean time to growth detection in the BacT system was 25.62 h while the Bactec was 27.30 h (P < 0.01). Both automated blood culture systems detected all episodes of simulated candidemia when specialized mycology media were used. However, when only standard aerobic and anaerobic media were used, the BacT performed better than the Bactec in overall growth detection, time to growth detection, and number of false-negatives.

Candida↗

Bullis fever: a vanished infection of unknown etiology.

Camp Bullis, Texas, is an active training facility for the U.S. Army and Air Force with a storied history dating back to the late 19th century. In the early 1940s, an epidemic of a seasonal tick-borne rickettsial-like illness occurred at Camp Bullis; the last case was reported in 1947. To date, the etiology of this disease has remained elusive. In an attempt to retrospectively identify the causal pathogen, we surveyed Camp Bullis for the presumed tick vector with intent to screen molecularly for Rickettsia and Ehrlichia. However, no ticks were recovered from primary dragging attempts in the spring or from harvested deer in the fall. Moreover, pathologic and microbiologic materials obtained during the epidemic are no longer extant, making them unavailable for analysis. In this study, we review potential circumstances that impact emerging and, in this case, vanishing infections. The etiology of Bullis fever will probably remain undetermined, and this once-emerging infection may have vanished into history. However, given Camp Bullis' status as an active medical training site, awareness of and surveillance for the disease should continue.

Animals↗

Susceptibility of Leptospira serovars to antimalarial agents.

Leptospirosis has recently been described to cause concomitant infection with malaria. Only doxycycline has proven to have chemoprophylactic and therapeutic efficacy for both malaria and leptospirosis. To assess whether other traditional antimalarial agents have antileptospiral activity, we performed broth microdilution susceptibility testing of 16 Leptospira serovars (6 species/14 serogroups) to various agents. Artemisinin, atovaquone, chloroquine, mefloquine, primaquine, proguanil, pyrimethamine, sulfadoxine, quinine, quinidine, and combinations of atovaquone/proguanil and pyrimethamine/sulfadoxine all had a 90% minimum inhibitory concentration (MIC(90)) > 25 microg/mL (the upper limit of testing). The only agents identified with the potential to treat both infections other than doxycycline (MIC(90) = 1.56 microg/mL) were azithromycin (MIC(90) = 0.002 microg/mL) and clindamycin (MIC(90) = 0.2 microg/mL).

Antimalarials↗

A study of'febrile illnesses on the Thai-Myanmar border: predictive factors of rickettsioses.

We have performed a case-control analysis to determine the significance of clinical, laboratory and epidemiological features as predictive factors of rickettsioses among patients in Sangkhla Buri, Thailand (Thai-Myanmar border). Fifteen serologically-confirmed rickettsiosis patients including Spotted Fever Group (SFG) rickettsioses, scrub typhus, and murine typhus were classified as 'cases'; one hundred and sixty-three acutely febrile patients presenting to the same hospital during the same time period, who had no serological evidence of acute rickettsiosis, were classified as 'controls'. Patients' report of rash/arthropod bite [Odds ratio (OR) 22.90, 95% CI (confidence interval) 6.23, 84.13] and history of jungle trips (OR 5.30, 95% CI 1.69-16.62) were significant risk factors. Elevated ALT (OR 3.04, 95% CI 1.04, 8.88) and depressed platelet count (OR 3.38, 95% CI 1.13, 10.10) were also useful differentiating markers of rickettsioses in this population. Definitive diagnosis of rickettsioses is difficult without specialized diagnostic capabilities that are rarely available in remote areas such as Sangkhla Buri, where other acute febrile illnesses with similar presentation are commonly found. The relative importance of predictive factors presented here may provide clinicians with some useful guidance in distinguishing rickettsioses from other acute febrile illnesses. Timely administration of empiric treatment in highly suspicious cases can deter potential morbidity from these arthropod-borne infections.

Adult↗

Rapid diagnostic testing for malaria.

Malaria rapid diagnostic devices (MRDD) have been developed with the hope that they would offer accurate, reliable, rapid, cheap and easily available alternatives to traditional methods of malaria diagnosis. The results from early malaria rapid diagnostic studies were quite promising, especially for detecting Plasmodium falciparum at densities of more than 100-500 parasites/microl. Despite the introduction of these devices over a decade ago, only a few target antigens have been introduced. Of greater concern, these devices have shown limitations in sensitivity, ability to differentiate species and robustness under field conditions in the tropics. Recent trials have revealed wide variability in sensitivity both within and between products. We review the recent trials assessing MRDD use for the diagnosis of P. falciparum and non-P. falciparum infections in endemic and non-endemic countries and describe the various aspects of these devices which need further improvement. High quality, accurate, rapid and affordable diagnostic tools are urgently needed now that new antimalarial regimens, characterized by higher cost and increased toxicity, have been introduced more widely in response to emerging multi-drug resistance.

Animals↗

In vitro susceptibilities of seven Leptospira species to traditional and newer antibiotics.

Human leptospirosis is generally treated with penicillin or doxycycline. We studied the susceptibilities of 11 serovars (seven species) of Leptospira to 14 antibiotics. With the exception of chloramphenicol, all tested agents were at least as potent as penicillin and doxycycline, with the macrolide and ketolide drugs producing the lowest MICs (and minimal bactericidal concentrations).

Anti-Bacterial Agents↗

Detection of simulated candidemia by the BACTEC 9240 system with plus aerobic/F and anaerobic/F blood culture bottles.

We studied the ability of the BACTEC 9240 automated blood culture system to detect simulated candidemia, including both Candida albicans and non-albicans Candida species. Simulated blood cultures were produced using 50 Candida isolates and BACTEC Plus Aerobic/F and Anaerobic/F blood culture bottles. Ten milliliters of blood and a suspension of each isolate containing 1,000 CFU were introduced into each bottle and then incubated at 35 degrees C in the BACTEC 9240 system. The system detected growth in 56 of 100 bottles. Four isolates did not have growth detected in either bottle after 21 days of incubation, resulting in four missed episodes of candidemia. If the blood culture bottles had been incubated for 5 days, an additional episode of candidemia would have remained undetected. If the bottles had been incubated for only 3 days, another episode would have been missed, resulting in up to six missed episodes of candidemia (four Candida glabrata isolates, one C. albicans isolate, and one Candida rugosa isolate). Terminal subculture of bottles without detected growth recovered yeast in 93% (41 of 44) of the bottles, representing 41 false negatives. In bottles where growth was detected, the time to detection was approximately 24 h. However, the mean time to growth detection for C. glabrata isolates in anaerobic medium was 22.14 +/- 2.47 h, but it was 120.89 +/- 35.33 h in aerobic medium (P < 0.001). The BACTEC 9240 system detected growth of most Candida isolates; however, the delayed time to detection of C. glabrata is clinically significant. Given the high rate of false negatives, terminal subcultures may be helpful in certain situations.

Aerobiosis↗

Devices for rapid diagnosis of Malaria: evaluation of prototype assays that detect Plasmodium falciparum histidine-rich protein 2 and a Plasmodium vivax-specific antigen.

The ParaSight F test was developed as a pioneer industry effort in the large-scale, process-controlled production of a device for the rapid diagnosis of malaria. This device performed well in field settings but was limited to the detection of a single malaria species, Plasmodium falciparum. The ParaSight F+V assay advanced upon the ParaSight F test format by incorporating a monoclonal antibody directed against a proprietary Plasmodium vivax-specific antigen, in addition to the antibody directed against P. falciparum histidine-rich protein 2, which was used in the ParaSight F assay. The modified assay was developed to add the capability to detect P. falciparum and P. vivax in a single-test-strip format. The present study evaluated three distinct ParaSight F+V prototypes with samples from symptomatic patients in regions of Thailand and Peru where malaria is endemic. Over a 2-year enrollment period (1998 and 1999), a total of 4,894 patients consented to participation in the study. Compared with the results for duplicate microscopic examinations of Giemsa-stained blood smears as the reference diagnostic standard, each successive prototype showed substantial improvement in performance. The final ParaSight F+V prototype, evaluated in 1999, had an overall sensitivity for detection of asexual P. falciparum parasites of 98%. The sensitivity of the device was 100% for P. falciparum densities of >500 parasites/ micro l, with a sensitivity of 83% for parasite densities of </=500/ micro l. The specificity for the exclusion of P. falciparum was 93%. For P. vivax, the overall sensitivity was 87% for the final 1999 prototype. The sensitivities calculated for different levels of P. vivax parasitemia were 99% for parasite densities of >5,000/ micro l, 92% for parasite densities of 1,001 to 5,000/ micro l, 94% for parasite densities of 501 to 1,000/ micro l, and 55% for parasite densities of 1 to 500/ micro l. The specificity for the exclusion of P. vivax was 87%. The areas under the receiver operating characteristic curves for the diagnostic performance of the assay for the detection of P. falciparum and P. vivax were 0.8907 and 0.8522, respectively. These findings indicate that assays for rapid diagnosis have the potential to enhance diagnostic capabilities in those instances in which skilled microscopy is not readily available.

Animals↗

Direct isolation of Candida spp. from blood cultures on the chromogenic medium CHROMagar Candida.

CHROMagar Candida is a selective and differential chromogenic medium that has been shown to be useful for identification of Candida albicans, Candida krusei, Candida tropicalis, and perhaps Candida glabrata. Colony morphology and color have been well defined when CHROMagar Candida has been used to isolate yeast directly from clinical specimens, including stool, urine, respiratory, vaginal, oropharyngeal, and esophageal sources. Direct isolation of yeast on CHROMagar Candida from blood cultures has not been evaluated. We evaluated whether the color and colony characteristics produced by Candida spp. on CHROMagar Candida were altered when yeasts were isolated directly from blood cultures. Fifty clinical isolates of Candida were inoculated into aerobic and anaerobic blood culture bottles and incubated at 35 degrees C in an automated blood culture system. When growth was detected, an aliquot was removed and plated onto CHROMagar Candida. As a control, CHROMagar Candida plates were inoculated with the same isolate of yeast grown on Sabouraud dextrose agar simultaneously. No significant difference was detected in color or colony morphology between the blood and control isolates in any of the tested organisms. All C. albicans (n = 12), C. tropicalis (n = 12), C. glabrata (n = 9), and C. krusei (n = 5) isolates exhibited the expected species-specific colony characteristics and color, whether isolated directly from blood or from control cultures. CHROMagar Candida can be reliably used for direct isolation of yeast from blood cultures. Direct isolation could allow mycology laboratories to more rapidly identify Candida spp., enable clinicians to more quickly make antifungal agent selections, and potentially decrease patient morbidity and mortality.

Aerobiosis↗