A randomized clinical trial comparing metabolic parameters after 48 weeks of standard- and low-dose stavudine therapy and tenofovir disoproxil fumarate therapy in HIV-infected South African patients.

OBJECTIVES: Low-dose stavudine therapy may have a lower toxicity profile compared with standard dose. A randomized controlled trial comparing these two doses of stavudine with tenofovir disoproxil fumarate (tenofovir DF) was performed to assess the effects on anthropometry, markers of inflammation, and lipid and glucose metabolism in Black South African patients. METHODS: Sixty patients were randomized 1:1:1 to either standard-dose (30-40 mg) or low-dose (20-30 mg) stavudine or tenofovir DF (300 mg), each combined with lamivudine and efavirenz, for 48 weeks. Anthropometry, markers of inflammation, and lipid and glucose metabolism were assessed using standard techniques. RESULTS: In all three treatment arms, there was a significant increase in lipid levels over the study period. At 48 weeks, fasting glucose level (P < 0.005) and homeostasis model assessment (HOMA) score (P < 0.05) increased significantly in the standard-dose stavudine arm, as did insulin and C-peptide levels in both the standard- and low-dose stavudine arms. At week 48, a significant decrease (P < 0.05) in adiponectin was noted in the standard-dose stavudine arm, but there was an increase (P < 0.005) in the tenofovir DF arm. In both the stavudine arms, significant increases in anthropometric measures occurred at 24 weeks but these decreased by week 48. Mitochondrial toxicities occurred in both the stavudine arms. Immunological and virological outcomes were similar for all three arms. CONCLUSIONS: This study highlights the occurrence of metabolic abnormalities with both stavudine and tenofovir DF treatment. Awareness of the potential increased cardiovascular risk should be of concern with the use of both these therapies.

The early effects of stavudine compared with tenofovir on adipocyte gene expression, mitochondrial DNA copy number and metabolic parameters in South African HIV-infected patients: a randomized trial.

OBJECTIVES: Stavudine is being phased out because of its mitochondrial toxicity and tenofovir (TDF) is recommended as part of first-line highly active antiretroviral therapy (HAART) in South Africa. A prospective, open-label, randomized controlled trial comparing standard- and low-dose stavudine with TDF was performed to assess early differences in adipocyte mtDNA copy number, gene expression and metabolic parameters in Black South African HIV-infected patients. METHODS: Sixty patients were randomized 1:1:1 to either standard-dose (30-40 mg) or low-dose (20-30 mg) stavudine or TDF (300 mg) each combined with lamivudine and efavirenz. Subcutaneous fat biopsies were obtained at weeks 0 and 4. Adipocyte mtDNA copies/cell and gene expression were measured using quantitative polymerase chain reaction (qPCR). Markers of inflammation and lipid and glucose metabolism were also assessed. RESULTS: A 29% and 32% decrease in the mean mtDNA copies/cell was noted in the standard-dose (P < 0.05) and low-dose stavudine (P < 0.005) arms, respectively, when compared with TDF at 4 weeks. Nuclear respiratory factor-1 (NRF1) and mitochondrial cytochrome B (MTCYB) gene expression levels were affected by stavudine, with a significantly (P < 0.05) greater fall in expression observed with the standard, but not the low dose compared with TDF. No significant differences were observed in markers of inflammation and lipid and glucose metabolism. CONCLUSIONS: These results demonstrate early mitochondrial depletion among Black South African patients receiving low and standard doses of stavudine, with preservation of gene expression levels, except for NRF1 and MTCYB, when compared with patients on TDF.

Comparative in vitro activities of ciprofloxacin, gemifloxacin, grepafloxacin, moxifloxacin, ofloxacin, sparfloxacin, trovafloxacin, and other antimicrobial agents against bloodstream isolates of gram-positive cocci.

The in vitro activity of gemifloxacin against 316 bloodstream isolates of staphylococci, pneumococci, and enterococci was compared with the activities of six fluoroquinolones and three other antimicrobial agents. Of the antimicrobial agents tested, gemifloxacin was the most potent against penicillin-intermediate and -resistant pneumococci, methicillin-susceptible and -resistant Staphylococcus epidermidis isolates, and coagulase-negative staphylococci.

Prevention of disseminated Mycobacterium avium complex infection with reduced dose clarithromycin in patients with advanced HIV disease.

OBJECTIVE: To evaluate the ability of once daily reduced dose clarithromycin to prevent disseminated Mycobacterium avium complex (dMAC) infection in patients with advanced HIV disease. DESIGN: Non-randomized, retrospective study. SETTING: Outpatient clinic of an urban university-affiliated municipal hospital. PATIENTS: A group of 192 HIV-infected patients with a CD4 count < 100 x 10(6) cells/l who were followed for at least 90 days during a 6-year period (1991-1996) before the use of protease inhibitors. INTERVENTIONS: Clarithromycin 500 mg orally once daily (n = 84), rifabutin 300 mg orally once daily (n = 47) or no prophylaxis (n = 61). MAIN OUTCOME MEASURES: Positive blood culture for M. avium complex (MAC), time to development of dMAC, and time to death. RESULTS: When compared with no prophylaxis or rifabutin, the incidence of dMAC and time to development of dMAC were improved among those patients receiving clarithromycin (P < 0.001). Prolonged survival was associated with both clarithromycin and rifabutin use when compared with no prophylaxis (P < 0.002). In patients who failed prophylaxis, resistance to clarithromycin and rifabutin was observed. CONCLUSIONS: In the era prior to protease inhibitor use, once daily clarithromycin at a dose of 500 mg was associated with a reduction in the incidence of dMAC, appeared to be superior to rifabutin, and was associated with prolonged survival in patients with advanced HIV disease.

Mycobacterium bovis BCG causing vertebral osteomyelitis (Pott's disease) following intravesical BCG therapy.

We report a case of Mycobacterium bovis BCG vertebral osteomyelitis in a 79-year-old man 2.5 years after intravesical BCG therapy for bladder cancer. The recovered isolate resembled M. tuberculosis biochemically, but resistance to pyrazinamide (PZA) rendered that diagnosis suspect. High-pressure liquid chromatographic studies confirmed the diagnosis of M. bovis BCG infection. The patient was originally started on a four-drug antituberculous regimen of isoniazid, rifampin, ethambutol, and PZA. When susceptibility studies were reported, the regimen was changed to isoniazid and rifampin for 12 months. Subsequently, the patient was transferred to a skilled nursing facility for 3 months, where he underwent intensive physical therapy. Although extravesical adverse reactions are rare, clinicians and clinical microbiologists need to be aware of the possibility of disseminated infection by M. bovis BCG in the appropriate setting of clinical history, physical examination, and laboratory investigation.

Monitoring and diagnosis of cytomegalovirus infection in renal transplantation.

In this study, the utility of the cytomegalovirus antigen (CMV-AG) and the shell vial (SV) tests in the diagnosis and monitoring of posttransplant CMV infection were compared. Previous retrospective studies from the authors' center suggested that the CMV-AG test, which uses monoclonal antibodies to detect viral antigen in circulating peripheral blood leukocytes (PBL) may be both a more sensitive and specific test. A cohort of 32 renal transplant recipients was followed-up prospectively with serial CMV-AG testing, as well as conventional culture and SV for blood and urine and tests for immunoglobulin M (IgM) antibody. It was discovered that the CMV-AG test was not only more sensitive than the SV test in detecting CMV infection, but that the degree of antigenemia as expressed by the number of positive cells per 50,000 PBL correlated with the likelihood and degree of symptomatic infection. All patients with a count > 10 positive cells/50,000 PBL developed clinical symptoms; therefore, this threshold could be useful in deciding clinically whether fever is related to CMV infection. Alternatively, if antigenemia were monitored serially after transplant, the same threshold could be used as a trigger for instituting antiviral therapy, because it was often reached prior to the onset of symptoms and had a high specificity for subsequent symptomatic infection. Such an approach could obviate unnecessary treatment of patients not destined to become symptomatic. Based upon the findings in this study, the CMV-AG test is superior to the SV assay because the actual count helps determine the likelihood that symptoms are a result of the virus and the processing time is shorter, it can be used to monitor the response to therapy and as a guide to the institution of preemptive therapy.

The laboratory diagnosis of cytomegalovirus infections.

Rapid and accurate diagnosis of cytomegalovirus (CMV) infection is imperative with the advent of effective antiviral therapy (gangiclovir, foscarnet, CMV hyperimmune globin). Applications of conventional cell culture (CC), shell vial assay (SV), serological testing, antigenemia assay (AG) as well as molecular methods [polymerase chain reaction (PCR), branch DNA (b-DNA) and hybrid capture (HC)] to various patient populations and specimen types are discussed. A three year study of 670 specimens [354 urines, 205 peripheral blood leukocytes (PBLs), 56 upper respiratory and 55 tissues] compared CMV CC and SV isolation rates. Of the total, 124 (18.5%) were positive by either or both techniques. For each specimen type the number of positives detected by SV was greater than CC (urine 28 vs 15, PBLs, 12 vs 2). However, of 124 positives, 21 were solely CC positive. A comparison of SV to AG in 230 PBLs yielded a sensitivity of 100% and specificity of 68.3%. The low specificity when compared to SV may be due to the increased sensitivity of AG. Fifty-nine PBLs were examined for differing immunostaining techniques [immunoperoxidase (IP) vs Immunofluorescence (IF)]. IF stained PBLs showed an increased number of positive cells per preparation and greater stain intensity for ease of interpretation.

Polymerase chain reaction assays for the detection of cytomegalovirus in organ and bone marrow transplant recipients.

Cytomegalovirus (CMV) infection is ubiquitous and results in a wide spectrum of clinical manifestations ranging from asymptomatic infection to severe life threatening disease. Infection in normal children and adults usually causes no symptoms but in the immunocompromised host, CMV may result in severe opportunistic infections with high morbidity and mortality. Historically, virus detection was dependent on culture of the virus or on a centrifugation culture system referred to as a shell vial assay. The shell vial assay frequently lacked sensitivity and was unable to detect infection in its early phase. Also, as with culture assays, the results were affected by antiviral therapy. The CMV antigenemia assay was developed to provide more rapid results and has gained wide usage. This assay is limited to detection of the virus in white blood cells and is more sensitive than culture or the shell vial assay. Application of the polymerase chain reaction (PCR) to these problems has resulted in the development of assays for CMV which are more sensitive than previously available methods. This method employs liquid hybridization with 32P labeled probes and gel retardation analysis for detection of amplified DNA specific for each virus. A comparison of the detection of CMV by an antigenemia assay or the PCR method in the leukocytes of renal transplant patients revealed that the PCR assay detects cytomegalovirus earlier and more consistently than the antigenemia assay. Finally, the application of a fluorescent dye detection system and image analysis of the acrylamide gel with a laser scanner provides additional sensitivity to the detection of cytomegalovirus, as well as avoiding the use of radioactivity, making the assay more adaptable to the clinical laboratory.

The laboratory diagnosis of tuberculosis in a period of resurgence: challenge for the laboratory.

OBJECTIVE: To review the current and contemporary approaches to the laboratory diagnosis of Mycobacterium tuberculosis and related mycobacteria. DATA SOURCES: Current literature. STUDY SELECTION: Determined by the author. DATA EXTRACTION: Determined by the author. DATA SYNTHESIS: The definitive diagnosis of mycobacterial disease depends upon the laboratory for the isolation and identification of the infecting microorganism. Laboratory studies encompass microscopic examination for the presence of AFB; isolation and recovery of the organism by cultural methods; phenotypic biochemical or other contemporary means to identify the recovered organism; and anti-tuberculosis susceptibility testing. Because of the extended growth period of this group of organisms, it is imperative that the lab use the most rapid means to provide information to the clinician for isolation of the patient if needed and for the initiation of prompt rational therapy as determined by susceptibility testing. More than 25 species in the Mycobacterium genus are capable of causing human disease. In the United States, the five most frequently encountered species are M. tuberculosis, M. avium, M. kansasii, M. fortuitum and M. chelonei. CONCLUSION: Tuberculosis is a reemerging disease with significant health problem implications in the US and worldwide. Diagnosis and appropriate treatment are dependent on the prompt response of the laboratory.

Mycobacterium malmoense bacteremia in two AIDS patients.

We report two cases of Mycobacterium malmoense bacteremia in two patients with AIDS. These are the first reported cases of disseminated M. malmoense in human immunodeficiency virus patients occurring in the United States. This slow-growing organism can cause invasive disease mimicking Mycobacterium avium complex infection; recognition and identification of this organism by mycobacteriology laboratories are essential for appropriate diagnosis and therapy of disseminated disease.

Mechanical dysfunction in the border zone of an ovine model of left ventricular aneurysm.

BACKGROUND: The pathophysiology of regional mechanical dysfunction in the border zone (BZ) region of left ventricular aneurysm was studied in an ovine model using magnetic resonance imaging tissue-tagging and regional deformation analysis. METHODS: Transmural infarcts were created in adult Dorsett sheep (n = 8) by ligation of the distal homonymous coronary artery and were allowed to mature into left ventricular aneurysms for 8 to 12 weeks. Animals were imaged subsequently using double oblique magnetic resonance imaging with radiofrequency tissue tagging. Short axis slices were selected for analysis that included predominantly the septal component of the aneurysm as well as adjacent BZ regions in the anterior and posterior ventricular walls. Dark grid patterns of magnetic presaturations were placed on the myocardium and tracked as they deformed during the diastolic, isovolumic systolic, and systolic ejection phases of the cardiac cycle. Regional ventricular wall strains were calculated in BZ regions and regions remote from the aneurysm and compared with strains measured in corresponding regions from normal control sheep (n = 6). RESULTS: Diastolic midwall circumferential strains (fiber extensions) were relatively preserved, but abnormal circumferential lengthening strains were observed in the BZ regions during isovolumic systole. Peak circumferential strains ranged from 0.04 to 0.07 in the BZ regions but averaged -0.05 in the normal hearts (p = 0.002 for the anterior BZ and p = 0.001 for the posterior BZ). Midwall end-systolic fiber strains were depressed in the anterior BZ (-0.03 to -0.09 for the BZ versus -0.11 for the normal heart, p < 0.0001) but not in the posterior BZ (p = 0.19). CONCLUSIONS: Our data support the theory that the stretching of BZ fibers during isovolumic systole contributed to a reduction in fiber shortening during systolic ejection and thus reduced the overall contribution of these fibers to forward ventricular output.

The cytomegalovirus-antigenemia assay in the diagnosis of posttransplant cytomegalovirus infection.

Cytomegalovirus (CMV) infection continues to be a major cause of morbidity and mortality in transplant recipients, yet prompt diagnosis remains a problem. A new assay has been developed that detects CMV antigens in peripheral blood leukocytes (CMV-AG). A retrospective analysis of the experience with this assay was performed, and its usefulness in the diagnosis of CMV infection in renal transplant recipients with unexplained fever was compared with that of conventional modalities (buffy coat culture, detection of circulating anti-CMV immunoglobulin M). The results suggest that the CMV-AG assay is a more rapid and sensitive test than existing modalities in the early diagnosis of CMV infection. When expressed quantitatively, it can discriminate between CMV infection and CMV disease, and it is useful in monitoring the course of infection and the response to therapy.

In vitro activity of sparfloxacin, ciprofloxacin, ofloxacin, and other antibiotics against bloodstream isolates of gram-positive cocci.

The in vitro activity of sparfloxacin was compared with the activities of ciprofloxacin, ofloxacin, and six other antimicrobial agents against 323 bloodstream isolates of staphylococci (both oxacillin susceptible and resistant) enterococci, and pneumococci. Sparfloxacin was more active than both ciprofloxacin and ofloxacin against all the isolates tested. Its activity (MIC for 90% of strains tested < or = 0.10 microgram/ml) against oxacillin-susceptible staphylococci was superior to that of ciprofloxacin and ofloxacin by at least fourfold. Sparfloxacin was also more potent against pneumococci. However, fluoroquinolone resistance was noted among oxacillin-resistant strains of Staphylococcus aureus and coagulase-negative staphylococci.

In vitro activities of ramoplanin, selected glycopeptides, fluoroquinolones, and other antibiotics against clinical bloodstream isolates of gram-positive cocci.

The susceptibilities of 316 gram-positive bacteremic isolates to ramoplanin, vancomycin, and teicoplanin and seven other antibiotics were tested. Ramoplanin demonstrated MICs of < or = 0.25 microgram/ml for at least 99% of Staphylococcus aureus isolates and 100% of coagulase-negative staphylococci tested. For both oxacillin-susceptible and oxacillin-resistant S. aureus and coagulase-negative staphylococci, the activity of ramoplanin surpassed those of both vancomycin and teicoplanin. Ramoplanin and teicoplanin had comparable activities against enterococci and Streptococcus pneumoniae and were superior to vancomycin.

Comparison of two culture approaches, blind passage and dual observation, for detecting Chlamydia trachomatis in various prevalence populations.

Chlamydia trachomatis diagnosis in our laboratory consisted of dual inoculation of shell vials and detection of inclusions by using fluorescein-conjugated monoclonal antiserum; the second culture vial was conventionally used for blind passage when the first vial was negative. We compared the increase in positivity using blind passage with that of a strategy utilizing observation of two stained monolayers (dual observation) without blind passage, in an effort to reduce the reporting time and labor associated with the conventional approach. A total of 4,329 specimens were obtained from an obstetrics and gynecology (OB-GYN) clinic (2,563 specimens) and the sexually transmitted disease clinic (1,766 specimens). These specimens were used to compare the two strategies. Blind passage of 1,269 initially culture-negative specimens from the OB-GYN clinic resulted in an additional 6 positive chlamydial diagnoses. In comparison, a similar number of specimens (1,294) from the OB-GYN clinic collected subsequently to the first group were tested by dual observation. There were five additional positive findings. A similar evaluation of specimens from the sexually transmitted disease clinic was performed. Blind passage of 313 initially culture-negative specimens yielded 3 additional positive diagnoses, whereas dual observation of 1,435 similar specimens resulted in 9 positive diagnoses. On the basis of analysis of 4,332 specimens, sensitivity of dual observation is comparable to that of blind passage; labor, cost, and reporting time of dual observation are reduced in comparison to those of blind passage.

Detection of bacteriuria and pyuria by URISCREEN a rapid enzymatic screening test.

A multicenter study was performed to evaluate the ability of the URISCREEN (Analytab Products, Plainview, N.Y.), a 2-min catalase tube test, to detect bacteriuria and pyuria. This test was compared with the Chemstrip LN (BioDynamics, Division of Boehringer Mannheim Diagnostics, Indianapolis, Ind.), a 2-min enzyme dipstick test; a semiquantitative plate culture method was used as the reference test for bacteriuria, and the Gram stain or a quantitative chamber count method was used as the reference test for pyuria. Each test was evaluated for its ability to detect probable pathogens at greater than or equal to 10(2) CFU/ml and/or greater than or equal to 1 leukocyte per oil immersion field, as determined by the Gram stain method, or greater than 10 leukocytes per microliter, as determined by the quantitative count method. A total of 1,500 urine specimens were included in this evaluation. There were 298 specimens with greater than or equal 10(2) CFU/ml and 451 specimens with pyuria. Of the 298 specimens with probable pathogens isolated at various colony counts, 219 specimens had colony counts of greater than or equal to 10(5) CFU/ml, 51 specimens had between 10(4) and 10(5) CFU/ml, and 28 specimens had between 10(2) and less than 10(4) CFU/ml. Both the URISCREEN and the Chemstrip LN detected 93% (204 of 219) of the specimens with probable pathogens at greater than or equal to 10(5) CFU/ml. For the specimens with probable pathogens at greater than or equal to 10(2) CFU/ml, the sensitivities of the URISCREEN and the Chemstrip LN were 86% (256 of 298) and 81% (241 of 298), respectively. Of the 451 specimens with pyuria, the URISCREEN detected 88% (398 of 451) and Chemstrip LN detected 78% (350 if 451). There were 204 specimens with both greater than or equal to 10(2) CFU/ml and pyuria; the sensitivities of both methods were 95% (193 of 204) for these specimens. Overall, there were 545 specimens with probable pathogens at greater than or equal to 10(2) CFU/ml and/or pyuria. The URISCREEN detected 85% (461 of 545), and the Chemstrip LN detected 73% (398 of 545). A majority (76%) of the false-negative results obtained with either method were for specimens without leukocytes in the urine. There were 955 specimens with no probable pathogens or leukocytes. Of these, 28% (270 of 955) were found positive by the URISCREEN and 13% (122 of 955) were found positive by the Chemstrip LN. A majority of the false-positive results were probably due, in part, to the detection of enzymes present in both bacterial and somatic cells by each of the test systems. Overall, the URISCREEN is rapid, manual, easy-to-perform enzymatic test that yields findings similar to those yielded by the Chemstrip LN for specimens with both greater than or equal to 10(2) CFU/ml and pyuria or for specimens with greater than or equal to 10(5) CFU/ml and with or without pyuria. However, when the data were analyzed for either probable pathogens at less 10(5) CFU/ml or pyuria, the sensitivity of the URISCREEN was higher (P less than 0.05).

Microbiological aspects of peritonitis associated with continuous ambulatory peritoneal dialysis.

The process of continuous ambulatory peritoneal dialysis has provided a useful, relatively inexpensive, and safe alternative for patients with end-stage renal disease. Infectious peritonitis, however, has limited a more widespread acceptance of this technique. The definition of peritonitis in this patient population is not universally accepted and does not always include the laboratory support of a positive culture (or Gram stain). In part, the omission of clinical microbiological findings stems from the lack of sensitivity of earlier microbiological efforts. Peritonitis results from decreased host phagocytic efficiency with depressed phagocytosis and bactericidal capacity of peritoneal macrophages. During episodes of peritonitis, fluid movement is reversed, away from the lymphatics and peritoneal membrane and toward the cavity. As a result, bloodstream infections are rare. Most peritonitis episodes are caused by bacteria. Coagulase-negative staphylococci are the most frequently isolated organisms, usually originating from the skin flora, but a wide array of microbial species have been documented as agents of peritonitis. Clinical microbiology laboratories need to be cognizant of the diverse agents so that appropriate primary media can be used. The quantity of dialysate fluid that is prepared for culture is critical and should constitute at least 10 ml. The sensitivity of the cultural approach depends on the volume of dialysate, its pretreatment (lysis or centrifugation), the media used, and the mode of incubation. The low concentration of microorganisms in dialysate fluids accounts for negative Gram stain results. Prevention of infection in continuous ambulatory peritoneal dialysis patients is associated with the socioeconomic status of the patient, advances in equipment (catheter) technology, and, probably least important, the application of prophylactic antimicrobial agents.