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Biomedical subjects

D Amsterdam

Publications and source records attributed to D Amsterdam.

At least 19 recordsLinked to original sources
PubMed2000

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.

Anti-Bacterial Agents↗
PubMed1999

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.

AIDS-Related Opportunistic Infections↗
PubMed1999

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.

Administration, Intravesical↗
PubMed1997

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.

Antigens, Viral↗
PubMed1997

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.

Cytomegalovirus↗
PubMed1996

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.

Acquired Immunodeficiency Syndrome↗
PubMed1994

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.

Antigens, Viral↗
PubMed1993

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.

Anti-Bacterial Agents↗
PubMed1993

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.

Anti-Bacterial Agents↗
PubMed1992

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.

Bacteria↗
PubMed1992

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.

Bacteriological Techniques↗
PubMed1992

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).

Bacteriological Techniques↗
PubMed1991

The in-vitro activity of temafloxacin, against gram-positive bacteria.

Temafloxacin, a new fluoroquinolone with enhanced activity against Gram-positive bacteria, was compared with other antibiotics. A review of the literature on the in-vitro activity of temafloxacin was also done. The susceptibility of Gram-positive cocci isolated from blood cultures was determined using a broth microdilution method. Temafloxacin MIC90s for Staphylococcus aureus (oxacillin-sensitive and -resistant) and Streptococcus pneumoniae were less than 0.12, less than 0.12 and 0.76 mg/L respectively. Temafloxacin was more active than either ciprofloxacin or ofloxacin against these organisms. A review of the literature supported these findings. Temafloxacin was the most active of the quinolones tested against a small number of S. pneumoniae with decreased sensitivity to penicillin. Temafloxacin activity was not appreciably affected by changes in pH or the presence of serum, but activity was slightly reduced in urine at pH 6.5-7.2, and at high magnesium ion concentrations. With the exception of S. pneumoniae at high concentration, no significant inoculum effect was observed.

Anti-Infective Agents↗
PubMed1991

Evaluation of a visual, rapid, membrane enzyme immunoassay for the detection of herpes simplex virus antigen.

We evaluated a 12-min, direct, monoclonal antibody-based enzyme immunoassay (EIA) (SureCell; Kodak, Rochester, N.Y.) which aids in the detection of herpes simplex virus infection; the assay system is also approved for culture confirmation. The test was evaluated from direct clinical samples and compared with conventional culture methodology by using a single swab. A total of 265 specimens from 180 female cervical-urogenital sites, 62 male urogenital sites, 4 rectal sites, 3 skin sites, 6 oral sites, and 10 colposcopy sites were collected on Dacron or cotton swabs and placed in viral transport medium (VTM). Within 6 h of receipt, 0.2 ml of the vortexed VTM was inoculated into each of two replicate cell cultures. Cell monolayers were observed daily for ten days, and cytopathic effect was confirmed by using an indirect immunoperoxidase reagent. The procedure for the SureCell assay conformed to the manufacturer's recommendations. When conventional culture was compared with EIA results, the overall sensitivity, specificity, positive predictive value, negative predictive value, and agreement were 64.4, 98.9, 96.7, 84.4, and 87.2%, respectively. Variables affecting the EIA sensitivity are the stage of the lesion and conventional culture methodologies. A review of culture results for 32 EIA false-negative tests indicated that 15 were detected after 48 h of incubation. Cytopathic effect observed at 48-, 72-, and 96-h cutoffs altered the sensitivity for the EIA. To ensure detection of SureCell herpes simplex virus-negative specimens, it is recommended that an unused aliquot of VTM be tested in cell culture.

Antigens, Viral↗
PubMed1990

Case report and seeded blood culture study of Brucella bacteremia.

Diagnosis of brucellosis requires prompt detection and identification of the coccobacillus for appropriate patient management, as the organism is associated with a potentially severe outcome. In a recent experience, an 18-year-old migrant farm worker presented at a local hospital with nonspecific symptoms. A significant Brucella titer of 2,560 was followed by the recovery of a gram-negative coccobacillus, subsequently identified as Brucella abortus, from subcultured 5-day-old BACTEC NR730 negative blood cultures. The organism proved to be susceptible to a variety of antimicrobial agents and resistant to nitrofurantoin. The patient was administered antimicrobial therapy for Brucella spp. consisting of tetracycline and streptomycin for 21 days. During the course of therapy the patient experienced defervescence and was discharged with the recommendation for periodic follow-up examinations. Seeded culture studies of this isolate with fresh human blood and target inocula of 5 and 500 CFU/ml indicated that the larger (500-CFU/ml) inoculum produced positive instrument detection within 2 days, whereas the smaller (5-CFU/ml) inoculum required 5.5 to 7.5 days for detection, depending on the medium used. These findings underscore the potential for Brucella bacteremia to escape instrument detection given a low bacterial inoculum.

Adolescent↗
PubMed1989

Comparative in vitro activities of teicoplanin, vancomycin, oxacillin, and other antimicrobial agents against bacteremic isolates of gram-positive cocci.

The in vitro activities of teicoplanin and vancomycin were compared with those of six other antimicrobial agents against 460 bacteremic isolates of gram-positive cocci. Teicoplanin was as active as vancomycin but less active than ciprofloxacin against staphylococci. Teicoplanin was the most potent of all agents tested against enterococci and had excellent activity against pneumococci.

Anti-Bacterial Agents↗