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R J Hamill

Publications and source records attributed to R J Hamill.

At least 19 recordsLinked to original sources
PubMed2001

Cryptococcosis in human immunodeficiency virus-negative patients in the era of effective azole therapy.

We conducted a case study of human immunodeficiency virus (HIV)-negative patients with cryptococcosis at 15 United States medical centers from 1990 through 1996 to understand the demographics, therapeutic approach, and factors associated with poor prognosis in this population. Of 306 patients with cryptococcosis, there were 109 with pulmonary involvement, 157 with central nervous system (CNS) involvement, and 40 with involvement at other sites. Seventy-nine percent had a significant underlying condition. Patients with pulmonary disease were usually treated initially with fluconazole (63%); patients with CNS disease generally received amphotericin B (92%). Fluconazole was administered to approximately two-thirds of patients with CNS disease for consolidation therapy. Therapy was successful for 74% of patients. Significant predictors of mortality in multivariate analysis included age > or =60 years, hematologic malignancy, and organ failure. Overall mortality was 30%, and mortality attributable to cryptococcosis was 12%. Cryptococcosis continues to be an important infection in HIV-negative patients and is associated with substantial overall and cause-specific mortality.

Adolescent↗
PubMed2001

Trends in antifungal drug susceptibility of Cryptococcus neoformans isolates in the United States: 1992 to 1994 and 1996 to 1998.

The antifungal drug susceptibilities of two collections of Cryptococcus neoformans isolates obtained through active laboratory-based surveillance from 1992 to 1994 (368 isolates) and 1996 to 1998 (364 isolates) were determined. The MICs of fluconazole, itraconazole, and flucytosine were determined by the National Committee for Clinical Laboratory Standards broth microdilution method; amphotericin B MICs were determined by the E-test. Our results showed that the MIC ranges, the MICs at which 50% of isolates are inhibited (MIC(50)s), and the MIC(90)s of these four antifungal agents did not change from 1992 to 1998. In addition, very small numbers of isolates showed elevated MICs suggestive of in vitro resistance. The MICs of amphotericin B were elevated (>or=2 microg/ml) for 2 isolates, and the MICs of flucytosine were elevated (>or=32 microg/ml) for 14 isolates. Among the azoles, the fluconazole MIC was elevated (>or=64 microg/ml) for 8 isolates and the itraconazole MIC (>or=1 microg/ml) was elevated for 45 isolates. Analysis of 172 serial isolates from 71 patients showed little change in the fluconazole MIC over time. For isolates from 58 patients (82% of serial cases) there was either no change or a twofold change in the fluconazole MIC. In contrast, for isolates from seven patients (12% of serial cases) the increase in the MIC was at least fourfold. For isolates from another patient there was a 32-fold decrease in the fluconazole MIC over a 1-month period. We conclude that in vitro resistance to antifungal agents remains uncommon in C. neoformans and has not significantly changed with time during the past decade.

Antifungal Agents↗
PubMed2000

Clinical prediction model for differentiation of disseminated Histoplasma capsulatum and Mycobacterium avium complex infections in febrile patients with AIDS.

BACKGROUND: Disseminated infection with Histoplasma capsulatum and Mycobacterium avium complex (MAC) in patients with AIDS are frequently difficult to distinguish clinically. METHODS: We retrospectively compared demographic information, other opportunistic infections, medications, symptoms, physical examination findings and laboratory parameters at the time of hospital presentation for 32 patients with culture documented disseminated histoplasmosis and 58 patients with disseminated MAC infection. RESULTS: Positive predictors of histoplasma infection by univariate analysis included lactate dehydrogenase level, white blood cell (WBC) count, platelet count, alkaline phosphatase level, and CD4 cell count. By multivariate logistic regression analysis, those characteristics that remained significant included a lactate dehydrogenase value > or =500 U/L (risk ratio [RR], 42; 95% confidence interval [CI], 18.53-97.5; p < .001), alkaline phosphatase < or =300 U/L (RR, 9.35; 95% CI, 2.61-33.48; p = .008), WBC < or =4.5 x 10(6)/L (RR, 21.29; 95% CI, 6.79-66.75; p = .008), and CD4 cell count (RR, 0.958; 95% CI, 0.946-0.971; p = .001). CONCLUSIONS: A predictive model for distinguishing disseminated histoplasmosis from MAC infection was developed using lactate dehydrogenase and alkaline phosphatase levels as well as WBC count. This model had a sensitivity of 83%, a specificity of 91%, and a misclassification rate of 13%.

AIDS-Related Opportunistic Infections↗
PubMed1998

Ventilator-associated pneumonia.

Mechanically ventilated patients are at a substantially higher risk for developing nosocomial pneumonia. Overall, there is a relatively constant 1&!TN!150;3% risk per day of developing pneumonia while receiving mechanical ventilation. The sensitivity and specificity of clinical criteria alone for diagnosis of ventilator-associated pneumonias (VAP) is low. Several techniques have been developed to sample and quantitate the lower respiratory tract to improve the diagnostic yield. Gram-negative bacillary pneumonias account for the majority of the VAP. Strategies for prevention of VAP such as use of sucralfate for stress ulcer prophylaxis and selective decontamination of the digestive tract have been the focus of many clinical studies. Cost-effective preventive measures are needed to combat the increasing antimicrobial resistance, growing population of immunocompromised patients and increasing number of mechanically ventilated patients.

Cross Infection↗
PubMed1998

Acute respiratory failure associated with cryptococcosis in patients with AIDS: analysis of predictive factors.

The incidence of acute respiratory failure (ARF) associated with cryptococcal disease in patients with AIDS is underestimated in the literature. We performed a retrospective, case-control (referent) study to determine the prevalence of ARF associated with cryptococcal disease and analyzed associated factors. Potential cases of ARF were identified at four university-affiliated teaching hospitals from a cohort of 210 patients with AIDS who had positive cryptococcal antigen tests and/or Cryptococcus neoformans isolated from any body site. Twenty-nine of the 210 (13.8%) had ARF associated with cryptococcal disease. Nineteen were thought to have respiratory failure due solely to C. neoformans. The demographic, clinical, laboratory, treatment, and outcome data of 19 cases of respiratory failure were compared with data for 20 patients without respiratory failure. In-hospital mortality was 100% and median survival was 2 days for cases, vs. 25% and > 365 days, respectively, for referents. The clinical presentation was identical to that of Pneumocystis carinii pneumonia. In multivariate analysis, variables independently predictive of ARF in patients with cryptococcal disease were black race, a lactate dehydrogenase level of > or = 500 IU/L, the presence of interstitial infiltrates, and the presence of cutaneous lesions. ARF with cryptococcosis in patients with AIDS is associated with disseminated disease and high mortality. The diagnosis frequently is not considered before death. Serum cryptococcal antigen testing is a sensitive and rapid screening method.

AIDS-Related Opportunistic Infections↗
PubMed1997

Treatment of cryptococcal meningitis associated with the acquired immunodeficiency syndrome. National Institute of Allergy and Infectious Diseases Mycoses Study Group and AIDS Clinical Trials Group.

BACKGROUND: Treatment with low-dose amphotericin B (0.4 mg per kilogram of body weight per day) or oral azole therapy in patients with the acquired immunodeficiency syndrome (AIDS) and cryptococcal meningitis has been associated with high mortality and low rates of cerebrospinal fluid sterilization. METHODS: In a double-blind multicenter trial we randomly assigned patients with a first episode of AIDS-associated cryptococcal meningitis to treatment with higher-dose amphotericin B (0.7 mg per kilogram per day) with or without flucytosine (100 mg per kilogram per day) for two weeks (step one), followed by eight weeks of treatment with itraconazole (400 mg per day) or fluconazole (400 mg per day) (step two). Treatment was considered successful if cerebrospinal fluid cultures were negative at 2 and 10 weeks or if the patient was clinically stable at 2 weeks and asymptomatic at 10 weeks. RESULTS: At two weeks, the cerebrospinal fluid cultures were negative in 60 percent of the 202 patients receiving amphotericin B plus flucytosine and in 51 percent of the 179 receiving amphotericin B alone (P=0.06). Elevated intracranial pressure was associated with death in 13 of 14 patients during step one. The clinical outcome did not differ significantly between the two groups. Seventy-two percent of the 151 fluconazole recipients and 60 percent of the 155 itraconazole recipients had negative cultures at 10 weeks (95 percent confidence interval for the difference in percentages, -100 to 21). The proportion of patients who had clinical responses was similar with fluconazole (68 percent) and itraconazole (70 percent). Overall mortality was 5.5 percent in the first two weeks and 3.9 percent in the next eight weeks, with no significant difference between the groups. In a multivariate analysis, the addition of flucytosine during the initial two weeks and treatment with fluconazole for the next eight weeks were independently associated with cerebrospinal fluid sterilization. CONCLUSIONS: For the initial treatment of AIDS-associated cryptococcal meningitis, the use of higher-dose amphotericin B plus flucytosine is associated with an increased rate of cerebrospinal fluid sterilization and decreased mortality at two weeks, as compared with regimens used in previous studies. Although consolidation therapy with fluconazole is associated with a higher rate of cerebrospinal fluid sterilization, itraconazole may be a suitable alternative for patients unable to take fluconazole.

AIDS-Related Opportunistic Infections↗
PubMed1997

Colonization by Streptococcus pneumoniae among human immunodeficiency virus-infected adults: prevalence of antibiotic resistance, impact of immunization, and characterization by polymerase chain reaction with BOX primers of isolates from persistent S. pneumoniae carriers.

Pharyngeal colonization by Streptococcus pneumoniae was evaluated in 103 human immunodeficiency virus (HIV)-infected subjects (<200 CD4 cells/microL, 57; > or = 200 CD4 cells/microL, 46) and 39 non-HIV-infected controls who were participants in a vaccine study. At baseline, 7%, 20%, and 10% of subjects in the <200 and > or = 200 CD4 cell groups and in the control group were colonized with S. pneumoniae: Rates at 6 months were 23%, 22%, and 0%, respectively. Of 34 isolates from HIV-infected subjects, 25 were penicillin-resistant and 19 were resistant to > or = 3 antimicrobials; of 8 isolates from controls, 1 was resistant. Resistance to trimethoprim-sulfamethoxazole was significantly higher among HIV-infected subjects with <200 CD4 cells/microL than in those with more CD4 cells. Polymerase chain reaction DNA analysis with BOX primers demonstrated that 12 HIV-infected subjects were persistently colonized with the same S. pneumoniae strain for > or = 1 month compared with none of the controls. HIV-infected subjects were more likely to be persistent pneumococcal carriers and to carry antibiotic-resistant isolates than were non-HIV-infected subjects.

Adult↗
PubMed1996

Fluconazole therapy for histoplasmosis. The National Institute of Allergy and Infectious Diseases Mycoses Study Group.

We assessed the efficacy of oral fluconazole (200-800 mg daily) in the treatment of non-life-threatening acute pulmonary histoplasmosis, chronic pulmonary histoplasmosis, or disseminated histoplasmosis in patients without human immunodeficiency virus infection. Of 27 evaluable patients, two had progressive acute pulmonary histoplasmosis, 11 had chronic pulmonary histoplasmosis, and 14 had disseminated histoplasmosis. Median durations of treatment in each of the three groups were 6 months, 7 months, and 11 months, respectively. Nineteen patients were treated with 400 mg of fluconazole daily (two of these patients received 800 mg daily for a portion of their treatment courses), seven were treated with 200 mg daily, and one was treated with 800 mg daily. Treatment was successful in 17 (63%) of 27 cases. Both of the patients with acute pulmonary infection responded to therapy, as did five (46%) of 11 patients with chronic pulmonary infection and 10 (71%) of 14 patients with disseminated infection. No substantial toxicity was observed. We conclude that fluconazole therapy for histoplasmosis is only moderately effective and should be reserved for patients who cannot take itraconazole.

Female↗
PubMed1996

Immunoprophylaxis against klebsiella and pseudomonas aeruginosa infections. The Federal Hyperimmune Immunoglobulin Trial Study Group.

To determine if passive immunization could decrease the incidence or severity of Klebsiella and Pseudomonas aeruginosa infections, patients admitted to intensive care units of 16 Department of Veterans Affairs and Department of Defense hospitals were randomized to receive either 100 mg/kg intravenous hyperimmune globulin (IVIG), derived from donors immunized with a 24-valent Klebsiella capsular polysaccharide plus an 8-valent P. aeruginosa O-polysaccharide-toxin A conjugate vaccine, or an albumin placebo. The overall incidence and severity of vaccine-specific Klebsiella plus Pseudomonas infections were not significantly different between the groups receiving albumin and IVIG. There was some evidence that IVIG may decrease the incidence (2.7% albumin vs. 1.2% IVIG) and severity (1.0% vs. 0.3%) of vaccine-specific Klebsiella infections, but these reductions were not statistically significant. The trial was stopped because it was statistically unlikely that IVIG would be protective against Pseudomonas infections at the dosage being used. Patients receiving IVIG had more adverse reactions (14.4% vs. 9.2%).

Antibodies, Bacterial↗
PubMed1996

Molecular subtype distribution of Cryptococcus neoformans in four areas of the United States. Cryptococcal Disease Active Surveillance Group.

To improve understanding of the epidemiology of cryptococcal disease, we analyzed the multilocus genotype distribution of 358 Cryptococcus neoformans isolates obtained from 251 patients through active surveillance in four U.S. geographic areas from 1992 through 1994. Isolates of the predominant enzyme electrophoretic type (ET), ET-1, were recovered in significantly greater proportion from Atlanta, Ga., Houston, Tex., and all major metropolitan areas of Alabama than from San Francisco, Calif. ET-2 and ET-7 complex (serotype AD) isolates were recovered predominantly from San Francisco. ET-3 was recovered less frequently from San Francisco than from the three other locations. These findings may reflect geographic differences in exposure to environmental strains or the identification of previously unrecognized C. neoformans clusters. Analysis by random amplified polymorphic DNA-PCR subtyping further divided 67 ET-1 isolates into 19 additional subtypes, none of which could be associated with a particular geographic region. Multiple isolates from the same patient always revealed the same multilocus enzyme electrophoresis and random amplified polymorphic DNA subtypes. No differences in subtype distribution were found when isolates from AIDS patients were compared with those from persons without or with another underlying disease, although one C. noeformans var. gattii isolate was obtained from an AIDS patient. When body site distribution was analyzed, ET-4 was disproportionately recovered from skin or surface body sites. Evidence for linkage disequilibrium in this fungal population suggests that virulent C. neoformans possesses a clonal population structure. Continued application of molecular subtyping methods will be useful in tracking the source, transmission, and relative virulence of different C. neoformans strains.

AIDS-Related Opportunistic Infections↗
PubMed1995

An outbreak of Burkholderia (formerly Pseudomonas) cepacia respiratory tract colonization and infection associated with nebulized albuterol therapy.

OBJECTIVE: To investigate an outbreak of Burkholderia (formerly Pseudomonas) cepacia respiratory tract colonization and infection in mechanically ventilated patients. DESIGN: A retrospective case-control and bacteriologic study. SETTING: Veterans Affairs medical center. PATIENTS: 42 mechanically ventilated patients who developed respiratory tract colonization or infection with B. cepacia and 135 ventilator-dependent controls who were not colonized and did not develop infections. MEASUREMENTS: Clinical and demographic data; benzalkonium chloride concentrations and pH levels in albuterol sulfate solutions; repetitive-element polymerase chain reaction (PCR)-mediated molecular fingerprinting on eight patient isolates and three environmental B. cepacia isolates that were available for study. RESULTS: 42 patients had B. cepacia respiratory tract colonization or infection. Observation of intensive care unit and respiratory care personnel showed faulty infection control procedures (for example, the same multiple-dose bottle of albuterol was used for many mechanically ventilated patients). More case patients (39 [92.9%]) than controls (95 [70.4%]; P = 0.006) received nebulized albuterol, and case patients (67.5 treatments) received more treatments than controls (18 treatments; P < 0.001). In-use albuterol solutions had pH values that were unstable, and benzalkonium chloride concentrations declined over time to levels capable of supporting bacterial growth. Medication nebulizers and in-use bottles of albuterol harbored B. cepacia. Molecular fingerprints of patient isolates and environmental B. cepacia isolates were identical using repetitive-element PCR. No further isolates of B. cepacia were identified after institution of appropriate infection control procedures. CONCLUSIONS: Multiple-dose medications and reliance on benzalkonium chloride as a medication preservative provide a mechanism for nosocomial spread of microorganisms, particularly if infection control procedures are not carefully followed. Repetitive-element PCR is a useful fingerprinting technique for molecular epidemiologic studies of B. cepacia.

Aged↗
PubMed1995

Molecular epidemiology of infections due to Enterobacter aerogenes: identification of hospital outbreak-associated strains by molecular techniques.

Molecular techniques were used to study the epidemiology of infections due to Enterobacter aerogenes in a tertiary-care hospital. Sixty-two clinical isolates were collected from 43 patients over 3 months. Restriction endonuclease analysis (REA) of chromosomal DNA and repetitive-element polymerase chain reaction (rep-PCR) with primers based on repetitive extragenic palindromic (REP) and enterobacterial repetitive intergenic consensus (ERIC) bacterial DNA sequences were used for genomic fingerprinting. REA with HindIII or EcoRI yielded complex banding patterns that differentiated community-acquired from some hospital-acquired organisms. Less complex fingerprints were obtained with rep-PCR, which also distinguished between epidemiologically unrelated strains. More discriminatory DNA fingerprints were provided by rep-PCR when REP primers rather than ERIC primers were used. Two clusters of genomically distinct isolates from patients with recent or current exposure to the hospital environment were identified by REA and rep-PCR. Most isolates within each cluster contained characteristic plasmids, and some isolates contained additional plasmids. These results suggest colonization and infection with genotypically related strains of E. aerogenes in a nosocomial setting. Although REA and plasmid profiling are useful techniques for the epidemiological typing of E. aerogenes, genomic fingerprinting with rep-PCR may offer the advantages of ease, speed, and broad species applicability over existing molecular-typing techniques.

Adult↗
PubMed1995

Case report: vitamin D-mediated hypercalcemia in fungal infections.

Hypercalcemia has been well described in a variety of neoplastic and granulomatous diseases. One mechanism for this hypercalcemia is via the excess production of 1,25-dihydroxyvitamin D from extra-renal sources. The authors describe an AIDS patient infected with Cryptococcus neoformans who had suggestive evidence of vitamin D-mediated hypercalcemia. He had an elevated serum 1,25-dihydroxyvitamin D value, a normal 25-hydroxyvitamin D value, and low values for parathyroid hormone and parathyroid hormone-related peptide. Most previously reported cases of hypercalcemia associated with fungal infections did not include sufficient evidence to implicate a role for excess 1,25-dihydroxyvitamin D production, except for two case reports involving patients with hypercalcemia with infections due to Pneumocystis carinii and Candida albicans. The authors' patient's hypercalcemia resolved during treatment of his underlying infection. Patients with hypercalcemia or in whom hypercalcemia develops during a disseminated fungal infection should have vitamin D metabolites measured as part of their work-up.

AIDS-Related Opportunistic Infections↗
PubMed1995

In vitro evaluation of the role of humoral immunity against Bartonella henselae.

The contribution of humoral immunity against Bartonella henselae was evaluated by examining the in vitro bactericidal activity of sera and the ability of these microorganisms to activate complement and stimulate phagocytosis and an oxidative burst in polymorphonuclear leukocytes. The organism was killed by complement-mediated cytolysis. Complement activation preferentially proceeded by the alternative pathway. The presence of specific antibodies did not increase the serum bactericidal activity or complement activation. However, phagocytosis and the subsequent production of oxygen radicals, evaluated by flow cytometry, were significantly enhanced in the presence of bacteria previously opsonized with immune sera.

Adult↗
PubMed1995

Genomic fingerprinting of Bartonella species by repetitive element PCR for distinguishing species and isolates.

Repetitive-element PCR (rep-PCR) with primers based on repetitive extragenic palindromic (REP) and enterobacterial repetitive intergenic consensus (ERIC) repeated DNA sequences was used for genomic finger-printing of Bartonella species. This technique was applied by using either extracted genomic DNA or preparations of whole bacterial cells directly. PCR fingerprints with either the REP-based primers (REP-PCR) or primers based on the ERIC repeat (ERIC-PCR) revealed species-specific band patterns for the various Bartonella isolates. DNA fingerprints obtained from rep-PCR of extracted genomic DNA or from preparations of whole cells yielded comparable patterns. ERIC-PCR banding patterns were less complex than those obtained by REP-PCR but allowed better discrimination between strains within species. By combining results of REP-PCR and ERIC-PCR, five different fingerprint profiles were identified among 17 isolates of Bartonella henselae, but only one profile was identified among the five isolates of Bartonella quintana. Other Bartonella species yielded distinct rep-PCR fingerprints. rep-PCR is a useful technique for identification of Bartonella organisms to the species level and offers the advantage of ease of performance, with only small quantities of cells needed for the whole-cell procedure. This technique also appears to be useful for subtyping B. henselae isolates.

AIDS-Related Opportunistic Infections↗