Chronic airway disease: the infection connection.
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Adult↗
Biomedical subjects
R L Atmar
Publications and source records attributed to R L Atmar.
Diagnosis of respiratory viruses in cancer and transplant patients.
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Adenoviruses, Human↗
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↗
Common emergence of amantadine- and rimantadine-resistant influenza A viruses in symptomatic immunocompromised adults.
The importance and significance of amantadine- or rimantadine-resistant influenza viruses in immunocompromised patients was studied in a population of adult bone marrow transplant (BMT) recipients and patients with leukemia prospectively cultured for respiratory viruses. Influenza A viruses were isolated from 29 patients with acute respiratory illness (14 BMT recipients and 15 patients with leukemia). Fifteen patients (52%) received amantadine (n = 4) or rimantadine (n = 11) therapy. All influenza isolates recovered from six patients shedding virus for > or = 3 days were screened for antiviral susceptibility; resistant isolates were further genetically characterized. Initial influenza isolates were susceptible to amantadine or rimantadine, but subsequent isolates from five of six patients were resistant. Influenza-associated mortality was similar among patients with and without documented antiviral resistance (2 of 5 vs. 5 of 24). We conclude that development of antiviral resistance in immunocompromised individuals should be considered when they have been treated with antivirals and have shed influenza virus for a prolonged period. Isolation procedures should be instituted for all immunocompromised patients with influenza, both during and after therapy with amantadine or rimantadine.
Adult↗
Oral immunization with recombinant Norwalk virus-like particles induces a systemic and mucosal immune response in mice.
Recombinant Norwalk virus-like particles (rNV VLPs) produced in insect cells were evaluated as an oral immunogen in CD1 and BALB/c mice by monitoring rNV-specific serum total and subclass immunoglobulin G (IgG) and intestinal IgA responses. Dose and kinetics of response were evaluated in the presence and absence of the mucosal adjuvant cholera toxin (CT). rNV-specific serum IgG and intestinal IgA were detected in the absence of CT, and the number of responders was not significantly different from that of mice administered VLPs with CT at most doses. The use of CT was associated with induction of higher levels of IgG in serum; this effect was greater at higher doses of VLPs. IgG in serum was detected in the majority of animals by 9 days postimmunization (dpi), and intestinal IgA responses were detected by 24 dpi. In the absence of CT, IgG2b was the dominant IgG subclass response in both mouse strains. Thus, nonreplicating rNV VLPs are immunogenic when administered orally in the absence of any delivery system or mucosal adjuvant. These studies demonstrate that rNV VLPs are an excellent model to study the oral delivery of antigen, and they are a potential mucosal vaccine for NV infections.
Administration, Oral↗
Distribution of Norwalk virus within shellfish following bioaccumulation and subsequent depuration by detection using RT-PCR.
Consumption of raw bivalve mollusks contaminated with pathogens from human feces continues to present a human health risk. The purpose of this study was to monitor the uptake, localization, and removal of Norwalk virus (NV) in shellfish (oyster and clam) tissues by analyzing virus distribution in selected dissected tissues. Live shellfish were allowed to bioaccumulate different input titers of NV for time periods from 4 to 24 h. In some experiments, depuration by shellfish that bioaccumulated NV and Escherichia coli bacteria was allowed to proceed for 24 or 48 hours. Dissected stomach (St), digestive diverticula (DD), adductor muscle (AM), and hemolymph cells (HC) tissues were assayed for NV by the reverse transcription polymerase chain reaction (RT-PCR) method. An internal RNA standard control was added to the RT-PCR to identify the presence of inhibitors to RT-PCR. NV titers in DD tissues before and after depuration were estimated using quantitative RT-PCR end-point dilution. NV was found in the alimentary tract (DD or St) at all concentrations of input virus, but was present more frequently after exposure to higher levels of virus. NV was detected in AM and HC only following exposure to higher levels of virus. In experiments where depuration by oysters was continued for 48 h, depuration of bacteria was efficient (95% reduction of bacteria), but minimal (7%) reduction of NV titers from DD tissues was detected. These findings indicate that NV can localize both within and outside the alimentary tract of shellfish, and NV is poorly depurated using conditions favorable for E. coli depuration.
Animals↗
Cytokines and impaired CD8+ CTL activity among elderly persons and the enhancing effect of IL-12.
We have previously demonstrated that about 70% of elderly persons exhibit deficient cytotoxic T lymphocyte (CD8+ CTL) responses against influenza viruses when compared to young persons. Since IFN-gamma, a Th1 cytokine and IL-4, a Th2 cytokine, stimulate and inhibit CD8+ CTL responses respectively, their role(s) in the age-related CTL deficiency was investigated. Lymphocytes from young adults (34 +/- 5 years old) and elderly subjects (71 +/- 1 years old) were stimulated in vitro with influenza A/H3N2, A/H1N1 or influenza B virus for 6-7 days. The CD8+ CTL activity against virus-infected autologous target cells was significantly lower among the elderly than the young subjects (P < 0.01). Following stimulation with influenza virus, IL-4 production in both age groups was similar on day 3 but significantly higher among elderly persons on day 6 (P < 0.05). In contrast, T cells from the elderly produced significantly lower IFN-gamma than did those from young persons on both days (P < 0.05). Treatment of T cells from young and elderly adults with recombinant human IL-12, a pivotal cytokine that stimulates Th1 cytokines, resulted in enhancement of CD8+ CTL activity and IFN-gamma production in a dose dependent manner (P < 0.01). IL-12-dependent enhancement of CTL activity was not always abrogated by anti-IFN-gamma antibody treatment. These results suggest that deficient influenza virus-specific CTL activity among the elderly is attributable to a Th1 to Th2 cytokine production switch. Immunotherapy with IL-12 could represent a useful approach to correct the CD8+ CTL deficiency and cytokine imbalance among elderly humans.
Adolescent↗
Effects of requiring prior authorization for selected antimicrobials: expenditures, susceptibilities, and clinical outcomes.
Antimicrobial control programs are widely used to decrease drug expenditures, but effects on antimicrobial resistance and outcomes for patients are unknown. When a requirement for prior authorization for selected parenteral antimicrobial agents was initiated at our urban, county teaching hospital, total parenteral antimicrobial expenditures decreased by 32%. Susceptibilities to all beta-lactam and quinolone antibiotics increased, with dramatic increased susceptibilities in isolates recovered in intensive care units, increased susceptibilities in isolates recovered in other inpatient sites, and little change in susceptibilities in isolates recovered in outpatient sites despite no change in infection control practices. For patients with bacteremia due to gram-negative organisms, overall survival did not change with restrictions. No differences occurred in the median time from initial positive blood culture to receipt of an appropriate antibiotic or in the median time from positive blood culture to discharge from the hospital. Thus, requiring preapproval for selected parenteral agents can decrease antimicrobial expenditures and improve susceptibilities to antibiotics without compromising patient outcomes or length of hospital stay.
Acinetobacter↗
Dual respiratory virus infections.
We retrospectively reviewed eight prospective epidemiological studies conducted between 1991 and 1995 for dual respiratory virus infection (DRVI) to determine the frequency, associated comorbid conditions, clinical presentations, and morbidity related to DRVI among immunocompetent persons. Two viruses were identified as the cause of 67 (5.0%) of 1,341 acute respiratory virus infections. DRVI was detected in patients from < 1 year to 79 years of age, in both sexes, and in many races. Forty-two percent of patients with DRVI were < or = 4 years old. Fifty-eight percent of patients with DRVI had underlying chronic lung disease. DRVI was associated with upper respiratory tract illness; lower respiratory tract illness, including pneumonia; systemic influenza-like illnesses; and exacerbations of asthma or chronic obstructive pulmonary disease. All of the common acute respiratory viruses were identified; picornaviruses and influenzavirus A were the most common. The rate of DRVI (11.6%) was highest in the epidemiological studies in which cell culture, serology, and polymerase chain reaction were used together. Patients with DRVI were hospitalized significantly more often than those with respiratory infection due to a single virus (46.3% vs. 21.7%; P < .01). The percentage of DRVIs increased proportionally with the number of diagnostic methods used.
Comorbidity↗
Granuloma cytokines in murine cysticercosis.
Neurocysticercosis, caused by Taenia solium, is one of the most common causes of seizures worldwide. The symptoms result from granulomatous inflammation associated with dying cyst forms of the parasite. Although the invasive larvae can be killed by immune serum plus complement, immunity to the cyst stage depends on a cellular response. This dichotomous immune response is reminiscent of the extremes of the immune response associated with T helper 1 (Th1) and Th2 cytokine profiles. To characterize the cytokine response in cysticercosis, granulomas were removed from the peritoneal cavity of mice infected with Taenia crassiceps cysts and examined for cytokine message by in situ hybridization using 35S-labeled RNA probes. The granulomas were staged based on histologic appearance of the degenerating parasite. Message for gamma interferon (IFN-gamma) was identified by light microscopy in 11 of the 12 granulomas, and interleukin-2 (IL-2) message was identified in 9 of the 12. By laser scanning confocal microscopy, significantly increased IFN-gamma and IL-2 pixel intensity was identified in nearly all of the granulomas from early histologic stages. Message for IL-4 was seen in 6 of the 12 granulomas. Only granulomas with complete destruction of the parasite architecture displayed more than minimal amounts of IL-4 message by light microscopy, and only 2 of 12 granulomas had IL-4 pixel intensity significantly above background. Only minimal amounts of IL-10 message were detected in 4 of 11 granulomas. Thus, early granulomas in cysticercosis are predominantly associated with a Th1 response, whereas later granulomas, in which parasite destruction is complete, have a mixture of Th1 and IL-4. The Th1 response appears to play an important role both in the pathogenesis of disease as well as in the clearing of the parasites, with IL-4 involved in downregulation of the initial response.
Animals↗
Use of heat release and an internal RNA standard control in reverse transcription-PCR detection of Norwalk virus from stool samples.
Norwalk virus (NV) and the Norwalk-like viruses are important human pathogens that cause epidemic acute viral gastroenteritis. Current techniques used to recover NV from clinical samples involve multistep viral extraction and elution procedures with subsequent viral detection by reverse transcription-PCR (RT-PCR). In this study, a simple method using heat to recover viral RNA from 45 stool samples was compared to a conventional viral RNA extraction technique, with subsequent analysis by RT-PCR. In addition, we used an internal RNA standard for the detection of inhibitors present in processed samples. Our results indicate that the use of heat to recover NV RNA from stool samples has a sensitivity for the detection of NV RNA that is similar to the more labor-intensive, time-consuming, conventional RNA extraction technique. The use of an RNA internal standard permits the detection of inhibitors present in processed samples, allowing the identification of false negatives. The standard we developed has the advantage of allowing differential detection between wild-type viral RNA and standard using internal oligoprobe hybridization.
Enzyme-Linked Immunosorbent Assay↗
Enforcing antimicrobial restrictions.
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Anti-Bacterial Agents↗
Evaluation of a degenerate primer for the PCR detection of human caliciviruses.
Numerous outbreaks of gastroenteritis have been associated with Norwalk virus and Small Round Structured Viruses (SRSVs). These single-stranded RNA viruses, recently classified in the Caliciviridae, have been divided into three genogroups. Antigenic relationships also have been established among the different strains. As both an in vitro culture system and an animal model are lacking for these viruses, virus detection depends primarily on electron microscopy, immunological assays or molecular detection. In this study we first analyzed the genetic homology of the RNA polymerase region for 40 SRSV strains. From a consensus sequence for these strains, we designed a degenerate oligonucleotide to prime cDNA synthesis from viral RNA. We evaluated the degenerate primer in combination with three previously described primers in PCR reactions. A panel of 15 stools containing SRSVs, typed when possible by solid phase immune electron microscopy (SPIEM), were selected to represent all three genogroups and four different SPIEM antigenic types. Serial dilutions of the purified viral nucleic acids were amplified using the three different primer sets. Virus-specific probes were used to characterize the amplicons obtained. Virus-specific amplicons were obtained with at least one primer pair for each strain, but apparent viral RNA titers differed as much as 1000-fold between primer sets. Amplicons from all but one of the 15 strains were confirmed as virus-specific using a panel of 10 different probes. Correlations between the most sensitive primer pair and SPIEM type were seen. This study showed that a single degenerate primer could be used in cDNA synthesis for a variety of SRSVs but that the sensitivity of the RT-PCR assay depended upon the second primer and virus-specific probes used.
DNA Primers↗
Typing and subtyping clinical isolates of influenza virus using reverse transcription-polymerase chain reaction.
BACKGROUND: Influenza virus infections are a major cause of morbidity and the identification of the type or subtype of a clinical isolate has important clinical and epidemiological implications. OBJECTIVES: To evaluate the ability of a reverse transcription-polymerase chain reaction (RT-PCR) assay to type and subtype clinical human isolates of influenza virus. STUDY DESIGN: Reference strains of influenza A H1N1, A/H3N2, and B viruses and human clinical isolates of influenza virus representing antigenic variants from the last 15 years were evaluated using an RT-PCR assay. RESULTS: Amplicons of 325, 198 and 365 base pairs in length were obtained from RNA extracted from influenza A/H1N1, A/H3N2 and B viruses, respectively. All human-derived A/H1N1, A/H3N2, and B reference strains and antigenic variants tested were correctly identified. CONCLUSIONS: RT-PCR is an effective alternative to traditional methods for typing and subtyping influenza viruses.
Animals↗
Unanticipated diagnoses found at autopsy in an urban public teaching hospital.
The authors set out to evaluate the use of the autopsy in an urban public teaching hospital setting during the AIDS era. Demographic and length of hospital stay data were obtained from weekly mortality review reports on all patients dying on the medicine service between 1/1/92 and 12/31/93. Clinical and autopsy diagnoses were compared for those patients who had autopsies. The autopsy rate was 16% (152/974). Significant, unsuspected diagnoses were found in 35% (53/152) of the cases, with infections, pulmonary emboli, and myocardial infarctions being most common. Human immunodeficiency virus-infected patients had a greater percentage of unsuspected findings (55%, 23/42), and many of these also were from an infectious etiology. The authors conclude that valuable, unsuspected information frequently can be obtained from autopsies in this clinical setting.
Acquired Immunodeficiency Syndrome↗
Collaborative evaluation of a method for the detection of Norwalk virus in shellfish tissues by PCR.
A multicenter, collaborative trial was performed to evaluate the reliability and reproducibility of a previously described method for the detection of Norwalk virus in shellfish tissues with the PCR (R.L. Atmar, F. H. Neill, J. L. Romalde, F. Le Guyader, C. M. Woodley, T. G. Metcalf, and M. K. Estes, Appl. Environ. Microbiol. 61:3014-3018, 1995). Virus was added to the stomachs and hepatopancreatic tissues of oysters or hard-shell clams in the control laboratory, the samples were shipped to the participating laboratories, and viral nucleic acids were extracted and then detected by reverse transcription-PCR. The sensitivity and specificity of the assay were 85 and 91%, respectively, when results were determined by visual inspection of ethidium bromide-stained agarose gels; the test sensitivity and specificity improved to 87 and 100%, respectively, after confirmation by hybridization with a digoxigenin-labeled, virus-specific probe. We have demonstrated that this method can be implemented successfully by several laboratories to detect Norwalk virus in shellfish tissues.
Animals↗
Detection and analysis of a small round-structured virus strain in oysters implicated in an outbreak of acute gastroenteritis.
Outbreaks of shellfish-transmitted viral disease occur periodically, but frequently the causative agent is not identified. In November 1993, during investigation of a multistate outbreak of acute gastroenteritis, incriminated lots of oysters were collected. Oyster tissues (stomachs and digestive diverticula) were processed for virus extraction and nucleic acid purification. Human calicivirus sequences were sought by reverse transcriptase PCR using different primer sets. Amplicons were obtained from 9 of 10 shellfish samples from four different lots when primers specific for the outbreak virus strain were used. The specificity of the amplification was confirmed by hybridization. The amplicons from the nine positive oysters were cloned and sequenced. The sequence of each of the clones was identical to the others but showed some variation (7 of 81 bp) from the sequences obtained from the stools of three persons made III by the outbreak.
Animals↗
Increasing doses of purified influenza virus hemagglutinin and subvirion vaccines enhance antibody responses in the elderly.
The reactogenicities and immunogenicities of two influenza virus vaccines were compared in a placebo-controlled clinical trial among healthy ambulatory persons > or = 65 years old (mean age, 72 years). Volunteers were assigned randomly to receive 15-, 45-, or 135-micrograms doses of monovalent influenza A/Taiwan (H1N1) hemagglutinin (HA) or subvirion (SV) vaccine intramuscularly or a placebo. Increasing doses of SV vaccine were associated with a higher rate of injection site discomfort (P < 0.05; chi-square test for linear trend), but all doses of both vaccines were well tolerated. Increasing the dose of the HA or the SV vaccine resulted in increasingly higher postimmunization levels of serum hemagglutination inhibition and neutralizing antibody levels (P < 0.001; multiple linear regression). Mean serum antibody titers at 1 month increased two- to threefold with a ninefold increase in dose; the frequencies of fourfold or greater rises in titer likewise increased. An increase in the dose of the HA or the SV vaccine also resulted in increased frequencies of rises in immunoglobulin A or G antibody titers in nasal wash specimens. The frequencies increased approximately twofold for each vaccine with a ninefold increase in the dose. These data suggest that increasing the HA vaccine dose is a promising approach to the development of improved influenza virus vaccines for use in elderly people.
Aged↗