Metals and Organohalogen Contaminants in Bald Eagles (Haliaeetus leucocephalus) from Ontario, 1991-2008

We examined the degree of exposure of lead (Pb), mercury (Hg), and several organohalogen contaminants and its potential impact on survival of bald eagles in Ontario from 1991 to 2008. Overall, results for 43 dead or dying bald eagles collected in the province indicate that 23% (10/43) of birds died of Pb poisoning and 9% (4/43) died of suspected Hg poisoning. Pb poisoning was diagnosed based on exceedances of toxicity thresholds in liver and kidney and supported by clinical observations, necropsy results, and histology findings when available. Evidence for Hg poisoning in eagles was limited; however, Hg concentrations exceeded the toxicity threshold in kidney. Pb concentrations ranged widely in liver and kidney. Total Hg concentrations were relatively higher in kidney compared with liver and were significantly correlated with selenium (Se) concentrations in both tissues. Concentrations of p,p'-DDE and sum PCBs in livers of 12 bald eagles collected from 2001 to 2004 were likely below concentrations associated with adverse effects. Hepatic concentrations of total polybrominated diphenyl ethers were generally higher in birds collected from southern Ontario compared with northern Ontario. Potential impacts of exposure to these flame retardants and others are not known. Elevated metal exposure appears to influence survivorship and may affect the recovery of bald eagles in the province, particularly in southern Ontario and along the Great Lakes where a disproportionate number of poisoned eagles were collected. Increased efforts are needed to identify sources of exposure and develop measures to reduce metal exposure in this top predator.

Relationships among mercury, selenium, and neurochemical parameters in common loons (Gavia immer) and bald eagles (Haliaeetus leucocephalus)

Fish-eating birds can be exposed to levels of dietary methylmercury (MeHg) known or suspected to adversely affect normal behavior and reproduction, but little is known regarding Hg's subtle effects on the avian brain. In the current study, we explored relationships among Hg, Se, and neurochemical receptors and enzymes in two fish-eating birds--common loons (Gavia immer) and bald eagles (Haliaeetus leucocephalus). In liver, both species demonstrated a wide range of total Hg (THg) concentrations, substantial demethylation of MeHg, and a co-accumulation of Hg and Se. In liver, there were molar excesses of Se over Hg up to about 50-60 microg/g THg, above which there was an approximate 1:1 molar ratio of Hg:Se in both species. However, in brain, bald eagles displayed a greater apparent ability to demethylate MeHg than common loons. There were molar excesses of Se over Hg in brains of bald eagles across the full range of THg concentrations, whereas common loons often had extreme molar excesses of Hg in their brains, with a higher proportion of THg remaining as MeHg compared with eagles. There were significant positive correlations between brain THg and muscarinic cholinergic receptor concentrations in both species studied; whereas significant negative correlations were observed between N-methyl-D-aspartic acid (NMDA) receptor levels and brain Hg concentration. There were no significant correlations between brain Se and neurochemical receptors or enzymes (cholinesterase and monoamine oxidase) in either species. Our findings suggest that there are significant differences between common loons and bald eagles with respect to cerebral metabolism and toxicodynamics of MeHg and Se. These interspecies differences may influence relative susceptibility to MeHg toxicity; however, neurochemical responses to Hg in both species were similar.

Re-establishment of neurochemical coding of preganglionic neurons innervating transplanted targets

We investigated the effect on neurochemical phenotype of changing the targets innervated by sympathetic preganglionic neurons. In neonatal rats, the adrenal gland was transplanted into the neck, to replace the postganglionic neurons of the superior cervical ganglion. Transplanted adrenal glands survived, and contained noradrenergic and adrenergic chromaffin cells, and adrenal ganglion cells. Retrograde tracing from the transplants showed that they were innervated by preganglionic neurons that would normally have supplied postganglionic neurons of the superior cervical ganglion. The neurochemical phenotypes of preganglionic axons innervating transplanted chromaffin cells were compared with those innervating the normal adrenal medulla or superior cervical ganglion neurons. As in the normal adrenal gland, preganglionic nerve fibres apposing transplanted chromaffin cells were cholinergic. The peptide and calcium-binding protein content of preganglionic fibres was similar in normal and transplanted adrenal glands. In both cases, cholinergic fibres immunoreactive for enkephalin targeted adrenergic chromaffin cells, whilst cholinergic fibres with co-localised calretinin-immunoreactivity innervated noradrenergic chromaffin cells and adrenal ganglion cells. In contrast to the innervation of normal adrenal glands, these axons lacked immunoreactivity to nitric oxide synthase. In a set of control experiments, the superior cervical ganglion was subjected to preganglionic denervation in rat pups the same age as those that received adrenal transplants, and the ganglion was allowed to be re-innervated over the same time course as the adrenal transplants were studied. When the superior cervical ganglion was re-innervated by preganglionic nerve fibres, we observed that all aspects of chemical coding were restored, including cholinergic markers, nitric oxide synthase, enkephalin, calcitonin gene-related peptide and calcium binding proteins in predicted combinations, although the density of nerve fibres was always lower in re-innervated ganglia. These data show that the neurochemical phenotypes expressed by preganglionic neurons re-innervating adrenal chromaffin cells are selective and similar to those seen in the normal adrenal gland. Two explanations are advanced: either that contact of preganglionic axons with novel target cells has induced a switch in their neurochemical phenotypes, or that there has been target-selective reinnervation by pre-existing fibres of appropriate phenotype. Regardless of which of these alternatives is correct, the restoration of normal preganglionic codes to the superior cervical ganglion following denervation supports the idea that the target tissue influences the neurochemistry of innervating preganglionic neurons.

Therapy of nosocomial pneumonia

HAP remains a major cause of morbidity and mortality among hospitalized patients. Although early appropriate therapy results in improved outcomes, the cause of HAP frequently is not known at the time antimicrobial therapy is initiated. Most cases of HAP result from microaspiration of oropharyngeal secretions previously colonized with pathogenic bacteria, and the spectrum of potential pathogens is broad. Taking several factors into account can narrow this spectrum, including severity of illness, length of stay before the onset of pneumonia, and presence of risk factors for specific pathogens. When therapy has been initiated, follow-up of microbial studies and careful monitoring of the patient's course is important. The clinical improvement, even when therapy is appropriate, frequently takes days; therapy should not be changed for the first 2 to 3 days unless frank deterioration is noted. Patients who fail to respond or experience clinical deterioration should be re-examined carefully, and thought should be given to the possibility of other noninfectious processes.

Hygiene at winter bird feeders in a southwestern Ontario city

To further understand the source of the epidemic of salmonellosis in some species of birds using bird feeders in southern Ontario in the winter of 1997-1998, 124 bird feeder stations were examined for their state of hygiene and for Salmonella on 5 occasions during the winter of 1999 in a city of 100,000 people in southwestern Ontario. No Salmonella were isolated from feed contaminated with feces recovered from the feeders. Squirrel-proof feeders were significantly less contaminated with feces than were other feeder types (hopper, platform, silo), which did not differ significantly in their hygiene scores. Contamination of squirrel-proof feeders increased significantly through the course of the study, but other feeder types showed no significant change. Hygiene was poorer if feeders were maintained equally by both male and female household members, particularly as they grew older, but no age or gender effect was observed if only one person was largely responsible for maintaining the feeders. We concluded that winter bird feeder stations in a southern Ontario city were not contaminated with Salmonella but that bird feeder stations could be designed better to reduce fecal contamination of feed.

Treatment of hospital-acquired penumonia

Hospital-acquired pneumonia (HAP) remains a significant cause of morbidity and attributable mortality, especially among patients undergoing mechanical ventilation. The clinical approach to this disorder continues to evolve. Although our understanding of the epidemiology, risk factors, and pathogenesis of this disorder are expanding, consensus on diagnostic, therapeutic, and preventive strategies is lacking. Although outcome is significantly improved by the rapid introduction of appropriate antimicrobial therapy, presently available diagnostic tests rarely are able to identify a specific pathogen when antimicrobial choices are made. Thus, most therapy is by necessity empirical. The American Thoracic Society (ATS) published guidelines for the empiric treatment of HAP in 1996, this article reviews the recommendations of these guidelines and, if new information is available, updates these recommendations.

Practice guidelines for the management of patients with blastomycosis. Infectious Diseases Society of America

Guidelines for the treatment of blastomycosis are presented; these guidelines are the consensus opinion of an expert panel representing the National Institute of Allergy and Infectious Diseases Mycoses Study Group and the Infectious Diseases Society of America. The clinical spectrum of blastomycosis is varied, including asymptomatic infection, acute or chronic pneumonia, and extrapulmonary disease. Most patients with blastomycosis will require therapy. Spontaneous cures may occur in some immunocompetent individuals with acute pulmonary blastomycosis. Thus, in a case of disease limited to the lungs, cure may have occurred before the diagnosis is made and without treatment; such a patient should be followed up closely for evidence of disease progression or dissemination. In contrast, all patients who are immunocompromised, have progressive pulmonary disease, or have extrapulmonary disease must be treated. Treatment options include amphotericin B, ketoconazole, itraconazole, and fluconazole. Amphotericin B is the treatment of choice for patients who are immunocompromised, have life-threatening or central nervous system (CNS) disease, or for whom azole treatment has failed. In addition, amphotericin B is the only drug approved for treating blastomycosis in pregnant women. The azoles are an equally effective and less toxic alternative to amphotericin B for treating immunocompetent patients with mild to moderate pulmonary or extrapulmonary disease, excluding CNS disease. Although there are no comparative trials, itraconazole appears more efficacious than either ketoconazole or fluconazole. Thus, itraconazole is the initial treatment of choice for nonlife-threatening non-CNS blastomycosis.

Antimicrobial effects of lidocaine in bronchoalveolar lavage fluid

The antimicrobial activity of lidocaine in bronchoalveolar lavage fluid (BAL(f)) was investigated. Clinical respiratory isolates were added to BAL(f) suspensions containing lidocaine and to normal saline. The growth of two of four isolates of Streptococcus pneumoniae was significantly reduced in the presence of lidocaine-BAL(f) compared with controls in saline. Growth of Moraxella catarrhalis isolates was reduced in normal saline when compared with BAL(f) containing lidocaine. There was no effect upon the growth of Haemophilus influenzae, Pseudomonas aeruginosa and Candida albicans isolates. The recovery of isolates of S. pneumoniae may be reduced below the critical threshold of 10(5) cfu/mL during bronchoscopy when using lidocaine as a local anaesthetic.

Drug-resistant pathogens in community- and hospital-acquired pneumonia

Antimicrobial resistance has been a problem since the early days of the antibiotic era, but in recent years, this resistance has increased in the hospital and is being recognized more in the community setting. Respiratory pathogens such as S. pneumoniae and H. influenzae, for example, have developed resistance to traditional antimicrobial therapy, often over a very short period of time. This increase in resistance patterns requires physicians to closely monitor antimicrobial resistance in their community and to appreciate that some antimicrobial resistance mechanisms may result in resistance for a complete class of antibiotics or different classes of antibiotics with similar mechanisms of action.

The role of antimicrobial therapy in acute exacerbations of chronic bronchitis

Acute exacerbations of chronic bronchitis (AECB) result in increased morbidity and mortality. The role of bacteria in AECB, the importance of antimicrobial therapy, and the choice of antimicrobial agents have been debated for decades. Fortunately, within the past few years, a number of studies and one consensus statement have been reported that have increased the understanding of the role of bacteria in AECB and suggest approaches in selecting antimicrobial therapy. This article will review these studies and present an empiric approach in treating AECB based upon the patient's presenting findings, related risk factors, and potential antimicrobial resistance patterns that may be encountered.

Commentary on the 1993 American Thoracic Society guidelines for the treatment of community-acquired pneumonia

Early treatment of community-acquired pneumonia (CAP) is associated with improved outcome. Since extensive diagnostic testing identifies an etiologic agent in only half of the cases and usually requires several hours or even days for results, CAP is most often initially treated empirically. In 1993, the American Thoracic Society (ATS) established guidelines to assist primary care physicians in antibiotic selection for the initial empiric treatment of CAP in immunocompetent adults. Since publication of the guidelines, the incidence of certain bacteria has been redefined, antimicrobial resistance patterns have changed, risk factors for stratifying need for hospitalization have been further defined, and newer antibiotics have been introduced. These changes necessitate a reevaluation of the 1993 ATS guidelines. This article proposes a modification of the ATS guidelines. This modification continues to classify patients into groups, based on specific risk factors, to which a limited number of likely pathogens are identified and for which antibiotic treatment regimens are developed. The modification differs from the original ATS guidelines because of the changes in risk factors. Patient groups are still broadly divided into outpatient and inpatient care, but earlier risk factors of age and coexisting illness have been refined. Risk factors suggested herein as considerations to guide treatment include the presence of cardiopulmonary disease, history of smoking, severity of illness, risk of drug-resistant Streptococcus pneumoniae and Pseudomonas aeruginosa, and need for ICU admission.

Health of tree swallows (Tachycineta bicolor) nesting in pesticide-sprayed apple orchards in Ontario, Canada. I. Immunological parameters

The degree of pesticide exposure and its effects on the immune system and its development were determined in 16-d-old tree swallow (Tachycineta bicolor) chicks from 4 sprayed apple orchards and three nonsprayed sites in southern Ontario, Canada, during 1994-1995. Persistent contaminant residues were measured in tree swallow eggs and in each chick hepatic ethoxyresorufin O-deethylase (EROD) activity; body, immune organ, and liver masses; lymphocyte blastogenesis response; respiratory burst and phagocytic responses; hemarological evaluation; and histological development of thymus, bursa of fabricius, and spleen were determined. Chemicals sprayed on apple orchards were mainly ethylene bisdithiocarbamate and myclobutanil fungicides and organophosphorus, carbamate, and synthetic pyrethroid insecticides. During the period between oviposition of the first egg in each nest to d 16 after hatching, individual nests in orchards were exposed to between 4 and 11 individual chemical applications and up to 3 mixtures of pesticide sprays. Concentrations of pesticides, polychlorinated biphenyls (PCBs), and lead and arsenic residues in tree swallow eggs and liver were low and not variable among sites except p,p'-DDE, which was as high as 2.29 microg/g wet weight in eggs. EROD activity was not different among sites. Organochlorine and trace metal residues and EROD activity were not correlated with any immune parameter. In sprayed birds, we found a significantly increased blastogenic response to pokeweed mitogen (12.5 microg/ml). However, nests were initiated over a period of several weeks and we also found changes in other tree swallow immune parameters that were related to the date of chick collection. Hematological parameters, bursal and thymic masses, phagocytic response, and thymic development were all correlated with the day the chicks were 16 d of age. After accounting for the collection date of birds from each nest, we found cell proliferation in the cortex and delayed thymic involution correlated positively with increasing spray exposure. We also found that birds in sprayed orchards were slightly anemic compared to birds from nonsprayed sites, and there were smaller bursal masses and an increase in relative heterophil concentrations in the sprayed orchard birds. The local inflammation may have been caused by trematode parasite infections, although pesticide exposure also correlated positively with these parameters. This is the first study of the immunology and effects of current pesticide exposures in wild passerines; therefore it is difficult to predict the long-term consequences of the apparent stimulated immune systems in sprayed birds. However, some environmental contaminants that overtly stimulate the immune system in mammals have induced hypersensitivity and/or autoimmunity. Therefore we speculate that these effects are possible in tree swallows.

All-D peptides recognized by an anti-carbohydrate antibody identified from a positional scanning library

Monoclonal antibodies recognize antigens with high affinity and specificity, but the structural basis for molecular mimicry remains unclear. It is often assumed that cross-reactive antigens share some structural similarity that is specifically recognized by a monoclonal antibody. Recent studies using combinatorial libraries, which are composed of millions of sequences, have examined antibody cross-reactivity in a manner entirely different from traditional epitope mapping approaches. Here, peptide libraries were screened against an anti-carbohydrate monoclonal antibody for the identification of peptide mimics. Positional scanning libraries composed of all-l or all-d hexapeptides were screened for inhibition of monoclonal antibody HGAC 39.G3 binding to an antigen displaying N-acetyl-d-glucosamine (GlcNAc) residues on a polyrhamnose backbone. Inhibitory activity by mixtures from the all-d hexapeptide library was greater than the activity from the all-l libraries. The most active d-amino acid residues defined in each of the six positions of the library were selected to prepare 27 different individual hexapeptides. The sequence Ac-yryygl-NH2 was specifically recognized by mAb HGAC 39.G3 with a relative affinity of 300 nM when measured in a competitive binding assay. The contributions to overall specificity of the residues of the all-d peptide (Ac-yryygl-NH2) in binding to mAb HGAC 39.G3 were examined with a series of truncation, l and d-amino acid substitution, and retro analogs. Dimeric forms of the all-d peptide were recognized with tenfold to 100-fold greater affinities relative to the monomer. The all-d peptide was found to inhibit mAb HGAC 39.G3 binding to an anti-idiotype antibody with approximately 1000-fold greater affinity than GlcNAc. As demonstrated here, the study of immune recognition using combinatorial chemistry may offer new insights into the molecular basis of cross-reactivity.

Characterization of antigen-antibody interactions using single substitution analogs and mixture-based synthetic combinatorial libraries

In an effort to use monoclonal antibodies (mAbs) as selective probes for early detection of breast cancer, the specificities of a number of antipeptide mAbs have been studied at the individual amino acid level using single substitution peptide analogs and peptide combinatorial libraries. In this study, the mapping results are presented for mAb172-12A4, which was raised against the haptenic peptide LGSGAFGTIYKG(C), corresponding to residues 138-149 of the oncogene v-erbB. This peptide is homologous with a region in epidermal growth factor receptor (EGFR) and human oncogene c-erbB-2, and contains the ATP binding motif that is common among protein kinases. The substitution profile of this interaction correlated well with the results from the screening of hexa- and decapeptide positional scanning libraries. Based on the results of this mAb's specificity for the antigenic determinant (-AFGTIYK-), proteins that have sequence homology were found from a database search of human sequences. Thirty-two unique peptide sequences, a majority of which was from protein kinases, were synthesized and tested for recognition by mAb 172-12A4. Eleven peptides had activities that differed from the original peptide by less than an order of magnitude, and the activities for 29 of the 32 (90%) could be accurately predicted based on the individual substitution analog results. While both epitope mapping approaches address the amino acid level of mAb specificity, positional scanning libraries offer an advantage of identifying the positional importance of each antigenic determinant residue without any prior knowledge of the mAb's specificity. The fine specificity mapping of peptide-specific mAbs using the synthetic tools illustrated here will be useful for the development of immunodiagnostics that detect cancer-related proteins in clinical samples.

Hospital-acquired pneumonia: epidemiology, etiology, and treatment

Despite improvements in diagnosis, treatment, and prevention, hospital-acquired pneumonia (HAP) remains the number one cause of nosocomial mortality. This article reviews the current knowledge regarding the incidence, epidemiology, and causes of HAP, with the appreciation that the available information is incomplete and that controversies are common, and thus the authors provide a rational approach to the initial management of HAP in immunocompetent adults. A discussion of therapy and what to do with patients who do not respond to the empiric therapy are included. The American Thoracic Society (ATS) statement on HAP has served as a foundation for this review but has been supplemented by newer literature that was not available when the ATS statement was developed.

Hospital-acquired pneumonia: recent advances in diagnosis, microbiology and treatment

Nosocomial or hospital-acquired pneumonia occurs frequently, despite preventative measures and advances in diagnostic procedures and treatment of this severe infection. This article will highlight the recent literature with emphasis on significant publications and advances in the area of pneumonia pathogenesis, microbiology, diagnosis, and response to antimicrobial therapy.

Drug-resistant Streptococcus pneumoniae

Streptococcus pneumoniae remains a major cause of infection in both children and adults, annually resulting in significant morbidity and mortality. The past two decades have seen an alarming worldwide increase in the incidence of drug-resistant S. pneumoniae (DRSP). DRSP is now common throughout the United States, and physicians are questioning how best to approach this epidemic. With the introduction of a number of newer antimicrobial agents, the potential for improved preventive measures, and a better understanding of DRSP, the approach to the management of DRSP infections may change greatly in the next few years. In this article we will review the development of DRSP, identify populations at increased risk of exposure to DRSP, address what approaches might be used to limit its spread, and suggest initial empirical therapy when treating patients with pneumonia due to DRSP.

Hospital-acquired pneumonia: recent advances in diagnosis, microbiology and treatment

Nosocomial or hospital-acquired pneumonia occurs frequently, despite preventative measures and advances in diagnostic procedures and treatment of this severe infection. This article will highlight the recent literature with emphasis on significant publications and advances in the area of pneumonia pathogenesis, microbiology, diagnosis, and response to antimicrobial therapy.

Nosocomial pneumonia guidelines: an international perspective

Hospital-acquired pneumonia is a serious illness with substantial morbidity and mortality. Management of this illness is challenging for the physician and a number of diverse issues must be considered when initiating therapy. Guidelines for the treatment of hospital-acquired pneumonia have been developed in Canada and the United States. A questionnaire sent to infectious disease physicians or clinical microbiologists in 29 countries showed that Australia, Sweden, and France had national guidelines in addition to Canada and the United States, while Hong Kong and France had single hospital-based guidelines. These guidelines are reviewed and some of the controversial issues relating to nosocomial pneumonia are discussed.

Limitations of diagnostic testing in the initial management of patients with community-acquired pneumonia

Community-acquired pneumonia (CAP) remains a major cause of morbidity and mortality in the United States. The ideal of a simple diagnostic evaluation yielding a specific etiologic diagnosis allowing directed antimicrobial therapy remains elusive. Empiric therapy is justified as initial management, as the specific bacteriological etiology of most cases of CAP is usually unknown, and delaying therapy while attempting to find a diagnosis may be injurious to the patient. Guidelines have been developed to assist in the recognition and evaluation of CAP based on age and underlying medical illness as predictors of outcome. While these criteria are by no means perfect and cannot be applied to every individual, they offer a rational approach to the initial management of the patient.

Duration of Borrelia burgdorferi infectivity in white-footed mice for the tick vector Ixodes scapularis under laboratory and field conditions in Ontario

The duration of Borrelia burgdorferi infectivity in white-footed mice (Peromyscus leucopus) experimentally inoculated or infested with infected Ixodes scapularis nymphs was evaluated. Infectivity was assessed by infesting these mice with unfed I. scapularis larvae at 7, 21, 35 and 49 days post-inoculation (DPI) or post-infestation (PI). At 7 DPI, B. burgdorferi was transmitted from 18 of 24 syringe-inoculated mice and all three tick-infected mice to I. scapularis larvae which fed upon them. However, at 21, 35 and 49 DPI, significantly fewer mice were infective. Borrelia burgdorferi was isolated from tissues of 14 of 22 syringe-inoculated mice about 56 DPI, and from all three tick-infected mice. However, the level of agreement between xenodiagnosis and bacterial culture was no greater than would be expected by chance alone. We also determined if B. burgdorferi infectivity of mice varied in relation to periods of tick feeding in the field. White-footed mice were trapped during April, July and August 1993 from two habitats on Long Point peninsula (Ontario, Canada), where B. burgdorferi is endemic. Mice from each habitat were infested with laboratory-reared I. scapularis larvae. Ticks from each mouse were subsequently examined by immunofluorescent assay for B. burgdorferi infection and mice were cultured for B. burgdorferi. None of 3577 I. scapularis larvae fed on 62 mice captured within the cottonwood dune habitat were infected with B. burgdorferi, although it was isolated from six of these mice. Within the maple forest habitat, 0/24, 8/21 (38%) and 1/21 (5%) mice transmitted B. burgdorferi to I. scapularis larvae during April, July and August, respectively. Most mice from the maple forest with B. burgdorferi-positive tissues (14/21) were collected during July, although the level of agreement between xenodiagnosis and tissue culture was poor. Because B. burgdorferi infectivity in mice appears to be of short duration, overwintered I. scapularis larvae and nymphs may have to feed upon infected hosts at the same time of year in order for a cycle of B. burgdorferi infection to be maintained on Long Point. Infected I. scapularis nymphs, rather than persistently infected vertebrate hosts, likely serve as the overwintering "reservoir" for B. burgdorferi on Long Point.

Diagnosis of blastomycosis

During the 100 years since Blastomyces dermatitidis was discovered as a cause of human disease, diagnostic tests, methods of collection of specimens, and laboratory techniques have improved significantly. Radiographic advances and the introduction of the fiberoptic bronchoscopy have allowed for more reliable clinical diagnoses. More sensitive serologic techniques and DNA probes have significantly improved the sensitivity of laboratory diagnosis. At present, the most reliable serologic tests are the sandwich enzyme immunoassay (sensitivity 88%, specificity 100%) and the 120-kd antigen radioimmunoassay (sensitivity 85%, specificity 100%). When positive and negative predictive values are applied, the sandwich enzyme immunoassay appears to be the most accurate. At the present time, a negative serologic test cannot be used to exclude blastomycosis. Further advances in refining the B dermatitidis antigen(s) for use in the newer, more sensitive, and specific assay techniques may allow for a definitive serologic diagnosis in the future, avoiding the necessity for invasive tests.

Treatment of blastomycosis with higher doses of fluconazole. The National Institute of Allergy and Infectious Diseases Mycoses Study Group

Recent clinical data suggest that fluconazole at daily doses of 200 to 400 mg for at least 6 months is moderately effective therapy for non-life-threatening blastomycosis. To examine the usefulness of higher doses of fluconazole therapy for this disorder, we conducted a multicenter, randomized, open-label study to determine the efficacy and safety of two different daily doses of fluconazole (400 and 800 mg) in the treatment of non-life-threatening blastomycosis. Of 39 patients evaluable for efficacy analysis, 34 (87%) were successfully treated, including 89% and 85% of patients who received 400 and 800 mg, respectively. Five (83%) of six patients for whom prior antifungal therapy had failed were successfully treated. The mean duration of therapy was 8.9 months for successfully treated patients. Nineteen patients (48%) reported adverse events, although most were minor. We conclude that fluconazole at daily doses of 400 to 800 mg for at least 6 months is effective therapy for non-life-threatening blastomycosis.

Intrapulmonary pharmacokinetics of azithromycin in healthy volunteers given five oral doses

The intrapulmonary pharmacokinetics of oral azithromycin were studied in 25 healthy volunteers, each of whom received an initial dose of 500 mg and then 250 mg once daily for four additional doses. Bronchoscopy, bronchoalveolar lavage, and venipuncture were performed 4, 28, 76, 124, 172, 244, 340, and 508 h after the first dose was administered. Azithromycin concentrations in epithelial lining fluid (ELF), alveolar macrophages, peripheral blood monocytes, and serum were measured by high-performance liquid chromatography. Azithromycin was extensively concentrated in cells and ELF. Drug concentrations in AMs (peak mean +/- standard deviation, 464 +/- 65 micrograms/ml) exceeded 80 micrograms/ml up to 508 h (21 days) following the first dose, while concentrations in PBMs (peak, 124 +/- 28 micrograms/ml) exceeded 20 micrograms/ml up to 340 h (14 days). Azithromycin concentrations in ELF peaked at 124 h (3.12 +/- 0.93 micrograms/ml) and were detectable up to 172 h (7 days), when they were 20 times the concurrent serum concentrations. Although the clinical significance of antibiotic concentrations in these compartments is nuclear, the sustained lung tissue penetration and extensive phagocytic accumulation demonstrated in this study support the proven efficacy of azithromycin administered on a 5-day dosage schedule in the treatment of extracellular or intracellular pulmonary infections.

Nosocomial pneumonia

Nosocomial pneumonia remains a major cause of morbidity, mortality, and significant hospital cost despite continued refinements in antimicrobial treatment, improved methods for diagnosis, and better supportive and preventive measures. While clinical experience is considerable, appreciation of the epidemiologic and pathogenic factors responsible for NP development and pathogen selection are limited, and consensus regarding optimal prevention and diagnostic and therapeutic strategies is lacking. This article reviews the recent literature with an emphasis on significance, pathogenesis, etiology, and therapy of nosocomial pneumonia.

Anion gap in turpentine-induced pleural effusions. Correlation with pH and protein level

Since the pleural fluid proteins and lactate are unmeasured anions, the pleural fluid anion gap (Na+K-Cl-total CO2) should vary with the protein level and should be high in acidic effusions (which have high lactate levels). The anion gap is also convenient and inexpensive to measure, and less subject to artifact than the pH measurement. To test the hypothesis that the anion gap correlates with the pH, protein level, and other traditional pleural fluid measurements, we used a well-described model of turpentine-induced effusions in nine New Zealand white rabbits. Nonacidic exudative effusions were induced by an intrapleural injection of turpentine; acidic exudative effusions were induced by a second injection. Pleural fluid and blood were obtained just before (0 h) and 9, 24, 48, and 72 h after the second injection. We found the anion gap correlated with pH, the glucose, protein, and lactate dehydrogenase levels, pleural-fluid/plasma protein and lactate dehydrogenase ratios, and WBC count (all p < 0.001). The pH and protein ratio together accounted for 95% of all anion gap variation within individual subjects. We also found the influence of the PCO2 level on pH was not significant after taking into account the influence of the anion gap. These results suggest the anion gap may be useful in the clinical evaluation of pleural effusions and could potentially replace the pH measurement.

Nosocomial pneumonia in the noncritical care setting

The optimal approach to the recognition, management, and prevention of nosocomial pneumonia is evolving. A broad spectrum of potential pathogens is recognized in the hospital setting, and more invasive procedures have been developed in attempts to improve diagnostic accuracy. Newer, broad spectrum antimicrobial agents are continually introduced, yet the presence of resistant organisms is increasingly recognized. The reports released in the past year show physicians are making advances toward gaining a better understanding of this common infection.

Nosocomial viral pneumonia in the intensive care unit

The role viruses play in nosocomial ICU pneumonias is not well documented except for outbreaks of influenza and respiratory syncytial virus (RSV) infections. Clinically, viral pneumonias are difficult to differentiate from bacterial pneumonias, and most routine diagnostic tests are able to diagnose viral pathogens. Therefore, the incidence of viral pneumonias is almost certainly underestimated. The likelihood of a viral pneumonia is increased if the patient is not responding to antimicrobial agents, if pneumonia occurs during the winter months, or if there is evidence of viral outbreaks in the hospital or community. In the past few years, new diagnostic tests and a number of effective antiviral agents have been introduced; this makes the rapid diagnosis and treatment of viral pneumonia possible.

Overview of community-acquired pneumonia. Prognosis and clinical features

Despite the introduction of newer antibiotics, vaccinations, and better supportive care, CAP remains a common, frequently fatal disease. Age and coexisting illness influence which infectious agents are most likely to cause infection. Severity of illness and clinical features are influenced by various host factors and by the virulence of the infectious agent. Mortality and morbidity are reduced by the rapid institution of appropriate antimicrobial therapy. Because of the limitations of presently available diagnostic tests, many patients are begun on empiric regimens, and in up to half of these individuals, a cause is not identified. Although there are a number of potential pathogens, it is possible to identify likely pathogens based on easily identifiable clinical factors (age, presence of coexisting disease, severity of illness at presentation, and the need for hospitalization). Using this approach, CAP in immunocompetent adults may be divided into four categories. Once empiric therapy has been initiated, therapy should be continued for at least 72 hours unless clinical deterioration is noted. Within 4 days, fever and leukocytosis should return to baseline, but abnormal physical findings (i.e., crackles) require longer to resolve, especially with coexisting illness, and chest radiographic findings are the last to return to baseline and are especially delayed if the patient is bacteremic or has structural lung disease. Not all patients respond to initial empiric therapy. Reasons for this include antimicrobial resistance, the presence of nonbacterial pathogens (respiratory viruses), unusual bacterial pathogens, noninfectious causes that may mimic CAP, infectious complications (i.e., empyema), and pneumonia occurring in patients with unrecognized severe immunosuppression. Failure to improve after 72 hours and development of deterioration are indications for repeat diagnostic workup and consideration of alternative diagnoses. More invasive diagnostic tests are appropriate in severely ill patients and in those whose condition is deteriorating rapidly.

Antinuclear antibodies in pleural fluid

Systemic lupus erythematosus (SLE) frequently involves the pleura with resultant pleural effusion. Previous studies have reported that detection of antinuclear antibodies (ANA) in pleural fluid using animal tissue as substrate was a sensitive and specific method for distinguishing SLE pleural effusions from other etiologies. The HEp-2 ANA, which uses a human cell line as substrate, is now the preferred ANA test; however, to our knowledge, no studies on pleural fluid using this assay have been reported. To determine its sensitivity and specificity, when measured in pleural fluid, HEp-2 ANA levels were determined in pleural effusion samples associated with a variety of different etiologies, including SLE, malignancy, congestive heart failure, pneumonia, tuberculosis, and a miscellaneous group of diseases. Pleural fluid ANA results were positive in 14 of 82 samples. Six of the eight (75 percent) pleural fluid samples collected from patients with SLE were ANA positive, and all but one had high titers (> 1:160) with a homogenous staining pattern. The remaining two patients with SLE with negative pleural fluid ANA had recurrent pulmonary emboli and congestive heart failure, rather than lupus pleuritis. Eight of 74 patients (10.8 percent) without clinical evidence of SLE had a positive pleural fluid ANA, with the majority having a speckled pattern. High titers were noted in three. These results indicate that a negative or low titer ANA and a speckled staining pattern in pleural fluid from a patient suspected of lupus pleuritis suggest an alternative diagnosis. High pleural fluid titers (up to 1:640) were seen occasionally in patients with inflammatory pleural effusions in the absence of SLE.

Erysipelothrix rhusiopathiae, serotype 17, septicemia in moose (Alces alces) from Algonquin park, Ontario

Erysipelothrix rhusiopathiae septicemia was diagnosed in three of four moose found dead in Algonquin Provincial Park, Ontario, Canada, in the spring of 1989. Type 17 E. rhusiopathiae was isolated from liver, lung, kidney, and lymph nodes of affected animals, which were in poor body condition, and suffering hair loss associated with tick (Dermacentor albipictus) infestations. Microscopic lesions consisted of mild, multifocal, necrotizing myocarditis, sarcocystosis, and lymph node atrophy. The bacterium may have gained entry to these animals via ingestion of, or percutaneous exposure to, contaminated water, or possibly by the bites of ticks. Malnutrition and tick infestation may have predisposed the animals to infection by this opportunistic pathogen.

Response of the meadow vole (Microtus pennsylvanicus) to experimental inoculation with Borrelia burgdorferi

The response of the meadow vole (Microtus pennsylvanicus) to infection by experimental inoculation with Borrelia burgdorferi was evaluated. Forty-two adult voles were inoculated subcutaneously with 0.5 x 10(6) spirochetes. Sera taken during the 196 day trial were tested by indirect fluorescent antibody (IFA) assay for antibodies to B. burgdorferi. Tissues from animals which died during the trial, and from animals killed at 28, 112 and 196 days post-inoculation (DPI), respectively, were cultured in BSK-II medium for < or = 6 weeks. They also were examined histologically for lesions and the presence of spirochetes. All inoculated animals developed antibodies by 14 DPI and maintained titers > or = 1:10 for the duration of the trial. Spirochetes were isolated from ears, bladder, and spleen. Spirochetes also were identified by Bosma-Steiner silver stain or tissue IFA assay in sections of ears, bladder, kidney and heart. Infection as confirmed by re-isolation persisted for < or = 111 days. No lesions were identified in association with the presence of spirochetes. No increase in mortality was observed in inoculated animals compared with controls. Sensitivity of the IFA test at a cut-off titer of 1:10 was 100% from > or = 14 DPI, but at 1:20 reached a maximum of 97%. Specificity at 1:10 was 84% and at 1:20 was 97%. Use of antiserum to Microtus immunoglobulin (Ig) in a double-layered test provided no significant advantages over use of a commercial fluorescein-conjugated anti-mouse Ig in a single-layered IFA test.

Preservation of pulmonary function by an outer membrane protein F vaccine. A study in rats with chronic pulmonary infection caused by Pseudomonas aeruginosa

This study investigated the ability of a protein F vaccine to reduce macroscopic evidence of lung damage and preserve pulmonary function in immunized animals in a rat model of chronic pulmonary infection caused by Pseudomonas aeruginosa. Other membrane protein F of P aeruginosa was purified by extraction from polyacrylamide gels of cell envelope proteins of the PAO1 immunotype 7 strain. Rats were immunized intramuscularly with either 25 micrograms of the purified protein F or bovine serum albumin on days 0 and 14 and then challenged on day 28 via intratracheal inoculation of agar beads containing cells of an immunotype 3 clinical isolate of P aeruginosa. Also, included was a noninfected control group which received only sterile agar beads. On day 35, the lungs were excised, pulmonary compliance measured, and the lungs examined macroscopically for the presence and severity of lesions. The protein F-immunized rats had a significant (p < 0.01) reduction in the number of severe pulmonary lesions as compared with bovine serum albumin-immunized rats. Lung compliance (CL) was significantly (p < 0.001) reduced in rats which were immunized with bovine serum albumin (n = 17, CL = 0.12 +/- 0.008), whereas CL of protein F-immunized rats (n = 12, CL = 0.17 +/- 0.006) was similar to that of noninfected control rats (n = 5, CL = 0.15 +/- 0.008). This study demonstrated that a protein F vaccine has the ability to decrease macroscopic lung lesions from infection and preserve pulmonary function in actively immunized rats upon subsequent challenge with P aeruginosa in this model of chronic lung infection.

Community-acquired pneumonia: new outpatient guidelines based on age, severity of illness

Pneumonia is a common and important infectious disease in all age groups but especially in the elderly. Mortality and morbidity are quite high when associated with certain risk factors such as comorbid medical conditions and clinical features that implicate more severe disease. In the absence of such features, patients can be treated quite safely out of the hospital, as long as followup and compliance issues are not a problem. Therapy should be directed toward gram-positive and gram-negative aerobic bacteria and, at times, be further expanded to cover atypical organisms such as Legionella sp. Appropriate antimicrobial agents are those that not only cover expected microorganisms but are compatible with each patient's existing medical regimen.