Viral Pneumonia

Pediatric human nose organoids demonstrate greater susceptibility, epithelial responses, and cytotoxicity than adults during RSV infection

Respiratory syncytial virus (RSV) is a common cause of respiratory infections, causing significant morbidity and mortality, especially in young children. Why RSV infection in children is more severe as compared to healthy adults is not fully understood. In the present study, we infect both pediatric and adult human nose organoid-air liquid interface (HNO-ALIs) cell lines with two contemporary RSV isolates and demonstrate how they differ in virus replication, induction of the epithelial cytokine response, cell injury, and remodeling. Pediatric HNO-ALIs were more susceptible to early RSV replication, elicited a greater overall cytokine response, demonstrated enhanced mucous production, and manifested greater cellular damage compared to their adult counterparts. Adult HNO-ALIs displayed enhanced mucus production and robust cytokine response that was well controlled by superior regulatory cytokine response and possibly resulted in lower cellular damage than in pediatric lines. Taken together, our data suggest substantial differences in how pediatric and adult upper respiratory tract epithelium responds to RSV infection. These differences in epithelial cellular response can lead to poor mucociliary clearance and predispose infants to a worse respiratory outcome of RSV infection.

Asthma and COVID-19: Emphasis on Adequate Asthma Control

Asthmatics are at an increased risk of developing exacerbations after being infected by respiratory viruses such as influenza virus, parainfluenza virus, and human and severe acute respiratory syndrome coronaviruses (SARS-CoV). Asthma, especially when poorly controlled, is an independent risk factor for developing pneumonia. A subset of asthmatics can have significant defects in their innate, humoral, and cell-mediated immunity arms, which may explain the increased susceptibility to infections. Adequate asthma control is associated with a significant decrease in episodes of exacerbation. Because of their wide availability and potency to promote adequate asthma control, glucocorticoids, especially inhaled ones, are the cornerstone of asthma management. The current COVID-19 pandemic affects millions of people worldwide and possesses mortality several times that of seasonal influenza; therefore, it is necessary to revisit this subject. The pathogenesis of SARS-CoV-2, the virus that causes COVID-19, can potentiate the development of acute asthmatic exacerbation with the potential to worsen the state of chronic airway inflammation. The relationship is evident from several studies that show asthmatics experiencing a more adverse clinical course of SARS-CoV-2 infection than nonasthmatics. Recent studies show that dexamethasone, a potent glucocorticoid, and other inhaled corticosteroids significantly reduce morbidity and mortality among hospitalized COVID-19 patients. Hence, while we are waiting for more studies with higher level of evidence that further narrate the association between COVID-19 and asthma, we advise clinicians to try to achieve adequate disease control in asthmatics as it may reduce incidences and severity of exacerbations especially from SARS-CoV-2 infection.

Successful Treatment of Severe Parainfluenza Pneumonia in a Liver Transplant Recipient with Oral Ribavirin and Intravenous Immunoglobulin

: The most common viruses affecting immunocompromised hosts include cytomegalovirus, herpes simplex virus, varicella-zoster virus, influenza virus, measles virus, and adenovirus. Parainfluenza virus infection is common among human populations. It causes non-specific symptoms in immune-competent hosts; therefore, it may go undiagnosed. However, it is particularly dangerous for immunocompromised patients by presenting a high risk of morbidity and sometimes mortality among them. Patients who have bone marrow or solid organ transplantation need to follow an intense immunosuppressing routine, which leaves them extremely vulnerable to opportunistic agents such as parainfluenza viruses. Several factors determine the severity of parainfluenza virus infections, such as the type of the virus, the level of immunosuppression, and co-infection with other agents. Co-infection is especially important because it makes a correct differential diagnosis difficult. While almost all bodies of influenza infection information in immunocompromised patients are from studies of bone marrow transplant recipients, there are very limited data available on influenza infections in liver transplant patients. We present a liver transplant patient with severe parainfluenza pneumonia that was improved significantly with oral ribavirin and intravenous immunoglobulin. A 23-year-old female patient with a history of liver transplantation from 18 months ago presented with a one-week cough and tachypnea. Chest computed tomography demonstrated ground-glass opacities and diffuse infiltrates throughout both lungs. A multiplex polymerase chain reaction for the detection of respiratory viruses in the nasopharynx was positive for parainfluenza virus type 3 and she was successfully treated with oral ribavirin and intravenous immunoglobulin. Respiratory infection with the parainfluenza virus in immunocompromised adults, including transplant patients, is associated with significant morbidity and mortality, and early treatment with ribavirin and intravenous immunoglobulin may markedly improve their outcomes. To the best of our knowledge, this is the first case report of the successful treatment of parainfluenza infection with ribavirin and intravenous immunoglobulin in a patient with liver transplantation.

Pulmonary measles disease: old and new imaging tools

BACKGROUND

Measles virus can cause lower respiratory tract infection, so that chest radiography is necessary to investigate lung involvement in patients with respiratory distress.

PURPOSE

To assess measles pneumonia imaging during the measles outbreak occurred in 2016-2017 in Italy.

MATERIAL AND METHODS

We retrospectively observed adult patients with a serological diagnosis of measles, who underwent chest-X rays for suspected pneumonia. If a normal radiography resulted, the patient underwent unenhanced CT. A CT post processing software package was used for an additional quantitative lung and airway involvement analysis .

RESULTS

Among 290 patients affected by measles, 150 underwent chest-X ray. Traditional imaging allowed the pneumonia diagnosis in 114 patients (76%). The most frequent abnormality at chest X-rays was bronchial wall thickening, observed in 88.5% of the cases; radiological findings are faint in the 25% of the cases (29/114 patients). In nine subjects with a normal chest X-ray, unenhanced CT with a quantitative analysis was performed, and depicted features consistent with constrictive bronchiolitis.

CONCLUSION

Measles may produce bronchiolitis and pneumonia. In the cases in which involvement of pulmonary parenchyma is not sufficient to result in radiological abnormalities, CT used with a dedicated postprocessing software package, provides an accurate lungs and airways analysis, also determining the percentage of lung involvement.

How to approach and treat viral infections in ICU patients

Patients with severe viral infections are often hospitalized in intensive care units (ICUs) and recent studies underline the frequency of viral detection in ICU patients. Viral infections in the ICU often involve the respiratory or the central nervous system and can cause significant morbidity and mortality especially in immunocompromised patients. The mainstay of therapy of viral infections is supportive care and antiviral therapy when available. Increased understanding of the molecular mechanisms of viral infection has provided great potential for the discovery of new antiviral agents that target viral proteins or host proteins that regulate immunity and are involved in the viral life cycle. These novel treatments need to be further validated in animal and human randomized controlled studies.

Findings in children severely infected with a novel influenza A virus of swine origin: pulmonary imaging

BACKGROUND

This article reviews the chest radiography of children with severe infection caused by a novel influenza A (H1N1) virus of swine origin (S-OIV). We analyzed the role of their pulmonary images in predicting the severity and diagnosis of the disease.

METHODS

Among 97 patients with confirmed novel H1N1 infection, 42 patients treated with mechanical ventilation formed group 1, and the remaining 55 patients constituted group 2. The initial and subsequent radiograhic findings in groups 1 and 2 were compared with respect to the pattern, distribution, and extent of the abnormality.

RESULTS

In group 1, 24 patients presented with three or more lung zone diseases, whereas only 5 patients in group 2 demonstrated these findings (P<0.001). A pneumomediastinum or pneumothorax was observed in 24/42 patients in group 1 and in 18/55 patients in group 2 (P=0.019). Twelve patients in group 1 and 5 in group 2 developed a ground-glass opacity cyst with a honeycomb appearance (P=0.007).

CONCLUSIONS

The most common radiographic and computed tomography findings in children who were severely infected with S-OIV included unilateral or bilateral ground-glass opacities with or without associated focal or multifocal areas of consolidation. Children with bilateral involvement or with greater opacity on the chest radiographs were more likely to worsen and require the mechanical ventilation.

Pandemic 2009 influenza A(H1N1) virus infection coinciding with invasive pulmonary aspergillosis in neutropenic patients

In patients receiving anti-neoplastic chemotherapy, the impact of influenza on the incidence of invasive pulmonary aspergillosis (IPA) remains unknown. We matched data of the Cologne Cohort of Neutropenic Patients (CoCoNut) with records from the Institute for Virology and compared the findings to historical data. During the pandemic, we diagnosed influenza A(H1N1) in five patients with malignancies and febrile neutropenia refractory to antibiotic therapy. Probable IPA was diagnosed in three of these patients on the grounds of typical computed tomography morphology and microbiological results. Three of five patients receiving remission-induction chemotherapy for acute myeloid leukaemia developed aspergillosis although receiving posaconazole prophylaxis. In the 3 years before the influenza pandemic, only 2/77 patients of this group developed infection. Infection with influenza A(H1N1) may increase the risk for invasive aspergillosis in neutropenic patients. Pulmonary aspergillosis is an important additional differential diagnosis in neutropenic influenza patients with pneumonia.

Distinguishing characteristics between pandemic 2009-2010 influenza A (H1N1) and other viruses in patients hospitalized with respiratory illness

Background

Differences in clinical presentation and outcomes among patients infected with pandemic 2009 influenza A H1N1 (pH1N1) compared to other respiratory viruses have not been fully elucidated.

Methodology/Principal Findings

A retrospective study was performed of all hospitalized patients at the peak of the pH1N1 season in whom a single respiratory virus was detected by a molecular assay targeting 18 viruses/subtypes (RVP, Luminex xTAG). Fifty-two percent (615/1192) of patients from October, 2009 to December, 2009 had a single respiratory virus (291 pH1N1; 207 rhinovirus; 45 RSV A/B; 37 parainfluenza; 27 adenovirus; 6 coronavirus; and 2 metapneumovirus). No seasonal influenza A or B was detected. Individuals with pH1N1, compared to other viruses, were more likely to present with fever (92% & 70%), cough (92% & 86%), sore throat (32% & 16%), nausea (31% & 8%), vomiting (39% & 30%), abdominal pain (14% & 7%), and a lower white blood count (8,500/L & 13,600/L, all p-values<0.05). In patients with cough and gastrointestinal complaints, the presence of subjective fever/chills independently raised the likelihood of pH1N1 (OR 10). Fifty-five percent (336/615) of our cohort received antibacterial agents, 63% (385/615) received oseltamivir, and 41% (252/615) received steroids. The mortality rate of our cohort was 1% (7/615) and was higher in individuals with pH1N1 compared to other viruses (2.1% & 0.3%, respectively; p = 0.04).

Conclusions/Significance

During the peak pandemic 2009–2010 influenza season in Rhode Island, nearly half of patients admitted with influenza-like symptoms had respiratory viruses other than influenza A. A high proportion of patients were treated with antibiotics and pH1N1 infection had higher mortality compared to other respiratory viruses.

[Six adult cases of respiratory complications caused by pandemic 2009 influenza A (H1N1) compared to seasonal influenza]

The first case in Japan of 2009 pandemic influenza A (H1N1) was reported in May, with pediatric hospitalization exceeding that of adults. We evaluated six adults hospitalized for 2009 H1N1 respiratory complications and compared the pandemic to seasonal influenza. Hospitalization was due to aggravated asthma in four of the six, two of whom had simultaneous pneumonia probably virus-caused, and two cases of bacterial pneumonia. Among the three seasons examined, the number of adults increased slightly but the hospitalization rate was low in 2009-2010. Respiratory complications such as viral pneumonia were not seen outside of 2009-2010. Attention should therefore be paid to respiratory complications in adults with pandemic 2009 influenza A (H1N1) virus.

Pneumonia in the immunocompetent patient

Pneumonia is an acute inflammation of the lower respiratory tract. Lower respiratory tract infection is a major cause of mortality worldwide. Pneumonia is most common at the extremes of life. Predisposing factors in children include an under-developed immune system together with other factors, such as malnutrition and over-crowding. In adults, tobacco smoking is the single most important preventable risk factor. The commonest infecting organisms in children are respiratory viruses and Streptoccocus pneumoniae. In adults, pneumonia can be broadly classified, on the basis of chest radiographic appearance, into lobar pneumonia, bronchopneumonia and pneumonia producing an interstitial pattern. Lobar pneumonia is most commonly associated with community acquired pneumonia, bronchopneumonia with hospital acquired infection and an interstitial pattern with the so called atypical pneumonias, which can be caused by viruses or organisms such as Mycoplasma pneumoniae. Most cases of pneumonia can be managed with chest radiographs as the only form of imaging, but CT can detect pneumonia not visible on the chest radiograph and may be of value, particularly in the hospital setting. Complications of pneumonia include pleural effusion, empyema and lung abscess. The chest radiograph may initially indicate an effusion but ultrasound is more sensitive, allows characterisation in some cases and can guide catheter placement for drainage. CT can also be used to characterise and estimate the extent of pleural disease. Most lung abscesses respond to medical therapy, with surgery and image guided catheter drainage serving as options for those cases who do not respond.

Imaging findings in a fatal case of pandemic swine-origin influenza A (H1N1)

OBJECTIVE

Although most cases of swine-origin influenza A (H1N1) virus (S-OIV) have been self-limited, fatal cases raise questions about virulence and radiology's role in early detection. We describe the radiographic and CT findings in a fatal S-OIV infection.

CONCLUSION

Radiography showed peripheral lung opacities. CT revealed peripheral ground-glass opacities suggesting peribronchial injury. These imaging findings raised suspicion of S-OIV despite negative H1N1 influenza rapid antigen test results from two nasopharyngeal swabs; subsequently, those results were proven to be false-negatives by reverse transcriptase polymerase chain reaction. This case suggests a role for CT in the early recognition of severe S-OIV.

Chest CT findings of influenza virus-associated pneumonia in 12 adult patients

Objective  In this study, we describe the chest computed tomography findings of influenza virus‐associated pneumonia in adult patients.

Methods  Our retrospective study included 12 adult patients who had proven influenza virus ‐ associated pneumonia.

Results  Out of 12 patients, six were diagnosed as having pure influenza virus pneumonia, five as having bronchopneumonia caused by bacteria associated with influenza A infection, and one as having a cryptogenic organizing pneumonia associated with influenza A infection.

Conclusion  Radiographic findings of influenza virus pneumonia in adult patients consist of ground‐glass attenuation. Localized patchy consolidations were observed in cases of bronchopneumonia.

Causative agent distribution and antibiotic therapy assessment among adult patients with community acquired pneumonia in Chinese urban population

BACKGROUND

Knowledge of predominant microbial patterns in community-acquired pneumonia (CAP) constitutes the basis for initial decisions about empirical antimicrobial treatment, so a prospective study was performed during 2003-2004 among CAP of adult Chinese urban populations.

METHODS

Qualified patients were enrolled and screened for bacterial, atypical, and viral pathogens by sputum and/or blood culturing, and by antibody seroconversion test. Antibiotic treatment and patient outcome were also assessed.

RESULTS

Non-viral pathogens were found in 324/610 (53.1%) patients among whom M. pneumoniae was the most prevalent (126/610, 20.7%). Atypical pathogens were identified in 62/195 (31.8%) patients carrying bacterial pathogens. Respiratory viruses were identified in 35 (19%) of 184 randomly selected patients with adenovirus being the most common (16/184, 8.7%). The nonsusceptibility of S. pneumoniae to penicillin and azithromycin was 22.2% (Resistance (R): 3.2%, Intermediate (I): 19.0%) and 79.4% (R: 79.4%, I: 0%), respectively. Of patients (312) from whom causative pathogens were identified and antibiotic treatments were recorded, clinical cure rate with beta-lactam antibiotics alone and with combination of a beta-lactam plus a macrolide or with fluoroquinolones was 63.7% (79/124) and 67%(126/188), respectively. For patients having mixed M. pneumoniae and/or C. pneumoniae infections, a better cure rate was observed with regimens that are active against atypical pathogens (e.g. a beta-lactam plus a macrolide, or a fluoroquinolone) than with beta-lactam alone (75.8% vs. 42.9%, p = 0.045).

CONCLUSION

In Chinese adult CAP patients, M. pneumoniae was the most prevalent with mixed infections containing atypical pathogens being frequently observed. With S. pneumoniae, the prevalence of macrolide resistance was high and penicillin resistance low compared with data reported in other regions.

[Adenoviral respiratory diseases in healthy children: a study of 116 hospital cases]

Adenoviruses most commonly cause respiratory illness; however, depending on the infecting serotype, they may also cause various other diseases. Diagnosis may be difficult to achieve.The clinical findings for 116 children hospitalised with adenoviral infection were studied retrospectively. In 71 children, the diagnosis was based on detection of adenovirus antigen in the nasopharyngeal specimens and in 71 children on viral culture. The clinical picture of adenoviral infection was characterised by high-grade (mean 39°1C) and prolonged fever (mean duration 4,3 days). Upper respiratory and lower respiratory symptoms were the most common infections. Twelve had been admitted to the hospital due to febrile convulsions, 6 had meningitis. Laboratory findings varied from normal values to values seen in bacterial infections. Thus it was difficult to distinguish adenoviral disease from a bacterial disease. Fifty-nine children were referred to the hospital due to infection unresponsive to antimicrobial therapy.Symptoms of respiratory infection caused by adenovirus may range from the common cold syndrome to pneumonia, croup and bronchiolitis. Adenoviruses can be responsible for severe consequences, even in previously healthy children. Studies of the molecular mechanisms of viral infections of the airways could provide important insights into the nature of the inflammatory process involved in asthma and chronic obstructive pulmonary disease. Most infections are mild and require no therapy or only symptomatic treatment. There are at present time no recognised antiviral agents that are effective in treating serious adenovirus disease. The rapid detection of adenovirus antigen in nasopharygeal specimens proved to have a great clinical value in the diagnosis.

Viral Infections of the Lung

The lungs are among the most vulnerable to microbial assault of all organs in the body. From a contemporary vantage, lower respiratory tract infections are the greatest cause of infection-related mortality in the United States, and rank seventh among all causes of deaths in the United States.2,3 From a global and historic perspective, the scope and scale of lower respiratory tract infection is greater than any other infectious syndrome, and viral pneumonias have proven to be some of the most lethal and dramatic of human diseases. The 1918–1919 influenza pandemic, perhaps the most devastating infectious disease pandemic in recorded history, resulted in an estimated 40 million deaths worldwide, including 700,000 deaths in the U.S.4 The global outbreak of severe acute respiratory syndrome (SARS) during 2003, although considerably smaller in scale, resulted in 8098 cases and 774 deaths5 and is a dramatic contemporary example of the ability of viral pneumonias to rapidly disseminate and cause severe disease in human populations.

Antibiotic use in children is not influenced by the result of rapid antigen detection test for the respiratory syncytial virus

BACKGROUND

Rapid antigen detection test (RADT) for respiratory syncytial virus (RSV) is widely used in children hospitalized with acute respiratory tract infection (ARTI), but its influence on antibiotic (AB) use is uncertain.

OBJECTIVE

To evaluate if confirmation of RSV infection by RADT modified AB use and elucidate others factors associated with the continuation of antibiotics.

STUDY DESIGN

Charts of children hospitalized with viral ARTI aged 0-35 months were reviewed. Modification of antibiotics according to RSV RADT results was compared using Kaplan-Meier estimates and multivariate Cox regression.

RESULTS

Of children receiving antibiotics when the RSV RADT result was available, RSV RADT was positive in 144 and negative in 54. Positive RSV RADT results did not lead to modification of antibiotic use. Factors independently associated with cessation of intravenous antibiotics were age > or = 3 months (HR 2.44 [1.41-4.21]) and absence of pneumonia (HR 1.50 [1.03-2.19]). Absence of otitis was associated with cessation of oral antibiotics (HR 9.16 [95% CI, 2.35-35.76]).

CONCLUSION

Confirmed presence of RSV by RADT did not influence antibiotic use in young children with ARTI. Except with pneumonia, the risk of bacterial superinfection of RSV infected children is minimal and confirmation of RSV infection should prompt treating physicians to interrupt antibiotics.

Severe community-acquired pneumonia: approach to therapy

Despite substantial progress in therapeutic options, severe community-acquired pneumonia (CAP) remains a significant cause of morbidity and mortality worldwide. Recognising the clinical importance of CAP over the past several years, different medical societies and health organisations in different countries have proposed specific guidelines for the management of CAP. Early and rapid initiation of antimicrobial therapy has been advocated for a favourable outcome. Treatment is empirical as the diagnostic yield for potential pathogens does not exceed 50%. Dual therapy is emerging as the preferred therapy for severe CAP. The regimen is based on an epidemiological approach with emphasis on covering both typical and atypical pathogens. Non-antimicrobial adjuvant therapies including non-invasive ventilation and immunomodulatory agents are emerging as promising area for future development.

Impact of antibiotic restrictions: the physician's perspective

In recent years, there have been worldwide efforts to reduce inappropriate antibiotic prescribing. This has mainly been in response to mounting concerns about the emergence of antimicrobial resistance. Surprisingly, there has been little systematic investigation of the impact of antibiotic restrictions on the complications of infection. It is difficult to address this question using randomised clinical trials in light of the often limited numbers of patients that can be included, who are also often atypical of the broad population of patients receiving antibiotic therapy. Observational data from the UK indicate an association between recent reductions in antibiotic prescribing for lower respiratory tract infection in general practice and an increase in pneumonia mortality. These studies suggest a need for further investigations examining the changing patterns of antibiotic prescribing and their effects on patient outcomes in other countries and in other common infectious diseases. Such studies may provide a useful comparison with the changes observed in lower respiratory tract infection in the UK, and could help to improve antibiotic prescribing practices worldwide. It is also important to study whether associated worse outcomes are limited to certain at-risk groups who should be targeted for care.

Viral pneumonia in children

Viral pneumonia causes a heavy burden on our society. In the United States, more than one million cases of pneumonias afflict children under the age of 5 years, costing hundreds of millions of dollars annually. The majority of these infections are caused by a handful of common viruses. Knowledge of the epidemiology of these viruses combined with new rapid diagnostic techniques will provide faster and more, reliable diagnoses in the future. Although the basic clinical epidemiology of these viruses has been carefully investigated over the last 30 years, new molecular techniques are greatly expanding our understanding of these agents and the diseases they cause. Antigenic and genetic variations are being discovered in many viruses previously thought to be homogeneous. The exact roles and the biological significance of these variations are just beginning to be explored, but already evidence of differences in pathogenicity and immunogenicity has been found in many of these substrains. All of this information clearly will impact the development of future vaccines and antiviral drugs. Effective drugs exist for prophylaxis against influenza A and respiratory syncytial virus, and specific therapy exists for influenza A. Ribarivin is approved for use in respiratory synctial virus infections, and it alone or in combination with other agents (eg, IGIV) may be effective in immunocompromised patients, either in preventing the development of pneumonia or in decreasing morbidity and mortality. Many new antiviral agents are being tested and developed, and several are in clinical trials.

Serious and lethal respiratory tract infections of viral etiology in children

Viruses may lead to serious and lethal pulmonary infections in immunocompetent and immunocompromised children. Series of children with acute respiratory distress syndrome and series of children requiring extracorporeal membrane oxygenation, as well as reported series of nosocomial viral illness, offer an insight into the extent of serious viral disease documented in the medical literature. Series of children with specific viral respiratory illness also will be reviewed, as will the means of diagnosis in these groups of patients. Copyright © 2000 by W.B. Saunders Company

Guide to selection of fluoroquinolones in patients with lower respiratory tract infections

Newer fluoroquinolones such as levofloxacin, moxifloxacin, gatifloxacin and gemifloxacin have several attributes that make them excellent choices for the therapy of lower respiratory tract infections. In particular, they have excellent intrinsic activity against Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis and the atypical respiratory pathogens. Fluoroquinolones may be used as monotherapy to treat high-risk patients with acute exacerbation of chronic bronchitis, and for patients with community-acquired pneumonia requiring hospitalisation, but not admission to intensive care. Overall, the newer fluoroquinolones often achieve clinical cure rates in > or =90% of these patients. However, rates may be lower in hospital-acquired pneumonia, and this infection should be treated on the basis of anticipated organisms and evaluation of risk factors for specific pathogens such as Pseudomonas aeruginosa. In this setting, an antipseudomonal fluoroquinolone may be used in combination with an antipseudomonalbeta-lactam. Concerns are now being raised about the widespread use, and possibly misuse, of fluoroquinolones and the emergence of resistance among S. pneumoniae, Enterobacteriaceae and P. aeruginosa. A number of pharmacokinetic parameters such as the peak concentration of the antibacterial after a dose (C(max)), and the 24-hour area under the concentration-time curve (AUC24) and their relationship to pharmacodynamic parameters such as the minimum inhibitory and the mutant prevention concentrations (MIC and MPC, respectively) have been proposed to predict the effect of fluoroquinolones on bacterial killing and the emergence of resistance. Higher C(max)/MIC or AUC24/MIC and C(max)/MPC or AUC24/MPC ratios, either as a result of dose administration or the susceptibility of the organism, may lead to a better clinical outcome and decrease the emergence of resistance, respectively. Pharmacokinetic profiles that are optimised to target low-level resistant minor subpopulations of bacteria that often exist in infections may help preserve fluoroquinolones as a class. To this end, optimising the AUC24/MPC or C(max)/MPC ratios is important, particularly against S. pneumoniae, in the setting of lower respiratory tract infections. Agents such as moxifloxacin and gemifloxacin with high ratios against this organism are preferred, and agents such as ciprofloxacin with low ratios should be avoided. For agents such as levofloxacin and gatifloxacin, with intermediate ratios against S. pneumoniae, it may be worthwhile considering alternative dose administration strategies, such as using higher dosages, to eradicate low-level resistant variants. This must, of course, be balanced against the potential of toxicity. Innovative approaches to the use of fluoroquinolones are worth testing in further in vitro experiments as well as in clinical trials.

Imagerie moderne des pneumonies infectieuses aiguës

Les pneumonies infectieuses aiguës constituent un problème de santé publique important, car elles sont une cause majeure de morbidité et de mortalité chez l’adulte. Si les données cliniques et radiographiques permettent le plus souvent de faire le diagnostic de pneumonie infectieuse, le diagnostic étiologique est plus difficile. En effet, de nombreux agents pathogènes peuvent être responsables de pneumonie et la réaction du parenchyme pulmonaire est peu variée, d’où la faible spécificité des lésions radiologiques observées en dehors de quelques cas particuliers. C’est pourquoi la compréhension des mécanismes physiopathologiques permet d’expliquer certains aspects radiologiques. De même, la connaissance des bases anatomocliniques et radiologiques autorise la reconnaissance de trois aspects radiographiques principaux. Quant à l’appréciation des contextes épidémiologique et immunitaire, ils peuvent permettre également d’approcher le germe en cause.

Fatal Type 3 Adenoviral Pneumonia in Immunocompetent Adult Identical Twins

We describe adult twin sisters who developed severe adenoviral pneumonia with relative leukopenia, progressive focal infiltrates, shock, and hypoxia. Potential determinants of severe adenoviral disease are discussed.

Radiographic and high-resolution CT findings of influenza virus pneumonia in patients with hematologic malignancies

OBJECTIVE

We sought to describe the radiographic and high-resolution CT findings of influenza virus pneumonia in patients with hematologic malignancies.

CONCLUSION

Radiologic findings of influenza virus pneumonia in immunocompromised patients consist of patchy or confluent consolidation and nodular opacities on chest radiography and ground-glass attenuation, consolidation, centrilobular nodules, and branching linear opacities on high-resolution CT.

Parainfluenza viruses

Human parainfluenza viruses (HPIV) were first discovered in the late 1950s. Over the last decade, considerable knowledge about their molecular structure and function has been accumulated. This has led to significant changes in both the nomenclature and taxonomic relationships of these viruses. HPIV is genetically and antigenically divided into types 1 to 4. Further major subtypes of HPIV-4 (A and B) and subgroups/genotypes of HPIV-1 and HPIV-3 have been described. HPIV-1 to HPIV-3 are major causes of lower respiratory infections in infants, young children, the immunocompromised, the chronically ill, and the elderly. Each subtype can cause somewhat unique clinical diseases in different hosts. HPIV are enveloped and of medium size (150 to 250 nm), and their RNA genome is in the negative sense. These viruses belong to the Paramyxoviridae family, one of the largest and most rapidly growing groups of viruses causing significant human and veterinary disease. HPIV are closely related to recently discovered megamyxoviruses (Hendra and Nipah viruses) and metapneumovirus.

Viral pneumonias in adults: radiologic and pathologic findings

Numerous viruses, including influenza virus, measles virus, Hantavirus, adenovirus, herpesviruses, varicella-zoster virus, cytomegalovirus, and Epstein-Barr virus, can cause lower respiratory tract infection in adults. Viral pneumonia in adults can be classified into two clinical groups: so-called atypical pneumonia in otherwise healthy hosts and viral pneumonia in immunocompromised hosts. Influenza virus types A and B cause most cases of viral pneumonia in immunocompetent adults. Immunocompromised hosts are susceptible to pneumonias caused by cytomegalovirus, herpesviruses, measles virus, and adenovirus. The radiographic findings, which consist mainly of patchy or diffuse ground-glass opacity with or without consolidation and reticular areas of increased opacity, are variable and overlapping. Computed tomographic findings, which are also overlapping, consist of poorly defined centrilobular nodules, ground-glass attenuation with a lobular distribution, segmental consolidation, or diffuse ground-glass attenuation with thickened interlobular septa. The radiologic findings reflect the variable extents of the histopathologic features: diffuse alveolar damage (intraalveolar edema, fibrin, and variable cellular infiltrates with a hyaline membrane), intraalveolar hemorrhage, and interstitial (intrapulmonary or airway) inflammatory cell infiltration. Clinical information such as patient age, immune status, community outbreaks, symptom onset and duration, and presence of a rash remain important aids in diagnosis of viral causes.

The role of atypical pathogens in community-acquired pneumonia

The atypical pathogens in community-acquired pneumonia traditionally have included Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella spp. Recent studies documenting their epidemiology and clinical characteristics have shown that these organisms are indistinguishable from the pneumococcus. Furthermore, therapy no longer depends on the specific bacterial cause of community-acquired pneumonia. Etiologic diagnosis is still difficult, although new methods are becoming available. This article focuses on these issues and on why the term atypical is no longer meaningful.

Viral pneumonias. Multifaceted approach to an elusive diagnosis

Despite enhanced laboratory techniques such as viral culture, rapid antigen detection, and gene amplification, a confident diagnosis of viral pneumonia continues to be a challenge. The nonspecific nature of clinical characteristics and the extreme sensitivity of laboratory techniques make the diagnosis difficult, even when a viral agent is detected. Understanding the limitations of these technological advances and the use of histopathologic techniques can greatly enhance a skilled clinician's ability to make an accurate diagnosis.

Respiratory viral infections in the elderly

Viral respiratory infections represent a significant challenge for those interested in improving the health of the elderly. Influenza continues to result in a large burden of excess morbidity and mortality. Two effective measures, inactivated influenza vaccine, and the antiviral drugs rimantadine and amantadine, are currently available for control of this disease. Inactivated vaccine should be given yearly to all of those over the age of 65, as well as younger individuals with high-risk medical conditions and individuals delivering care to such persons. Live, intranasally administered attenuated influenza vaccines are also in development, and may be useful in combination with inactivated vaccine in the elderly. The antiviral drugs amantadine and rimantadine are effective in the treatment and prevention of influenza A, although rimantadine is associated with fewer side-effects. Recently, the inhaled neuraminidase inhibitor zanamivir, which is active against both influenza A and B viruses, was licensed for use in uncomplicated influenza. The role of this drug in treatment and prevention of influenza in the elderly remains to be determined. Additional neuraminidase inhibitors are also being developed. In addition, to influenza, respiratory infections with respiratory syncytial virus, parainfluenza virus, rhinovirus, and coronavirus have been identified as potential problems in the elderly. With increasing attention, it is probable that the impact of these infections in this age group will be more extensively documented. Understanding of the immunology and pathogenesis of these infections in elderly adults is in its infancy, and considerable additional work will need to be performed towards development of effective control measures.

Tracheal aspirate as a substrate for polymerase chain reaction detection of viral genome in childhood pneumonia and myocarditis

BACKGROUND

Infectious respiratory disorders are important causes of childhood morbidity and mortality. Viral causes are common and may lead to rapid deterioration, requiring mechanical ventilation; myocardial dysfunction may accompany respiratory decompensation. The etiologic viral diagnosis may be difficult with classic methods. The purpose of this study was to evaluate polymerase chain reaction (PCR) as a diagnostic method for identification of causative agents.

METHODS AND RESULTS

PCR was used to amplify sequences of viruses known to cause childhood viral pneumonia and myocarditis. Oligonucleotide primers were designed to amplify specific sequences of DNA virus (adenovirus, cytomegalovirus, herpes simplex virus, and Epstein-Barr virus) and RNA virus (enterovirus, respiratory syncytial virus, influenza A, and influenza B) genomes. Tracheal aspirate samples were obtained from 32 intubated patients and nucleic acid extracted before PCR. PCR results were compared with results of culture, serology, and antigen detection methods when available. In cases of myocarditis (n=7), endomyocardial biopsy samples were analyzed by PCR and compared with tracheal aspirate studies. PCR amplification of viral genome occurred in 18 of 32 samples (56%), with 3 samples PCR positive for 2 viral genomes. Amplified viral sequences included RSV (n=3), enterovirus (n=5), cytomegalovirus (n=4), adenovirus (n=3), herpes simplex virus (n=2), Epstein-Barr virus (n=1), influenza A (n=2), and influenza B (n=1). All 7 cases of myocarditis amplified the same viral genome from heart as found by tracheal aspirate.

CONCLUSIONS

PCR is a rapid and sensitive diagnostic tool in cases of viral pneumonia with or without myocarditis, and tracheal aspirate appears to be excellent for analysis.

[Severe type 7 Adenovirus pneumoniae in an immunocompetent adult]

We report a case of severe Adenovirus type 7 pleuropneumonia in an immunocompetent adult. The treatment required a mechanical ventilation with tracheostomy. The sequelae was a restrictive respiratory insufficiency. Adenovirus is a common cause of pneumonia in children, in military recruits or in immunocompromised adults. However, it is an infrequent cause of such a severe complication in a healthy adult.

Viral and atypical pneumonias

Acute respiratory infections are the most common illnesses in the pediatric age group. Although pneumonia accounts for only 10% to 15% of all respiratory infections, it causes significant morbidity and mortality among children. Even in the age of multigenerational antibiotics and ever-emerging antiviral agents the recognition, differentiation, and treatment of pneumonia in the pediatric age group continues to be a challenge. The focus of this article is limited to viral and atypical pneumonias. Viral or Mycoplasma pneumoniae infection has been detected in 17% to 31% of outpatient pneumonias studied.

Afebrile pneumonia in infants

Afebrile or atypical pneumonia is a relatively common illness in infants. These children often present afebrile with diffuse or bilateral infiltrates on chest radiograph. The definition and causes of this clinical entity are discussed. The role of agents such as Chlamydia, Ureaplasma, Pneumocystis, and viruses is elucidated. Techniques for diagnosis and recommended treatment regimens are presented.

Acute and chronic human adenovirus pneumonia: cellular and extracellular matrix components

We present a comparative histopathological study of both acute and chronic human adenovirus pneumonia, with reference to the cellular and extracellular matrix components. Seventeen lungs from autopsied patients whose ages ranged from 2 to 60 months were studied. Adenovirus types 1, 2, 3, 5, and 7 were isolated from 15 patients with acute lung disease, and types 2 and 7 were isolated from the other two patients with chronic pulmonary illness. The results indicated the occurrence of two basic patterns of adenovirus interstitial pneumonia (1) classic pattern (acute), characterized by necrosis and degeneration and many type II pneumocytes with intranuclear inclusion bodies, which were positive for adenovirus DNA by in situ hybridization, and (2) proliferative or proliferative-productive pattern (chronic), which presented with diffuse pulmonary fibrosis and the interstitial proliferation of fibroblast-like cells, compatible with myofibroblasts (positive for vimentin and alpha smooth muscle actin), and increase in collagen types I and III, elastic fibers, and proteoglycans. Alveolar collapse appears to be an important pathogenetic mechanism in the development of this pattern.

Treatment of adenoviral pneumonitis with intravenous ribavirin and immunoglobulin

A 67 year old woman developed a severe adenoviral pneumonitis whilst receiving immunosuppressive therapy. She showed clinical and radiological evidence of a response to treatment with nebulised and intravenous ribavirin and intravenous pooled normal human immunoglobulin. To our knowledge this is the first time that such a therapeutic approach has been used in the treatment of a condition which normally carries a very high mortality.