Agreement in surfactant measurements of sputum induced with hypertonic and normal saline

Severe acute respiratory syndrome coronavirus as an agent of emerging and reemerging infection

Before the emergence of severe acute respiratory syndrome (SARS) coronavirus (SARS-CoV) in 2003, only 12 other animal or human coronaviruses were known. The discovery of this virus was soon followed by the discovery of the civet and bat SARS-CoV and the human coronaviruses NL63 and HKU1. Surveillance of coronaviruses in many animal species has increased the number on the list of coronaviruses to at least 36. The explosive nature of the first SARS epidemic, the high mortality, its transient reemergence a year later, and economic disruptions led to a rush on research of the epidemiological, clinical, pathological, immunological, virological, and other basic scientific aspects of the virus and the disease. This research resulted in over 4,000 publications, only some of the most representative works of which could be reviewed in this article. The marked increase in the understanding of the virus and the disease within such a short time has allowed the development of diagnostic tests, animal models, antivirals, vaccines, and epidemiological and infection control measures, which could prove to be useful in randomized control trials if SARS should return. The findings that horseshoe bats are the natural reservoir for SARS-CoV-like virus and that civets are the amplification host highlight the importance of wildlife and biosecurity in farms and wet markets, which can serve as the source and amplification centers for emerging infections.

Issues relevant to the adoption and modification of hospital infection-control recommendations for avian influenza (H5N1 infection) in developing countries

The reemergence of avian influenza (H5N1 infection) has heightened concern for a potential human influenza pandemic. Recommendations regarding preparation for a global avian influenza pandemic are available, and it is imperative that health care workers participate in preparedness planning and training. In developing countries, health care worker preparedness training should address the modes of avian influenza transmission and specify how to implement appropriate infection-control strategies to prevent and control the spread of avian influenza. We provide evidence for avian influenza transmission methods and identify prevention strategies relevant to infection control for hospitals in developing countries. Pandemic influenza preparedness plans must include health care administrative support, mechanisms to rapidly create temporary isolation facilities, systems to restrict access to exposed health care workers, and plans to involve specialists to screen and identify cases early, to provide for continuous monitoring to ensure adherence to optimal infection-control practices, and to provide regular feedback to health care workers.

Why did outbreaks of severe acute respiratory syndrome occur in some hospital wards but not in others?

BACKGROUND

Most documented "superspreading events" of severe acute respiratory syndrome (SARS) occurred in hospitals, but the underlying causes remain unclear. We systematically analyzed the risk factors for nosocomial outbreaks of SARS among hospital wards in Guangzhou and Hong Kong, China.

METHODS

A case-control study was conducted. Case wards were hospital wards in which superspreading events of SARS occurred, and control wards were wards in which patients with SARS were admitted, but no subsequent nosocomial outbreaks occurred. Information on environmental and administrative factors was obtained through visits to the wards and interviews with ward managers or nursing officers. Relevant information about host factors was abstracted from the medical records. Logistic regression analyses were used to identify the major risk factors for superspreading events.

RESULTS

Eighty-six wards in 21 hospitals in Guangzhou and 38 wards in 5 hospitals in Hong Kong were included in the study. Six risk factors were significant in the final multiple-logistic regression model: minimum distance between beds of < or = 1 m (odds ratio [OR], 6.94; 95% confidence interval [CI], 1.68-28.75), availability of washing or changing facilities for staff (OR, 0.12; 95% CI, 0.02-0.97), whether resuscitation was ever performed in the ward (OR, 3.81; 95% CI, 1.04-13.87), whether staff members worked while experiencing symptoms (OR, 10.55; 95% CI, 2.28-48.87), whether any host patients (index patient or the first patient with SARS admitted to a ward) required oxygen therapy (OR, 4.30; 95% CI, 1.00-18.43), and whether any host patients required bi-level positive airway pressure ventilation (OR, 11.82; 95% CI, 1.97-70.80).

CONCLUSIONS

Our results revealed that factors that were associated with the ward environment and administration were important in nosocomial outbreaks of SARS. The lessons learned from this study remain very important and highly relevant to the daily operation of hospital wards if we are to prevent nosocomial outbreaks of other respiratory infections in the future.

'Free' surfactant in gastric aspirates and bronchoalveolar lavage in children with and without reflux oesophagitis

AIM

Dipalmitoylphosphatidycholine (DPPC) is the characteristic and main constituent of surfactant. Adsorption of surfactant to epithelial surfaces may be important in the masking of receptors. The aims of the study were to (i) compare the quantity of free DPPC in the airways and gastric aspirates of children with gastroesophageal reflux disease (GORD) to those without and (ii) describe the association between free DPPC levels with airway cellular profile and capsaicin cough sensitivity.

METHODS

Children aged <14 years were defined as 'coughers' if a history of cough in association with their GORD symptoms was elicited before gastric aspirates and nonbronchoscopic bronchoalveolar lavage (BAL) were obtained during elective flexible upper gastrointestinal endoscopy. GORD was defined as histological presence of reflux oesophagitis. Spirometry and capsaicin cough-sensitivity test was carried out in children aged >6 years before the endoscopy.

RESULTS

Median age of the 68 children was 9 years (interquartile range (IQR) 7.2). Median DPPC level in BAL of children with cough (72.7 microg/mL) was similar to noncoughers (88.5). There was also no significant difference in DPPC levels in both BAL and gastric aspirates of children classified according to presence of GORD. There was no correlation between DPPC levels and cellular counts or capsaicin cough-sensitivity outcome measures.

CONCLUSION

We conclude that free DPPC levels in the airways and gastric aspirate is not influenced by presence of cough or GORD defined by histological presence of reflux oesophagitis. Whether quantification of adsorbed surfactant differs in these groups remain unknown. Free DPPC is unlikely to have a role in masking of airway receptors.

The relationship between inflammation and dipalmitoyl phosphatidycholine in induced sputum of children with asthma

BACKGROUND

Animal studies have shown elevated surfactant production in response to lung injury. In human airways, the contribution of surfactant to the airway epithelial barrier and importance of eosinophilic inflammation is increasingly appreciated. The relationship between blood and sputum inflammatory indices of childhood asthma to surfactant levels is unknown. In this study we hypothesized that the degree of inflammation influences the level of dipalmitoyl phosphatidycholine (DPPC) in airways of children with asthma.

METHODS

Sixteen children with asthma (ages 5.5-16 years) underwent venipuncture, skin prick test, spirometry, hypertonic saline challenge, and induced sputum during a nonacute phase. Sputum (sp) and blood (se) markers of inflammation (eosinophils, neutrophils, eosinophilic cationic protein [ECP]), were related to sputum DPPC levels and several markers of asthma severity (airway hyperresponsiveness, quality of life, FEV1).

RESULTS

On multiple regression, sp-DPPC significantly correlated to sp-ECP (r=0.53, P=0.0048). Se-ECP, se-Eo, sp-eosinophils, sp-neutrophils, se-neutrophils, and inhaled steroids dose did not significantly influence sp-DPPC. Exposure to smoke did not influence inflammatory markers. FEV1 and quality of life data did not relate to any blood or sputum variable. A significant association between AHR and se-eosinophils, but not between AHR and se-ECP, sp-eosinophils, or sp-ECP was found.

CONCLUSION

Elevated DPPC levels occur in the presence of chronic eosinophilic inflammation in airways of children with stable asthma. Whether this represents an inherent lung mechanism for epithelial protection remains to be elucidated.