Current Respiratory Medicine Reviews - Volume 6, Issue 3, 2010

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Community acquired pneumonia (CAP) is among the leading causes of death worldwide. Despite intense research in the field and the development of new therapies, mortality remains largely unaltered for the past three decades. Antimicrobial agents are the cornerstone of therapy against CAP, but sometimes despite early diagnosis and the initiation of antibiotics, mortality remains high. A possible explanation may be due to several other host-related factors that keep the septic reaction intense. Part of this intensity may be attributed to the host-pathogen interaction and the deterioration of the host that is evoked by an immunologic overreaction. There is substantial evidence that macrolides have an inmunomodulatory effect on the host immune response, with multiple observational and prospective studies supporting a significant increased survival rate in patients with CAP treated with macrolides. We will review the significance of this non-antimicrobial effect of macrolides for the management of CAP.

Pneumonia is the second leading cause of hospitalization in the United States, and along with influenza is the 8th leading cause of death. The risk of death during a pneumonia-related hospitalization is significantly higher than from many other major causes of hospitalization, as in 2005 it caused 4.6 deaths per 100 discharges. Recent studies have suggested that the use of statins may lead to better outcomes for subjects hospitalized with pneumonia or other infectious diseases. In this article, we examine the possible underlying mechanisms that may result in a beneficial effect of statins on infectious diseases, and describe the existing research that has examined this association. Further studies are needed to determine whether the long-term use of statins for cardioprotective effects also provides protection for patients at risk for pneumonia, or may serve as an acute treatment for pneumonia patients who require hospitalization.

Inhaled corticosteroids (ICS) have been recommended for use in patients with chronic obstructive pulmonary disease (COPD) in order to decrease exacerbation rates and improve health related quality of life parameters. Nevertheless, recent studies have reported an increased risk of pneumonia associated with this treatment. However, most studies were not specifically designed to detect pneumonia as a possible secondary effect and for this reason it is difficult to determine whether this risk exists and assess its magnitude. This paper reviews the published studies reporting pneumonia events in COPD patients treated with ICS.

Noninvasive mechanical ventilation (NIV) is an effective treatment in acute hypercapnic respiratory failure associated with exacerbated chronic obstructive pulmonary disease and obesity hypoventilation syndrome, among other respiratory diseases. There is less scientific evidence on its application in situations of acute hypoxemic respiratory failure other than acute lung edema. There have been few randomized controlled trials on its efficacy versus standard oxygen therapy or conventional mechanical ventilation in the treatment of severe community-acquired pneumonia, and the results have been contradictory. Its application in selected immunosuppressed patients and patients with acute hypoxemic respiratory failure or chronic obstructive pulmonary disease-associated community-acquired pneumonia may reduce the orotracheal intubation rate, hospital stay, and mechanical ventilation-associated morbidity and mortality. A therapeutic trial with NIV may be appropriate in these situations, but only when the treatment can be continuously monitored and is controlled by specifically-trained professionals.

Infections after lung transplantation are a major cause of morbidity and mortality. Bacteria, fungus and virus are the most common pathogens at the respiratory tract. This short review analyzes pneumonias in LTR with special emphasis on preventive strategies.

Previous studies have indicated an increased susceptibility to pneumonia in burn injury patients [1-5]. Despite numerous advances in understanding it, its incidence is still quite high and represents a significant cause of morbidity and mortality in this population. In the last few years numerous articles have been published on diagnosis, treatment and prevention. In this review, we have selected those articles that could potentially lead to changes in the clinical practice and handling of pneumonia in adult patients with burn injuries.

Invasive pneumococcal disease is a major cause of morbimortality worldwide. The presence of bacteremia in pneumococcal pneumonia constitutes an additional factor of worse prognosis, although the highest virulence of invasive pneumococcal infection is clustered in certain serotypes. Antibiotic resistances are a challenge for the clinician when choosing the most appropriate antibiotic treatment. However, the influence of these in the evolution of the disease is a controversial issue, and it is clinically irrelevant if the MIC is lower than 4 μg/ml. The control of antibiotic pressure on Streptococcus pneumoniae has proved the most effective tool for monitoring resistances. Prevention strategies through pneumococcal vaccination have been shown to reduce the incidence of invasive pneumococcal disease in vaccinated children and the unvaccinated adult population. However, a phenomenon of increased infections by serotypes not included in the vaccine has been described. The development of antibiotics and vaccination have achieved great progress in the control of this disease, although Streptococcus pneumoniae continues to develop mechanisms of survival and adaptation.

Methicillin-resistant Staphylococcus aureus (MRSA) has been recognized as an in-hospital acquired pathogen responsible for an increasing number of cases of hospital and ventilator associated pneumonia. However, this previously considered a purely nosocomial pathogen has been diagnosed with increasing frequency at hospital admission and new infections and outbreaks have been reported in individuals from the community with absence of risk factors. This new strain of MRSA is currently recognized in the literature as community-associated MRSA (CA-MRSA). The spectrum of infections due to CA-MRSA can range from simple cutaneous abscesses and soft tissue infections to septic shock and severe necrotizing pneumonia. CA-MRSA pneumonia usually presents in a previously healthy individual with the presence of a previous influenza like illness followed by shortness of breath, bilateral pulmonary infiltrates, sepsis and prompt clinical detriment and death if no proper treatment is established soon. The objective of this review is to familiarize the clinician with CA-MRSA as cause of community acquired pneumonia, review the epidemiological, clinical, microbiological characteristics, in order to minimize delays in the administration of the adequate antimicrobial treatment to improve patient's outcomes of this deadly condition.

To evaluate the relationship between Chlamydia pneumoniae infection and lung cancer, we conducted a metaanalysis of studies comparing the antibodies of C. pneumoniae between lung cancer patients and controls. The random-effects model or fixed-effects model was used according to the results of heterogeneity tests. Total, 8 studies with 1602 cases and 1734 controls were included. The analysis showed that the pooled OR of the association between C. pneumoniae IgA and lung cancer was 1.82 (95% CI, 1.21-2.74), while the association between C. pneumoniae IgG and lung cancer was 1.77 (95% CI, 1.13-2.78). Thus, statistically significant differences were observed between C. pneumoniae antibodies and lung cancer. This meta-analysis suggests that C. pneumoniae infection may be a potential risk factor for lung cancer.

Recurrent respiratory papillomatosis is caused by the Human Papilloma Virus and occurs primarily in children and adolescence. Most commonly, disease remains localized to the larynx and spontaneously regresses, but in rare cases there may be pulmonary involvement. We present a case of a 17 year old female with recurrent respiratory papillomatosis who develops pulmonary involvement in the form of squamous papilloma. We present the clinical findings; discuss the potential for malignant transformation and the need for screening and prevention.

The effects of pulmonary blood flow on respiratory mechanics have been studied mostly in children undergoing surgery for congenital heart diseases. Most studies reported an increase of respiratory system elastance and resistance with increased pulmonary blood flow. Recently only respiratory mechanics were measured in experiments on healthy rats by the end-inflation occlusion technique, in which the pulmonary blood flow was changed by acute blood volume expansion (BVE). Modelling the respiratory system as composed by two compartments, the technique allows the measurement of static and dynamic elastances, of the ohmic resistance of the airway, and of the additional resistance due to pendelluft and stress-relaxation. Furthermore, the measurements were not subjected to the possible confounding effects of chronic modifications of lung parenchyma and/or vessels. Pulmonary blood flow increment was confirmed to have a detrimental effect on respiratory mechanics, causing an increased work of breathing secondary to respiratory system elastances and resistances increments. Resistive pressure dissipation due to the visco-elastic behaviour of the lung parenchyma (stress-relaxation) and lung mechanical inhomogeneity (pendelluft) increased also, as well as respiratory system hysteresis. The literature allows to conclude that pulmonary blood flow significantly influences respiratory mechanics and the related work of breathing. The subject is of both theoretical and practical interest, since BVE is a frequent medical intervention, and the associated increase of pulmonary blood flow may happen in different physiopathological situations. It is suggested that blood volume expansions need to be cautiously performed, most of all in the treatment of unstable patients with mechanical respiratory failure.