Respiratory infections: Community-acquired pneumonia and newer microbes

Abstract

Respiratory infections, especially community-acquired forms of pneumonia (CAP), are challenging for clinicians because (1) a causative microorganism can only be found in about 50% of cases; (2) initial therapy, therefore, must be based on a probable or most likely etiology in the context of the patient's overall medical condition; and (3) new microbes or those considered previously as normal flora or less virulent forms seem responsible for some cases. It is important to be acquainted with new causes of infection which include Legionella species, Chlamydia pneumoniae, diphtheroids in certain instances (Corynebacterium pseudodiphtheriticum), and viruses such as the Hanta strains. Infections with Bordetella pertussis are increasing. However, the ever present and most common cause of CAP, Streptococcus pneumoniae, continues to present problems because of increasing antibiotic resistance, the high case fatality rate when bacteremia accompanies pneumonia, and the inability to give prophylactic immunization to all people with risk factors for this infection.

The Pathology of Community-Acquired Pneumonia

“…There is proliferation and desquamation of alveolar lining cells (Gregory & Schaffner, 1997). C. pneumoniae is the third or fourth most frequent cause of CAP (Reynolds, 1996). Ninety percent of the infections are mild or asymptomatic, but severe pneumonia has been reported in the elderly and persons with underlying disease, where small pleural effusions have been described (Johnson & Cunha, 1993;Grayston & Thom, 1991).…”

“…This bacterium is often part of the usual microbial flora of the nasopharynx of healthy individuals but also seems to have a predilection for the airway mucosal surfaces of subjects with chronic lung diseases (Reynolds, 1996).…”

A multicenter, open-label, randomized comparison of levofloxacin and azithromycin plus ceftriaxone in hospitalized adults with moderate to severe community-acquired pneumonia

“…3,4 Pneumococcal bacteremia is a major complication in hospitalized patients with CAP, with an attributable mortality rate ranging from 20% to 4 1% . 5 The mortality rate in patients with severe CAP who are bacteremic is -3 times that in patients with severe CAP who have negative blood cultures6…”

Clinical evaluation methods for new antimicrobial agents to treat respiratory infections: Report of the Committee for the Respiratory System, Japan Society of Chemotherapy

“…Above all, collecting an appropriate specimen, selection of its culture methods, and, finally, proper evaluation is of utmost importance. [36][37][38] Inclusion criteria for patients…”

“…Even though the severity of an which cannot be detected in general bacterial culture. [29][30][31][32][33][34][35][36][37][38][39][40] These pathogens are encountered quite often in trials targeting pneumonia. It is therefore important to identify them using special media and selection media, or by serological tests.…”