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Objective In Japan, the aging demographic structure is becoming pronounced, and the full-blown graying of society appears not far off, which indicates an increasing population that will require healthcare contact. Klebsiella spp. are major pathogens in healthcare-associated infections, and their importance is increasing. The aim of this study was to clarify the characteristics of Klebsiella spp. chest infections by evaluating the differences in the characteristics of chest infections caused by Klebsiella spp. and pneumoniae. Methods We conducted a retrospective study of consecutive patients hospitalized with pneumonia, lung abscess/necrotizing pneumonia, and empyema due to Klebsiella spp. and S. pneumoniae for 15 years at our institution in Saitama, Japan. Patients Patients with chest infections due to Klebsiella spp. (K group, n=76) and S. pneumoniae (S group, n=446) were included. Results The K group more frequently was male, older, coinfected by Pseudomonas aeruginosa, and had diabetes mellitus, a history of upper digestive system surgery, alcohol drinking habit, a smoking habit, and an impaired premorbid performance status than the S group. The percentages of lung abscesses or necrotizing pneumonia (31.6% vs. 0.9%) and empyema without pulmonary parenchymal shadow (3.9% vs. 0.7%) were higher in the K group than those in the S group. Severity on admission and mortality did not differ between the groups; however, patients in the K group required a longer duration of antibiotics administration and hospital stay than those in the S group. Conclusion Klebsiella spp. chest infections have some marked characteristics when compared with pneumococcal infections, and our results serve to differentiate Klebsiella spp. infection from pneumococcal infection.

Although empyema affects more than 65,000 people each year in the United States and in the United Kingdom, there are limited data on the pathogenesis of pleural infection. We investigated the pathogenesis of empyema using animal and cell culture models of Streptococcus pneumoniae infection. The pathological processes during the development of empyema associated with murine pneumonia due to S. pneumoniae (strain D39) were investigated. Lungs were examined using histology, and pleural fluid and blood bacterial colony-forming units, cytokine levels, and cellular infiltrate were determined over time. Bacterial migration across mesothelial monolayers was investigated using cell culture techniques, flow cytometry, and confocal microscopy. After intranasal inoculation with 10(7) S. pneumoniae D39 strain, mice developed pneumonia associated with rapid bacterial invasion of the pleural space; raised intrapleural IL-8, VEGF, MCP-1, and TNF-α levels; and caused significant intrapleural neutrophilia followed by the development of fibrinous pleural adhesions. Bacterial clearance from the pleural space was poor, and in vitro assays demonstrated that S. pneumoniae crossed mesothelial layers by translocation through cells rather than by a paracellular route. This study describes key events during the development of S. pneumoniae empyema using a novel murine model of pneumonia-associated empyema that closely mimics human disease. The model allows for future assessment of molecular mechanisms involved in the development of empyema and evaluation of potential new therapies. The data suggest that transmigration of bacteria through mesothelial cells could be important in empyema development. Furthermore, upon entry the pleural cavity offers a protected compartment for the bacteria.

Streptococci that colonize the mouth and upper respiratory tract tend to be considered harmless commensals. In 45 cases of acute pneumonia and/or pulmonary abscess and 25 cases of thoracic empyema, the predominant species recovered were anaerobic bacteria and the Streptococcus milleri group, which encompasses the oral species Streptococcus anginosus, Streptococcus constellatus, and Streptococcus intermedius. The isolation of most S. milleri organisms along with oral anaerobes indicated synergy between these groups. Studies in a mouse model of pneumonia demonstrated this synergy; mortality was higher, histopathologic abnormalities were more marked (reflecting acute pneumonia followed by pulmonary abscess or empyema), and viable bacteria were more numerous in the lungs of mice with mixed infections caused by the S. milleri group and anaerobes than in the lungs of those with monomicrobial infection. In vitro studies elucidated a possible mechanism of this synergistic effect: anaerobes may enhance the growth of the S. milleri group and/or inhibit the bactericidal activity of the host. We conclude that the S. milleri group is more important in pulmonary infections than has previously been recognized.

Seventy-one strains of Streptococcus milleri were isolated from 68 patients admitted to Tamana Central Hospital. (1985.2-1989.1) S. milleri was isolated from the following specimens: sputum (15 strains), urine (10), ascites (9), postoperative wound (9), pleural effusate (6), bile (5), genital discharge (3), aspirated fluid from lung abscess (2) and others (12). In 12 patients (18%), S. milleri was isolated in pure culture and in 56 patients (82%) as part of a mixed flora. Other bacteria isolated in association with S. milleri were obligate anaerobes (41%), Gram-negative rods (40%), Gram-positive cocci (16%) and others (3%). In 71 strains of S. milleri, 9 strains (13%) were beta-haemolytic, 62 (87%) were alpha-haemolytic (week) or non-haemolytic. In 68 patients, type specific male-female ratio was 15:9 for S. milleri I, 20:15 for II and 1:8 for III respectively. The patient's age ranged from 7 to 86 years and 75% of patients were more than 50 years old. In respiratory infection, 10 cases (pyothorax, 6; pneumonia, 3; lung abscess, 1) were related to S. milleri infection and considered clinically significant. 8 cases had underlying disease, however, 2 cases (pyothorax, lung abscess) had no underlying disease. In these 2 cases, S. milleri was isolated in pure culture. Successful treatment of these ten cases usually required either antibiotic therapy or drainage of the lesion. S. milleri was isolated from various clinical specimens and some cases were associated with serious infections. S. milleri was more commonly associated with suppurative infections than other viridans group streptococci. S. milleri may therefore have different characteristics which other streptococcal species of normal flora have not.

Acute destructive pneumonia in children was found to be complicated by acute pleural empyema (APE) on days 3-21 of the disease. The time of the development of this complication depended on the state of the nonspecific resistance of the body: the greater was the degree of deficiency as manifested by cell-mediated and humoral immunity indices, the earlier developed APE. Staphylococci and Pseudomonas aeruginosa infected the pleural cavity of children under the conditions of essentially decreased phagocytic activity, phagocytic index, C'H50 and one of the classes of immunoglobulin. The reaction of the body to staphylococci and P. aeruginosa took its course after the type of primary or secondary immune response, depending on the time of infection.

The main cause of anaerobic pulmonary infections is aspiration of saliva, upper airway secretions of gastric content. Predisposing conditions include prominent dental disease, chronic upper respiratory tract infections and reduced consciousness. Fusobacterium nucleatum, Bacteroides melaninogenicus and anaerobic Gram-positive cocci are the most frequently encountered organisms. The clinical presentations are lung abscess, lung gangrene and empyema, which all tend to take a slow and indolent course. Preferred localization are dependent lung segments, most often of the right side. For bacteriological examination in these infections, only transtracheal aspirate and aspirate from the lung or pleural space are considered adequate. In 26 cases of empyema treated in our hospital during the last 3 years, adequate specimens had been taken in 19. Fifteen had been adequately examined, and anaerobes were cultured in 6. Among 29 abscesses treated during the same period, adequate specimens had been taken in only 14, and 11 had been properly examined. Seven specimens grew anaerobes on culture. In prospective studies of transtracheal aspirate in 15 chronic bronchitis without emphysema, anaerobes were not demonstrated. In 11 patients with bronchiectasis, anaerobic bacteria were cultured in 3. Finally, no anaerobic bacteria could be demonstrated in the transtracheal aspirate from 76 patients with acute exacerbation of chronic bronchitis. Anaerobic, pulmonary infections do not represent an intriguing medical problem in our region. However, knowledge of these infections is necessary to secure adequacy in collection of specimens and in their bacteriological examination. Except for metastatic infections, the key word for all lower respiratory infections is aspiration.(ABSTRACT TRUNCATED AT 250 WORDS)

In certain geographic areas, among which most South European countries are included, brucellosis continues to be an important health problem. Despite the disease's continued high prevalence, the advances made in its diagnosis and treatment have contributed to the rarity of different focal locations, such as the lung. Formerly, these occurrences were much more frequent. The present work offers a review of the literature on pulmonary brucellar affection and describes a case report of brucellar pulmonary empyema with isolation of Brucella melitensis from the pleural exudate. This constitutes an exceptional circumstance even in areas considered hyperendemic, such as a large part of Spain.