Đang chuẩn bị nút TẢI XUỐNG, xin hãy chờ
Tải xuống
Diagnostic Microbiology In patients with community-acquired pneumonia, a pneumococcal etiology is strongly suggested by the microscopic demonstration of large numbers of PMNs and slightly elongated gram-positive cocci in pairs and chains in the sputum. A sample such as the one shown in Fig. 128-2 is highly specific for pneumococcal infection of the lower airways. In the absence of such microscopic findings, the identification of pneumococci by culture is less specific, possibly reflecting colonization of the upper airways. Prior treatment with antibiotics can rapidly clear pneumococci from sputum. These factors need to be considered when sputum cultures from patients who. | Chapter 128. Pneumococcal Infections Part 5 Diagnostic Microbiology In patients with community-acquired pneumonia a pneumococcal etiology is strongly suggested by the microscopic demonstration of large numbers of PMNs and slightly elongated gram-positive cocci in pairs and chains in the sputum. A sample such as the one shown in Fig. 128-2 is highly specific for pneumococcal infection of the lower airways. In the absence of such microscopic findings the identification of pneumococci by culture is less specific possibly reflecting colonization of the upper airways. Prior treatment with antibiotics can rapidly clear pneumococci from sputum. These factors need to be considered when sputum cultures from patients who appear to have pneumococcal pneumonia are said to yield only normal mouth flora and when the medical literature describes what appear to be poor results of sputum culture. A study of sputum Gram s stain and culture in patients with proven bacteremic pneumococcal pneumonia showed that about half of patients could not provide a sputum sample provided a sample of poor quality or had received antibiotics for 18 h results in the remaining cases showed 80 sensitivity of microscopic examination of a Gram-stained sputum sample and 90 sensitivity of a sputum culture. Blood cultures yield S. pneumoniae in 25 of patients hospitalized for pneumococcal pneumonia. Figure 128-2 Gram-stained sputum from a patient with pneumococcal pneumonia shows polymorphonuclear cells with no epithelial cells indicating the origin of the sample in inflammatory exudate without contamination by saliva. Slightly pleomorphic gram-positive coccobacilli appear generally in pairs. Displacement of stained proteinaceous background material outlines a capsule surrounding some of the organisms. When obtained from a patient with pneumonia a sample like this one is highly specific in identifying the pneumococcus as the etiologic agent. Complications Empyema is the most common complication of .
