Amoxicillin with food

Dullness to percussion is present in approximately 50% of cases. Crackles on careful auscultation are heard in nearly all cases but, in patients with chronic lung disease, it is often difficult to be certain that such sounds signify the presence of pneumonia. Bronchial or tubular breath sounds may be heard if consolidation is present. Flatness to percussion at the lung base and an inability to detect the expected degree of diaphragmatic motion with deep inspiration suggest the presence of pleural fluid.

Unless all the vital signs are normal, which substantially reduces the likelihood of pneumonia, no set of physical findings can reliably replace the chest X-ray in diagnosing the presence or absence of pneumonia. The finding of a heart murmur raises concern about endocarditis, a rare but serious complication.

Confusion, obtundation, or particularly neck stiffness suggest the presence of meningitis. In

most

An air bronchogram, which reflects especially dense air-space consolidation, highly correlates with bacteremia.

Computed tomography may reveal cavitation in 6 to 7% of cases, but this finding does not alter the prognosis. A thick-walled lung abscess is distinctly rare, and its finding raises the likelihood of other etiologic agents. Although careful prospective study may reveal pleural effusion in up to 40% of patients with pneumococcal pneumonia, only 10% have sufficient amounts of fluid to aspirate, and in only a minority of these, perhaps 2% of the total, is empyema present.

25% of patients with pneumococcal pneumonia have a hemoglobin level of less than or equal to 11g/dL. The majority of patients have leukocytosis (a white blood cell count [WBC] of >12,000/mm 3 ), But 25% may have normal WBC counts, at least at the time of admission.

A WBC count less than 6,000/mm 3 occurs in 5 to 10% of persons hospitalized for pneumococcal pneumonia and indicates a very poor prognosis. A low serum albumin level may reflect malnutrition—and therefore indicates a predisposing condition, or may appear as a manifestation of sepsis.

Serum bilirubin may be increased to 3 to 4mg/dL; the pathogenesis of this abnormality is multifactorial, with hypoxia, hepatic inflammation, and breakdown of red blood cells in the lung all thought to contribute. Complications.Empyema, the most common infectious complication of pneumococcal pneumonia, occurs in approximately 2% of cases.

Persistence of fever, even if only low grade, and leukocytosis after 4 to 5 days of appropriate antibiotic treatment of pneumococcal pneumonia is suggestive of empyema, and this diagnosis is even more likely if the radiograph shows persistence of any pleural fluid. Under such conditions, attempts should be undertaken to drain the fluid completely.

(As a general matter, drainage is indicated if pleural fluid is present at the time of diagnosis of pneumococcal pneumonia.) The presence of frank pus in the pleural space, a positive Gram stain or fluid with a pH of less than or equal to 7.1 is an indication for aggressive and complete drainage with repeated needle aspiration or prompt insertion of a chest

tube

If no response is seen, immediate removal of infected material by pleuroscopy or open thoracotomy is then indicated. Acute cardiac events have recently been recognized as important noninfectious complications of pneumococcal pneumonia.

In a recently reported series, of 170 veterans hospitalized for this disease: 33 (19.4%) had at least one major cardiac complication including: 12 (7%) with acute myocardial infarction (of whom two also had arrhythmia and five had new-onset or worsening congestive heart failure [CHF]).

Eight (5%) with new-onset atrial fibrillation or ventricular tachycardia that was transient in every case.

13 (8%) with newly diagnosed or worsening CHF, without myocardial infarction or new arrhythmias.

Mechanisms for these cardiac events include: (1) increased local inflammatory response in vulnerable plaques in coronary arteries; (2) decreased oxygen supply because of ventilation/perfusion mismatch; and (3) increased cardiac demand related to fever and shunting. pneumoniae is the most common cause of sporadic bacterial meningitis.

No distinctive clinical or laboratory features of pneumococcal meningitis enable the physician to suspect S. Headache, fever, and stiff neck or neck pain predominate.

A clouded sensorium reflects the involvement of the superficial cortex by the inflammatory process. A spinal tap should be done urgently, without even delaying for a computed tomography scan of the head if no localizing signs are present on neurological examination.

CSF generally contains a WBC count of greater than 300 with a neutrophil predominance, a glucose level of less than 30mg/dL and a protein level greater than 100mg/dL. Using current laboratory techniques, examination of a Gram-stained specimen of CSF provides the correct diagnosis in nearly all cases unless 3 to 6 hours have passed since the administration of an effective antibiotic. Immunologic detection of pneumococcal capsular material (“bacterial antigen”) generally does not add information beyond what is determined by Gram stain, although nuclear probes may eventually be useful in this situation.

pneumoniae can be implicated in a wide variety of infectious states. For unclear reasons, isolated or amoxicillin 500 buy epidemic conjunctivitis is caused by unencapsulated pneumococci. Pneumococcal endocarditis is seen once or twice per decade at a large tertiary care hospital; most infections involve previously normal heart valves, and the disease tends to be rapidly progressive and severe.

Pneumococcal pericarditis has become exceedingly rare in the antibiotic era.

Pneumococci reach the peritoneum via the blood stream, causing peritonitis; this generally occurs in the absence of a documented source of infection elsewhere. Peritonitis occurs via hematogenous spread in patients who have pre-existing ascites. In patients who do not have pre-existing ascites, pneumococci may be carried to the peritoneal cavity via the female reproductive tract, with or without clinically recognizable infection of the female reproductive organs (e.g., salpingitis), or may follow bowel perforation. Septic arthritis occurs spontaneously in natural or prosthetic joints and ocurs with increased frequency in patients with rheumatoid arthritis.

Osteomyelitis in adults tends to involve the vertebral bones. Soft tissue infections occur, especially in persons who have connective tissue diseases or HIV infection.

What common complications are associated with infection with this pathogen?

Empyema, a complication of pneumonia, is described above.

Infection of other organs may be a complication of bacteremia that appears during pneumonia or other respiratory infection or may result from bacteremia without a recognized focus, as discussed earlier in this chapter.

An etiologic role for pneumococcus in pneumonia is strongly suggested by microscopic

demonstration

More than 25 pneumococci are generally present per microscopic field, although occasionally, far fewer may be seen. If sufficient numbers of inflammatory cells are not present, relevant material has not been obtained.

If many

epithelial

A good-quality sputum specimen is far more likely to be obtained by a physician, who best understands its central role in establishing an etiologic diagnosis and determining therapy, than by ancillary personnel, who may not.

If patients are able to provide an adequate specimen and have not received antibiotics for more than 12 hours, Gram stain and culture each are more than 85% likely to reveal pneumococci in the expectorated sputum of patients with pneumococcal pneumonia. Other tests, such as antigen detection or polymerase chain reaction, that look for pneumococci in the sputum are not helpful because they are confounded by the potential problem of detecting carriage rather than infection. The Binax® test detects pneumococcal cell wall polysaccharide in the urine of approximately 75% of patients who have bacteremic pneumococcal pneumonia and a lower percentage of those with pneumonia without bacteremia.

In adults, this test is regarded as specific for diagnosing pneumococcal pneumonia.

In contrast, in children, this test is positive with pharyngeal colonization, and it is not useful diagnostically.

Pneumococcus appears on a blood agar plate as an alpha-hemolytic streptococcus.

This microbiological observation is important clinically; because alpha-hemolytic streptococci predominate in saliva, it can be difficult to identify pneumococci in sputum cultures unless a good-quality specimen has been obtained.

Colonies can be identified within 12 to 14 hours, and identification can be made soon thereafter. Blood cultures are generally positive within 12 hours of being placed in the incubator. Pneumococci colonize the nasopharynx by adhering to respiratory epithelial cells and proliferating. From their location as colonizers of the nasopharynx, pneumococci may be carried locally to adjacent areas such as the middle ear, the sinuses, the bronchi, and the lungs.

If they are not cleared by normal defense mechanisms, their capacity to cause an intense inflammatory reaction leads to disease. Remote infection may result from

bacteremia

Infrequently, colonizing pneumococci may invade mucous membranes directly, making their way directly to lymphatics or to the blood stream and causing infection in the CNS or at other sites in the body. Pathogen recognition

receptors

Peptidoglycan and lipoteichoic acid interact with cluster of differentiation (CD)14, stimulating toll-like receptor (TLR) 2. Pneumolysin interacts with TLR4 to induce nuclear factor kappa B (NF-?B).

The result is a “two-edged sword.” These stimuli facilitate uptake of pneumococci in the absence of antibody to any of its constituents.

At the same time, they stimulate a vigorous inflammatory response by upregulating production of inflammatory cytokines interleukin (IL)-1, IL-6, and tumor necrosis factor (TNF) alpha, thereby contributing to pneumococcal disease, which is largely a result of inflammation and is often severe in direct proportion to the intensity of the inflammatory response. All pneumococci produce pneumolysin, a thiol-activated toxin that inserts into the lipid bilayer of cell membranes via its interaction with cholesterol. Pneumolysin is cytotoxic for phagocytic and respiratory epithelial cells and causes inflammation by activating complement and inducing the production of TNF-alpha and interleukin-1. Injection of pneumolysin into rat lung causes all the histologic findings of pneumonia, and immunization of mice with this substance before pneumococcal infection or challenge with genetically engineered pneumococci that do not produce it is associated with a significant reduction in virulence.

Proteins on the pneumococcal surface that bind to choline residues may mediate attachment to and penetration of mammalian cells, particularly if these cells have been upregulated by prior cytokine exposure. Pneumococcal surface protein A is present on the surface of nearly all pneumococci and exerts an antiphagocytic force, perhaps by blocking deposition of complement.

Despite some antigenic variability, antibody raised against pneumococcal surface protein A protects experimental animals to a greater or lesser extent against challenge with the same or different strain, and genetically engineered mutants that lack it have reduced virulence for mice. Human antibody to this protein protects mice against pneumococcal infection and may protect humans against pneumococcal colonization. This substance is a major constituent of a vaccine that is currently in development (see vaccination). In addition to pneumococcal surface adhesin A, a surface-expressed permease, neuraminidase and autolysin are also thought to contribute to pathogenesis.

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