Pneumococcal Pneumonia

Essentials of Diagnosis

General Considerations

Pneumonia is an inflammatory process in lung parenchyma most commonly caused by infection. The consolidation of pneumonia must be differentiated from pulmonary infarction, atelectasis with bronchial obstruction, and congestive heart failure, but it may coexist with any of these conditions. The pneumococcus accounts for 80 per cent or more of primary bacterial pneumonias; types I-VIII are most commonly found in adults, whereas type XIV is common in children. These pathogenic organisms are frequently present among the normal flora of the respiratory tract. The development of pneumonia must therefore usually be attributed to an impairment of natural resistance. Conditions leading to aspiration of secretions include obliteration of the cough or epiglottal reflex, impairment of upward migration of mucous sheets (propelled by cilia), and impairment of alveolar phagocyte function. Among conditions which predispose to pneumonia are viral respiratory diseases, malnutrition, exposure to cold, noxious gases, alcohol intoxication, depression of cerebral functions by drugs, and cardiac failure. Pneumonic consolidation may be in one or more lobes, or patchy in distribution.

Clinical Findings

A. Symptoms and Signs: The onset is usually sudden, with shaking chills, "stabbing" chest pain (exaggerated by respiration but sometimes referred to the shoulder, abdomen, or flank), high fever, cough and "rusty" sputum, and occasionally vomiting. A history of recent respiratory illness can often be elicited.

The patient appears severely ill, with marked tachypnea (30-40/minute) but no orthopnea. Respirations are grunting, nares flaring, and the patient often lies on the affected side in an attempt to splint the chest. Herpes simplex lesions are often present. Initially, chest excursion is diminished on the involved side, breath sounds are suppressed, and fine inspiratory rales are heard. Later, the classical signs of consolidation appear. A pleural friction rub or abdominal distention may be present. During resolution of the pneumonia, the signs of consolidation are replaced by rales. Physical findings are often inconclusive, and repeated x-ray examination is helpful.

B. Laboratory Findings:

Blood cultures are positive for pneumococci in 15-25 per cent of cases early in the disease. In peripheral blood, leukocytosis (20-35 thousand; cu mm) is the rule, and a low white count carries a poorer prognosis.

Expectorated sputum must be examined by Gram's stain and by culture. In the smears, the presence of many squamous epithelial cells suggests heavy contamination with saliva and nasopharyngeal secretions, and such specimens are of doubtful value. Typical sputum from pneumococcal pneumonia contains many red and white cells and many pneumococci. If good sputum specimens are not obtainable, a transtracheal aspirate may reveal the etiologic agent, but this procedure is not without risk. A microscopic "quellung" reaction with pooled antiserum most rapidly identifies pneumococci in sputum.

C. X-Ray Findings :

Initially, there may be no findings or a vague haziness across the involved part of the lung field. Later, typical consolidation is well defined either in lobar or in patchy distribution. Fluid shadows in the costophrenic angles may appear before pleural exudate can be detected by physical examination. During resolution of the consolidation, areas of radiolucency may appear, suggesting "pseudocavitation.

Treatment

A blood culture and a good sputum specimen for smear and culture should always be obtained before treatment is started. The dosage and route of administration of antimicrobial drugs are influenced to some extent by the clinical severity of the disease, the presence of unfavorable prognostic signs and the presence of complications.

A. Antibacterial Therapy:

Penicillin G is the drug of choice. It is given parenterally at first in dosages ranging from procaine penicillin, 600,000 units every 12 hours IM for moderate illness, to aqueous penicillin G, 10 million units per 24 hours by IV infusion in the most severe cases. Only after there has been a definite response to treatment should oral penicillin V (400,000 units every 4-6 hours) be considered. All pneumococci are susceptible to penicillin at present. Some strains resistant to tetracyclines, erythromycin, or lincomycin have been encountered. Therefore, these alternatives to penicillin (eg, in patients with documented hypersensitivity) may fail, but they (or cephalexin, 0.5 gm every 4-6 hours) can be tried orally in mildly ill patients. In more severely ill persons, cephalothin (Keflin®), 8-12 gm IV daily, or cephaloridine (Keflordin®, Loridine®), 4 gm IV or IM daily, would be a reasonable alternative.

Sulfonamides have not been in favor recently because the therapeutic response is slower than with penicillin. However, sulfisoxazole diolamine or sodium sulfadiazine, 4-6 gm IV, followed by maintenance doses IV or orally, is adequate (if not optimal) treatment for many cases of pneumococcal pneumonia. The usual sulfonamide precautions should be observed.

B. General Supportive Treatment:

  1. Ventilation and oxygenation- An adequate air-way must be maintained if necessary, by tracheal suction, endotracheal tube, or tracheostomy. Oxygen must be supplied to any patient with severe pneumonia, cyanosis, or marked dyspnea; this will also help to prevent pulmonary edema. Oxygen may be supplied by nasal catheter, soft rubber mask, or oxygen tent. With masks, a 95 per cent oxygen concentration can be maintained, whereas with nasal tubes or tents the concentration will reach only 40-50 per cent. However, masks are difficult to tolerate because of cough and expectoration. Oxygen must be humidified to prevent drying of secretions.
  2. Shock and pulmonary edema- These are the most frequent causes of death in pneumonia. Oxygen administration tends to prevent pulmonary edema; impending right heart failure must be managed, and digitalization is urgent. Treat shock as outlined in Chapter 1.
  3. Toxic delirium- This occurs in any severe pneumonia and may be particularly difficult to manage in alcoholics. It must be controlled to prevent exhaustion and circulatory failure. This is best done by means of a phenothiazine (eg, promazine [Sparine®], 50-100 mg IM) or paradehyde (8-12 ml orally, repeated as necessary every 4 hours; or 5 ml IM, repeated in 30 minutes is necessary). Anxiety and restlessness during waking hours may also be treated with phenobarbital, 15-30 mg every 4 hours. Pentobarbital, 0.1 gm at bedtime, helps to ensure adequate rest. While administering sedatives or tranquilizers, it is helpful to check the patient's sensorium frequently for any change suggestive of pneumococcal meningits, which would make a diagnostic lumbar puncture mandatory.
  4. Fluids- Patients with pneumococcal pneumonia may perspire profusely and lose much fluid and salt. Sufficient fluid must be given to maintain a daily urinary output of at least 1500 ml. Electrolytes must be kept in balance.
  5. Diet- Initially, the dyspneic patient will be anorexic, and a liquid diet will be preferred. With improvement, a normal diet will be tolerated. If complications suggest a long illness, a high-protein, high caloric diet with vitamin supplementation is indicated.
  6. Cough- If cough interferes with sleep and rest, it may be suppressed with codeine phosphate, 15-30 mg every 3-4 hours subcut or orally; or by elixir of terpin hydrate with codeine, 1 tsp every 3-4 hours as necessary.
  7. Pleuritic pain- For mild pain, spray ethyl chloride over the area of greatest pain for about 1 minute, and then along the long axis of the body through the entire area of pain, so that a line of frost about 1 inch wide is formed. This gives relief for 1-10 hours in the great majority of patients. Codeine phosphate, 15-30 mg, may be given as necessary for pain. For severe pain, give procaine hydrochloride solution, 0.5-1 per cent, subcut, in a series of injections passing through the area of greatest pain and 5 cm higher and lower. For very severe pain, use meperidine (Demerol®), 50-100 mg, or morphine sulfate, 10-15 mg.
  8. Abdominal distention- Abdominal distention is usually due to air swallowing in severe dyspnea, and is a frequent problem in patients with pneumonia. Breathing oxygen in high concentrations (90-100 per cent) is useful because oxygen is rapidly absorbed from the intestines. Neostigmine methylsulfate, 1:2000, 1 ml subcut, and insertion of a rectal tube will usually produce rapid initial decompression. Gastric dilatation can be relieved by suction through a nasal tube passed into the stomach.
  9. Congestive failure- (Distinguish from shock and pulmonary edema.) In elderly patients or patients with preexisting heart disease, congestive failure be precipitated by pneumonia. Rapid digitalization is indicated.
  10. Cardiac arrhythmias- Extrasystoleser quire no treatment. If atrial fibrillation or flutter develops, rapid failure may be precipitated. Rapid digitalization is usually indicated in these cases.

C. Evaluation of Treatment: With proper selection of antimicrobial drugs improvement and defervescence in 72 hours or less. if this fails to occur. on; must consider 3 main possibilities: (1) the presence of a serious complication such as empyema, pulmonary suppuration associated with bronchial obstruction, endocarditis, or meningitis; (2) infection by an organism other than the pneumococcus and resistant to the drug used; and (3) possible drug fever or other associated disease. If there is evidence of pleural fluid, it must be aspirated promptly, smeared, and cultured to detect infection or empyema which requires drainage. If an organism other than the pneumococcus is shown by laboratory examination to be the probable etiologic agent, treatment must be directed against it.

Complications

Complications of pneumococcal pneumonia occur with the following approximate frequencies: sterile pleural effusion (4-8 per cent), empyema (0.5-2 per cent), endocarditis and meningitis (0.1-0.3 per cent), and pericarditis (0.1 per cent). Other complications, eg, pneumococcal arthritis, are even more rare. Fibrous organization of the pneumonia (in place of resolution) occurs sometimes but rarely causes disability. All pleural fluid collections must be aspirated and examined by smear and culture to permit early treatment of empyema.

Prognosis

Untreated pneumococcal pneumonia has a mortality rate of 20-40 per cent depending upon the presence or absence of the following unfavorable prognostic signs: age over 45 years, presence of other disease (eg, heart failure, cirrhosis), pregnancy, absence of leukocytosis, bacteremia, marked proteinuria, pulmonary edema, and shock.

With early and adequate penicillin treatment, the fatality is about 5 per cent. Virtually all fatalities occur in the age groups under 2 years and over 45-50 years. In untreated, uncomplicated cases, resolution by crisis (or more gradually) occurs 7-10 days after onset.

Other Bacterial Pneumonias

Primary bacterial pneumonias caused by single bacterial species other than the pneumococcus may account for up to 15 per cent of all bacterial pneumonias at present. All of these pneumonias may have somewhat similar physical findings and x-ray evidence of pulmonary infiltration or consolidation. For proper treatment it is crucial to identify the etiologic agent by blood culture and by sputum examination with stained smear and culture. Transtracheal aspiration or even lung puncture may be needed for specific diagnosis and treatment.

Klebsiella Pneumonia

Klebsiella pneumoniae (Friedlander's bacillus) occurs as a member of the normal bacterial flora in the respiratory tract or gut of 5-20 per cent of the population. Primary pneumonia due to this organism occurs mainly in persons 40-60 years of age with a history of alcoholism, malnutrition, or debilitating diseases. Klebsiella pneumonia is also a frequent type of superinfection in persons hospitalized for serious disease, including other types of pneumonia treated with antimicrobial drugs.

The onset is usually sudden, with chills, fever, dyspnea, cyanosis, and profound toxicity. The sputum is often red ("currant jelly"), mucoid, sticky, and, difficult to expectorate. Physical findings and white counts are variable. The disease may be fulminating and progress rapidly to a fatal outcome. In subacute forms, there is a tendency to necrosis of lung tissue and abscess formation.

The diagnosis is based on finding short, encapsulated gramnegative bacteria as the predominant organism in sputum smears (in poorly stained smears they may be mistaken for pneumococci) and klebsiellae in blood and sputum cultures. Immediate intensive antimicrobial treatment is essential. Kanamycin (Kantrex®), 0.5 gm, is injected IM every 6-8 hours (15 mg/kg/day); and cephalothin (Keflin®), 6-10 gm IV, is sometimes given in addition.

When drug resistant klebsiella infections occur in a hospital environment, gentamicin. 3-5 mg/kg/day, may be injected IM in 3 equal doses.

Antimicrobial treatment may have to be continued for more than 2 weeks to avoid relapses. General supportive treatment is the same as for pneumococcal pneumonia.

The fatality rate in untreated klebsiella pneumonia is near 80 per cent: Even with apparently adequate treat-ment, the fatality rate may be near 40 per cent.

Haemophilus Influenzae Pneumonia

This is a rare form of primary bacterial pneumonia in adults. It has occurred in the presence of cardiac disease, hypogammaglobulinemia, and chronic lung disease.

Symptoms and signs do not distinguish this from other bacterial pneumonias. The sputum may be bloody, but gram-stained smears may be misinterpreted. The diagnosis ultimately rests on the results of cultures of blood and sputum.

Treatment with ampicillin, 1-1.5 gm orally every 6 hours or 150 mg/kg/day IV, may be expected to cure the infection. An alternative method of treatment is with chloramphenicol, 0.5 gm orally every 6 hours. General measures are the same as for pneumococcal pneumonia.

Pseudomonas Pneumonia & Proteus Pneumonia

Pneumonias caused by P,seudomonas aeruginosa and by various species of proteus occur with increasing frequency in debilitated persons with chronic lung or heart disease and alcoholism, or as superinfections in patients who have required inhalation therapy or tracheal suction and have received antimicrobial drugs. Contaminated equipment may be an important etiologic factor.

These pneumonias are associated with early delirium, massive consolidation often proceeding to necros is and multiple abscess formation, and a high fatality rate. Gentamicin, 3-5 mg/kg/day IM in 3 divided doses, plus carbenicillin, 18-30 gm/day by IV infusion, appears to be a possible method of treatment. With renal failure, the dosage must be adjusted down-ward to prevent nephrotoxicity.

Streptococcal Pneumonia

Pneumonia due to hemolytic streptococci occurs usually as a sequel to viral infection of the respiratory tract, especially influenza or measles, or in persons with underlying pulmonary disease. The patients are usually severely toxic and cyanotic. Pleural effusion develops frequently and early and progresses to empyema in one-third of untreated patients. The diagnosis rests on finding large numbers of streptococci in smears of sputum and culturing hemolytic streptococci from blood and sputum.

The treatment of choice is with penicillin G in a dosage similar to that for pneumococcal pneumonia. If treatment is started early, the prognosis is good.

Staphylococcal Pneumonia

Pneumonia caused by Staphylococcus aureus occurs as a sequel to viral infections of the respiratory tract (eg, influenza) and in debilitated (eg, postsurgical) patients or hospitalized infants, especially after antimicrobial drag administration. There is often a history of a mild illness with headache, cough, and generalized aches which abruptly changes to a very severe illness with high fever, chills, and exaggerated cough with purulent or blood streaked sputum and deep cyanosis. There may be early signs of pleural effusion, empyema, or tension pneumothorax. X-ray examination reveals lung consolidation, pneumatoceles, abscesses, empyema, and pneumothorax. The demonstration of pyopneumothorax and of cavities with air-fluid levels by x-ray is highly suggestive of staphylococcal pneumonia. The diagnosis must be made by examination of sputum by smear (masses of white cells and gram positive cocci, many intracellular), culture (predominantly S aureus), pleural fluid culture, and blood culture. The white count is elevated, usually to more than 20,000/cu mm.

Intial therapy (based on sputum smear) consists of full systemic doses of a cephalosporin, a penicilinase-resistant penicillin, or vancomycin. The dosages are as follows : cephalothin (Keflin®), 8-14 gm/day IV; methicillin, 8-16 gm/day IV; vancomycin (Vancocin®), 2 gm/day IV; nafcillin, 6-12 gm/day IV. If the staphylococcus proves to be penicillin-sensitive by laboratory test, pencillin G, 20-60 million units/day IV, is the antibiotic of choice. If empyema develops, drainage must be established.

The prognosis varies with the underlying condition of the patient and the durg susceptibility of the organism.

Bacteroides Pneumonia

Pneumonias caused by anaerobic Bacteroides species occur as complications of abdominal or pelvic bacteroides infections and min patients with chronic lung disease. Pleural effusions and empyema develop early and are a main feature of the, disease, which is often subacute or chronic. The diagnosis is based on the foul odor of the empyema and the demonstration of pleomorphic gram negative anaerobes. Drainage of empyema must be combined with intensive penicillin or clindamycin treatment.

Pneumocystis Carinii Pneumonia

This is a rare disorder which occurs in debilitated children or in patients who are immunosuppressed or suffer from leukemia. The diagnosis can be made by lung biopsy and the demonstration of typical cysts of the parasite P carinii in impression smears from lung tissue stained with methenamine -silver. Pentamidine isethionate (Lomidine®), 4 mg/kg/day IM, may be curative.

"Mixed" Bacterial Pneumonias

(Hypostatic Pneumonia, "Terminal" Pneumonia, Bronchopneumonia)

Essentials of Diagnosis

Variable onset of fever, cough. dyspnea, ex-pectoration.

Symptoms and signs often masked by pri-mary (debilitating) disease. Greenish yellow sputum (purulent) with mixed flora.

Leukocytosis (often absent in aged and de-bilitated).

Patchy infiltration on chest x-ray.

General Considerations

Mixed bacterial pneumonias include those in which culture and smear reveal several organisms, not one of which can clearly be identified as the etiologiar agent. They usually appear as complications of surgery or other trauma, various chronic illnesses (cardiac failure, advanced carcinoma, uremia), and certain acute illnesses (eg, measles, influenza). They are common complications of chronic pulmonary diseases such as bronchiectasis and erthphysema. Old people are most commonly affected ("terminal" pneumonia). Patients treated with intermittent positive pressure breathing apparatus or immunosuppressive drugs may develop pneumonia due to gram-negative rods.

The following findings in a debilitated, chronically ill, or aged person suggest a complicating pneumonia: (1) worsening of cough, dyspnea, cyanosis; (2) low-grade, irregular fever; (3) purulent sputum: and (4) patchy basal densities on a chest film (in addition to previously noted densities caused by a primary un-derlying disease, if any).

Clinical Findings

A. Symptoms and Signs:

The onset is usually insidious, with low grade fever, cough, expectoration, and dyspnea which may become marked and lead to cyanosis. The physical findings are extremely variable and may not be impressive against a background of chronic cardiac or pulmonary disease. Those signs listed under other bacterial pneumonias may also be present with this type.

B. Laboratory Findings:

The appearance of a greenish or yellowish (purulent) sputum should suggest a complicating pneumonia. Smears and cultures reveal : mixed flora. Predominant types should be noted as a guide to therapy. Leukocytosis is often absent in the aged and debilitated patient.

C. X-Ray Findings:

X-ray shows patchy, irregular infiltrations, most commonly posterior and basal (in bedridden patients).

Abscess formation may be observed. Careful interpretation is necessary in order to avoid confusion with shadows due to preexisting heart or lung disease.

Differential Diagnosis

Mixed bacterial pneumonias must be differentiat-ed from tuberculosis, carcinoma, and other specific mycotic, bacterial, and viral pulmonary infections (to any of which they may also be secondary).

Treatment

Where no specific etiologic microorganisms are present in the sputum, broad-spectrum antibiotics can be used. Give ampicillin, 1-1.5 gm, or tetracycline, 0.5 gm, every 6 hours orally. If staphylococci are present in the sputum in large numbers, treat as for staphylococcal pneumonia. If gram-negative rods are prevalent, their identification and drug sensitivity guide treatment.

Prognosis

The prognosis depends upon the nature and severity of the underlying pulmonary disease and varies with the predominating organism.

Aspiration Pneumonia

Aspiration pneumonia is an especially severe type of pneumonia with a high mortality rate. It results from the aspiration of gastric contents. Important predisposing factors include impairment of the swallowing mechanism (eg, esophageal disease), inadequate cough reflex leg, anesthesia, postoperative state, CNS disease, drug abuse). and impaired gastric emptying (eg, pyloric obstruction). Pulmonary injury is due in large part to the low pH (< 2.5) of gastric secretions.

Scattered areas of pulmonary edema and bronchospasm occur, and the x-ray appearance may be confused with that of pulmonary emboli, atelectasis, bronchopneumonia, and congestive heart failure.

Treatment is as for "mixed" bacterial pneumonias. The use of corticosteroids in full doses seems to be of value in reducing the severity of the inflammatory reaction (eg, hydrocortisone, 200 mg IM initially and 50 mg IM every 6 hours for 2 days; then 25 mg IM every 6 hours for the next 2 days).

Bronchoscopic aspiration may be attempted, but it may be possible to remove only a small amount of the aspirated fluids.

Primary Atypical Pneunmonia (Viral Pneumonia, Mycoplasmal Pneunxmoia)

Essentials of Diagnosis

General Considerations

The PAP syndrome may be caused by a variety of viral and mycoplasmal agents. It must be differentiated front specific bacterial, mycobacterial, and fungal pneumonias and from neoplastic diseases.

An attempt should be made to diagnose the specific agent causing the infection by means of appropriate laboratory tests and epidemiologic investigations.

Prominent causative agents include adenoviruses (especially types 4, 7, and 14 in military personnel), influenza viruses, and Mycoplasrna pneumoniae ("Eaton agent"). Viral and myco plasmal pneumonias are transmitted by droplets from person to person.

Only 10-20 per cent of M pneurnoniae infection produce pneumonia; the others are asymptomatic or present as upper respiratory disease. However, mycoplasmal pneumonia is probably the most common type of pneumonia encountered in otherwise healthy young adults (eg, university students).

Clinical Findings

A. Symptoms and Signs:

The clinical picture varies widely, both in the spontaneous and experimentally induced forms. Symptoms may be mild, as in the "common cold" or "flu"; hence the likelihood that many diseases previously diagnosed as "upper respiratory infection" were in fact pneumonias. Occasional severe cases occur which may be fatal.

The disease often begins as a mild upper respiratory tract infection proceeding to a dry cough which grows worse, increasing fever, hoarseness, headache, and generalized aching. Extreme fatigue is common. Pleuritic pain and effusion are uncommon.

Physical findings are frequently sparse and some-times completely absent in the face of a surprising degree of infiltration as seen on x-ray. Rales are usually heard. Diminished breath sounds over the involved areas may be noted in early cases.

B. Laboratory Findings:

The sputum is scanty, rarely blood-tinged. The smear shows a striking lack of bacteria and yields only the usual flora of the mouth on culture.

The white count may be normal or may show mild to severe leukopenia. Mild leukocytosis may appear later in the course of the disease.

Autohemagglutinins for human type O erythrocytes (cold agglutinins) appear in the convalescent phase of mycoplasmal pneumonia (seldom before the second week) in about 50 per cent of cases.

To be significant, a rise in titer must be > l :10 during the second week. Specific antibodies to mycoplasma may be dem-onstrated. M pneumoniac can be grown from respiratory secretions on special media.

C. X-Ray Findings: Linear infiltrates tend to appear first at hilar areas, extending later into the middle and basal portions of both lungs. The initial appearance of these changes may be delayed, and clearing on x-ray usually occurs within 3 weeks. There is considerable variation in the x-ray pattern, and no configuration is diagnostic.

Complications

Pleural effusions occur in 5-20 per cent of cases. Atelec-tasis, pneumothorax, pericarditis, myocarditis, secondary bacterial pneumonia, and acute hemolytic anemia may occur. Bronchiectasis also has been seen as a late complication.

Treatment

General measures are as for pneumococcal pneumonia.

In mild cases of mycoplasmal pneumonia antimicrobial drugs are not indicated. Severe cases may be treated with erythromycin (0.5 gin orally every 6 hours) or tetracycline (0.5 gm orally every 6-8 hours). Rarely is it necessary to administer these drugs intravenously.

Prognosis

Mortality in untreated cases is low. Fever usually disappears by the 10th day, although x-ray abnormalities persist for longer periods.

The author is a pediatrician particing in New Jersey, USA.

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