STAPHYLOCOCCAL PNEUMONIA.

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Pneumonia caused by S. aureus

serious and rapidly progressive infection.

less frequent than viral or pneumococcal pneumonia. 

Epidemiology.

preceded by a viral upper respiratory tract infection.

30% of all patients are younger than 3 mo

70% are younger than 1 yr.

Boys are affected more commonly than girls.

Pathogenesis.

cause confluent bronchopneumonia

often unilateral or more prominent on one side than the other

extensive areas of hemorrhagic necrosis and irregular areas of cavitation.

The pleural surface is covered by a thick layer of exudate.

Numerous abscesses occur, containing clusters of staphylococci, leukocytes,

erythrocytes, and necrotic debris.

Rupture of a small subpleural abscess may result in pyopneumothorax, which may erode

into a bronchus, producing a bronchopleural fistula.

Pneumonia due to S. aureus may be

primary (hematogenous) or

secondary after a viral infection such as influenza.

Hematogenous pneumonia may be secondary to septic emboli, right-sided endocarditis,

or the presence of intravascular devices.

Inhalation pneumonia is caused by alterations of mucociliary clearance, leukocyte

dysfunction, or bacterial adherence initiated by a viral infection.

high fever,

abdominal pain,

tachypnea, dyspnea,

localized or diffuse bronchopneumonia

lobar disease.

Staphylococci cause

necrotizing pneumonitis

empyema, pneumatoceles, pyopneumothorax,

bronchopleural fistulas

diffuse interstitial disease characterized by extreme dyspnea, tachypnea, and cyanosis.

Clinical Manifestations.

Infants younger than 1 yr are commonly affected

history of an upper respiratory tract infection for several days to 1 wk.

A rapid progression of symptoms is characteristic.

onset with high fever, cough, and evidence of respiratory distress.

Signs and symptoms

tachypnea,

grunting respirations,

sternal and subcostal retractions,

nasal flaring,

cyanosis, and

anxiety.

lethargic , irritable and toxic.

may develop severe dyspnea and a shocklike state.

gastrointestinal disturbances, = vomiting, anorexia, diarrhea, and abdominal distention

secondary to a paralytic ileus.

Physical findings depend on the stage of pneumonia.

Early

diminished breath sounds,

scattered rales, and rhonchi are commonly heard over the affected lung.

With the development of effusion, empyema, or pyopneumothorax, dullness on

percussion is noted, and breath sounds and vocal fremitus are markedly diminished.

A lag in respiratory excursion occurs on the affected side.

Results of physical examination may, , be misleading, in young infants, with findings

disproportionate to the degree of tachypnea.

Diagnosis.

Recognizing early staphylococcal pneumonia in infants is often difficult.

Abrupt onset and rapid progression of symptoms of pneumonia in infants should be

considered to be due to staphylococci until proved otherwise.

A history of furunculosis, a recent hospital admission, or maternal breast abscess should

also alert physicians to the possibility of this diagnosis.

Other bacterial pneumonias that cause empyema or pneumatoceles and thus may be

confused with staphylococcal disease include S. pneumoniae, group A Streptococcus,

Klebsiella, H. influenzae (both type b and nontypable), and primary tuberculous

pneumonia with cavitation.

Aspiration of a radiolucent foreign body followed by pulmonary abscesses may

occasionally lead to a similar clinical and radiologic picture.

LABORATORY FINDINGS.

Leukocytosis

increase primarily among the polymorphonuclear cells.

Mild to moderate anemia is common.

cultures -obtained by tracheal aspiration or pleural tap

Gram stain reveals gram-positive cocci in clusters.

The finding of staphylococci in the nasopharynx is of no diagnostic value,

blood cultures may be positive.

Pleural fluid reveals an exudate with polymorphonuclear cell counts of 300-

100,000/mm3 , protein above 2.5 g/dL, and a low glucose concentration.

ROENTGENOGRAPHIC FINDINGS.

nonspecific bronchopneumonia early in the illness.

The infiltrate may become patchy and limited in extent

may be dense and homogeneous and involve an entire lobe or hemithorax.

The right lung is involved in about 65% of cases

bilateral involvement occurs in fewer than 20% of patients

A pleural effusion or empyema

pyopneumothorax occurs in approximately 25%.

Pneumatoceles of various sizes

no roentgenographic change can be considered diagnostic

rapid progression from bronchopneumonia to effusion or pyopneumothorax with or

without pneumatoceles is highly suggestive of staphylococcal pneumonia

Chest films should be obtained at frequent intervals if the diagnosis is suspected

Clinical improvement usually precedes roentgenographic clearing by weeks,

pneumatoceles may persist for months.

Treatment.

antibiotics

drainage of collections of pus.

should be given oxygen and placed in a semireclining position to relieve cyanosis and

anxiety.

intravenous hydration and nutrition

Assisted ventilation may be needed.

A semisynthetic, penicillinase-resistant penicillin should be administered intravenously

immediately after cultures are obtained (cloxacillin,100 mg/kg/24 hr for 4 to 6 weeks

initially IV and when tolerates oral change to tablets. Infant can be given tablet after

making it powder mix with honey).

Pleural tap even if only a small empyema is present, in order to reduce the chance of

bronchopleural fistula

Generally, pus reaccumulates so rapidly and becomes so viscous or loculated that closed

drainage with a chest tube of the largest possible caliber is required

The appearance of pyopneumothorax is another indication for immediate insertion of a

catheter into the pleural space.

Once begins to improve and the lung has re-expanded, the tubes can be removed,

Complications.

empyema,

pyopneumothorax,

pneumatoceles

= are considered part of the natural course of the illness and not complications.

Septic lesions outside the respiratory tract = pericarditis, meningitis, osteomyelitis, and

metastatic abscesses in soft tissue

Prognosis.

mortality still ranges from 10-30%

Factors =

the length of illness before hospitalization

age of the patient,

adequacy of therapy,

the presence of other illness or complications. 

Source:DR.NS.MANI.MD Associate Professor in Pediatrics

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