Case 01:
i. What does the Gram stain show?
ii. What is the most likely diagnosis?
iii. What additional diagnostic considerations are raised by this clinical presentation?
Case 02:
This previously well 36-year-old East African female has had increasing shortness of breath for 3 weeks associated with a dry cough and some retrosternal chest pain on deep breathing. On examination, she is pyrexial at 37.7°C and cyanosed, with a respiratory rate of 40 breaths/min. Auscultation of the chest reveals some fine bilateral crepitations, and blood and sputum cultures are both negative. Her chest X-ray (2a) and CT scan (2b) are shown.
i. What is the likely diagnosis?
ii. How can the diagnosis be confirmed, and what is a likely underlying condition?
iii. What is the recommended treatment?
Answer Case 01:
i. The sputum Gram stain shows numerous polymorphonuclear leukocytes, strands of mucus, and many Gram-positive, lancet-shaped diplococci. Refractile capsules are evident on many of the bacteria.
ii. The young patient has an acute pneumococcal pneumonia and has suffered numerous recurrent respiratory infections.
iii. Most patients with recurrent respiratory infections have no identifiable host defect. However, recurrent pneumonias in the same lobe or segment should suggest an anatomical abnormality. When multiple sites have been involved, disorders of mucociliary clearance such as cystic fibrosis or the ciliary dyskinesia syndrome (Kartagener’s syndrome) are an important consideration.
Recurrent infections with encapsulated organisms such as the pneumococcus are consistent with a defect in opsonization (e.g. complement, IgG or IgG subtype deficiencies). Deficiencies of complement components are rare and are best managed by immunization and by the early treatment of infectious complications.
Immunoglobulin deficiencies can also be primary (inherited) or acquired due to acquired B-cell disorders, medications, or intercurrent illnesses. IgA is heavily concentrated in mucosal secretions, where it inhibits bacterial adherence. Although selective IgA deficiency is common, it rarely results in serious respiratory infection unless other deficiencies coexist. IgG deficiency (either generalized or restricted to subclasses IgG1 and IgG3) predisposes to more frequent and more severe respiratory infections. Intravenous immunoglobulin replacement may be helpful.
Answer Case 02:
i. The combination of an insidious but progressive illness with cough, marked hypoxaemia, and a chest radiograph showing bilateral perihilar infiltrates with peripheral sparing (2a) (confirmed as mainly upper lobe symmetrical ground-glass infiltrates with peripheral sparing on CT scan (2b)) are highly suggestive of Pneumocystis jirovecii pneumonia (formerly Pneumocystis carinii pneumonia or PCP). In addition, the patient belongs to a high-risk population (sub-Saharan African).
ii. P. jirovecii pneumonia is the classical opportunistic pneumonia affecting HIV- positive patients, especially once their lymphocyte CD4-positive count has fallen to less than 200 cells/μl. Presentation is usually a slow onset of dyspnoea associated with an unproductive cough, sometimes associated with a distinctive retrosternal pain on inspiration or coughing. The pyrexia is relatively mild, and chest signs are often limited. Patients characteristically have a fall in oxygen saturations on exercise and a marked reduction in their carbon monoxide transfer factor.
Diagnosis requires obtaining a BAL or induced sputum sample for cytology, in which the characteristic cysts can be identified by cytology using Grocott’s methenamine silver staining (which stains the cysts black), or immunofluorescence with specific antibodies. A classical presentation in someone known to be HIV positive can be treated empirically, reserving invasive investigations for if the patient fails to respond. Pneumocystis jirovecii pneumonia also occurs in patients with other T-cell defects such as those who have had organ or bone marrow transplantation, or individuals on long-term immuosuppression.
iii. Treatment is with high-dose co-trimoxazole (120 mg/kg in divided doses daily for 3 days, and then 90 mg/kg). If the PaO2 is <9.3 kPa (70 mmHg) or the alveolar oxygen gradient is >4.7 kPa (33 mmHg), adjuvant corticosteroids have been shown to improve outcome (e.g. 40 mg prednisolone twice a day for 5 days, followed by 40 mg for 5 days and then 20 mg for 11 days). For patients who are intolerant of Septrin (co-trimoxazole), second-line therapy is usually primaquine 15 mg once daily and clindamycin 600 mg four times a day.
The photomicrograph shows a Gram stain of sputum expectorated by a 19-year-old male with symptoms of fever, rigors, and a productive cough of 2 days’ duration. He has experienced four episodes of radio-graphically documented pneumonia and numerous episodes of acute otitis media and sinusitis in the past.
i. What does the Gram stain show?
ii. What is the most likely diagnosis?
iii. What additional diagnostic considerations are raised by this clinical presentation?
Case 02:
This previously well 36-year-old East African female has had increasing shortness of breath for 3 weeks associated with a dry cough and some retrosternal chest pain on deep breathing. On examination, she is pyrexial at 37.7°C and cyanosed, with a respiratory rate of 40 breaths/min. Auscultation of the chest reveals some fine bilateral crepitations, and blood and sputum cultures are both negative. Her chest X-ray (2a) and CT scan (2b) are shown.
i. What is the likely diagnosis?
ii. How can the diagnosis be confirmed, and what is a likely underlying condition?
iii. What is the recommended treatment?
Answer Case 01:
i. The sputum Gram stain shows numerous polymorphonuclear leukocytes, strands of mucus, and many Gram-positive, lancet-shaped diplococci. Refractile capsules are evident on many of the bacteria.
ii. The young patient has an acute pneumococcal pneumonia and has suffered numerous recurrent respiratory infections.
iii. Most patients with recurrent respiratory infections have no identifiable host defect. However, recurrent pneumonias in the same lobe or segment should suggest an anatomical abnormality. When multiple sites have been involved, disorders of mucociliary clearance such as cystic fibrosis or the ciliary dyskinesia syndrome (Kartagener’s syndrome) are an important consideration.
Recurrent infections with encapsulated organisms such as the pneumococcus are consistent with a defect in opsonization (e.g. complement, IgG or IgG subtype deficiencies). Deficiencies of complement components are rare and are best managed by immunization and by the early treatment of infectious complications.
Immunoglobulin deficiencies can also be primary (inherited) or acquired due to acquired B-cell disorders, medications, or intercurrent illnesses. IgA is heavily concentrated in mucosal secretions, where it inhibits bacterial adherence. Although selective IgA deficiency is common, it rarely results in serious respiratory infection unless other deficiencies coexist. IgG deficiency (either generalized or restricted to subclasses IgG1 and IgG3) predisposes to more frequent and more severe respiratory infections. Intravenous immunoglobulin replacement may be helpful.
Answer Case 02:
i. The combination of an insidious but progressive illness with cough, marked hypoxaemia, and a chest radiograph showing bilateral perihilar infiltrates with peripheral sparing (2a) (confirmed as mainly upper lobe symmetrical ground-glass infiltrates with peripheral sparing on CT scan (2b)) are highly suggestive of Pneumocystis jirovecii pneumonia (formerly Pneumocystis carinii pneumonia or PCP). In addition, the patient belongs to a high-risk population (sub-Saharan African).
ii. P. jirovecii pneumonia is the classical opportunistic pneumonia affecting HIV- positive patients, especially once their lymphocyte CD4-positive count has fallen to less than 200 cells/μl. Presentation is usually a slow onset of dyspnoea associated with an unproductive cough, sometimes associated with a distinctive retrosternal pain on inspiration or coughing. The pyrexia is relatively mild, and chest signs are often limited. Patients characteristically have a fall in oxygen saturations on exercise and a marked reduction in their carbon monoxide transfer factor.
Diagnosis requires obtaining a BAL or induced sputum sample for cytology, in which the characteristic cysts can be identified by cytology using Grocott’s methenamine silver staining (which stains the cysts black), or immunofluorescence with specific antibodies. A classical presentation in someone known to be HIV positive can be treated empirically, reserving invasive investigations for if the patient fails to respond. Pneumocystis jirovecii pneumonia also occurs in patients with other T-cell defects such as those who have had organ or bone marrow transplantation, or individuals on long-term immuosuppression.
iii. Treatment is with high-dose co-trimoxazole (120 mg/kg in divided doses daily for 3 days, and then 90 mg/kg). If the PaO2 is <9.3 kPa (70 mmHg) or the alveolar oxygen gradient is >4.7 kPa (33 mmHg), adjuvant corticosteroids have been shown to improve outcome (e.g. 40 mg prednisolone twice a day for 5 days, followed by 40 mg for 5 days and then 20 mg for 11 days). For patients who are intolerant of Septrin (co-trimoxazole), second-line therapy is usually primaquine 15 mg once daily and clindamycin 600 mg four times a day.
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