Question

Read the Case Study and answer the questions that follow.

The Patient was a 70-year-old female who one year previously was diagnosed with multiple myeloma. She had been treated with five cycles of immunosuppressive drugs including prednisone, with the last cycle completed 6 weeks previously. The patient presented with a 2-day history of dyspnea and a cough productive of white phlegm. She denied hemoptysis, night sweats, fever, chills, abdominal pain, nausea, vomiting, or chest pain. On physical examination, she had a fever of 38.8 o C, pulse of 120/min, and respiratory rate of 120/min. Chest auscultation was significant for bilateral crackles with expiratory wheezes.Chest radiograph showed bilateral, diffuse pulmonary infiltrates with effusion. White blood cell count was 1,700 cells per l. She had a pO 2 of 38 mm Hg which was corrected by receiving oxygen by nasal cannula. Sputum and blood cultures were obtained, and she was
begun on Cefotazime and Clindamycin intravenously for presumed bacterial pneumonia.Gram stain of the organism recovered from both cultures revealed a Gram-positive coccus. The organism produced alpha hemolysis on blood agar.

Answer the following

1. What has this patient been diagnosed with? What risk factors does this woman possess for developing infection with this organism?

2. What is the major virulence factor for this organism and its role in the pathogenesis of disease?

3. What other populations are at risk for infection with this organism?

4. What can be done to try to prevent infections with it?

Thank you

Answer 1

Answer :

1. Pneumococcal pneumonia is the likely diagnosis.

Streptococcus pneumoniae (Pneumococcus) is Gram positive lancet shaped diplococcus.

Risk factors in this case for developing Pneumococcal pneumonia:

A. Multiple myeloma - Multiple myeloma is a gammopathy in which defective immunoglobulin is produced in large abnormal quantities. These defective monoclonal immunoglobulins are not protective against many pathogens.

B. Age > 65 years is also a risk factor (Patient's age is 70 years)

C. Leucopenia - Total leucocyte count as given is 1700/micro litre (Normal TLC= 4000-11000 cells/microlitre)

D. Immunosuppressive therapy - Patient has received many cycles of immunosuppressive therapy including prednisone (steroid)

2. Major virulence factor of Pneumococcus is capsule composed of polysaccharide.

Capsule inhibits phagocytosis of bacteria and thus protects from immune system of the host.

3. Population at risk for Pneumococcal pneumonia:

* Age < 2 years or > 65 years

* Person with defective immunity (defect in complement or immunoglobulins)

* Person with chronic lung disease

* Person with chronic liver disease

* Diabetic

* Alcoholic

* Asplenia or hyposplenia

* Immunocompromised status such as HIV

* Person living in overcrowded place.

4. Person can be vaccinated after consultation with the doctor to provide protection against Pneumococcus.Two common vaccines which can prevent Pneumococcal pneumonia:

* Pneumococcal polysaccharide vaccine (PPV)-23 consists of 23 most common capsular types that cause invasive pneumococcal disease.

* Polysaccharide - protein conjugate vaccine (PCV) targets seven serotypes responsible for most pneumococcal pneumonia.

Discussion and explanation:

Pneumonia is exudative inflammation of lung parenchyma.

There are four stages of pneumonia:

1) Stage of congestion - Just congestion without actual alveolar exudate.Crepitations can be heard in this stage.

2) Stage of red hepatisation - Alveolar exudate containing red blood cells. Bronchial breathing is usually heard.

3) Stage of grey hepatisation - Exudate mainly contains white blood cells with minimum red blood cells. Bronchial breathing is heard usually.

4) Stage of resolution - Exudate is gradually absorbed, crepitations are usually heard in this stage.

Pneumococcus is probably the most common bacteria causing pneumonia. These are Gram positive cocci occurring in pairs which show alpha hemolysis on blood agar producing green color.

Patient usually presents with cough, fever, headache and shortness of breath.

Diagnosis can be done by microscopic examination and culture of sputum.