A 33-year-old housewife with no premorbidities presented with sudden onset of breathlessness after a 4-day history of cough and fever. On examination, she was febrile (fever) and tachypnoeic (abnormal rapid breathing), with oxygen saturation of 84% on high-flow oxygen. Respiratory system examination showed bronchial breath sounds in left supraclavicular and interscapular areas; all other systems were within normal limits. Hence a clinical diagnosis of left upper lobe pneumonia with acute respiratory distress syndrome (ARDS) was initially made, based on the presentation.
Laboratory investigations showed normal white cell counts (WCC) with mildly elevated erythrocyte sedimentation rate (31 mm/h) and mild elevation of aspartate aminotransferase/alanine transaminase (liver enzymes) at (144/152 U/L) levels. Other routine blood parameters were normal. Initial workup for fever, including malaria, dengue, scrub typhus and leptospirosis tests, were negative, thereby ruling out the other common causes of ARDS prevalent in the locality. Hepatitis B surface antigen and HIV were also negative. Chest X-ray showed left hemithorax haziness. ECG showed sinus tachycardia (rapid heart rate) and two-dimensional echocardiography was normal. The ultrasound study of the abdomen was normal. Arterial blood gases showed respiratory alkalosis with PO2/FiO2 of 121. A clinical diagnosis of left upper lobe pneumonia with ARDS was considered, and the patient was started on broad-spectrum antibiotics. She was also started on oseltamivir, after collecting respiratory samples, in view of the possibility of H1N1 influenza, which is commonly seen at that time of the year in the community.
As the patient continued to be tachypnoeic and subsequent investigations showed increasing WCC, she was electively intubated and antibiotics were escalated. Meanwhile, blood and urine cultures were reported as sterile (no bacteria), and viral studies were negative for influenza and other common respiratory viruses. Sputum samples for acid-fast bacilli were reported as negative.
As the patient was not improving on current therapies, on the fourth day of admission, the patient's sputum was again cultured and this time was positive. It was considered that this could be a "false" positive as possibly only normal upper respiratory flora, therefore, a repeat culture of endotracheal aspirate was cultured. This culture was also positive. CT scan of the thorax was suggestive of an acute infective aetiology in both lungs, predominantly in the left upper lobe.
Required:
a) Why did the patient not respond to the previous course of antibiotics?
b) Culturing of the sputum and endotracheal aspirate revealed what type of organism present?
Colonies on the agar appeared initially as a white dense mat with the surface later becoming brownish-black as the culture matured, but a visible whiter edge was still apparent. Microscopic examination revealed septate hyphae with chains of spores arising from the terminal bulb of the aerial hyphae.
c) What specific genus do you suspect is the causative agent of the patient’s ARDS?
d) Would you expect to see other spores present under the scope? If so, what type?
e) What phyla does this organism belong to? How did you determine its classification? Name at least two other medically relevant members of this phyla.
f) Based on this finding, what type of treatment should this patient be started on?
g) Who usually gets this disease type of disease?
h) How do individuals acquire the disease and from where?
i) How common is the disease? In the U. S. how many people are usually hospitalized annually with the disease?
j) Is the disease serious? Can it be fatal? What is the prognosis for this patient?
k) How can the disease be prevented?