The most likely organism is enterohemorrhagic verotoxin-producing E.coli. It usually causes haemolytic uremic syndrome.
Crohn’s disease rarely manifests in an acute manner.
Polio and giardiasis usually manifest with non-bloody diarrhoea.

The cause for bone marrow suppression in this patient is most probably mercaptopurine toxicity.
Azathioprine is metabolized to 6-mercaptopurine (6-MP), which itself is metabolized by xanthine oxidase.
Xanthine oxidase inhibition by allopurinol leads to the accumulation of 6-MP which then precipitates bone marrow failure.
This may be potentially fatal if unrecognized.
Clinical presentation:
Toxicity symptoms include gastrointestinal symptoms, bradycardia, hepatotoxicity, myelosuppression.

Burkholderia cepacia is an aerobic gram-negative bacillus found in various aquatic environments. B cepacia is an organism of low virulence and is a frequent colonizer of fluids used in the hospital (e.g., irrigation solutions, intravenous fluids).
B cepacia, as a non-aeruginosa pseudomonad, is usually resistant to aminoglycosides, antipseudomonal penicillin, and antipseudomonal third-generation cephalosporins and polymyxin B.
B cepacia is often susceptible to trimethoprim plus sulfamethoxazole (TMP-SMX), cefepime, meropenem, minocycline, and tigecycline and has varying susceptibility to fluoroquinolones.
Based on the options available, ceftazidime and aminoglycoside would be the best option.

Varicella zoster virus (VZV) presents in this way and the rash transforms from macules to vesicles. Pneumonitis is a common complication of VZV infection.

Ankylosing spondylitis (spondylarthritis) is a chronic inflammatory disease of the axial skeleton that leads to partial or even complete fusion and rigidity of the spine. Males are disproportionately affected and upwards of 90% of patients are positive for the HLA-B27 genotype, which predisposes to the disease. The most characteristic early finding is pain and stiffness in the neck and lower back, caused by inflammation of the vertebral column and the sacroiliac joints. The pain typically improves with activity and is especially prominent at night. Other articular findings include tenderness to percussion and displacement of the sacroiliac joints (Mennell’s sign), as well as limited spine mobility, which can progress to restrictive pulmonary disease.
The most common extra-articular manifestation is acute, unilateral anterior uveitis. Diagnosis is primarily based on symptoms and x-ray of the sacroiliac joints, with HLA-B27 testing and MRI reserved for inconclusive cases. There is no curative treatment, but regular physiotherapy can slow progression of the disease. Additionally, NSAIDs and/or tumour necrosis factor-α inhibitors may improve symptoms. In severe cases, surgery may be considered to improve quality of life. The spine adopts a bamboo shape, not lordosis. The pain usually improves as the day progresses. leg raise test causes pain in cases of meningitis etc not in this case.

MRA is next appropriate management for this case. It is non-invasive and has been shown to correlate with angiographic appearance. Although Renal arteriography is considered gold standard, it is invasive, so a non-invasive option is preferred as first line of investigation in this case.

Weight gain is an extremely common (5-40%) adverse effect of atypical antipsychotics such as olanzapine (dose dependent). Olanzapine causes orthostatic hypotension ≥20% of reported cases. Parkinsonism reactions occurs in 4% of people.

Hypotensive effect of streptokinase occurs during the streptokinase infusion which is usually transient. Acute mitral regurgitation due to rupture of papillary muscles, ventricular septal defects and reinfarctions (left or right) are known to cause hypotension after 24 hrs. Pulmonary embolism is less likely but cannot be excluded.

Hashimoto thyroiditis is the most common cause of hypothyroidism in developed countries. In contrast, worldwide, the most common cause of hypothyroidism is an inadequate dietary intake of iodine. This disease is also known as chronic autoimmune thyroiditis and chronic lymphocytic thyroiditis.

The prompt is suggestive of acute appendicitis. The Alvarado score is a clinical scoring system used to determine the likelihood of appendicitis, so this is the correct answer. A score greater than 6 is generally considered at risk for having acute appendicitis. It has 8 different criteria included (symptoms, signs, and lab results) and divides patients into appendicitis unlikely, possible, probable, and definite. The Center Score is a score to access the likelihood that pharyngitis is due to Strep. The Child-Pugh score predicts prognosis in liver cirrhosis. The Glasgow score is two different scores– the Glasgow coma score in trauma, which estimates level of consciousness, essentially, and The Glasgow Imrie Criteria which determines the severity of acute pancreatitis based on 8 lab values. The MELD score predicts the severity of end-stage liver disease.