Organisms and associated clinical features Adapted from Dr Andrew Coggin’s ‘Revision Notes for the FACEM Fellowship Exam’ document Organism/Condition Streptococcus Mycoplasma Legionella Chlamydia Staphylococcus Klebsiella Pseudomonas Nosocomial Haemophillis Influenzae Moraxella Catarrhalis Aspiration Hanta Virus Yersinia Pestis Bacillus Anthrax Tularemia Q Fever Psittacosis Fungal SARS Virus Immunocompromised Classical Presentation
Gram positive. Encapsulated diplococcic. High spiking fevers and rigors. The prototype atypical pneumonia. Younger patients. Epidemics. The organism is not shown on gram stain. Penicillin is ineffective. Vague changes on CXR (often bilateral). There are multiple associations including Myringitis, Erythema Multiforme and Guillain Barré Syndrome. High mortality. First described at a Legionnaires convention in the 1970s. Spread from air vents/air conditioning. Relatively normal vitals (ie not tachycardic) but can be very unwell looking. No patient‐to‐patient transmission. Associated GI symptoms and deranged LFTs. Can sometimes be typical in its presentation. Gradual onset. Dry cough, fever, wheeze, infiltrates. Neonate with an afebrile staccato‐like cough (transmitted from birth canal). Less common than Streptococcus. High mortality with MRSA. Severe pneumonia of gradual onset. Cavitations on CXR. Often follow a viral illness. Gram positive cocci in clusters on microscopy. Consider if there are central lines, medical devices or recent surgery. Classically seen in alcoholics, COPD, diabetes and the elderly. Red currant jelly sputum. Usually involves one of the upper lobes, bulging fissure on CXR. Typical symptoms are fever and rigors. Can also cause cavities. Associated with hospital acquired pneumonia, cystic fibrosis and hot tub use.
After 48 hours of admission or intubation. Consider gram negative organisms including pseudomonas and MRSA. Ventilator associated = high mortality. Gradual onset. Vague, patchy infiltrate. Gram negative cocco‐bacilli on microscopy. Elderly patients, background of COPD, smokers. Pleural effusions are common.
Neurological and muscular disease. Anaerobes common. Location of infiltrate depends on positioning of patient at time of aspiration. Abscesses are common. An initial chemical pneumonitis occurs. Antibiotics are not required unless there is a fever or the patient becomes symptomatic. ARDS, from rodent urine/droppings/saliva. No person‐to‐person spread The Plague. Spread by fleas. Spore‐borne. No person‐to‐person spread. Terrorist use. Eschars and a severe pulmonary syndrome. Wide mediastinum on CXR. Gram positive rods on microscopy. Rabbit skinner’s disease. Lymphadenopathy common.
Coxiella burnetii. From cattle, sheep, goats. Seen in abattoir workers. Person‐to‐
person transmission is rare. Gram negative on microscopy. Bird handler’s pneumonia
Histoplasmosis, Coccidioidomycosis, Blastomycosis. Cavities on CXR. Coronavirus. Severe inflammatory response in young people. Highly infectious.
Most common organisms are typical – eg streptococcus.
Consider TB, CMV and PJP. PJP is an insidious pneumonia causing progressive SOB. Patients desaturate, particularly on walking. Treatment includes Bactrim, pentamidine and steroids.