Interactive Quiz: Abdominal Pain
Welcome to Pulmonology Consultant’s latest interactive diagnostic quiz. Over the next few pages, we'll present a case and ask you to make the diagnosis and treat the patient. Along the way, we'll provide details about the case, and at the end, we'll share the patient's outcome.
First, let’s meet the patient…
A 56-year-old woman with a history of type 2 diabetes mellitus, hypertension, and hyperlipidemia presented to the emergency department with abdominal pain. She reported constant left-sided abdominal pain that had progressively worsened for a week, with associated profuse nonbloody diarrhea.
She reported having had mild shortness of breath with prolonged exertion over the past 6 weeks, but it had not been significant enough to concern her. She denied a history of HIV or having HIV risk factors. She denied cough, fevers, chills, sick contacts, and recent domestic or international travel but reported having noted a foul odor in her apartment that had intensified since the beginning of the summer months.
On initial evaluation, the patient was noted to be hypoxic, requiring high levels of oxygen via nasal cannula in order to maintain oxygen saturation above 90% as measured by pulse oximetry (Spo2). She was afebrile, with a blood pressure of 94/53 mm Hg, a pulse rate of 90 beats/min, a respiratory rate of 32 breaths/min, and an Spo2 of 90% on 8 L/min of oxygen via nasal cannula.
She was noted to have increased respiratory effort with decreased breath sounds in all right lung fields, left basilar crackles, and coarse breath sounds on the left middle and left upper lung fields. Cardiac examination findings were normal. Her abdomen was tender to light palpation in left upper and left lower quadrants without rebound tenderness or guarding. No deficits were appreciated on neurologic examination except for marked delay in responses to simple questions.
Answer: Regular blood test
Laboratory studies revealed the following values: sodium, 138 mEq/L (reference range, 136-142 mEq/L); potassium, 3.1 mEq/L (reference range, 3.5-5.0 mEq/L); chloride, 100 mEq/L (reference range, 96-106 mEq/L); bicarbonate, 24 mEq/L (reference range, 21-28 mEq/L); urea nitrogen, 51 mg/dL (reference range, 8-23 mg/dL); lactate, 10.8 mg/dL (reference range, 5.0-15.0 mg/dL); and creatinine, 3.04 mg/dL (reference range, 0.6-1.2 mg/dL).
Arterial blood gas tests revealed the following values: pH, 7.48 (reference range, 7.35-7.45); partial pressure of carbon dioxide, 35 mm Hg (reference range, 35-45 mm Hg); partial pressure of oxygen, 51 mm Hg (reference range, 80-100 mm Hg); and bicarbonate, 26.1 mEq/L (reference range, 21-28 mEq/L). The results of urinalysis and urine drug screening tests were both negative.
A chest radiograph (Figure 1) showed asymmetric patchy alveolar interstitial infiltrates and middle to lower lobe consolidation, findings that were visualized on a chest computed tomography (CT) scan (Figure 2).
Answer: Legionnaire disease
The patient was tested for the Legionella pneumophila antigen, the results of which were positive, leading us to the diagnosis and proper management.
The United States has an annual incidence of 8000 to 18,000 new cases of Legionnaire disease. Most cases occur during the late spring or early fall, and there is a mildly increased incidence in northern states.1,2
The responsible pathogen was identified in 1976 as L pneumophila, although this bacterium is one of 42 species constituting 64 serogroups.2,3 It is a small, gram-negative, catalase-positive, weakly oxidase-positive, aerobic, waterborne bacterium that is nonmotile and often lives in symbiosis with various amoebic species that are common residents of water-rich environments. These water-rich environments include the cooling systems found in hotels, apartments, cruise ships, and hospitals, as well as showers, decorative fountains, humidifiers, and whirlpool spas, among other structures, in which the bacteria can survive at an optimal temperature.
Humans often become infected through inhalation of aerosolized particles or via aspiration of contaminated liquid. Legionella infection typically is not transferrable directly from human to human.4 Our patient became infected via her window air conditioner that she had begun to use during the late spring.
Answer: Any of the above
Once the diagnosis has been made, patients are often treated with macrolide, tetracycline, or fluoroquinolone antibiotics. The goal is to choose an antibiotic with adequate intracellular penetration due to the intracellular nature of Legionella.
The most commonly used antibiotics are azithromycin, doxycycline, and levofloxacin. Typically, antibiotic therapy is started in the hospital intravenously, with the therapy being switched to oral antibiotics once a patient’s condition has stabilized.
The duration of therapy is usually 3 to 5 days for azithromycin and 5 to 10 days for levofloxacin, unless there is severe disease with sepsis or if the patient is immunocompromised, in which treatment is extended.6
Prognosis is highly variable and often depends on a patient’s comorbid conditions as well how quickly treatment is initiated, with increasing mortality in nosocomial infections.6 Therefore, prevention is of the utmost importance and can be done by superheating water sources to 70°C to 80°C or utilizing copper-silver ionization units, or UV light, all of which eradicate the Legionella bacteria.8
Carlos Ruz-Pau, MD, and Jorge Parellada, MD
Orlando Regional Medical Center, Orlando, Florida
Zoran Pavlovic, MS-IV
University of Central Florida, Orlando, Florida
Ruz-Pau C, Pavlovic Z. Legionnaire disease. 2017;57(4):234-235. https://www.consultant360.com/articles/collection-conditions-affecting-lungs?page=1.
- Marston BJ, Plouffe JF, File TM Jr, et al. Incidence of community-acquired pneumonia requiring hospitalization: results of a population-based active surveillance study in Ohio. Arch Intern Med. 1997;157(15):1709-1718.
- Brunkard JM, Ailes E, Roberts VA, et al. Surveillance for waterborne disease outbreaks associated with drinking water—United States, 2000–2008. MMWR Surveill Summ. 2011;60(12):38-68.
- Kozak-Muiznieks NA, Lucas CE, Brown E. Prevalence of sequence types among clinical and environmental isolates of Legionella pneumophila serogroup 1 in the United States from 1982 to 2012. J Clin Microbiol. 2014; 52(1):201-211.
- Woo AH, Goetz A, Yu VL. Transmission of Legionella by respiratory equipment and aerosol generating devices. Chest. 1992;102(5):1586-1590.
- Newton HJ, Ang DKY, van Driel IR, Hartland EL. Molecular pathogenesis of infections caused by Legionella pneumophila. Clin Microbiol Rev. 2010; 23(2): 274-298.
- Cunha BA, Burillo A, Bouza E. Legionnaires’ disease. Lancet. 2016; 387(10016): 376-385.
- Tan MJ, Tan JS, Hamor RH, File TM Jr, Breiman RF. The radiologic manifestations of Legionnaire’s disease. Chest. 2000;117(2):398-403.
- Borella P, Bargellini A, Marchegiano P, Vecchi E, Marchesi I. Hospital-acquired Legionella infections: an update on the procedures for controlling environmental contamination. Ann Ig. 2016;28(2):98-10