Cedecea davisae’s Role in a Polymicrobial Lung Infection in a Cystic Fibrosis Patient

Chronic airway colonization and infection are the hallmark of cystic fibrosis (CF). Staphylococcus aureus, Pseudomonas aeruginosa, and Burkholderia cepacia are well-documented bacterial culprits in this chronic suppurative airway disease. Advanced molecular diagnostics have uncovered a possible role of a larger group of microorganisms in CF. Cedecea is a member of the family Enterobacteriaceae and is an emerging pathogen. We present a case of a polymicrobial healthcare-associated pneumonia in a CF patient caused by Cedecea davisae, among other bacteria. 1. Background Cystic fibrosis (CF) is an autosomal recessive disorder characterized by viscous secretions [1]. Tenacious secretions render mucus-clearing mechanisms and cough ineffective and predispose to the development of bronchiectasis. Furthermore, CF is characterized by episodic exacerbations and acute pulmonary infections. Most respiratory bacterial infections in CF patients are caused by Staphylococcus aureus, Pseudomonas aeruginosa, and Burkholderia cepacia complex [2]. Recent advances in molecular diagnostics have raised the possibility of more diverse bacterial infections, including anaerobes and Enterobacteriaceae [3]. Although these bacteria might play a role in exacerbations and acute pneumonias in this group of patients, they are not as persistent in the CF lung as the aforementioned bacteria. Cedecea davisae is an emerging pathogen [4, 5]. It is a Gram-negative bacterium that has been implicated in causing catheter-related blood stream infection, bacteremic skin and soft tissue infection, and lung infection [4–6]. We present a case of a polymicrobial pulmonary infection in a CF patient caused by methicillin-susceptible S. aureus (MSSA), B. cepacia, and C. davisae. The latter has not been reported in CF patients, nor has it been demonstrated to be as extensively drug resistant as in the case at hand. 2. Case Presentation A 20-year-old female patient with CF presented with 5-day history of fevers, progressive shortness of breath, and productive cough with increasing sputum amount and purulence. In the past 2 years, the patient had an average of 5 or 6 admissions per year for CF exacerbations. She was known to be colonized by multidrug-resistant (MDR) P. aeruginosa and Methicillin-resistant S. aureus (MRSA). She had an extensive exposure to all classes of antibiotics, including carbapenems and intravenous as well as nebulized colistin. The patient reported a sulfa allergy since childhood. On examination, the patient had severe cachexia and was in obvious respiratory distress. Temperature was