To the Editor: Acinetobacter radioresistens is a gram-negative coccobacillus, which is ubiquitous in soil and water, but however, is rarely responsible for causing clinically significant infections. We present a case of a 61-year-old white man with chronic obstructive pulmonary disease (COPD) and hepatitis C who developed septicemia because of A. radioresistens in the setting of pneumonia. CASE DESCRIPTION A 61-year-old white man presented to the emergency room with chills, fever, shortness of breath, and right-sided chest pain with mild cough for 3 days. The patient denied any recent travel, sick contacts, occupational hazards/exposures, animal hunting, or slaughtering. His history was significant for oxygen-dependent COPD; multiple, spontaneous right-sided pneumothoraxes due to COPD, which needed talc pleurodesis; gastroesophageal reflux disease; and hepatitis C virus (HCV). His medications included budesonide/formoterol, tiotropium, ginger root, and glucosamine/chondroitin. The patient was a former smoker and quitted smoking cigarettes 3 years ago. He admitted to drinking alcohol once every 1 to 2 weeks. Physical examination showed a temperature of 38.4°C (101.1°F), pulse of 132/min, respiratory rate of 27/min, blood pressure of 163/91 mm Hg, and an oxygen saturation of 92% on 3-L/min oxygen by nasal cannula. He was tachypneic and seemed in moderate respiratory distress with bibasilar lung crackles, prolonged expiratory breath sounds, and occasional generalized wheezing. The rest of the physical examination was unremarkable. Electrocardiogram showed sinus tachycardia. Influenza A/B/H1N1 polymerase chain reaction was negative. Complete blood cell count showed a white blood cell count of 10,600/mm3 (reference, 4000–11000/mm3) with 9000/mm3 neutrophils (reference, 2000–8000/mm3). Arterial blood gas showed a pH of 7.42, Pco2 of 31 mm Hg, and Po2 of 65 mm Hg on 3-L/min oxygen. The rest of the electrolytes were unremarkable. Chest radiograph showed severe emphysematous changes with bilateral basal patchy airspace disease/consolidation. He was empirically started on ceftriaxone and azithromycin for suspected pneumonia and was given intravenous methylprednisolone and albuterol nebulizers for presumptive exacerbation of COPD and was admitted to the hospital. The following day (after 24 hours), his blood cultures turned positive in aerobic bottle for gram-negative coccobacilli (BacT/ALERT System; BioMérieux, Marcy-l'Etoile, France), so he was switched to piperacillin-tazobactam. Nonlactose fermenting growth was seen on MacConkey agar, and whitish colonies of gram-negative coccobacillus were seen on blood and chocolate agars. Next day, bacterium was identified to be A. radioresistens using Vitek 2 automatic bacterial identification system (BioMérieux, Marcy-l'Etoile, France). Because the patient had no known predisposing risk factors for Acinetobacter infections such as open wound, trauma, indwelling line, or multiple recent hospitalizations, testing for human immunodeficiency virus was performed, which came back negative. His HCV viral RNA load was 1.8 million IU/mL (reference, <15), HCV genotype was 3a, and anti-HCV antibody was reactive. On further questioning, the patient revealed that he had been digging dirt a week before presenting to the emergency room, which resulted in few minor scratches/excoriations on his skin. Acinetobacter radioresistens was sensitive to piperacillin/tazobactam, ampicillin/sulbactam, cefepime, ciprofloxacin, levofloxacin, trimethoprim-sulfamethoxazole, imipenem, gentamycin, and tobramycin. The patient was treated with intravenous ampicillin-sulbactam for 14 days. He was also prescribed an oral tapering course of prednisone for his COPD as well. The patient finished a total 14-day course of antibiotics without any difficulty, and his shortness of breath improved significantly. DISCUSSION Acinetobacter radioresistens is a non–spore forming, aerobic gram-negative coccobacillus. Biochemically, it does not ferment lactose and is catalase positive and oxidase negative. Acinetobacter is ubiquitous in soil and water. It has also been found in stool and river water and on vegetables, pillows, and head lice. Its ability to withstand extreme desiccation and radiation exposure (hence the name radioresistens) helps it survive in extreme weather conditions and cause nosocomial infections.1 Acinetobacter radioresistens has previously been shown to cause septicemia in an immunocompromised individual where origin of septicemia was thought to be middle ear/sinus infection.2 Outside the United States, there has been a reported case, similar to ours, where this bacterium caused pneumonia in a patient with COPD.3 There have been reports of nosocomial outbreak of A. radioresistens from hospital pneumatic tube systems as well. Treatment of A. radioresistens infection is with antibiotics, and although the bacterium was pan-sensitive in our case, antibiotic susceptibilities are variable, and there is evidence of carbapenem, fluoroquinolone, and tetracycline resistance in the medical literature.4 Thus, treatment should be guided by local antibiotic susceptibility reports. Duration of treatment may be longer than 2 weeks and depends on patient's clinical response. CONCLUSIONS Acinetobacter radioresistens is a rare but important cause of community-acquired infection (septicemia in our case). This case adds to the growing scientific body of evidence that A. radioresistens, a rare gram-negative coccobacillus, is a true clinical pathogen. Rajanshu Verma, MD, FACP Department of Hospital Medicine Augusta Health Fishersville, VA [email protected]Allison L. Baroco, MD Department of Infectious Diseases Augusta Health Fishersville, VA
Read full abstract
Oct 15, 2024
Felipe L Pavarino + 9
Open Access