Clinical and evolutive aspects of Coxiella burnetii infection

Abstract

Introduction. Coxiella burnetii is the etiological agent of Q fever, a zoonosis that is still subject of „Query”. Formerly classified as a Rickettsia, C. burnetii is a highly infectious obligate intracellular bacteria, whose main animal reservoirs are cattle, sheep and goats. Commonly following transmission through inhalation of aerosols containing the pathogen spread during animal parturition, Q fever may present as a self-limited febrile illness, pneumonia or acute hepatitis. Nevertheless, the possibility of evolving towards a chronic form exists under certain circumstances, mainly involving previously affected heart valves or blood vessels. Diagnosis is usually serologically based and Doxycycline represents the most frequent choice of antibiotherapy. Objectives. The aim of this study is to analyse the clinical and laboratory settings that led to diagnosis of acute or chronic Q fever, the treatment regimens applied and consecutive outcome within the group of patients defined below. Materials and methods. The present paper represents an observational descriptive study performed on a group composed of 24 patients admitted in our hospital along 2018 and diagnosed with confirmed or probable acute or chronic Q fever. Both male and female subjects regardless of their age were included, under the condition of meeting the CDC case definition, by integrating the serological results into the clinical context. results and conclusions. A suggestive epidemiological frame was rarely proven. Out of the 24 subjects with ages between 34 and 80 years old, of which only 2 were women, 22 had acute Q fever, manifested mostly as a combination of atypical pneumonia and hepatitis (9 cases, representing 41. Only 2 of the acute Q fever cases had a confirmed diagnosis. Frequent complaints were fever (all cases), chills, headaches and vomiting. Only 28% of the radiologically confirmed pneumonias were accompanied by dry cough, whilst only 21% of the hepatitis cases associated jaundice. Biologically, although leukocytosis was more weakly cor-related with acute disease activity, all patients exhibited a moderate to high inflammatory response (through C reactive protein). Considering the latency of specific antibodies’ dosage results, the decision of initiating treatment was based on a clinical support. Antibiotherapy consisted of Doxycyclin, alone or in combinations meant to cover a larger spectrum, given the usually nonspecific symptoms and the initially low clinical suspicion for Q fever. Clinical evolution was favorable in all cases. Regarding the two patients with chronic Q fever, manifested as blood culture-negative endocarditis, of which only one was confirmed according to the CDC definition, both had presented valvular lesions before developing IE and had no history of acute infection with C. burnetii. In the first case, under empirical infective endocarditis agents (Ceftriaxone and Vancomycin), acute heart failure and necessity of surgical replacement of the affected valve occured, only afterwards be- ing followed by the elevated phase I IgG level that brought diagnostic confirmation. Meanwhile, the second patient did receive a combination with Doxycycline, followed by favorable clinical evolution during admission.