Septic shock with Chlamydia abortus infection

A 65-year-old man presented with an acute onset of fever (39·8°C), dizziness, and headache without evident predisposition. A CT scan showed left upper lobe pneumonia and he received imipenem–cilastatin (2 g every 8 h), but his symptoms did not improve. However, on day 3 of admission, he rapidly developed refractory hypoxaemia, respiratory failure, and septic shock. He then presented to the Department of Critical Care Medicine at Guangdong Provincial People's Hospital (Guangzhou, China). The severity of hypoxia and multiple organ dysfunction syndrome did not match the pulmonary imaging changes from day 4 to day 9 (figure). Despite the empirical use of anti-infective drugs and antibiotics (cefoperazone [3 g every 8 h], meropenem [1 g every 8 h], and linezolid [600 mg every 12 h] for 4 days), the hypoxia was not corrected. Serological analyses and bacterial culture ruled out the involvement of the common respiratory pathogens, such as Mycoplasma pneumoniae, Legionella pneumophila, Rickettsia conorii, and Chlamydia pneumoniae. On day 8 of admission, the patient's bronchoalveolar lavage fluid and blood were sent to two genetic testing companies (BGI Group and Vision Medicals Center for Medical Research). The results both showed that the DNA sequences of Chlamydia abortus were detected by next-generation sequencing. Despite absence of direct contact with infected animals, C abortus was identified as a causal agent of the infection. After adjustment of the treatment programme to azithromycin (500 mg every 12 h for 5 days) and levofloxacin (500 mg every 12 h for 6 days), the patient had a successful recovery. On day 9 of admission, his inflammatory indexes, including C-reactive protein, procalcitonin, white blood cell count, and neutrophil count, were improved. Meanwhile, his oxygenation index, temperature, and cardiopulmonary function examinations, including brain natriuretic peptide and troponin T, showed improvement. He was asymptomatic during 9 months of follow-up and had no recurrence of C abortus infection. C abortus-induced pneumonia is rare but can be devastating. It is vital to identify what symptoms can present with C abortus infection. Diagnosis of C abortus can be missed by serological analyses or bacteriological techniques alone; however, application of genetic tests is beneficial to some extent.