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An unusual presentation of a case of human psittacosis
Yannick Vande Weygaerde1, Charlot Versteele2, Elke Thijs1
1Dept. of Respiratory Medicine, Ghent University Hospital, Corneel Heymanslaan 10, B-9000, Ghent, Belgium.
Background:
Chlamydia psittaci is a gram-negative, obligate intracellular organism. Birds are the main reservoir, but also non-avian domestic animals and humans can be infected. In humans it mostly causes respiratory infections due to occupational exposure with varying severity. Sensitive and specific diagnostic tests are needed to define psittacosis in humans as these tests also allow rapid tracing of the animal source. However, diagnosis in humans is often based on time-consuming culture techniques and antibody detection assays as in many countries, the existing molecular diagnostic tests for psittacosis are not reimbursed by the public health insurance.
Case Presentation:
An 82-year old female was referred to the hospital with a non-productive cough since four weeks and since one week fever up to 39 °C, myalgia, generalized skin rash, acral edema and generalized weakness under treatment with moxifloxacin. Blood analysis showed signs of inflammation with mild eosinophilia. Chest CT showed multiple peripheral ground glass opacities with consolidation in both lungs. Pulmonary function testing only showed a mild decrease in diffusion capacity. Viral and bacterial serology were negative. As the patient kept a pet parakeet for over ten years, a nested PCR for C. psittaci was performed on a nasopharyngeal swab of the patient and on feces of the parakeet. Both returned positive for the same genotype. Genotyping was performed by a genotype-specific real-time PCR. The patient fully recovered after a ten-day course of azithromycin.
Conclusion:
Due to non-specific signs during psittacosis, early detection of the infection and differentiation from hypersensitivity pneumonitis can be challenging. Culture and antibody titers for C. psittaci have a lower sensitivity than PCR-testing due to several factors. We present a case of human psittacosis (presenting as pneumonia) with diagnosis based on clinical findings confirmed by means of nested PCR. This case suggests the added value of PCR in suspect cases despite negative serology. Our current paper underlines the need for a broader implementation of PCR for early diagnosis of human psittacosis and thus early initiation of correct antibiotic treatment with reduction of morbidity and mortality.
Insights
Early diagnosis of psittacosis in humans is crucial. Polymerase chain reaction (PCR) testing offers a sensitive and rapid method for detecting Chlamydia psittaci, enabling prompt treatment and improved patient outcomes.
Area of Science:
- Veterinary Medicine
- Human Medicine
- Infectious Diseases
Background:
- Chlamydia psittaci, an obligate intracellular bacterium primarily found in birds, can infect humans, often causing respiratory illness.
- Current diagnostic methods for human psittacosis, such as culture and antibody detection, are time-consuming and may lack sensitivity.
- The lack of reimbursement for molecular diagnostic tests in many countries hinders their widespread adoption for psittacosis diagnosis.
Observation:
- An 82-year-old female presented with non-specific symptoms including cough, fever, rash, and weakness, initially treated with moxifloxacin.
- Blood tests revealed inflammation and mild eosinophilia, while chest CT showed bilateral lung opacities.
- The patient owned a pet parakeet, prompting nested PCR testing on both the patient and the bird.
Findings:
- Nested PCR confirmed Chlamydia psittaci infection in both the patient and her pet parakeet, identifying the same genotype.
- Genotyping was further specified using genotype-specific real-time PCR.
- The patient recovered fully after a ten-day course of azithromycin.
Implications:
- The case highlights the diagnostic challenge of psittacosis due to non-specific symptoms and the limitations of traditional diagnostic methods.
- Polymerase chain reaction (PCR) testing demonstrated higher sensitivity than serology for diagnosing human psittacosis, even with negative antibody titers.
- Broader implementation of PCR for early psittacosis diagnosis is recommended to reduce morbidity and mortality through timely antibiotic treatment.
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