| Abstract|| |
Acute suppurative thyroiditis (AST) is an uncommon condition, in the patients with preexisting thyroid disease or immunosuppression. The most common cause of AST is bacterial, and the most common bacteria are Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, and Klebsiella species. Due to various complications such as septicemia, septic thrombophlebitis, necrotizing mediastinitis, or pericarditis, prompt diagnosis and treatment are the keys to reduce mortality and morbidity. Here, we describe a case of a 40-year-old female with AST caused by Citrobacter freundii. This is the first case report of isolation of this bacterium from AST in the world. It is important to differentiate AST from subacute thyroiditis, which is far more frequent and runs a more prolonged course. Various risk factors which predispose to this condition include structural abnormality in the thyroid gland or thyroid disease and immunocompromised state. The route of infection may be either hematogenous or lymphatic seeding. With the increase in number of immunocompromised patients, the cases of AST will increase.
Keywords: Acute suppurative thyroiditis, Citrobacter, Immunocompetent host
|How to cite this article:|
Mohi GK, Datta P, Chander J, Das A. Citrobacter freundii as a cause of acute suppurative thyroiditis in an immunocompetent adult female. Indian J Pathol Microbiol 2017;60:282-4
|How to cite this URL:|
Mohi GK, Datta P, Chander J, Das A. Citrobacter freundii as a cause of acute suppurative thyroiditis in an immunocompetent adult female. Indian J Pathol Microbiol [serial online] 2017 [cited 2022 Jan 24];60:282-4. Available from: https://www.ijpmonline.org/text.asp?2017/60/2/282/208400
| Introduction|| |
Acute suppurative thyroiditis (AST) is an extremely rare condition, accounting for only 0.1%–0.7% of all thyroid diseases. The thyroid gland is remarkably resistant to infection by virtue of its structural and physiological attributes such as rich blood supply to thyroid, excellent lymphatic drainage, encapsulation, high content of iodine, and generation of hydrogen peroxide. Infection usually happens in the presence of preexisting thyroid disease or immunosuppression.
The reported outcome of AST ranges from complete cure to mortality in 12% of cases in the absence of intervention. The likely complications of AST in an untreated patient would be septicemia, osteomyelitis, or septic thrombophlebitis. The infection may also spread to chest leading to necrotizing mediastinitis or pericarditis. Therefore, prompt diagnosis and treatment are the keys to reduce mortality and morbidity.
Here, we describe a case of a 40-year-old female with AST caused by Citrobacter freundii. A review of publication in English language did not reveal isolation of this bacterium in AST. This is the first case report of isolation of this bacterium from AST in the world.
| Case Report|| |
A 40-year-old female presented to the ENT outpatient department with complaints of pain in the front of neck and fever for the last 10 days. The swelling had been present for the past 3 years with an earlier diagnosis of hypothyroidism for which the patient was under medical treatment. The patient now had severe pain in the swelling, which was acute in onset associated with sudden increase in size and redness of swelling. The patient also had a history of intermittent fever, which did not relieve with medications.
Examination of the neck revealed a swelling in the anterior neck which was butterfly-shaped, approximately 6 cm × 4 cm in size and extending superiorly to the level of hyoid bone and inferiorly to suprasternal notch. The overlying skin was red and congested. No discharging sinus and pulsatile vessels were seen. The swelling moved with deglutition but not with tongue protrusion. On palpation, there was tenderness over the swelling and local rise of temperature. No cervical lymphadenopathy was seen.
The clinical diagnosis of AST was made and the patient was advised computed tomography (CT) scan of the neck. Contrast-enhanced CT revealed hypodense lesion involving the left lobe of thyroid measuring 4.8 cm × 3.9 cm × 4.2 cm. Ultrasound-guided therapeutic aspiration of the thyroid abscess was performed and 15 ml of thick purulent, yellowish-brown pus was sent for culture sensitivity and cytological analysis. Routine blood analysis revealed white blood cell count 14,000/mm 3 and a sedimentation rate of 120 mm/h. Serum T4, serum T3, and thyroid-stimulating hormone were however normal. The patient was empirically started on amoxicillin/clavulanic acid pending culture sensitivity report.
The pus sample grew Gram-negative bacilli which were identified as C. freundii according to standard microbiological procedures. It was sensitive to amikacin, gentamicin, doxycycline, ciprofloxacin, ceftriaxone, cefepime, amoxicillin/clavulanic acid, piperacillin/tazobactam. The patient was continued with amoxicillin/clavulanic acid 625 mg thrice daily for 5 days. However, there was no symptomatic improvement in pain and swelling. Thus, incision and drainage of abscess was again done and 20 ml of pus was drained and sent for culture and sensitivity. The culture again showed growth of C. freundii, showing similar sensitivity pattern as earlier. Amoxicillin/clavulanic acid was continued and the patient's condition improved. The neck pain and swelling decreased and the patient was discharged after 7 days.
| Discussion|| |
Although AST is a rare condition, it should be considered in any patient with a history of known thyroid disease, presenting with fever and tender neck mass.
Yu et al. reviewed 191 cases of AST and postulated various risk factors, which predispose to this condition. In about 70% of AST cases, there is structural abnormality in the thyroid gland or thyroid disease. This includes the presence of pyriform sinus fistula, goiter, and thyroglossal duct and thyroid carcinoma. In our case, the patient had a history of hypothyroid for the last 3 years. The next most common group of patients include the immunocompromised patients (24%) and those having AIDS, leukemia, lymphoma, etc.
The route of infection is most commonly either hematogenous or lymphatic seeding. In children, pyriform sinus fistulae or remnants of the thyroglossal duct provide a convenient route for pathogen to enter thyroid.Citrobacter species are normal commensals of GIT tract of human and animal. Therefore, in our patient, the most probable cause of AST is from enteric origin through disruption of intestinal barrier through blood and finally seeding of preexisting diseased thyroid gland.
Various studies documented that 35%–40% of total AST are due to Gram-positive bacteria such as Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus speciesand Gram-negative bacteria such as Escherichia coli, Klebsiella species, and Pseudomonas species account for 25% of the total AST. Anaerobes account for about 9%–12% of the AST cases and nearly 9% of cases are due to Mycobacterium tuberculosis and atypical Mycobacterium. About 15% of cases are due to fungal etiology such as Aspergillus species and Candida species, especially in immunocompromised patients.
In general, in a patient of AST, there are no signs or symptoms of hyper- or hypo-thyroidism. Yu et al. reported that 83% of patients with AST were euthyroid with notable exception being seen in patients with mycobacterial infection who have hyperthyroid status (in 50% of cases) and in patients with fungal AST tend to have hypothyroid status (62.5% of times).
CT is the ideal imaging modality in patients presenting with AST. Ultrasound is the another choice due to its ability to differentiate the internal anatomy of the gland, and it provides opportunity for therapeutic ultrasound-guided fine needle aspiration cytology. This aspirate fluid can be used for culture and antibiotics susceptibility. This may also serve as a mechanism for drainage of abscess and assist in healing.
The management of suppurative thyroiditis includes antimicrobial agents, incision and drainage, and/or surgical excision. In the last few decades, the management has shifted in favor of less invasive approach utilizing intravenous antibiotics without invasive surgery.,
C. freundii should also be added to the list of Gram-negative bacteria as a causative organism for AST. With effective treatment, patients with AST have excellent prognosis.
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Gursimran Kaur Mohi
Department of Microbiology, Government Medical College Hospital, Sector 32, Chandigarh - 160 030
Source of Support: None, Conflict of Interest: None