Abstract: Nontyphoid salmonellae can lead to bacteremia in immunocompromised patients and subsequent development of thyroid abscess, especially in patients with multinodular goiter. Coinfection with Strongyloides increases the risk of such bacteremia. We describe an unusual case of Strongyloidiasis complicated by Salmonella bacteremia and Salmonella thyroid abscess in a patient with AIDS and multinodular goiter.
Departments of *Internal Medicine and †Medicine, Division of Infectious Diseases, University of Texas Health Science Center, Houston, TX.
Address correspondence and reprint requests to Guha Ashrith, MD, Department of Medicine, University of Texas Health Science Center, Fannin, MSB 1.150, Houston, TX 77030. E-mail: Guha.Ashrith@uth.tmc.edu.
A 73-year-old African American man presented with weakness, dizziness, headache, and disorientation for 4 days. He also complained of chronic diarrhea and 25-lb weight loss over a 2-month period. The patient denied neck stiffness, fever, photophobia shortness of breath, or cough. His medical history was significant for multinodular goiter and AIDS diagnosed 2 years ago, off of antiretroviral therapy for 1 year. He was not taking any prophylactic medications to prevent opportunistic infections. On examination, the heart rate was 106 beats/min, blood pressure was 80/53 mm Hg, respiratory rate was 18 breaths/min, oxygen saturation was 98% on room air, and temperature was 39.1°C. The patient was alert and oriented only to person and place. Oral mucosa was dry without any thrush. He had an enlarged multinodular goiter weighing about 70 g, which was nontender and not warm to touch. The rest of the physical examination was unremarkable.
Laboratory results showed serum blood urea nitrogen of 86 mg/dL, serum creatinine of 4.9 mg/dL, hemoglobin of 10.1 g/dL, and white blood cell (WBC) count of 6.9 × 109/L with 32% neutrophils and 54% band forms. The CD4 lymphocyte count was 2 cells/mm3, and HIV viral load was more than 750,000 copies/mL. Cerebrospinal fluid (CSF) examination showed protein of 118 mg/dL, glucose of 35 mg/dL, WBC count of 2 μL, and red blood cell count of 4 μL. Polymerase chain reaction for herpes simplex virus, cryptococcal antigen, and VDRL on the CSF sample was negative. Fungal, viral, and bacterial cultures on the CSF sample did not grow any organism.
The patient was resuscitated with intravenous (IV) fluids and IV vancomycin and cefepime were started empirically for sepsis. The initial blood cultures grew Salmonella typhimurium (susceptible to ciprofloxacin, moxifloxacin, and meropenem; minimum inhibitory concentration for ciprofloxacin was ≤0.5 mg/dL). Thyroid ultrasound done at that time revealed a heterogeneous enlarged gland with multiple cystic nodules with 1 dominant nodule in the left lobe of the thyroid. The computed tomographic scan of the neck confirmed the cystic goiter with largest cyst measuring 4.6 × 7.2 cm. The stool examination revealed Strongyloides stercoralis larvae, and he was started on ivermectin at 18 mg/d, which was continued for 8 days. However, he continued to be febrile and became more obtunded. On day 3, ciprofloxacin was added for S. typhimurium, and cefepime was changed to IV ceftriaxone at 2 g every 12 hours to empirically treat meningitis. Other opportunistic infections were ruled out. The patient was still febrile on day 7, and aspiration of the largest thyroid cyst done at this time showed numerous degenerating neutrophils and histiocytes suggesting an abscess. The aspirate grew S. typhimurium. Surgical drainage was considered but declined by the patient. The patient continued to deteriorate, and the family decided to withdraw care and transfer him to a hospice facility.
Salmonellae are gram-negative bacilli that infect humans, causing a variety of manifestations including self-limiting gastroenteritis, enteric fever, and life-threatening bacteremia complicated by metastatic abscesses.1 Salmonella species which cause bacteremia are primarily Salmonella enterica serovar typhi, Salmonella paratyphi, and Salmonella choleraesuis. Salmonella typhimurium mainly causes gastroenteritis and seldom causes bacteremia. About 1.4 million people get infected, and 400 people die every year from nontyphoidal Salmonella.2
Severe strongyloidiasis has been associated with a high incidence of gram-negative bacteremia, and often, severe sepsis can be the initial presentation of the underlying parasitic infection as in the case of our patient.3 The transmission of gut flora or an enteric pathogen through the wall of the gut into the blood stream by the invading filariform larva and the adherence of bacteria to the surface epithelium of the larva as they migrate outside the gastrointestinal tract are 2 suggested mechanisms which implicate Strongyloides larva in the pathogenesis of septicemia.3,4 In our patient S. stercolaris larvae were seen on direct microscopy of the fecal smear. And also, aseptic meningitis with altered mental status and high protein with low glucose and normal WBC count in the CSF is seen with severe strongyloidiasis which we strongly suspected in our patient.4,5 Although the stool bacterial cultures were negative in our patient, history of diarrhea may suggest that he probably had Salmonella gastroenteritis, and subsequent hematogenous spread aided by the filariform larva resulted in sepsis. Metastatic infections associated with Salmonella bacteremia are mainly seen in endovascular sites, bone, liver, central nervous system, and lymph nodes.1 However, thyroid abscesses are rare, and very few Salmonella thyroid abscesses have been described in the literature. Suppurative thyroiditis is mainly caused by gram-positive bacteria such as Staphylococcus and Streptococcus.6 Gram-negative bacteria such as Salmonella rarely cause suppurative thyroiditis. Thyroid abscesses classically present with pain, hoarseness, dysphagia, and fever and are associated with tenderness to palpation and localized lymphadenopathy.6 All of these patients had a presenting complaints of dysphagia and neck pain along with diarrhea, vomiting, and fever suggestive of a gastrointestinal route of entry and subsequent bacteremia.7-10 Less than 50% of the patients with Salmonella thyroid abscess had bacteria isolated both from blood as well as the abscess fluid.7-10 Most cases reported have either been from North Africa and Asia, or the patients have had a history of travel to Africa.7-10 Eliciting a travel history in a patient with thyroid abscess may provide a clue if Salmonella is suspected. Salmonella thyroid abscess has been described in patients who have systemic immunocompromised states such as leukemia, uncontrolled diabetes, and chronic corticosteroid usage.8,9 Our patient presented with symptoms more suggestive of sepsis such as hypotension, altered mental status, and fever. Although there have been reported cases of asymptomatic thyroid abscesses, it is possible that our patient did not complain of local symptoms because of his mental status.
Nmadu11 have reported case series of suppurative thyroiditis. In this series, the patients with pre-existing nodular goiters had an infective rate as high as 10%. Our patient also had a nodular goiter which could have made him more susceptible to seeding of the bacteria in the thyroid.
We presented a case of an AIDS patient with S. typhimurium bacteremia complicated by thyroid abscess. The role that Strongyloides played and whether the patient had central nervous system infection related to this coinfection are unclear.
1. Hohmann EL. Nontyphoidal salmonellosis. Clin Infect Dis
2. Voetsch AC, Van Gilder TJ, Angulo FJ, et al. FoodNet estimate of the burden of illness caused by nontyphoidal Salmonella infections in the United States. Clin Infect Dis
. 2004;38(suppl 3):S127-S134.
3. Fardet L, Genereau T, Cabane J, et al. Severe strongyloidiasis in corticosteroid-treated patients. Clin Microbiol Infect
4. Vadlamudi RS, Chi DS, Krishnaswamy G. Intestinal strongyloidiasis and hyperinfection syndrome. Clin Mol Allergy
5. Keiser PB, Nutman TB. Strongyloides stercoralis
in the immunocompromised population. Clin Microbiol Rev
6. Jacobs A, Gros DA, Gradon JD. Thyroid abscess due to Acinetobacter calcoaceticus
: case report and review of the causes of and current management strategies for thyroid abscesses. South Med J
7. Conrad C. Ultrasonography of the thyroid. An intracystic carcinoma and mousetyphoid induced abscess. A report of two cases. Eur J Radiol
8. Dai MS, Chang H, Peng MY, et al. Suppurative Salmonella thyroiditis in a patient with chronic lymphocytic leukemia. Ann Hematol
9. Duraker N, Agac E, Ozpacaci T. Thyroid abscess caused by Salmonella typhi leading to vocal cord paralysis. Eur J Surg
10. Rehman MT, Basir N, Zia N, et al. Thyroid abscess 'an unusual complication of typhoid fever'. J Trop Med Hyg
11. Nmadu PT. Infective thyroiditis in northern Nigeria: a fifteen-year study. East Afr Med J