Salmonella Typhi: a rare cause of parotid abscess

Abstract

The incidence of extraintestinal infection caused by Salmonella spp has been increased during the past decade. Here we report a case of a parotid abscess caused by Salmonella enterica subspecies enterica serotype Typhi (S. Typhi) in an individual without any significant abnormality of the parotid gland. A 68-year-old man presented to the surgical department with high-grade intermittent fever associated with painful swelling over the right side of the face, extending into the neck. An ultrasound of the neck revealed an abscess of the right parotid gland. S. Typhi was isolated from the pus drained from the parotid gland. The patient was treated with intravenous followed by oral cephalosporin for a period of 7 days. This case gives an insight into one of the rarer aetiological agents causing parotid abscess.

Background

Parotid gland is the largest of the salivary glands, located lateral to the masseter muscle anteriorly and extending posterior over the sternocleidomastoid muscle behind the angle of the mandible. Parotid gland can become infected via ascending route through Stensen's duct, haematogenous route or contiguous spread following trauma.¹ Parotid gland is much more susceptible to infection due to its serous secretion which is devoid of antibodies, lysosomes and mucins. Acute parotitis is the inflammation of the parotid gland that commonly arises due to a viral or bacterial infection. Acute inflammation can lead to abscess formation over a period of time.² It is common in patients who are elderly, dehydrated, malnourished with additional predisposing factors like poor oral hygiene, ductal obstruction, gland tumours, diminished salivary flow, xerostomia, sialolithiasis and post dental procedures.³ Acute bacterial parotitis can result from stasis of salivary flow that may allow retrograde introduction of bacterial pathogens into the gland, resulting in localised infection.⁴

The most common pathogens associated with acute parotitis are Staphylococcus aureus, Streptococcus species, Escherichia coli, Klebsiella pneumoniae and anaerobic bacteria like Peptostreptococcus, Bacteroides, Fusobacterium and Prevotella. Less common agents include Hemophilus influenzae, Pseudomonas aeruginosa, Salmonella spp, Bartonella henselae, Eikenella corrodens, Treponema pallidum and in endemic areas, Mycobacterium tuberculosis. Staphylococcus aureus is the most common pathogen associated with bacterial parotitis, accounting for 80% of cases.⁵

The cardinal signs and symptoms of acute parotitis include pain which is aggravated during eating, fever, chills, swelling at the angle of the jaw, tenderness and erythema of the parotid region. It can be associated with trismus, facial asymmetry, facial nerve palsy, frank suppuration, dysphagia, odynophagia, difficulty in swallowing and marked systemic toxicity. Complications include respiratory obstruction due to massive swelling of the neck, infection of deep spaces of the head and neck, fistula formation, osteomyelitis of adjacent bones, septic jugular thrombophlebitis, septicaemia and meningitis.⁶

Infection with Salmonella spp is mainly seen in the tropical and subtropical areas where it is endemic. S. Typhi is a facultatively anaerobic, gram-negative bacilli which belongs to the family Enterobacteriaceae. Serotypes are differentiated based on the characterisation of the heat stable O antigen, heat labile flagellar H antigen and heat labile capsular Vi antigen. It is transmitted by fecal–oral route through contaminated food and water from a patient or a carrier. It is isolated from humans at times of infection and does not form a part of normal microbiota of the bowel.⁷ Carrier state can been identified by performing stool culture, urine culture and bile culture. S. Typhi causes enteric fever which manifests as prolonged fever with abdominal pain, diarrhoea or constipation.

Salmonella spp is known to cause focal infections following entry into gastrointestinal tract. Dissemination of Salmonella occurs through bloodstream. It causes abscesses in many internal organs like liver, spleen, gall bladder, breast, ovary and chest wall. It is also known to colonise the diseased tissues and sites of trauma.⁸ Here we report a case of Salmonella parotitis.

Case presentation

A 68-year-old man presented to the surgical department with complaints of high-grade intermittent fever for 20 days duration. It was associated with painful swelling over the right side of the face for 4 days. The patient had a history of intake of antipyretics and antibiotics (unknown) for 5 days prior to the hospital admission. The swelling progressively increased in size. He had a past history of two surgical procedures done in the oral cavity (1 year and 5 years back). Physical examination revealed the patient to be febrile (temperature 100 °F). Local examination of the right side of the face revealed a warm, fluctuant, tender swelling of 5×3 cm which was extending into the neck. Other systemic examination was unremarkable. Patient was admitted to the hospital for further evaluation.

Investigations

Ultrasound of the neck was done that showed an impression of a heterogeneous echotexture of the right parotid gland with hypoechoic areas of abscess due to the edematous state of the parenchyma (figure 1). Pus collected from the incision and drainage of the abscess was sent for bacterial culture. Gram stain showed occasional pus cells and occasional gram-negative bacilli (figure 2). Culture was performed on 5% sheep blood agar, chocolate agar and MacConkey agar. In sheep blood agar, non-lytic grey moist colonies were observed. On MacConkey agar, non-lactose fermenting colonies were observed. The organism was found to be motile, catalase positive and oxidase negative. It was found to produce hydrogen sulphide in triple sugar iron agar and ferment glucose and mannitol. It did not produce indole, utilise citrate, nor hydrolyse urea.

Figure 1.

Ultrasonogram showing heterogeneous echotexture of right parotid gland with hypoechoic areas of abscess.

Figure 2.

Gram stain of pus from parotid abscess showing long gram-negative bacilli.

Slide agglutination with antisera to somatic antigen D (serogroup 9) confirmed it to belong to Salmonella serogroup D. The organism was identified as Salmonella enterica subspecies enterica serotype Typhi in microscan walkaway 96 (Beckman Coulter, USA) with 99.9% probability. It was found to be susceptible to ampicillin, cefotaxime, ceftriaxone, cotrimoxazole, azithromycin, chloramphenicol and resistant to ciprofloxacin (according to Clinical and Laboratory Standards Institute, 2019 guidelines). Blood and urine cultures were found to be sterile.

Treatment

Incision and drainage of the abscess was done under general anaesthesia. Sterile compression dressing was applied. After the culture report, the patient was started on intravenous cefotaxime 500 mg two times per day for 3 days followed by oral cefixime 200 mg two times per day for 5 days, analgesics and chlorhexidine mouthwash.

Outcome and follow-up

The patient improved considerably and the fever subsided. He was discharged on the third postoperative day and was asked to review to the general surgery department after 7 days for follow-up. The patient was lost to follow-up.

Discussion

Parotid gland disease include viral and bacterial infections, autoimmune diseases and tumours of the salivary glands.⁹ The patient had undergone oral surgery which would have resulted in trauma to the tissues and made it favourable for the bacteria to multiply and lead to abscess formation.¹⁰ Parotid gland infection with Salmonella spp is rare. Treyce et al reported a case of parotitis caused by S. Typhi with abscess formation in a patient with HIV infection in 1997. The patient rapidly recovered after incision and drainage of the lesion and initiation of trimethoprim-sulfamethoxazole therapy.¹¹ In 1984, S. Typhi was isolated from a 15-year-old adolescent in India who developed bilateral parotid gland swelling following enteric fever.¹² A few cases of non-typhoidal Salmonella species like S. schwarzengrund, was isolated from a parotid abscess in a 79-year-old man with known cystic parotid disease after an episode of enterocolitis.¹³

In our case, the patient had no previous history of enteric fever. The blood culture was found to be sterile, which may be due to consumption of broad-spectrum antibiotics before the patient presented to surgical department and the blood sample was collected in the third week from the onset of fever. Blood culture is the ideal method for diagnosis of enteric fever and the rate of culture positivity is 90% in the first week. Thereafter the positivity declines to 75% in the second week and 60% in the third week and 25% until the fever subsides. Following initial bacteraemia, abscess formation can occur in 10% of patients after months or years.¹⁴

Among different imaging techniques available for the study of parotid gland diseases, ultrasonogram is useful in the evaluation as it is rapid, non-invasive, less expensive, easy to perform and provides detailed morphological evaluation.¹⁵

The treatment of parotid abscess is incision and drainage, followed by the correct antimicrobial based on pus culture and sensitivity. Based on the antimicrobial susceptibility pattern, the choice of antimicrobial agent for treatment can be selected. It is ideal that the patient should be on follow-up and carrier state should be ruled out.

Current recommendations suggest that it is ideal to treat the patient with antimicrobial agent for 7 to 14 days to ensure complete eradication and to prevent recurrence. Failure to select appropriate antibiotics leads to clinical failure.¹⁶ Antimicrobial agents play an important role in therapy for infections caused by S. Typhi. Potentially effective agents include ampicillin, chloramphenicol, fluoroquinolones, azithromycin, trimethoprim/sulfamethoxazole and third generation cephalosporins such as ceftriaxone.

However, S. Typhi has been known to exhibit resistance to fluoroquinolones, cotrimoxazole and ceftriaxone.¹⁷ Recurrence of the infection can be controlled by counselling the patient on good oral hygiene and maintaining sufficient hydration. Hence a clinical practitioner and microbiologist must have a high index of suspicion for early diagnosis, prompt treatment to prevent lethal complications and recurrence from incomplete therapy.

Learning points.

• Salmonella Typhi can cause parotid abscess.

• Early diagnosis and surgical intervention, usually incision and drainage, can help prevent the spread of infection and hasten recovery.

• Antibiotic treatment to be based on antimicrobial susceptibility pattern due to emerging multidrug resistant strains.