Cervical adenitis caused by Staphylococcus aureus in a newborn

Abstract

Cervical acute lymphadenitis is rarely described in neonates. We present the case of a 12-day-old preterm, fed by nasogastric tube, who presented a tender erythematous submandibular swelling. Laboratory data showed neutrophilia and an elevation of C reactive protein and procalcitonin. Ultrasound findings suggested cellulitis and adenitis with abscess. The culture of the drainage material identified methicillin-sensitive Staphylococcus aureus. With the administration of the right antibiotic treatment, a good clinical outcome was observed.

Background

Infectious lymphadenitis is common in children, but rare in neonates.¹ The most common agents are Gram-positive cocci, mainly group A streptococcus and Staphylococcus aureus.² In neonates, it has been rarely reported and predominantly associated with group B streptococcus.²

S. aureus is the second most common agent for late-onset neonatal infections.³ Epidemiological studies in children have demonstrated an association between this agent and both focal (such as cellulitis and adenitis) and deep (such as septic arthritis and osteomyelitis) infections.³

There are some risk factors for cervical lymphadenitis in neonates, already described, such as prolonged use of nasogastric tube for feed.¹ Respiratory support, low birth weight and antibiotic therapy are predisposing factors to invasive staphylococcal disease.¹

Case presentation

We present a case of a preterm boy child born from a healthy 36-year-old mother. At 33 weeks of gestational age, due to oligohydramnios (amniotic fluid index of 5 cm) and abnormal umbilical and middle cerebral arterial Doppler assessment, a caesarean section was performed. The newborn infant was born with an Apgar score of 9 at 1 min and 10 at 5 min of age and a birth weight of 1375 g (small-for-gestational age, fifth centile). The adaptation to extrauterine life and immediate neonatal period was uneventful, with cardiorespiratory stability. No ventilatory support or antibiotic therapy was required. Parenteral nutrition was started on day 1. Minimal enteral nutrition with breast milk was started on day 2 and he reached full feeds on day 6. Breastfeeding was introduced on day 10 of life, but, due to intake difficulties, the nasogastric tube (polyurethane CH6) feeding was kept partially, until day 15.

On day 12 (postmenstrual age of 35 weeks), a tender swelling of the left submandibular region was noted, about 1.5 cm in diameter, without inflammatory signs. The newborn was well perfused, pink, not irritable, afebrile and had normal vital parameters. No family history of immunodeficiency disease was known.

During the following hours, a rapid increase in the size of the swelling was observed (3×1.5 cm), becoming erythematous, warm and tense, with central fluctuation (figure 1A, B). The general status of the patient remained unremarkable, with no stridor or respiratory distress. There were no signs of ipsilateral local infections, including in the parotid region. No purulent material exuded from the Wharton’s duct.

Figure 1.

(A, B) Erythematous and tense left submandibular swelling.

Investigations

A blood culture was obtained, and the initial laboratory data revealed a peripheral leucocyte count of 18.6 x 10⁹/L (64% neutrophils), a procalcitonin level of 0.13 ng/mL and a C reactive protein serum concentration of 0.57 mg/dL. Within 12 hours, the C reactive protein reached 0.67 mg/dL.

An ultrasonography revealed hyperechogenicity of the subcutaneous tissue, extending to the parapharyngeal region and an enlarged lymph node (25×22×14 mm) with areas suggestive of suppuration/necrosis.

Differential diagnosis

The differential diagnosis of a submandibular swelling with inflammatory signs in neonates should be made with sialadenitis, cervical submandibular lymphadenitis and soft tissue abscesses.¹ Anatomical area and clinical features are important to obtain an accurate diagnosis, supported by ultrasound findings.¹

In our case, physical examination findings, such as erythema and swelling, were suggestive of infection. The dimension (>1 cm) and the submandibular location were suggestive of lymphadenitis, without parotid involvement. A soft tissue ultrasound scan confirmed the diagnosis of lymph node abscess with cellulitis.

Treatment

Empirical parenteral antibiotic treatment with gentamicin (4 mg/kg/dose every 24 hours) and vancomycin (15 mg/kg/dose every 12 hours) was initiated. After 1 day of antibiotics, an open incision and drainage were performed, with purulent discharge, and the abscess fluid was collected for culture.

Three days later, the abscess culture identified S. aureus sensitive to all tested antibiotics. The blood culture was negative. Due to the culture’s result, gentamicin was discontinued and vancomycin was maintained for a total of 12 days of treatment.

Outcome and follow-up

The neonate remained afebrile and there was a progressive improvement in local signs, with regression of the submandibular swelling and erythema within a few days.

Clinical recovery was documented, and on day 30 he was discharged and referred for immunodeficiency, otorhinolaryngology and developmental consultation.

During a 12-month follow-up, the child remained without any new relevant infections. In the immunodeficiency consultation, due to favourable evolution, no primary immunodeficiency disorder was considered and no additional investigation was carried out.

Discussion

S. aureus is a Gram-positive commensal of the human genitalia and skin.⁴ A high percentage of neonates (20%–90%) are colonised in the first week of life, and the transmission occurs through skin-to-skin contact or respiratory droplets.⁵ The major reservoirs are the umbilical cord, skin, nasopharynx and gastrointestinal tract.⁵

Our infant was of low birth weight and was on enteral feeds via nasogastric tube, both being risk factors for invasive staphylococcal disease.¹

In neonates, acute lymphadenitis could be part of cellulitis-adenitis syndrome, a rare but well-known acute localised skin inflammation with lymphadenitis.⁶ Since its first description, it has been associated with a late-onset group B streptococcal disease, with up to 90% of cases associated with bacteraemia and 24% with meningeal involvement.⁶ Group A streptococcus has also been associated.⁷

Prematurity appears to be a risk factor, and men account for 75% of the cases.^6–8 In addition, the submandibular region is described as the most affected area.⁶ However, the drainage culture was positive for S. aureus, for which the association with the cellulitis-adenitis syndrome has been rarely described.

After laboratory data and blood and abscess cultures, an empirical therapy with vancomycin plus gentamicin was started, with coverage of Gram-positives (such as S. aureus and group B streptococcus) and Gram-negatives and adjustment after the results from cultures were available.⁹

In conclusion, this case shares some clinical features with cellulitis-adenitis syndrome and highlights a rare and uncommon microorganism associated with cervical lymphadenitis. The prompt diagnosis allowed a successful treatment with complete resolution.

Learning points.

• Infections related to Staphylococcus aureus are increasing.

• Cervical acute lymphadenitis is rare in neonates, and the most common pathogen is group B streptococcus.

• Cellulitis-adenitis syndrome is defined as a localised inflammation of the skin with lymphadenitis and should be considered as a differential diagnosis.

• Although group B streptococcus is the most common pathogen, other microorganisms should be considered, such as S. aureus.

• Prompt antibiotic therapy, with coverage of Gram-positives and Gram-negatives with adjustment guided by cultures, allows clinical resolution.