Pseudomonas Aeruginosa Sepsis in a Previously Healthy Infant with Subcutaneous Nodules and Mastoid Bone Destruction

Abstract

Pseudomonas aeruginosa septicemia is rare in previously healthy children. Skin lesions such as subcutaneous nodules and ecthyma gangrenosum may be the first manifestation of Pseudomonas infection that have rarely been reported. Herein we reported a previously healthy 6-month-old boy patient who presented with suppurative otitis media, multiple nodules, septic shock, and P. aeruginosa was identified in cultures of the blood, skin lesions, and purulent material of his ears.

Introduction

Pseudomonas aeruginosa sepsis causes serious bacteremia especially in those with underlying chronic disease and situations with burns, malignancy, and immune deficiency and in premature infants. However, it rarely causes serious sepsis in healthy infants and children. ¹ Ecthyma gangrenosum (EG) is a skin lesion that results from either primary skin infection or hematogenous seeding of bacteria. EG gangrenous ulcer is characterized by a black eschar or central crust and may be surrounded by a red halo. The main causative agent is P. aeruginosa . It is rare in healthy infants and mortality is high. ² Herein we reported a case of P. aeruginosa sepsis and its serious complications in a previously healthy infant.

Case

A previously healthy 6-month-old boy was referred to our hospital with a 4-day history of fever, purulent discharge in both ears and skin lesions. Two days earlier, he was diagnosed with otitis media for which he was given amoxicillin clavulanate. However, there was no improvement in his complaints. He had no specific medical, family, travel, or allergy history. His parents were anti-vaxxers so he was not vaccinated.

On admission, he appeared unwell and he was lethargic. Vital signs showed axillary temperature of 38.4°C, pulse rate of 220 beats/min, blood pressure of 65/35 mm Hg and, oxygen saturation of 88%. His physical examination revealed severe respiratory distress, a prolonged capillary refill of 5-second multiple erythematous nodules on the limbs ( Fig. 1 ), and purulent discharge in his ears. Initial management included intravenous normal saline bolus for shock. Then he was intubated and admitted to the pediatric intensive care unit.

Fig. 1.

Multiple erythematous nodules on the limbs at admission.

Initial laboratory test results reflected leukopenia (white blood cell count, 2,210/mm ³ ; neutrophils, 42%), thrombocytopenia (platelet count, 115,000/mm ³ ), anemia (hemoglobin of 10 g/dL), elevated C-reactive protein (129 mg/L), hyponatremia (serum sodium, 126 mEq/L), hypopotassemia (serum potassium, 2.7 mEq/L), metabolic acidosis, and disseminated intravascular coagulation (prothrombin time, 24.2 seconds; partial thromboplastin time, 31.7 seconds; fibrinogen 175 mg/dL; D-dimer, 1,426 ng/mL). Chest radiograph was normal. Empiric treatment with ceftriaxone and vancomycin was implemented. He was mechanically ventilated and inotropic support with adrenalin and dopamine was given as hemodynamic instability lumbar puncture was not performed. On hospital day 2, erythematous nodules on the limb darkened in color, with centers purple and edges pale red and one to two bullae formations were observed. The antibiotic regimen was changed to meropenem, amikacin for the suspicion of ecthyma gangrenosum. He developed severe thrombocytopenia (20,000/mm ³ ) on the third day and plasma exchange was performed for 5 days with the diagnosis—thrombocytopenia-associated multiple-organ failure (TAMOF). P. aeruginosa was identified in cultures of the blood, skin lesions, and purulent material of his ears. It was sensitive to meropenem (minimum inhibitor concentration, 0.25 µg/mL). On the eighth day of admission, cutaneous lesions were totally transformed to ecthyma gangrenosum ( Fig. 2 ). The patient's clinical signs and blood parameters improved with the treatments and he was extubated on hospital day 12. After the extubation, right peripheral facial paralysis was recognized while he was crying. Computed tomography of the temporal bone revealed bilateral acute mastoiditis and loss of outer wall integrity in right mastoid bone. The patient underwent a mastoidectomy operation. Before the operation, the hearing status was evaluated with an auditory brainstem response test and the results showed severe sensorineural hearing loss on the right side. The infected mastoid cells were removed and the massive granulation tissue was cleaned surgically ( Fig. 3 ). There was no cerebrospinal fluid leak observed in the ear. Due to the hearing loss in the right ear, the patient was planned to have a hearing aid or cochlear implant during follow-up. Further extensive investigations for excluding immune deficiency and underlying predisposing condition including immunoglobulins, lymphocyte subset panels, dihydrorhodamine test, autoimmune and virology screen, chest X-ray, and abdominal ultrasound were all normal. Anti-human immunodeficiency virus (HIV) antibody titers were negative. The antibiotic treatment was completed at 32nd day and he was discharged. The patient is currently 11 months old with good neurologic and physical status apart from hearing loss in his right ear.

Fig. 2.

Ecthyma gangrenosum lesions on the 8th day of admission.

Fig. 3.

Surgical assessment of the right temporal bone. This view highlights the bone erosion and the massive granulation tissue filling the mastoid bone. Asterix indicates external ear canal and perforated tympanic membrane; whereas the black arrows in the image indicate bone erosion in mastoid area.

Discussion

P. aeruginosa is associated with a wide variety of infections, depending on the immunity of the host and the severity of underlying disease, ranging from self-limited folliculitis to septic shock. ¹ It rarely occurred among immunocompetent infants. Previously healthy children may get P. aeruginosa infection by the water, soil, or contaminated material sources. The skin or mucous membrane by a minor or penetrating wound may be the entrance. In addition to skin infections, healthy children may experience systemic infections, including corneal infection, otitis externa, mastoiditis, mastitis, septicemia, endocarditis, bone and joint infections. ² The characteristics of 73 previously healthy children with P. aeruginosa sepsis were reviewed in a report and they were observed with different clinical manifestations like skin lesions, fever, diarrhea, pneumonia, and shock. Mortality rate was reported approximately 55%. ³ Community-acquired P. aeruginosa sepsis may be the initial manifestation of an immune deficiency. Hypogammaglobulinemia, cyclic neutropenia, neutrophile dysfunction may be determined in most of these children. ⁴ Our patient had never been admitted to hospital before the admission to our pediatric intensive care unit. His immunoglobulin levels, lymphocyte subgroups, dihydrorhodamine test were in normal limits and anti-HIV antibody titer was negative. P. aeruginosa infection can cause neutropenia and it may be related to mortality. It is speculated that the neutropenia state is caused by toxin that inhibits migration of neutrophils into infected areas and also decreases the number of neutrophils in the circulation. ^{5 6} On admission decreased platelet count, leukopenia and neutropenia were observed in our patient and these parameters were improved with treatment.

The skin manifestations of Pseudomonas sepsis include ecthyma gangrenosum, subcutaneous nodules, hemorrhagic vesicles, bullae, gangrenous cellulitis, papules, macules, petechiae, and purpura. ⁷ Some authors reported Pseudomonas septicemia presenting with subcutaneous nodules that are very uncommon in immunocompetent patients. ^{3 7} Our patient was also presented with indurated nodules and septic shock; then the nodules were converted to ecthyma gangrenosum lesions in the following days. At the 16th hour of hospitalization, the antibiotic therapy was changed to antipseudomonal regimen immediately due to the suspicion of ecthyma gangrenosum.

P. aeruginosa can cause chronic suppurative otitis media and acute and chronic mastoiditis. ⁸ Chronic suppurative otitis media is a complication of inadequately treated acute otitis media and is manifested as a perforated tympanic membrane with persistent otorrhea. ⁹ Our patients was on his fourth day of oral antibiotics for acute otitis media so the primary cause of infection was thought to be inadequately treated acute otitis media. On the course of the disease facial paralysis and mastoiditis were determined. Suppurative otitis media did not respond to the appropriate antibiotic therapy so mastoidectomy was performed after his systemic illness was controlled. There is one case in the literature similar to our patient who was a healthy 6-month-old boy with Pseudomonas septic shock, acute mastoiditis, and facial paralysis. In our patient, mastoiditis infection progressed severely causing destruction of the bone tissue. He had decompressive surgery for the facial nerve. ⁷

Conclusion

This case report showed that Pseudomonas sepsis may progress very severely and cause serious complications in healthy infants. Subcutaneous nodules and EG are helpful skin manifestations for suspecting P. aeruginosa sepsis. The suspicion becomes stronger if sepsis is associated with otitis media, gastroenteritis, pneumonia with TAMOF, and neutropenia. In these clinical presentations, prompt treatment with antipseudomonal antibiotics is the cornerstone of life. Extensive immunologic evaluation should also be conducted.

Funding Statement

Funding None.