Case Presentation:  A 32 year old female with history of gestational diabetes presented with fevers, chills and swelling of the left breast. She delivered a healthy boy 2 weeks prior to admission by cesarean section. She had difficulty breastfeeding and developed pain, swelling and purulent drainage from the breast. She was prescribed dicloxacillin for mastitis, but her clinical status worsened after three days of antibiotics with fevers up to 102F, rigors and increasing erythema. She denied abdominal pain, dysuria, diarrhea, nausea or vomiting, and her C-section scar was healing well. On exam, the patient was ill-appearing with an extremely tender, tense and erythematous left breast. She was febrile to 100.5F, blood pressure 80/54 and HR 120.  Routine blood tests noted leukocytosis to 34K with 10% bands. She received a total of 5 liters normal saline and ultimately required vasopressor therapy. IV vancomycin and imipenem were started.  Breastmilk was cultured and grew methicillin sensitive staphylococcus aureus, beta hemolytic streptococcus and Candida parapsilosis; blood cultures were negative, breast ultrasound ruled out abscess and transvaginal ultrasound excluded retained products of conception and endometritis. Micafungin was then added to her treatment regimen with significant clinical improvement. The patient was discharged on amoxicillin-clavulanate and fluconazole for a total of 10 days with complete resolution of the mastitis.

Discussion: Mastitis is a relatively common puerperal infection affecting 1 out of 10 postpartum women, but very few cases have been ascribed to fungal species. The most striking feature of this case was the severity of her mastitis leading to septic shock. Most cases of lactational mastitis are caused by staphylococcal and streptococcal species and can often be treated with oral antibiotics. C. parapsilosis is an emerging fungal nosocomial pathogen, which is transmitted horizontally via contaminated medical devices, fluids or hands of health care workers. There have been case reports describing C. parapsilosis as the cause for endocarditis, peritonitis, and invasive ocular infections, but no reports of mastitis have been identified. Our patient rapidly improved after the initiation of anti-fungal treatment, which stresses the importance of prompt identification of atypical organisms that may be the culprit of refractory cases of a relatively treatable condition.

Conclusions: Mastitis is a common postpartum infection that can often be treated in the outpatient setting with antibiotics covering typical skin flora. Our case demonstrates a severe case of fungal mastitis caused by a rising nosocomial pathogen, C. parapsilosis, not previously described in the literature. Mastitis caused by common bacteria rarely leads to septic shock and when it does, clinicians should be attentive to fungal organisms. Early intervention with anti-fungal therapy should be considered in refractory cases of mastitis.