Salmonella spp., mycobacteria, and fungi such as Candida and Cryptococcus have been identified in rare instances.Recent research suggests that infectious pathogens play a much smaller role in the pathogenesis than was commonly assumed only a few years ago. Most detected pathogens are very common species that are natural part of the breast fauna and simple detection of their presence is not sufficient to prove a causative role. Furthermore, there are indications that treatment with antibiotics may have minimal impact, and over-all there is insufficient evidence to confirm or refute the effectiveness of antibiotic therapy for treating lactational mastitis. Diagnosis
The diagnosis of mastitis and breast abscess can usually be made based on a physical examination. The doctor will also take into account the signs and symptoms of the condition. However, if the doctor is not sure whether the mass is an abscess or a tumor, a breast ultrasound may be performed. The ultrasound provides a clear image of the breast tissue and may be helpful in distinguishing between simple mastitis and abscess or in diagnosing an abscess deep in the breast. The test consists of placing an ultrasound probe over the breast. In cases of infectious mastitis, cultures may be needed in order to determine what type of organism is causing the infection. Cultures are helpful in deciding the specific type of antibiotics that will be used in curing the disease. These cultures may be taken either from the breast milk or of the material aspirated from an abscess.
Nonpuerperal mastitis is treated by medication and possibly aspiration or drainage (see in particular treatment of subareolar abscess and treatment of granulomatous mastitis). According to a BMJ best practice report, antibiotics are generally to be used in all nonpuerperal mastitis cases, with replacement of the antibiotics by an antifungal agent such as fluconazole in cases of deep fungal infections, and corticosteroids are to be used in case of granulomatous mastitis (with differential diagnosis to tuberculosis infection of the breast).In idiopathic granulomatous mastitis, successful treatment includes invasive surgical procedures or less invasive treatment with steroid medications. Antibiotics
In lactational mastitis, antibiotics are not needed in the overwhelming majority of cases and should be used only for bacterial infections. For people with nonsevere infections, dicloxacillin or cephalexin are recommended. For people with severe infections, vancomycin is recommended. The length of antibiotic treatment ranges anywhere from 5–14 days. The effects of antibiotics has not been well studied as of 2013. Breast abscess
An abscess (or suspected abscess) in the breast may be treated by ultrasound-guided fine-needle aspiration (percutaneous aspiration) or by surgical incision and drainage; each of these approaches is performed under antibiotic coverage. In case of puerperal breast abscess, breastfeeding from the affected breast should be continued where possible.For small breast abscesses, ultrasound-guided fine needle aspiration such as to completely drain the abscess is widely recognized as a preferred initial management.One recommended treatment includes antibiotics, ultrasound evaluation and, if fluid is present, ultrasound-guided fine needle aspiration of the abscess with an 18 gauge needle, under saline lavage until clear.