BA can be lactational or non-lactational, the incidence being 10–30% and 5–9%, respectively [1, 2, 4]. Occasionally, BA can be present in males and neonates also [1–5]. Lactational BAs are mostly mono-bacterial, the most common causative organism being Staphylococcus aureus, mostly methicillin-resistant S. aureus (MRSA), followed by coagulase-negative Staphylococci [1, 6]. However, up to 40% of BAs are polymicrobial, with aerobic (Staphylococcus, Streptococcus, Enterobacteriaceae, Corynebacterium, Escherichia coli, and Pseudomonas) and anaerobic infection (Peptostreptococcus, Propionibacterium, Bacteroides, Lactobacillus, Eubacterium, Clostridium, Fusobacterium, and Veillonella) [2]. Rarely uncommon organisms like Salmonella paratyphi A, Burkholderia pseudomallei, Burkholderia vietnamiensis, Trueperella bernardiae, Actinotignum sanguinis may cause BA [7–11].
Non-lactational BAs are common in the fourth decade of life with risk factors like diabetes, smoking, obesity, trauma, malignancy, tuberculosis, rheumatoid arthritis [4, 5]. Non-lactational BAs are mostly polymicrobial with S. aureus, Streptococcus, and anaerobes [4, 12]. It is associated with squamous metaplasia of the epithelial layer of the lactiferous duct, ampulla, and subsequent keratinization and keratin plug formation. These keratin plugs and cellular debris result in blockage of the drainage of secretions and causes duct dilatation or ectasis. Later, the thin epithelial layer of the duct ruptures, resulting in the invasion of the causative organism to surrounding tissues. These abscesses are chronic and have recurrence episodes due to blocked ducts and the frequent formation of fistulas [5, 13]. As in our patient symptoms were for one year with recent aggravation of symptoms. Patients usually present with pain and swelling of the involved breast with associated tenderness. There may be an area of fluctuation, palpable mass, purulent discharge from the nipple or local area. The patient may also have a fever and a history of similar previous complaints. Most of the diagnoses of non-lactational BAs are clinical, augmented by imaging, and confirmed by culture. However, rarely fine-needle aspiration cytology, acid-fast staining, or cartridge-based nucleic acid amplification test (CBNAAT) is required based on clinical suspicion of malignancy or tuberculosis. In a case series, Mycobacterium tuberculosis could not be identified in around 88% of tubercular abscesses; patients were diagnosed based on the histological finding of granulomatosis associated with caseous necrosis [14]. A core needle biopsy is indicated in highly suspicious cases of malignancy like a hard lump with significant axillary lymphadenopathy [4].
Burkholderia contaminans is one of the 24 species in the Burkholderia cepacia complex (Bcc); a group of related bacterial species identified by the Burkholderia cepacia recA gene sequences [12,22]. Burkholderia contaminans, a nonfermenting Gram-negative aerobic bacillus, previously known as taxon K or group K, was recognized as novel species MLST-1 in 2009 using multilocus sequence typing [15]. Among Bcc, most human cases are associated with Burkholderia cenocepacia and Burkholderia multivorans, while Burkholderia contaminans is less frequently encountered in human infections [10, 16]. Burkholderia contaminans is an opportunistic pathogen with low virulence but extensive virulence factors. It is found ubiquitously in the environment and as contaminants in pharmaceuticals, cosmetics, disinfectants, medical instruments, ventilator nebulisers, saline solutions, and catheters. Bcc infections are commonly seen in patients with cystic fibrosis (CF). The spectrum of infections of Bcc varies from an asymptomatic carrier, chronic infection ranging from pulmonary involvement to invasive Bcc, and life-threatening presentation like cepacia syndrome, especially in CF and chronic granulomatous disease patients [16, 17]. It can also cause endophthalmitis after ophthalmic surgeries, community-acquired pneumonia, endocarditis in heroin addicts, spontaneous bacterial peritonitis in patients with liver cirrhosis, skin and soft tissue infections with and without deep-seated abscesses. Moreover, it can cause pneumonia, urinary tract infection, or bacteremia after using contaminated medical products in hospitalized patients [18]. However, rare cases are reported in immunocompetent patients as well. Our patients also had no immunosuppressant factor. We could find only one documented report of BA due to Bcc (Burkholderia vietnamiensis) in the literature [10]. Rarely, Burkholderia pseudomalai has been isolated in BA or cutaneous melioidosis of skin overlying breast. B. pseudomallei bacteria infect breast tissue via percutaneous spread through damaged skin or hematogenous spread from other organs to an already inflamed breast [8, 9]. A similar route of spread could be postulated for Burkholderia contaminans and other Bcc organisms.
BA should be managed by incision and drainage or image guided needle aspiration, undercover of enteral or parenteral antibiotics depending upon severity of the disease. Treatment of BA with antibiotics alone without abscess drainage is ineffective [1, 5]. Besides, Bcc has both intrinsic and acquired resistance to traditionally used antibiotics like aminoglycosides, polymyxins, first and second-generation cephalosporins, chloramphenicol, thus making treatment challenging. Different mechanisms like efflux pump, production of beta-lactamase, outer membrane hydrophilic permeability barrier, production of other enzymes, or alteration of antibiotic targets are responsible for resistance [18]. Because of the lack of studies for the effective antibiotic regime in Bcc infection, antibiotics need to be chosen depending upon in-vitro antibiotic susceptibility data. Most effective empirical antibiotics depending upon in vitro sensitivity data are trimethoprim-sulfamethoxazole, ceftazidime, meropenem, doripenem, doxycycline, and metronidazole. Typically in CF patients with Bcc-related pulmonary exacerbations, 14–21 days of antibiotic therapy is recommended [19]. The only reported case of Bcc-related BA had a spontaneous rupture followed by complete resolution with three weeks of antibiotics. In this case, Burkholderia contaminans was sensitive to ceftazidime, co-trimoxazole, levofloxacin, and minocycline; the patient responded to a 21 day course of levofloxacin with repeated aspiration.
BA should be managed by incision and drainage or image guided needle aspiration, undercover of enteral or parenteral antibiotics depending upon severity of the disease. Bcc has both intrinsic and acquired resistance to traditionally used antibiotics like aminoglycosides, polymyxins, first and second-generation cephalosporins, chloramphenicol, thus making treatment challenging.