Antibiogram Analysis and Biofilm Formation of Bacteria from Patients with Breast Cancer at Rasheed Shekoni Federal University Teaching Hospital Dutse, Jigawa State, Nigeria

Abstract

Breast cancer remains the most common malignancy among women worldwide and is the leading cause of cancer-related deaths in Nigeria. Patients often face heightened risks of bacterial infections due to immunosuppression from the disease itself and treatments such as chemotherapy, surgery, and radiation. Microorganisms growing in a biofilm are associated with chronic and recurrent human infections and are highly resistant to antimicrobial agents. This study investigated the antibiotic susceptibility and biofilm-forming capabilities of bacteria isolated from breast cancer patients at Rasheed Shekoni Federal University Teaching Hospital, Dutse. 118 bacterial isolates from six different species were examined in this cross-sectional investigation. Biochemical assays and colony morphology were used for identification. The Kirby-Bauer disc diffusion method was used to assess antibiotic susceptibility in accordance with CLSI standards. The gold-standard Tissue Culture Plate Method (TCPM) was used to quantify biofilm formation. S. aureus, CoNS, E. coli, Bacillus species, Proteus species, and Klebsiella species were among the pathogens found. Gram-positive isolates showed multidrug resistance (MDR) to rifampicin and streptomycin but remained sensitive to ciprofloxacin and gentamicin. Gram-negative isolates exhibited extensive resistance to older agents like streptomycin and several cephalosporins, whereas ciprofloxacin and gentamicin remained the most reliable treatments. Critically, 100% of tested MDR isolates were "strong" biofilm producers (OD > 0.68), with Klebsiella species recording the highest optical density (2.74). The universal presence of strong biofilms among MDR isolates poses a serious clinical challenge because biofilms shield bacteria from host immunity and increase antibiotic tolerance up to 1,500-fold. These findings highlight the need for routine susceptibility testing and enhanced antimicrobial stewardship in oncology.