Background: Breast cancer patients who undergo tissue expander surgery (TES) are at an increased risk of developing gram-negative rod (GNR) skin and soft-tissue infection (SSIs) and its complications including prolonged antibiotic therapy, antibiotics side effects, and implant removal. Current perioperative antimicrobials focus mostly on gram-positive organisms, but the presence of a foreign body increases the risk of GNR SSI. We describe here the most common GNR bacteria and their susceptibility patterns that cause SSI after TES among breast cancer patients. Methods: We conducted a retrospective cohort study at Moffitt Cancer Center, Tampa, FL from January 2016, to January 2018, on all breast cancer patients who developed GNR SSIs following TES. We reviewed records after approval from the Institutional Review Board. The data collected included patient’s age, pathogens from wound culture, antibiotic susceptibilities, the perioperative and definitive antibiotics used. Results: A total of 38 cases of GNR SSI with a mean age of 56 ± 11 years were identified. The 3 most common pathogens were Pseudomonas aeruginosa (45%), Serratia marcescens (16%), and Klebsiella pneumoniae (8%) (Figure 1). The susceptibility pattern was available for 33 cases. Pseudomonas and Klebsiella isolates were susceptible to all tested antibiotics (Table 1). The Stenotrophomonas isolates showed resistance to ceftazidime. Enterobacter cloacae, Enterobacter aerogenes, Morganella morganii, and Acinetobacter baumannii complex, showed resistance to cefazolin. Twenty-five cases (74%) received perioperative antibiotics for gram-positive organisms; mostly cefazolin, and vancomycin. The common antibiotics used for definitive treatment were ciprofloxacin, cefepime, ceftazidime, piperacillin–tazobactam, and meropenem. Conclusion: In centers with a high percentage of GNR SSI following TES should consider using perioperative antibiotics that include coverage against Pseudomonas aeruginosa, the most common isolate (45%). The use only of cefazolin or other antibiotics against gram-positive organism may be inadequate. However, GNR infection may occur from 48 hours to 2 weeks postoperatively and may be from the acquisition of the GNR at home in which perioperative antibiotics may have minimal effect
