Background Sixty two per cent of hospital infections are caused by Gram – bacteria (e.g. E. coli, Pseudomonas aeruginosa, K. Pneumoniae in primis), pathogens for which there is a trend of increasing antibiotic resistance and consequently a diminished efficacy of available therapeutic alternatives.

Purpose Analyse the cost of antibiotic therapies, DRG profitability and antibiotic resistance in complicated intra-abdominal infections (cIAIs) in an oncological surgery.

Materials and Methods A retrospective observational study was conducted.

The analysis considered 39 patients with a cIAI diagnosis hospitalised between 1 January and 31 December 2015.

Inclusion criteria:

• Patients with microbiological report.

• Documented antibiotic therapy (drug, duration, dosage).

Patients characteristics, antibiotic resistance, costs and length of antibiotic therapies, length of hospital stay, DRG revenue and access to intensive care.

Antibiotic resistance was defined as: for each of 16 isolated bacteria species was defined ‘resistance’ the pathogen for which resistance to one or more antibiotic drug has been reported in the antibiogram.

Results Average hospital stay was 24 days (20.29 std).

Six of 39 (15%) had access to intensive care, as a result of the infection and one died.

Average antibiotic cost was €411.73 including VAT.

The four highest cost cases resulted in an average pharmaceutical expense of €2,699, in 75% of cases they are characterised by pseudomonas aeruginosa and/or multi-resistant klebsiella pneumoniae infections (carbapenems, piparacillin+tazobactam, colistin, tigecycline).

The duration of hospitalisation in this group of patients was 37 days and was related to antibiotic therapy. Considering the DRG rate associated with them, a daily refund of €482 was calculated, far below the average cost for hospital stay (€767). Finally, two out of four patients had access to intensive care.

Conclusions In the cIAIs, the presence of multiresistant pseudomonas aeruginosa and klebsiella pneumoniae significantly increase the costs of antibiotic therapies and the length of stay. The current levels of antimicrobial resistance and over-prescription of antibiotics observed, raise serious questions about the efficacy and appropriate use of the available therapeutic alternatives.