8.1.1. Evidence summary and rationale for the recommendationThe urgent need for antibiotics in septic shock does not fallwithin the scope of these guidelines. Clinicians should consultcurrent guidelines on the management of septic shock. Theimmunosuppressed patients receive specific treatment.In HAP, no RCT has compared a strategy based on earlyempirical antibiotic therapy to definitive antibiotic therapy afterpathogen isolation, identification and susceptibility testing onpatient outcomes, with stratification on pre-test diagnosisprobability and clinical severity. However, several observationalstudies and a meta-analysis have shown that inappropriate initialantibiotic therapy, i.e. ineffective according to susceptibilitytesting of the causal pathogen, was associated with worseoutcomes (length of mechanical ventilation, length-of-stay andmortality), suggesting that the appropriate empirical antibiotictherapy is associated with improved outcomes [94–99].