The best type of fluid replacement and optimal volume of resuscitation in the setting of severe sepsis have been heavily debated but studies have provided guidance to the clinician. One trial comparing 4% albumin with normal saline for fluid resuscitation found no difference in mortality at 28 days. 24 A 2004 meta-analysis similarly found no mortality advantage with the use of colloids compared with the use of crystalloids. 25 The trial of EGDT revealed that patients in the treatment arm received far greater volumes of fluid in the first 6 hours of resuscitation than those in the control arm. In a large study of European ICUs, patients with a positive fluid balance at 72 hours had a poor outcome. 26 In a clinical trial of patients with acute lung injury, the use of a conservative fluid strategy targeting a CVP lower than 4 mm Hg and a pulmonary artery occlusion pressure (PAOP) lower than 8 mm Hg was associated with a fewer number of ICU and ventilators days. 27 The preponderance of data would suggest that aggressive fluid management be done in the acute phase of sepsis, followed by a more conservative phase in the following few days.
Bacterial virulence factors , such as glycocalyx and various adhesins , allow colonization, immune evasion, and establishment of disease in the host.  Sepsis caused by gram-negative bacteria is thought to be largely due to a response by the host to the lipid A component of lipopolysaccharide , also called endotoxin .   Sepsis caused by gram-positive bacteria may result from an immunological response to cell wall lipoteichoic acid .  Bacterial exotoxins that act as superantigens also may cause sepsis.  Superantigens simultaneously bind major histocompatibility complex and T-cell receptors in the absence of antigen presentation . This forced receptor interaction induces the production of pro-inflammatory chemical signals ( cytokines ) by T-cells. 
The process of infection by bacteria or fungi may result in systemic signs and symptoms that are variously described. Approximately 70% of septic shock cases were once traceable to gram-negative bacteria that produce endotoxins , however, with the emergence of MRSA and the increased use of arterial and venous catheters, gram-positive bacteria are implicated approximately as commonly as bacilli . In rough order of increasing severity these are, bacteremia or fungemia; sepsis, severe sepsis or sepsis syndrome; septic shock, refractory septic shock, multiple organ dysfunction syndrome, and death.