Chronic gastritis is caused by all except
Overuse of salicylates (NSAIDs) cause acute gastritis
Gastritis

Gastritis is the inflammation of Gastric mucosa.
It is a histological diagnosis and can be divided into -

A. Acute gastritis

It is acute mucosal injury, usually transient in injury and is associated with neutrophilic infiltration.
Important causes are


Heavy use of NSAIDs (aspirin)   
Alcohol and smoking   
Uremia         
Ischemia and shock
Severe stress (Trauma, burn, surgery)
Nasogastric intubation

B. Chronic gastritis

It is characterized by the presence of chronic mucosal inflammatory changes leading eventually to mucosal atrophy and intestinal metaplasia, usually in the absence of erosions.
Important causes are


H.pylori infection 
Alcohol and smoking         
Radiation 
Autoimmune, in association with pernicious anemia
Granulomatous conditions → Crohn disease
Miscellaneous - Amyloidosis, graft - versus - host disease, uremia.
H. Pylori
Pernicious anemia
Alcohol
Overuse of salicylates