Chest tube inseion in a case of effusion caused due to pneumococcal pneumonia is indicated in all pleural fluid findings, EXCEPT:

Empyema is the most common focal complication of pneumococcal pneumonia, occurring in <5% of cases. When fluid in the pleural space is accompanied by fever and leukocytosis after 4-5 days of appropriate antibiotic treatment empyema should be considered. Pleural fluid with frank pus, bacteria (detected by microscopic examination) pH of <=7.1 indicates empyema and demands chest tube inseion. Ref: Harisson, Edition - 18, Page 1155