;Conditions contributing to<unk>  * Aspiration of oropharyngeal or gastric secretion * Septic emboli * Necrotizing pneumonia * Vasculitis: Granulomatosis with polyangiitis * Necrotizing tumors: 8% to 18% are due to neoplasms across all age groups, higher in older people; primary squamous carcinoma of the<unk>  is the most common. ;Organisms In the post-antibiotic era pattern of frequency is changing. In older studies anaerobes were found in up to 90% cases but they are much less frequent now. * Anaerobic bacteria: Actinomyces, Peptostreptococcus, Bacteroides, Fusobacterium species, * Microaerophilic streptococcus : Streptococcus milleri * Aerobic bacteria: Staphylococcus, Klebsiella, Haemophilus, Pseudomonas, Nocardia, Escherichia coli, Streptococcus, Mycobacterium * * Fungi: Candida, Aspergillus * Parasites: Entamoeba histolytica
Lung abscess
Pleural empyema
Lobar pneumonia
Pleurisy
Mediastinitis
Malignant pleural effusion
Hydrothorax
Bronchitis kettle