Causes
Conditions contributing to lung abscessAspiration 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 lung is the most common.OrganismsIn 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

Diagnosis
Imaging studies
Lung abscesses are often on one side and single involving posterior segments of the upper lobes and the apical segments of the lower lobes as these areas are gravity dependent when lying down. Presence of air-fluid levels implies rupture into the bronchial tree or rarely growth of gas forming organism. Laboratory studies
Raised inflammatory markers (high ESR, CRP) are common but nonspecific. Examination of the coughed up mucus is important in any lung infection and often reveals mixed bacterial flora. Transtracheal or transbronchial (via bronchoscopy) aspirates can also be cultured. Fiber optic bronchoscopy is often performed to exclude obstructive lesion; it also helps in bronchial drainage of pus. Management
Broad spectrum antibiotic to cover mixed flora is the mainstay of treatment. Pulmonary physiotherapy and postural drainage are also important. Surgical procedures are required in selective patients for drainage or pulmonary resection. The treatment is divided according to the type of abscess, acute or chronic.
Epidemiology
The beta form of thalassemia is particularly prevalent among Mediterranean peoples, and this geographical association is responsible for its original name. Thalassemia resulted in 25,000 deaths in 2013 down from 36,000 deaths in 1990.In Europe, the highest concentrations of the disease are found in Greece, coastal regions in Turkey (particularly the Aegean Region such as İzmir, Balıkesir, Aydın, Muğla, and Mediterranean Region such as Antalya, Adana, Mersin), in southern Spain, in parts of Italy, particularly southern Italy. With the exception of the Balearics, the major Mediterranean Islands, such as Sicily, Sardinia, Malta, Corsica, Cyprus, and Crete are heavily affected. Other Mediterranean peoples, as well as those in the vicinity of the Mediterranean, also have high rates of thalassemia, including people from North Africa and West Asia. Far from the Mediterranean, South Asians are also affected, with the worlds highest concentration of carriers (16–18% of the population) in the Maldives.The disease is also found in populations living in Africa, the Americas, and in Tharu people in the Terai region of Nepal and India. It is believed to account for much lower rates of malaria illnesses and deaths, accounting for the historic ability of Tharus to survive in areas with heavy malaria infestation while others could not. Thalassemias are particularly associated with people of Mediterranean origin, Arabs (especially Palestinians and people of Palestinian descent), and Asians. The estimated prevalence is 16% in people from Cyprus, 1% in Thailand, and 3–8% in populations from Bangladesh, China, India, Malaysia and Pakistan.