This chapter is devoted to the presentation of pneumonia and lower respiratory tract infections due to various unusual, newly recognised, rarely described or changing presentations of previously recognised pathogens.

STREPTOCOCCAL (OTHER THAN Streptococcus pneumoniae) PNEUMONIA

In excess of 30 species belong to the Streptococcus genus. Blood agar haemolysis patterns, biochemical reactions, growth and morphological characterisation and genetic analysis are used to classify them. Streptococci showing a β-haemolytic pattern (and some with α haemolysis and γ (non-haemolysis) patterns) can be sero grouped – mainly A, B, C, D and G. The group D streptococci are now divided and regrouped into the enterococci and non-enterococci. Viridans streptococci are a heterogenous α haemolytical group. This section deals with pneumonia produced by streptococci other than S. pneumoniae. Although relatively uncommon, striking epidemiological and clinical changes are having important impacts on patient management.

Group Aβ haemolytic streptococcal pneumonia

Much concern and attention has been focused on the resurgence of severe life-threatening group A β haemolytic Streptococcus infections (GAS) in recent years. Invasive GAS are not new – necrotising fasciitis, pueperal fever, scarlet fever, and pneumonia have been known for centuries. Up to 5% of all cases of pneumonia in the UK were due to GAS in the preantibiotic era. Improved socioeconomic circumstances and infection control policies were associated with dramatic falls in GAS infections in the first half of this century.