Penicillin-resistant pneumococci.

Penicillin-resistant pneumococci were first reported in Australia in 1967 and appeared in the UK in 1976. Their prevalence is increasing but varies greatly worldwide. The mechanism of resistance lies in the alteration of penicillin-binding proteins. Penicillin-resistant strains are often also resistant to a variety of non-beta-lactam antibiotics. Many different serotypes have been found to be penicillin resistant, type 23 being the most common resistant serotype in the UK. Use of oxacillin discs is recommended for penicillin sensitivity testing, otherwise resistant isolates may escape detection. Treatment of infected patients depends on several factors including the degree of resistance of the infecting strain, the sensitivity to alternative agents and the achievable concentration of antibiotic at the site of the infection. Carriage of penicillin-resistant pneumococci is more common in children, especially the recently hospitalized and those recently exposed to antibiotics. Outbreaks of infection have occurred and various control measures have been suggested in attempts to limit the spread of resistant strains.