The Alexander Project 1996–1997: latest susceptibility data from this international study of bacterial pathogens from community-acquired lower respiratory tract infections

Abstract

The Alexander Project was established in 1992 to examine antimicrobial susceptibilities of bacterial isolates from community-acquired infections of the lower respiratory tract. Testing of a range of compounds was undertaken in a central laboratory. From 1992 to 1995, isolates were collected from geographically separated areas in countries in the European Union and various states in the USA. In 1996, the study was extended to include centres in Mexico, Brazil, Saudi Arabia, South Africa, Hong Kong and other European countries not included previously. Data generated by the project during 1996–1997 confirm France and Spain as European centres with high rates of resistance to penicillin among isolates of Streptococcus pneumoniae. Both intermediate (MIC 0.12–1 mg/L) and resistant (MIC 2 mg/L) phenotypes are present. Combined resistance rates (intermediate and resistant) were ≥50% in 1997. Combined resistance rates in excess of 20% were found in the Republic of Ireland, Portugal, the Slovak Republic and Hungary. Penicillin resistance continues to evolve in the USA, with combined resistance rates of 16.4% (1996) and 18.6% (1997). In the new, non-European centres, e.g. Mexico and, in particular, Hong Kong (where resistant strains accounted for 50% of all isolates of S. pneumoniae in 1996 and 55.5% in 1997), there are centres where rates of resistance are high. Macrolide resistance is increasing generally among both penicillin-resistant and penicillin-susceptible isolates of S. pneumoniae. There is variation between countries, and in four out of the 16 centres for which both 1996 and 1997 data are available, rates of macrolide resistance have fallen. Overall, the percentage of S. pneumoniae strains that is resistant to macrolides exceeds the percentage that is resistant to penicillin. In 1996, 16.5% of all S. pneumoniae isolates were resistant to macrolides compared with 10.4% resistant to penicillin, and in 1997 respective rates were 21.9% and 14.1%. β-Lactamase production was the principal mechanism of resistance observed among isolates of Haemophilus influenzae. However, considerable variation in the percentage of isolates producing β-lactamase (0–37.1%) was observed within this species. Within Europe, in the Republic of Ireland, France and Belgium, more than 15% of isolates were β-lactamase producers. In Spain rates were as high as 31.7%. Outside Europe and the USA high rates were described in Mexico (25%), Saudi Arabia (27.9%, 16.7%) and Hong Kong (37.1%, 28.9%). Of H. influenzae from the USA, 30.4% were β-lactamase producers in 1996 and 23.3% in 1997. β-Lactamase production among isolates of Moraxella catarrhalis was observed in >90% of the isolates tested in 1996 and 1997.