Susceptibility Patterns over 3 years in Community-acquired Lower Respiratory Infection in the UK and Ireland R. Reynolds, D. Felmingham BSAC Working Party on Respiratory Resistance Surveillance To hide the comments: On the View menu, click Comments. Question: Are resistance rates rising in community-acquired lower respiratory infection?

BSAC Respiratory Resistance Surveillance Programme ~ 20 laboratories over UK and Ireland winter seasons (October-April) community-acquired infection (patients in hospital > 48 hours excluded) duplicate isolates within 2 weeks excluded cystic fibrosis excluded central testing, BSAC agar dilution MIC

Acknowledgements COLLECTING LABORATORIES CENTRAL LAB - GR Micro Ltd., London SPONSORS during Abbott Aventis Bayer GSK

Numbers of isolates

% % above breakpoint  0.12  2 S. pneumoniae/beta- lactams: There are no significant differences between and S. pneumoniae/beta- lactams: There are no significant differences between and

%  0.12  2 % above breakpoint Shown on a full 100% scale, the low level of resistance is clear, and the apparent downward trend seen on the previous slide is seen as a very small effect.

%  0.12  2 % above breakpoint The addition of 95% confidence intervals emphasises the uncertainty involved in measuring low levels of resistance.

%  0.12  2 % above breakpoint All the same, the impression is of falling resistance to penicillin and cefuroxime. We are fairly confident that, at the least, these resistance levels are not rising.

S. pneumoniae, penicillin: MIC distribution % % Any change seen in penicillin is likely to be real because the breakpoint is well away from the main bulk of the distribution. Minor differences in MIC determination will have little effect on % non- susceptible.

%  2  1  4  2 % above breakpoint The difference between and is statistically significant for tetracycline and ciprofloxacin. See next two slides for more detail.

S. pneumoniae, tetracycline: MIC distribution % % In tetracycline also, the breakpoint is well clear of the main population and the measured %R is not subject to fluctuations resulting from minor technical shifts in MIC measurement.

S. pneumoniae, ciprofloxacin: MIC distribution % % However, for ciprofloxacin, the breakpoint falls in the peak of the distribution, so measurement of %R is less reliable. Therefore, the apparent rise in ciprofloxacin resistance in may be an artefact and is not a cause for alarm.

 2 % above breakpoint % No striking differences in H. influenzae with beta-lactams.

 2  16  2  1 % above breakpoint % Trimethoprim resistance in H. influenzae appears to have risen (statistically significant).

H. influenzae, trimethoprim: MIC distribution % % Some of the increase is contributed by isolates with MICs near the breakpoint, but some is well clear at 32 mg/L. Overall significance uncertain.

Conclusions Resistance rates in community-acquired LRTI in the UK and Eire are not rising generally. In S. pneumoniae for  -lactams and tetracycline they may be falling. Data for will clarify the picture. Results will be on