Antibiotic Resistance among invasive pneumococcal Isolates from Southwest Sweden 1998-2001

1. Antibiotic agent MIC 50 MIC 90 1 Other 1 median 90 percentile Other 12,5% 14,3% mg/L mg/L 17,8% 12F Penicillin G 0.016 0.023 9V 9V 8,6% Erythromycin 0.190 0.250 14 15,6% 8,5% Clindamycin 0.190 0.250 43,8% 9N 14 19A Tetracycline 0.125 0.190 7,8% 8 23F 6B Moxifloxacin 0.125 0.190 7F Trim /Sulfa 1/19*** 0.5 1 3 19F 7,8% 6B 4 19A 6A Antibiotic agent Total Sensitive Indeterminate Resistant number breakpoint** number number breakpoint** Penicillin G 827 805 < 0.06 mg/L 22(2.7%) 0 >1.0 mg/L Erythromycin 827 797 < 0.5 mg/L n.r.* 30 (3.6%) >0.5 mg/L Clindamycin 827 821 < 2 mg/L n.r.* 6 (0.7%) >2 mg/L Tetracycline 827 811 < 2 mg/L n.r.* 16 (1.9%) >2 mg/L Moxifloxacin 827 826 < 0.5 mg/L n.r.* 1 (0.1%) >0.5 mg/L Trim/Sulfa 1/19*** 827 815 < 16 mg/L 21(2.5%) 0 >32 mg/L *not relevant ** Species related breakpoints according to the Swedish Reference Group for Antibiotics system. *** Values on the MIC scale refer to the first component of the combination. S S S S S R I R I R R R 400 S R 500 400 500 400 400 400 400 300 300 300 300 300 300 Number Number Number 200 Number Number 200 Number 200 200 200 200 100 100 100 100 100 100 0 0 0 0 0 1,5 3 6 0 ,006 ,012 ,023 ,047 ,094 ,190 ,380 ,75 16 32 64 256 1,5 64 ,064 ,125 ,250 ,500 16 32 1 ,064 ,125 ,250 ,500 ,064 ,094 ,125 ,190 ,250 ,380 ,500 256 ,064 ,190 ,380 ,75 1,500 3 6 32 64 2 4 8 ,047 ,064 ,094 ,125 ,190 ,250 ,380 8 ,008 ,016 ,032 ,064 ,125 ,250 ,50 1 12 24 48 128 2 ,094 ,190 ,380 ,750 24 48 48 ,094 ,190 ,380 12 ,125 ,250 ,50 1,0 2 4 8 MIC (mg/L) MIC (mg/L) MIC (mg/L) MIC (mg/L) MIC (mg/L) MIC (mg/L) Poster at the 15th ECCMID, April 2-5 2005, Copenhagen Antibiotic Resistance among invasive pneumococcal Isolates from Southwest Sweden 1998-2001 Erik Backhaus1, Birger Trollfors2, Stefan Berg2, Berndt EB Claesson1, Rune Andersson. 1. 1Department of Infectious Diseases and Clinical Microbiology, Kärnsjukhuset, Skövde, 2Department of Paediatrics, The Queen Silvia Children's Hospital, Göteborg,SwedenCorrespondence: erik.backhaus@vgregion.se The abstract has been slightly revised with addition of new data. Objectives Streptococcus pneumoniae is a major human pathogen. In Southwest Sweden, with a population of 1.8 million, 200 patients are diagnosed each year with invasive pneumococcal disease. The rapid emergence of isolates with decreased susceptibility to several antibiotics is an increasing problem in many parts of the world. The aim of the present study was to investigate the pattern of susceptibility among invasive isolates, in order to see if the current treatment policies are appropriate, and to see if there seems to be a trend of increasing antibiotic resistance. Methods All clinical isolates of S. pneumoniae from blood, cerebrospinal and joint fluid were collected at the laboratories in Göteborg, Skövde, Borås, Uddevalla and Halmstad during 1998-2001. The MIC-values for seven commonly used antibiotics (penicillin G, erythromycin, clindamycin, tetracycline, moxifloxacin, cotrimoxazole and cefotaxime) were determined with E-test (AB Biodisk) according to standard methods. E-test Distribution of MIC’s Serotype distribution Results 827 invasive strains were tested. Of these, 766 were fully susceptible and 61 (7.4%) were classified as Indeterminate (I) or Resistant (R) for any of the tested antibiotics, according to the Swedish Reference Group for Antibiotics system of species related breakpoints. No isolate had a MIC>1.0 mg/L against penicillin (R). 22 isolates (2.7%) were classified as I to penicillin (MIC >0.06, 1.0 mg/L). 13 of them had MIC’s  0.5 mg/L. Among the 22 isolates classified as I to penicillin 12 isolates were also I against cefotaxime (MIC >0.12, 1.0 mg/L) (1.5%). The other tested antibiotics showed the following results: Erythromycin R (MIC >0.5 mg/L) 30 isolates (3.6%), clindamycin R (MIC>2 mg/L) 6 isolates (0.7%), tetracycline R (MIC>2mg/L) 16 isolates (1,9%), and moxifloxacin R (MIC>0,5 mg/L) 1 isolate (0.1%). There were no isolates classified as I for those antibiotics. There were 21 isolates (2,5%) classified as I against cotrimoxazole (MIC >16, 32 mg/L), but no R (MIC>32 mg/L). Conclusion The proportion of invasive isolates of pneumococci with decreased sensitivity to commonly used antibiotics is very low. Our results indicate that there might be a clonal spread of isolates of serotype 9V and 14 with reduced susceptibility to antibiotics. 61 isolates with elevated MIC All isolates (827 patients) Sensitivity pattern and serotypes Number of S, I and R to six antibiotics Distribution of MIC values for 827 invasive strains of Streptococcus pneumoniae Erythromycin Penicillin G Clindamycin Tetracycline Trimethoprim/sulphamethoxazole Moxifloxacin