Antimicrobial susceptibility of invasive group B streptococcal isolates from south-west Sweden 1988-2001.

The antibiotic susceptibility of 297 invasive isolates of group B streptococci (GBS) to a panel of 12 antibiotics was analysed using the E-test. The isolates (from 123 neonates and 174 adults) were collected from south-west Sweden during the 2 periods 1988-1997 and 1998-2001. The breakpoints of the Clinical and Laboratory Standards Institute were used. All isolates were sensitive to cefotaxime, meropenem, linezolid, vancomycin, moxifloxacin and quinupristin-dalfopristin. Two strains displayed a slightly decreased susceptibility to penicillin G (MIC 0.25 microg/ml) also when tested by the broth dilution method. Two per cent were resistant to erythromycin and 1% to clindamycin. Strains with intermediate sensitivity to erythromycin and clindamycin increased over the 2 study periods. 68% were resistant to doxycycline, and the resistance rate for doxycycline increased over the 2 study periods. No strain was resistant to trimethoprim-sulfamethoxazole. Serotype V dominated among strains with intermediate susceptibility to erythromycin and clindamycin. There were no other relationships between serotypes and decreased sensitivity to any agent. There were no significant differences in susceptibility to any agent tested between strains isolated from neonates and adults. In conclusion, penicillins remain the drug of choice in the region but with the increasing rates of intermediate susceptibility to both erythromycin and clindamycin, antibiotic sensitivity analysis should be performed on the GBS isolates from penicillin-allergic patients.

Antimicrobial susceptibility of invasive pneumococcal isolates from a region in south-west Sweden 1998-2001.

Invasive disease caused by antibiotic resistant pneumococci is a worldwide problem. All invasive pneumococcal strains in an area of south-west Sweden with 1.7 million inhabitants were collected prospectively during 1998-2001. Minimum inhibitory concentrations (MICs) were determined by E-test and correlated to serotypes and clinical characteristics. Of 827 strains, 744 (90%) were susceptible (S) to all agents tested and 83 (10%) were indeterminate (I) or resistant (R) to at least 1 agent. 22 isolates (2.7%) were I to penicillin (MIC >0.06 to < or = 1.0 mg/l), but none were R (MIC >1.0 mg/l). Numbers and proportions of decreased susceptibility against other agents tested were as follows: erythromycin R: 30 (3.6%), clindamycin R: 6 (0.7%), tetracycline R: 16 (1.9%), moxifloxacin R: 1 (0.1%), cotrimoxazole I: 17 (2%) and R: 31(4%). Non-susceptibility to at least 1 agent was not correlated with age, clinical manifestation, underlying diseases and outcome. The serotype distribution differed between non-susceptible and susceptible strains. The serotypes in the 7-valent pneumococcal conjugate vaccine covered 42% of all infections and 73% of those caused by non-susceptible strains. In conclusion, the impact of antibiotic resistance in invasive pneumococcal disease remains limited in south-west Sweden.

Serotypes of Streptococcus pneumoniae isolated from blood and cerebrospinal fluid related to vaccine serotypes and to clinical characteristics.

Pneumococci isolated from blood and cerebrospinal fluid from 1998 to 2001 in 2 counties in south-west Sweden were serotyped with the capsular reaction test. Of the 836 strains, 353 (42%), 598 (72%) and 789 (94%) belonged to serotypes included in the 7- and 11-valent pneumococcal conjugate vaccines and in the 23-valent polysaccharide vaccine, respectively. The most common serotype was type 1 (119 isolates) followed in descending frequency by serotypes 7F, 9V, 14, 4 and 12F (90-49 isolates per serotype). The coverage rates of the 7- and 11-valent conjugate vaccines among 58 strains isolated from children and adolescents 0-19 y of age were 46% and 93%, respectively. A comparison of clinical characteristics of infections caused by different serotypes showed that types 1 and 7F were less commonly associated with severe underlying diseases, that patients infected with these serotypes were younger than the average and, thus, had a lower case-fatality rate.