Frequency of isolation and antimicrobial susceptibility patterns of bacteria isolated from bloodstream infections in CHINET program in China during 2011

Objective To investigate the distribution and changing pattern of susceptibility in blood culture isolates in 15 hospitals across China during 2011. Methods The blood culture isolates were routinely isolated and identified. Antimicrobial susceptibility of these isolates were tested with more than 20 antimicrobial agents by Kirby-Bauey methods in the participating institutions. Results A total of 6 992 strains were isolated from blood specimens during 2011. Gram positive cocci and Gram negative bacilii accounted for 61.9% and 38.1%,respectively. The most frequent isolates were coagulase negative Staphylococcus (CNS) (43.6%), E.coli (15.2%), Enterococcus spp. (7.7%), Klebsiella spp. (7.5%), E.arreus (6. 3%), Acinetobactrr spp. (3.7%), E.viridans (3.0%), P. aeruginosa (2.7%), Entrobacter spp. (2.0%), Salmonella spp. (1.1%) and S. maltophilia (1.1%). All these species together accounted for 93.9% of all the blood culture isolates. Prevalence of MRSA and MRCNS among S. aureus and CNS were 42.5% and 68.0%, respectively. The prevalence of E. faecalis strains resistant to high level gentamicin and ampicillin was 37.0% and 11.1%,respectively. E. faecium isolates showed significantly higher resistant rates to most of the antimicrobial agents tested than the E. faecalis isolates. Penicillin resistance was identiiied in 8.4% of the S. viridans isolates. About 57.9% of the S. pneumoniae strains isolated from children were resistant to penicillin, signiiicantly higher than that in the strains isolated from adults (22.2%). No strains were found resistant to vancomycin or linezolid in the Staphylococcus spp., Streptococcus spp., S. pneumoniae and E. faecalis isolates. Vancomycin resistance was demonstrated in 4.6% of the E. faecium isolates. Enterobacteriaceee strains was highly susceptible to carbapenems. The prevalence of carbapenem-resistant isolates was less than 10%. Nonfermenters was highly resistant to carbapenems,especially in Acinetobacter isolates,more than 60% of which were resistant. Conclusions CHINE surveilance data of 2011 indicate that gram positive coccus, especilly CNS, plays an important role in blood stream infections. Resistance to the lirst line antibiotics is common among all blood isolates. Antimicrobial agents should be used appropriately to reduce the selection pressure. Hospital infection control should be strengthened to prevent the spread of resistant organisms.