[Distribution and antibiotic resistance of bacteria causing bloodstream infections in patients in intensive care...

To investigate the distribution and antibiotic resistance of bacteria causing bloodstream infections in intensive care unit (ICU) patients and to provide a basis for rational clinical use of antibiotics.

The data of positive specimens, including whole blood, catheter blood and bone marrow samples, were isolated from ICU patients from January 2010 to December 2012. Disc diffusion method, micro-dilution and Etest method were used to test drug sensitivity. Distribution and antibiotic resistance of bacteria were analyzed retrospectively.

A total of 1077 strains were isolated from 903 patients with bloodstream infection during 3 years. Gram-positive (G⁺) bacteria and Gram-negative (G⁻) bacteria accounted for 59.33% (639 isolates) and 40.67% (438 isolates) respectively. The 5 most frequently isolated bacteria were Staphylococcus epidermidis (20.06%, 216 isolates) followed in order by Escherichia coli (13.93%, 150 isolates), Acinetobacter baumannii (10.03%, 108 isolates), Klebsiella pneumonia (7.80%, 84 isolates) and Staphylococcus aureus (6.96%, 75 isolates). There was no significant difference in distribution of bacteria during 3 years. The resistance rate of Staphylococcus epidermidis was higher than that of Staphylococcus aureus to most of the tested drugs. The resistance rate of Staphylococcus epidermidis to quinoline/dalfopristin (4.2%) and nitrofurazone (15.3%) was relatively low, while resistance to penicillin (94.4%), linezolid (93.1%), piperacillin/tazobactam (90.3%), cefoperazone/sulbactam (87.5%) and oxacillin (83.3%) was over 80%. The resistance rate of Staphylococcus aureus to penicillin (96.0%), cefoperazone/sulbactam (84.0%), linezolid (76.0%) and oxacillin (76.0%) was over 70%, and resistance to the other common antibacterial drugs was below 70%. The resistance rate of Acinetobacter baumannii to amikacin (38.9%), nitrofurazone (91.7%), cefotetan (88.9%), ceftazidime (88.9%), ampicillin (88.9%), ceftriaxone (86.1%), the cefepime (86.1%), aztreonam (80.6%) and cefazolin (80.6%), and overall above 80%. The resistance rate of Escherichia coli to amikacin (30.0%), cefotetan (24.0%) and imipenem (16.0%) was below 30%, while resistance to ampicillin/sulbactam (94.0%), levofloxacin (84.0%), ampicillin (84.0%) and ceftriaxone (80.0%) was over 80%.

Among the bacteria causing bloodstream infection as isolated from ICU patients, G(+) and G(-) bacteria accounted for 59.33% and 40.67%, respectively. The resistance rate of G(-) was higher than that of G(+), and resistance rate of majority of bacteria was higher than 60% on average. Before obtaining the susceptibility test Results, both G(-) and G(+) should be taken into account on choosing antimicrobial drugs in the treatment of ICU patients.