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

OBJECTIVE: 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.

METHODS: 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.

RESULTS: 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%.

CONCLUSIONS: 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.