Distribution and antimicrobial resistance of pathogens isolated from hospi-talized patients with bloodstream infections / 中国感染控制杂志

Objective To investigate the species and drug resistance of pathogens causing bloodstream infections in hospitalized patients,and provide scientific evidence for antimicrobial use and control of healthcare-associated blood-stream infection.Methods From January 1 to December 31,2012,16 428 blood specimens were performed blood culture,pathogens were isolated and performed antimicrobial susceptibility testing.Results Of 16 428 blood speci-mens from 5 546 patients,384 (6.92%)were positive for blood culture,398 pathogenic isolates were detected,of which gram-positive bacteria,gram-negative bacteria,and fungi accounted for 23.62% (n=94),68.34% (n=272),and 8.04% (n=32)respectively,positive rate of blood culture were highest in 61-80 age group(8.26%), the top five departments of positive rate of blood culture were departments of burn,traditional Chinese medicine, cardiac intensive care unit,transplantation and traumatology;gram-positive cocci were highly susceptible to vanco-mycin,teicoplanin and linezolid,one Enterococcus faecium strain was found to be resistant to vancomycin;Among gram-negative bacilli,Enterobacteriaceae were highly susceptible to amikacin and carbapenems;drug resistance rates of Acinetobacterbaumannii and Pseudomonasaeruginosa to carbapenems was 70.97% and 35.90% respective-ly.Conclusion Gram-negative bacteria are the major pathogens causing bloodstream infection,positive rate of blood culture of elderly people is high.It is necessary to conduct regular surveillance on distribution and drug resistance of pathogens.

Investigation of antibacterial activity of topical antimicrobials against methicillin-resistant Staphylococcus aureus / 中华烧伤杂志

<p><b>OBJECTIVE</b>To investigate the antibacterial activity of silver sulfadiazine (SD-Ag), mupirocin, and clotrimazole used alone or in combination against methicillin-resistant Staphylococcus aureus (MRSA) isolated from burn wounds.</p><p><b>METHODS</b>Eighteen MRSA isolates from wound excretion of 18 burn patients hospitalized in our unit from July to December 2011 were collected continuously and non-repetitively. (1) Minimum inhibitory concentration (MIC), 50% MIC (MIC50), and 90% MIC (MIC90) of SD-Ag, mupirocin, and clotrimazole used alone, those of SD-Ag and mupirocin used in combination, and those of SD-Ag, mupirocin, and clotrimazole used in combination to MRSA were determined by checkerboard agar dilution method. (2) Fractional inhibitory concentration (FIC) index was calculated to determine the combined effect of SD-Ag plus mupirocin, and SD-Ag plus mupirocin and clotrimazole. Synergy with FIC index less than or equal to 0.5 or additivity with FIC index more than 0.5 and less than or equal to 1.0 was regarded as effective, and indifference with FIC index more than 1.0 and less than or equal to 4.0 or antagonism with FIC index more than 4.0 was regarded as ineffective. The effective ratio was compared with overall ratio (assumed as 0) by unilateral binomial distribution test.</p><p><b>RESULTS</b>The MIC, MIC50, and MIC90 of SD-Ag, mupirocin, and clotrimazole used alone against 18 MRSA isolates were respectively 8, 8, 16 µg/mL; 2, 16, 64 µg/mL; 2, 2, 2 µg/mL. MIC of antimicrobial agents used in combination decreased from 3.1% to 50.0% as compared with that of individual agent used alone. Compared with those of single application of SD-Ag and mupirocin, MIC50 of SD-Ag and that of mupirocin both decreased 75.0%, and MIC90 of them decreased 87.5% when SD-Ag and mupirocin were used in combination. Compared with those of single application of SD-Ag, mupirocin, and clotrimazole, MIC50 of SD-Ag, mupirocin, and clotrimazole respectively decreased 75.0%, 87.5%, and 50.0%; MIC90 of them respectively decreased 87.5%, 96.9%, and 50.0% when SD-Ag, mupirocin, and clotrimazole were used in combination. Among the 18 MRSA isolates, the combined effect of SD-Ag and mupirocin was synergic in 9 isolates, additive in 7 isolates, indifferent in 2 isolates, and antagonistic in 0 isolate; the combined effect of SD-Ag, mupirocin, and clotrimazole was additive in 16 isolates, indifferent in 2 isolates, and antagonistic in 0 isolate. There were statistically significant differences between effective ratio and overall ratio of 18 MRSA isolates treated with combined antimicrobial agents (P values all above 0.01).</p><p><b>CONCLUSIONS</b>For burn wounds at middle and late stages infected with Staphylococcus aureus or Staphylococcus aureus and Fungus, low dose of SD-Ag or combination of above-mentioned antimicrobial agents can effectively control infection and decrease the adverse effect of antimicrobial agents on wound healing.</p>

Relationship between antibiotic use and antimicrobial resistance in Acinetobacter baumannii / 中国感染与化疗杂志

Objective To investigate the relationship between antibiotic use and antimicrobial resistance in Acinetobacter bau-mannii for rational use of antibiotics.Methods Antibiotic use density (AUD)of common antibiotics in hospitalized patients were collected in a tertiary hospital between 2006 and 2010.Clinical isolates of A.baumannii from those patients were collect-ed.The resistance to common antimicrobial agents were tested by disk diffusion method according to Clinical and Laboratory Standards Institute (CLSI,2012)guidelines.Relationship between antibiotic use and antimicrobial resistance in A.baumannii was analysed by SPSS 16.0.Results The resistant rates of A.baumannii isolated from inpatients were high.Consumption of cephalosporins and quinolones were large.There was a positive correlation between the resistant rate of A.baumannii to imi-penem and AUD of carbapenems (r=0.975,P <0.05).The resistant rate of A.baumannii to meropenem showed significantly positive relation to AUD of carbapenems (r= 0.975,P <0.05).Resistant rates of aminoglycosides,quinolones,cephalospo-rins and beta-lactamase inhibitors was not correlated to AUD of those antibiotics.Conclusions We should pay more attention to the high prevalence of resistant A.baumannnii strains.Application of imipenem and meropenem should be strictly controlled.Amikacin and beta-lactamase inhibitors are better choice for empirical antibiotic therapy in the treatment of infections caused by A. baumannii.