Analysis of distribution characteristics and drug resistance of 2748 strains of pathogens isolated from burn patients / 中华烧伤杂志

<p><b>OBJECTIVE</b>To provide epidemiological data of the distribution characteristics and drug resistance of the pathogens isolated from burn patients in recent years for guiding rational use of antibiotics in clinic.</p><p><b>METHODS</b>Totally 2748 strains of pathogens were isolated from 1977 specimens (blood, catheter, wound excretion, etc.) collected from 478 patients hospitalized in Institute of Burn Research of Southwest Hospital from March 2003 to June 2011. After being identified by API strips, drug resistance of the 2748 isolated pathogens to 55 commonly-used antibiotics including gentamicin, tobramycin, piperacillin, amikacin, etc. was tested by K-B paper disk diffusion method. The WHONET 5.3 software was used to analyze the following subjects: the distribution of the pathogens with different types and different sources each year, the changes in drug-resistant rates of Gram negative bacilli, Gram positive cocci, and fungi to several antibiotics, and the changes in sensitive rates of Pseudomonas aeruginosa (PA), Staphylococcus aureus (SA), Acinetobacter baumannii (AB), Candida albicans (CA) to several antibiotics.</p><p><b>RESULTS</b>Among 2748 strains of pathogens, 1879 strains of Gram negative bacilli accounted for 68.38%, 628 strains of Gram positive cocci accounted for 22.85%, and 241 strains of fungi accounted for 8.77%. The isolation rate of strains from wound excretion ranked the first (1022 strains accounted for 37.19%), followed by those from respiratory tract (995 strains accounted for 36.21%) and blood (421 strains accounted for 15.32%). Strains isolated from other types of specimens were rare. Isolation rate of PA ranked the first (996 strains accounted for 36.24%), followed by SA (495 strains accounted for 18.01%) and AB (395 strains accounted for 14.37%). Isolation rate of AB showed a trend of increase year by year, but that of SA presented the opposite trend. Isolation rate of PA was quite stable. There were 484 strains of methicillin resistant SA among Staphylococci, accounting for 17.61%. Resistant rates of PA and AB to polymyxin B and polymyxin E were below 30.00%, and those of PA and AB to other antibiotics, such as the third generation cephalosporins, β-lactams, aminoglycosides, and quinolones, were from 57.91% to 100.00%. Resistant rate of AB to minocycline was 39.68%. From 2004 to 2011, sensitive rate of PA to quinolone antibiotics showed an increasing trend year by year, but that of AB to minocycline, netilmicin, imipenem, meropenem, tobramycin, and cefoperazone/sulbactam presented the opposite trend. Resistant rates of Enterococcus faecalis, Enterococcus faecium, and SA to teicoplanin and linezolid were less than 10.00%. Resistant rate of SA, Staphylococcus epidermidis and Enterococcus faecium to vancomycin was 0. Resistant rates of SA to quinupristin/dalfopristin, minocycline, fusidic acid, and compound sulfamethoxazole were low, respectively 0.82%, 9.35%, 2.21%, and 31.85%. Sensitive rates of SA to erythromycin, clindamycin, compound sulfamethoxazole, tetracycline, and minocycline showed an increasing trend year by year. Both infection rate and resistant rate of fungi were low. The resistant rates of CA to 5 kinds of antibiotics were less than 15.00%. The sensitive rate of CA to 5-flucytosine declined slightly, and those of CA to the other 4 antibiotics showed an increasing trend year by year.</p><p><b>CONCLUSIONS</b>The three dominant pathogens that cause infection in burn patients hospitalized in Institute of Burn Research of Southwest Hospital in recent years are PA, SA, and AB in order. PA and AB are outstandingly multidrug-resistant among the isolated strains. AB might replace PA as the main pathogenic bacterium that cause the death of burn patients with infection.</p>

Analysis of resistance phenotype and homology of Klebsiella pneumoniae in burn patients / 中华烧伤杂志

<p><b>OBJECTIVE</b>To study the resistance phenotype and homology of Klebsiella pneumoniae (KPN) in burn patients with infection.</p><p><b>METHODS</b>Fifty-four strains of KPN were isolated from wound excretion, blood, sputum, venous catheter, feces, and oral cavity of patients hospitalized in Institute of Burn Research of Southwest Hospital (briefly called our institute) from January 2007 to June 2011. Drug resistance of the 54 strains of KPN to 18 antibiotics commonly used in clinic, including ampicillin, ticarcillin, etc, was tested by K-B paper disk diffusion method after being identified. Extended-spectrum β-lactamase (ESBL)-producing KPN was screened based on the drug resistance result. The positive rates of drug-resistant genes SHV, TEM, and CTX-M of the ESBL-producing KPN were detected by polymerase chain reaction. The homology of the ESBL-producing KPN was analyzed by pulse field gel electrophoresis and clustering methodology. The homology of ESBL-producing KPN isolated in each year was analyzed too.</p><p><b>RESULTS</b>(1) The sensitive rate of the 54 strains of KPN to imipenem, meropenem, and ertapenem was respectively 96.30%, 92.59%, and 81.48%, that of these strains to cefotetan and cefoxitin was respectively 70.37% and 64.81%, and that of these strains to ceftazidime was 57.41%. The sensitive rates of the 54 strains of KPN to the other antibiotics were all lower than 40.00%. (2) Twenty-six ESBL-producing KPN strains were screened and the positive rate of SHV, TEM, and CTX-M was 96.15% (25/26), 76.92% (20/26), and 57.69% (15/26), respectively. Detection rate of ESBL-producing KPN strains carrying three genes at the same time was 42.31% (11/26), that of these strains carrying both SHV and TEM was 34.62% (9/26), and those of these strains carrying only a single gene were all less than 10.00%. (3) The twenty-six ESBL-producing KPN were classified into 9 gene types, with 30.77% (8/26) in type A, 19.23% (5/26) in type B, 15.38% (4/26) in type C, 11.54% (3/26) in type D, 7.69% (2/26) in type E, and the rest four strains respectively in type F, G, H, I [3.85% (1/26)]. (4) The major gene type of ESBL-producing KPN in the year of 2007 and 2010 was type A, respectively accounting for 2/3 and 1/2, while that in the year of 2009 was type B, accounting for 1/2. The three strains in 2008 was respectively in type C, E, and F. The four strains in 2011 was respectively in type A, D, H, I.</p><p><b>CONCLUSIONS</b>KPN in burn patients with infection in our institute are highly resistant to commonly used antibiotics in clinic, but carbapenems antibiotics can be used for the treatment. Most of the ESBL-producing KPN strains carry two or three drug-resistant genes, and the main gene type of them is type A.</p>