Objective To study the etiology and antibiotic resistance of bloodstream infections in low birth weight preterm infants .Methods A total of 95 cases of bloodstream infections in low birth weight preterm infants were treated in our hospital from January 2011 to April 2014 .The clinical data of these patients were analyzed retrospectively .Results A total of 96 pathogens were isolated ,including 57 strains of gram‐negative bacilli ,38 strains of gram‐positive cocci ,and 1 strains of Trichosporon asahii .The most frequently isolated pathogens were Klebsiella pneumoniae (40 strains)and coagulase‐negative Staphylococcus(31 strains).All gram‐negative bacilli were sensitive to carbapenems such as imipenem and panipenem . Streptococcus isolates were sensitive to most antibiotics .Most Staphylococcus isolates were methicillin‐resistant ,which were highly resistant to common antibiotics but all sensitive to linezolid , vancomycin and teicoplanin . Conclusions The most important pathogens responsible for bloodstream infections in low birth weight preterm infants in our hospital are K lebsiella pneumoniae and coagulase‐negative Staphylococcus . Early identification of responsible pathogen and rational antimicrobial therapy are critical for good prognosis of bloodstream infections in low birth weight preterm infants .

Objective To explore the influence of Rapamycin (RAPA) on apoptosis of acute lymphoblastic leukemia EU-4 cells induced by Methotrexate (MTX).Methods EU-4 cells were pretreated 0.5 h with 5 pμg/L,10 μg/L,25 μg/L,50 μg/L and 100 μg/L RAPA.RAPA untreated group was set up as control group.The cells were collected and the expression of LC-3 was assayed by using Western blot.The apoptosis of EU-4 cells was detected by using flow cytometry (FCM).The effects of different concentrations of RAPA pretreatment on autophagy and apoptosis of EU-4 cells were observed,and the pretreatment concentration of RAPA was determined.EU-4 cells were divided into RAPA pretreatment group and untreated group.The cells were treated with 0.05 μmol/L,0.10 pμmol/L and 0.20 μmol/L MTX for 24 h,respectively.The apoptotic rate was detected by using FCM.Western blot was performed to test the expression of LC-3 protein,while the absorbance(A562) was measured by using microplate reader,and the protein concentration in the sample was calculated according to the standard curve.Results The apoptotic rates of EU-4 cells in the control group and the different concentrations of PAPA pretreatment group showed that the control group,5 μg/L,10 μg/L,25 μg/L,50 μg/L and 100 μg/L RAPA were (7.51 ±0.32)％,(7.33 ±0.41)％,(7.71 ± 0.51) ％,(7.63 ± 0.38) ％,(7.80 ± 0.43) ％ and (16.66 ± 0.87) ％,respectively.The apoptotic rates of EU-4 cells in the 5 μg/L,10 μg/L,25 μg/L and 50 μg/L PAPA pretreatment group had no significant difference from those in the control group(t =0.427,-0.417,-0.297,-3.561,all P ＞ 0.05).The apoptotic rate of EU-4 cells in 100 μg/L PAPA pretreatment group was significantly higher than that in control group,and the difference was significant (t =-28.815,P ＜ 0.01).Combined with the results of Western blot and FCM,50 μg/L was used as the pretreatment of PAPA.The apoptosis rates of EU-4 cells in PAPA pretreatment group were (50.23 ± 2.11) ％,(66.88 ± 2.89) ％ and (73.11 ± 2.67) ％ after treated with 0.05 μmol/L,0.10 μmol/L and 0.20 μmol/L MTX for 24 h,respectively.The apoptotic rates of EU-4 cells in PAPA unpretreatment group were (22.53 ± 1.67) ％,(42.82 ± 2.26) ％ and (53.22 ± 1.93)％ after treated with 0.05 μmol/L,0.10 μmol/L and 0.20 μmol/L MTX for 24 h,respectively.The apoptotic rates of EU-4 cells in RAPA pretreatment group were significantly higher than those in untreated group in the same concentration of MTX treatment after 24 h,and the differences were significant(t =12.693,66.148,14.429;all P ＜ 0.01).Conclusion With RAPA pretreatment,relative low dose MTX can induce a great deal of acute lymphoblastic leukemia EU-4 cells apoptosis.