The Bacteriology Of Complicated Intra-abdominal Infection And Clinical Research Of Klebsiella Pneumoniae Bloodstream Infection

Objective: The purpose of this study was to determine the shifting trends in bacteriology and antimicrobial resistance of infectious specimens isolated from gastrointestinal(GI)fistula patients.And exploring the risk factors of polymicrobial bacteraemia involving K.pneumoniae(PBKP)and predictors of mortality mortality in patients with bacteraemia involving K.pneumoniae.Methods: We retrospectively reviewed the microbial records of intra-abdominal specimens at a teaching hospital from 2008 to 2015.Study period was divided into the first half(2008–2011)and the second half(2012–2015).Bacteriology and antimicrobial resistance were analysed.A retrospective observational study of patients with polymicrobial and monomicrobial bacteraemia involving K.pneumoniae was performed from January 2012 to December 2016.Risk factors related to the PBKP and bacteraemia-related mortality were analysed.Results:(1)Trends in bacteriology and antimicrobial resistance.A total of 874 intra-abdominal isolates were consecutively collected from 502 GI fistula patients(mean age,46.5 years,71.1% male)during the study period.Patients in the second study period(2012–2015)were older(>65 years)and more likely to have experienced cancer.Over the entire study period,most infections were caused by E.coli(24.2%)and K.pneumonia(14.1%).There was a significant decrease in the proportion E.coli isolates that were extended-spectrum beta-lactamase(ESBL)-positive(P = 0.026).The proportion of E.coli resistant to imipenem increased from 14.3% in 2008–2011 to 25.9% in 2012–2015(P = 0.037).Imipenem resistance prevalence was higher in ESBL-negative bacteria than ESBL-positive bacteria for both E.coli and K.pneumonia(P < 0.001).In Enterococcus,significant increase in resistance to ampicillin(P = 0.01)and moxifloxacin(P = 0.02)over time were observed.In Staphylococcus and fungi,rates of antibiotic resistance did not significantly change over the study period.(2)Risk factors and Clinical Outcomes of PBKB The study included 47(48.0%)patients with polymicrobial and 51(52.0%)patients with monomicrobial bacteraemia involving K.pneumoniae.The most common accompanying microorganism was E.coli from the polymicrobial group.As for the outcomes,patients with PBKP were more likely to have recurrent bloodstream infections(P=0.038),longer ICU lengths of stay(P=0.043),and a higher total cost of hospitalization(P=0.045).However,there were no significant differences in mortality between the two groups.In the multivariate analysis,longer hospital stay prior to the onset of bacteraemia(>20 days)is an independent risk factor for PBKP(P=0.034).Septic shock(P=0.023),inadequate source control(P=0.001),and iron supplementation(P=0.004)were independent predictors of bacteraemia-related mortality in bacteraemia involving K.pneumoniae patients.Conclusions:(1)Gram-negative bacteria predominated as causative agents of intra-abdominal infections in GI fistula patients,and there was an increase in levels of resistance to certain antibiotics,particularly carbapenems.Infection control and source control are important tools available to surgeons to prevent the emergence of antibiotic resistant pathogens.(2)The development of septic shock,inadequate source control and the concomitant use of iron supplementation are associated with higher mortality in patients with KP bacteraemia.PBKP did not increase mortality,possibly due to K.pneumoniae’s ability to obscure the effects of other bacteria.