Acta Academiae Medicinae Sinica

Abstract: Objective To investigate the incidence,pathogens,and clinical features of infection in consecutive cases from 2010 to 2012 in Peking Union Medical College Hospital. Method The incidence,pathogen,treatment,and outcomes of patients with hematological diseases who had positive findings of bacterium in their samples from 2010 to 2012 were retrospectively analyzed. Results There were 449 positive samples (5.8%) from 4 890 patients during this period,among which 388 were proved to be with pathogenic bacteria. Samples separated from patients with community-aquired infections accounted for 8.4% of all positive samples. Most community-aquired infections were caused by Gram-negative bacteria (75%),although no multidrug-resistant bacteria was observed. Samples separated from patients with nosocomial infections accounted for 91.6% of all positive samples. Respiratory tract (49.4%) and peripheral blood (32.6%) were the most common samples with positive results. Skin soft tissues (10.4%),and urine (3.7%) were less common samples. Most of the pathogenic bacteria of the nosocomial infections were Gram-negative (66.9%). The most common Gram-negative bacteria included Escherichia coli (13.8%),Pseudomonas aeruginosa (12.1%),and Klebsiella pneumonia (12.1%),while Staphylococcus aureus (10.4%),Enterococcus faecium (7.0%),and Staphylococcus epidermidis (5.1%) were the most common Gram-positive bacteria. Gram-negative bacteria consisted of most of sputum samples and peripheral blood samples. Samples from the surface of skin wound and anal swab were composed largely by Gram-positive bacteria (63.8%). The detection rates of extended-spectrum beta-lactamase-producing Klebsiella pneumonia/Klebsiella oxytoca,Escherichia coli,and Proteus mirabilis were 24.0%,87.9% and 38.4%,respectively. The resistance to Acinetobacter baumannii was serious. Multidrug-resistant,extensive drug resistant and pan drug resistant A. baumannii acountted for 74% of all A. Baumannii infections. Stenotrophomonas maltophilia showed low resistance to sulfamethoxazole/trimethoprim,levofloxacin and minocycline. Also,22 methicillin-resistant Staphylococcus aureus and 9 methicillin-resistant Staphylococcus Epidermidis were detected,which were only sensitive to vancomycin,teicoplanin,and linezolid. All patients were treated in the haematology wards and most of them were under agranulocytosis or immunosuppression. Finally,22 patients reached clinical recovery through anti-infective therapy,whereas 49 patients died. Among those deaths,42 patients attributed to severe infections and infection-associated complications. Fourteen of all the deaths might be infected with drug-resistance bacteria. There were 61 samples proved to be bacteria colonization. Nonfermenters such as Acinetobacter baumannii and Stenotrophomonas maltophilia made up for a large amount of bacteria colonization. Conclusions The pathogens of nosocomial infections in the hematology ward are mainly Gram-negative bacteria. The incidences and pathogens vary from different infection sites. Nosocomial infection still has a higher mortality rate. Once nonfermenters are detected positive,the pathogenic or colonial bacteria should be distinguished.

Key words: bacterial infection, hematological disease, nosocomial infection, Gram-negative bacteria, Gram-positive bacteria, drug resistance