A fatal case of liver abscess caused by hypervirulent Klebsiella pneumoniae in a diabetic adolescent:A clinical and laboratory study

Importance Hypervirulent variants of Klebsiella pneumoniae(hvKp)are capable of causing life-threatening pyogenic liver abscesses(PLAs),but hvKp caused PLAs was seldom reported in pediatric populations.Hence,there is an urgent need to raise our awareness of this phenomenon in pediatric populations.Objective This study aimed to report the clinical characteristics of hvKp that caused fatal PLA complicated by bacteremia in an adolescent and further identify the microbiological and genomic features of the causative strain.Methods A 14-year-old boy with diabetes mellitus was admitted to our hospital with a diagnosis of PLA complicated by bacteremia.A hypermucoviscous hvKp strain,KPN_19-106,was isolated from the drainage fluid present within the liver abscess cavity and blood.The hypermucoviscosity phenotype of the causative strain was determined by string test.Its virulence was measured using serum resistance assay and Galleria mellonella larvae-killing assay.Antimicrobial susceptibility was determined by broth microdilution method.Genetic information was obtained by whole-genome sequencing and bioinformatics analysis.Results KPN_19-106 belonged to sequence type 380 and serotype K2 and exhibited stronger serum resistance and higher in vivo lethality than the well-characterized hvKp NTUH-K2044 strain.Although KPN_19-106 is susceptible to most antibiotics,no sign of improvement was observed during treatment with such drugs.Whole-genome sequencing revealed that the isolate had integrated multiple mobile genetic elements related to virulence.Interpretation Antibiotic-susceptible hvKp can cause fatal PLA complicated by bacteremia in adolescents,with no improvement during antimicrobial therapy.The causative strain in this case had integrated multiple virulence genes and thus exhibited higher virulence both in vitro and in vivo when compared with NTUH-K2044.

Pathogenic analysis in different types of orthopedic implant infections

Background Diversity of orthopedic infections with various local environments affects the pattern and prevalence of pathogens.It is not well-characterized whether different pathogens have different propensity to cause different types of orthopedic infections.We aimed to investigate the frequency of different pathogens derived from orthopedic infections,and determine the relationship between the prevalence of clinical isolates and the type of orthopedic implants,especially focusing on staphylococci.Methods From January 2006 to December 2011,orthopedic infections were identified retrospectively from clinical microbiology laboratory and orthopedic medical records.The sources of orthopedic infections were divided into two main groups：those associated with implants and those not associated with implants.Implants-associated infections were further subdivided into five subgroups：arthroplasty,internal fixation,external fixation,internal and external fixation,and others.We analyzed microbiological spectrum in different groups and subgroups.Antibiotic susceptibility of staphylococci was analyzed.Results Only coagulase-negative staphylococci （CoNS） was significantly more likely to be associated with implantsassociated infections （P=0.029）.The overall pathogens prevalence of arthroplasty was significantly different from other subgroups （P 〈0.05）.65% isolates from external fixation was Gram-negative bacteria.Some percentage （55%） of S.aureus and （83%） CoNS were resistant to methicillin.No resistance to glycopeptide was seen in all of staphylococci.Conclusions Staphylococcus aureus was the most frequent isolates in orthopedic infections but was not associated with the presence or absence of implants.Only CoNS was implants-associated,especially for arthroplasty infection.Cefazolin alone is not enough for orthopedic surgery prophylaxis in settings with a high prevalence of methicillin-resistant staphylococci.

Epidemiological characteristics and risk factors of nosocomial carbapenem-resistant Enterobacteriaceae infections in children

Carbapenem-resistant Enterobacteriaceae(CRE)have spread worldwide as a global threat and CRE infection is associated with a significant mortality.However,data on epidemiology and treatment of CRE infection in children are comparatively lacking.[1]Therefore,we retrospectively conducted a matched case-control study to summarize the epidemiological characteristics,risk factors,treatment,and outcomes of nosocomial CRE infections in a children patient population,and also to identify the antimicrobial resistance and resistance genotyping of CRE isolates.

Thoracoscopic management for bronchiectasis with non-tuberculous mycobacterial infection

Background Non-tuberculous mycobacteria （NTM） have emerged as important opportunistic pathogens of the human being in recent years. Patients with pre-existing bronchiectasis are susceptible to NTM. However, information about its occurrence among bronchiectatic patients in Shenzhen, China is lacking and its impact on the course of bronchiectasis following surgical intervention is unknown. This preliminary study aimed to investigate the prevalence of NTM in bronchiectasis that required surgery in our center, evaluate the role of intraoperative routine screening for NTM, and summarize our initial experience in thoracoscopic management for bronchiectatic patients with NTM. Methods A retrospective analysis of clinical, microbiological data of our bronchiectatic patients with NTM over 5 years was made and 40 patients with bronchiectasis were studied to determine the role of intraoperative routine screening for NTM. Results The prevalence of NTM in this population of patients with bronchiectasis in our center was 6.7% （7/105）. The diagnostic yield of the 40 intraoperative specimens was 7.5% （3/40）. Of the 7 patients with bronchiectasis and NTM, 3 patients developed postoperative wound infections. All were cured with chemotherapy for 8-12 months along with vigorous surgical debridement. Another patient had a slow growth of mycobacteria involving double lungs and the right thoracic cavity and recovered after chemotherapy for nearly 14 months and tube drainage. The affected tissue was completely resected in the remaining 3 patients with no operative mortality and postoperative morbidity, and routine intraoperative screening for NTM was initiated in these patients. Conclusions NTM is not uncommon in bronchiectatic patients which deserves surgeons＇ utmost attention. Routine intraoperative screening for NTM identified otherwise unsuspected patients has shown favorable outcomes. Thoracoscopic management for bronchiectasis with NTM is technically feasible although its role remains to be defined.