Antibiotics Susceptability of Streptococcus pneumoniae Isolated from Single Tertiary Childrens' Hospital Since 2014 and Choice of Appropriate Empirical Antibiotics

PURPOSE: We investigated the distribution and antimicrobial resistance of pneumococcal isolates from hospitalized children at Asan Medical Center for recent 4 years, and aimed to recommend proper choice of empirical antibiotics for pneumococcal infection. METHODS: From March 2014 to May 2018, children admitted to Asan Medical Center Childrens' Hospital with pneumococcal infection were subjected for evaluation of minimal inhibitory concentration (MIC) for β-lactams and macrolide antibiotics. Patient's age, underlying disease, gender were retrospectively collected. Using Monte Carlo simulation model and MIC from our study, we predicted the rate of treatment success with amoxicillin treatment. RESULTS: Sixty-three isolates were analyzed including 20.6% (n=13) of invasive isolates, and 79.4% (n=50) of non-invasive isolates; median age were 3.3 years old, and 87.3% of the pneumococcal infections occurred to children with underlying disease. Overall susceptibility rate was 49.2%, 68.2%, and 74.6% for amoxicillin, parenteral penicillin, and cefotaxime respectively. 23.8% and 9.5% of the isolates showed high resistance for amoxicillin, and cefotaxime. Only 4.8% (n=3) were susceptible to erythromycin. Monte Carlo simulation model revealed the likelihood of treatment success was 46.0% at the dosage of 90 mg/kg/day of amoxicillin. CONCLUSIONS: Recent pneumococcal isolates from pediatric patients with underlying disease revealed high resistance for amoxicillin and cefotaxime, and high resistance for erythromycin. Prudent choice of antibiotics based on the local data of resistance cannot be emphasized enough, especially in high risk patients with underlying disease, and timely vaccination should be implemented for prevention of the spread of resistant strains.

Clinical Characteristics, Prognostic Factors and Influence of Prophylaxis in Children with Pneumocystis jirovecii Pneumonia

PURPOSE: The aim of this study was to investigate the prognostic factors for Pneumocystis jirovecii pneumonia (PCP) and to evaluate the influence of PCP prophylaxis in pediatric patients. METHODS: From January 2002 to April 2015, patients aged <18 years with a diagnosis of confirmed PCP at our institute were reviewed retrospectively. Clinical characteristics and outcomes were compared according to the groups with or without PCP prophylaxis. Risk factors associated with PCP-related death were analyzed by logistic regression analysis. RESULTS: During study period, a total of 24 patients were diagnosed with PCP by immunofluorescence assay and/or PCR. The median age of the patients was 5 years (range, 3 months-18 years) and 23 (96%) had immunocompromised conditions including hematologic disorders with or without hematopoietic stem cell transplantation (n=15), solid organ transplantation (n=4), and primary immune deficiency (n=4). Most common presenting symptoms were tachypnea and cough (92%, each). At the time of diagnosis, 79% (19/24) and 25% (6/24) suffered from respiratory failure and multi-organ dysfunction syndrome (MODS), respectively. Mechanical ventilation was required in 8 (33%) patients and 5 (21%) patients died of PCP. Multivariate analysis showed that MODS at initial presentation was an indicator of poor prognosis (OR, 17.1 [95% CI 1.13-257.67]; P=0.04). Compared to the patients without PCP prophylaxis, the frequency of MODS at diagnosis, need for mechanical ventilation and length of hospital days were significantly less common in the children who received PCP prophylaxis. CONCLUSIONS: MODS at presentation was a significant predictor for poor outcome and PCP prophylaxis could alleviate the clinical courses of pediatric PCP. Prospective study will be mandatory to determine the risk factors for development and deterioration of PCP in children.

Diagnostic Usefulness of Cytomegalovirus (CMV)-Specific T Cell Immunity in Predicting CMV Infection after Kidney Transplantation: A Pilot Proof-of-Concept Study / 감염과화학요법

BACKGROUND: Cytomegalovirus (CMV) is one of the most important opportunistic infections in transplant recipients. Currently sero-positivity for CMV IgG before solid organ transplantation is the laboratory test of choice for stratifying the risk of CMV reactivation after solid organ transplantation. Theoretically, CMV-specific cell-mediated immune responses before solid organ transplantation should further categorize patients as high or low risk of CMV development. We therefore evaluated the usefulness of the CMV-specific enzyme-linked immunospot (ELISPOT) assay in kidney transplant (KT) candidates for predicting the development of CMV infections after transplantation. MATERIALS AND METHODS: All adult CMV IgG (+) recipients admitted to the KT institute between March 2014 and June 2014 were enrolled, and CMV infections after KT were observed between March 2014 and December 2014. All patients underwent CMV pp65 and IE1-specific ELISPOT assays before transplantation. CMV infection was defined in the presence of CMV antigenemia, CMV syndrome, or tissue-invasive CMV disease. We used the data to select optimal cut-off values for pp65 and IE1, respectively, on ROC curves. RESULTS: A total of 69 transplant recipients involving 54 (78%) living-donor KT, 9 (13%) deceased-donor KT, 3 (4%) kidney-pancreas transplants, and 3 (4%) pancreas transplants were enrolled. Of the 69 patients, 27 (39%) developed CMV infections. There was no association between the IE1-specific ELISPOT assay and CMV infection. However, only 15 (31%) of the 48 patients with positive pp65-specific ELISPOT results (>10 spots/2.0 x 105 cells) developed CMV infections, whereas 12 (57%) of the 21 patients with negative pp65-specific ELISPOT results developed CMV infection (P = 0.04). CONCLUSION: Negative pp65-specific ELISPOT assay results before transplantation appear to predict the subsequent development of CMV infections after transplantation in CMV IgG (+) KT recipients. Therefore, risk stratification of CMV IgG (+) recipients using the CMV-specific ELISPOT, together with preventive strategies, may further reduce CMV development.