Gilsung Yoo

Multidrug-Resistant Corynebacterium striatum Bacteremia: First Case in Korea

Dear Editor Corynebacteria are aerobic, non-spore forming, and gram-positive bacilli that are commensal organisms of skin and mucosal membranes. C. striatum, like other Corynebacterium species, is a part of the normal human skin flora; therefore, it has been frequently dismissed as a blood and airway sample contaminant in the past. However, C. striatum is emerging as a cause of bloodstream infections and endocarditis [1]. Moreover, C. striatum infection outbreaks have been reported in long-stay patients with underlying disease [2]. We report a case of C. striatum bacteremia in a patient who had undergone gastrostomy. To our knowledge, there has been no report of C. striatum bacteremia in Korea so far. A 64-yr-old quadriplegic man visited the outpatient rehabilitation clinic for gastrostomy tube change. Before visiting our hospital, he was admitted to a secondary hospital and had hypertension and diabetes mellitus. Nine months before this visit, quadriplegia developed because of hypoxic ischemic encephalopathy; he underwent tracheostomy and gastrostomy tube placement. He was admitted to our hospital owing to persistent low-grade fever with blood pressure of 156/89 mmHg. The white blood cell count was 6.02×109/L (86% segmented neutrophils), and C-reactive protein level was 3.34 mg/dL (reference range: 128 µg/mL), and erythromycin (>128 µg/mL). At first, the physician assumed that C. striatum was a contaminant and the fever was caused by a urinary tract infection on the basis of the past history. Thus, only intravenous piperacillin/tazobactam was administered for the possible urinary tract infection. Culture for medical devices such as the gastrostomy or tracheostomy tubes was not performed. However, fever did not subside and C-reactive protein level was elevated; follow-up blood cultures performed on the 6th day of admission revealed C. striatum growth. The patient was continuously given intravenous piperacillin/tazobactam. As the fever subsided, he was transferred to a provincial medical center. The patient was readmitted for check-up a month after discharge and showed no sign of infection. It is difficult to distinguish simple colonization from real infection when Corynebacterium spp. are recovered from specimens [4]. C. striatum are commonly isolated in patients with significant underlying illnesses [2] and has close association with various medical devices such as prosthetic valve/joint and central venous catheter [5] and long hospitalization. In this case, the patient suffered from diabetes, hypertension, tracheostomy, and gastrostomy. Additionally, he had stayed at a secondary health care center before being admitted to our hospital. These factors probably increased the patients risk of C. striatum infection. Additionally, each of the blood culture sets was collected at regularly spaced intervals with adequate blood volumes, and turned positive within 24 hr. One of the recent issues related to C. striatum is the emergence and spread of multidrug resistance. Generally, most of the reported C. striatum isolates were susceptible to a wide range of antibiotics [6]; however, recent studies showed the emergence of multi-drug resistant strains with increasing use of broad-spectrum antibiotics (Table 1) [1, 4, 6, 7]. When invasive C. striatum infection is suspected, most initial therapies should include vancomycin, because in vitro resistance to vancomycin has not been reported in any of the Corynebacterium species [5]. If the patient is allergic to vancomycin, daptomycin may be an alternative. Fernandez et al. [1] reported successful treatment of a case of multidrug-resistant C. striatum endocarditis with daptomycin. Table 1 Multidrug resistant Corynebacterium striatum in the literature In conclusion, with increasing numbers of immunosuppressed patients and indwelling medical devices, C. striatum infections will be more commonly found and should never be overlooked as a contaminant. This report suggests the need to increase awareness of C. striatum as a pathogen causing bloodstream infections.

NDM-5 and OXA-48 Co-producing Uropathogenic Escherichia coli Isolate: First Case in Korea

Dear Editor, The increasing incidence of carbapenem-resistant Enterobacteriaceae (CRE) is a major concern for global health [1]. Among CRE, the prevalence of carbapenemase-producing Enterobacteriaceae (CPE) ranges from 11% to 20.1% in Korea [2, 3]. The most clinically significant CPE are of the KPC-, IMP-, VIM-, NDM-, and OXA-48 types, mostly identified from Klebsiella pneumoniae isolates as sources of nosocomial outbreaks [4]. The microorganisms carrying these genes are a grave threat to global health, not only because of their resistance capacity but also because the genes are carried on plasmids. OXA-48-producing Enterobacteriaceae have been found worldwide since the first isolation of this gene from a K. pneumoniae isolate in Turkey in 2003 [4]. Although only one isolate of OXA-48-producing Escherichia coli has been previously detected in Korea in a urine specimen from a foreign patient [2], such bacteria are likely to emerge and spread owing to travel or patient exchanges from other countries [4]. NDM-1and NDM-5-producing E. coli have been reported in Korea, although they are uncommon [5, 6]. While NDM and OXA co-producing Enterobacteriaceae are emerging [4, 7], NDM-5 and OXA-48 co-producing E. coli have not been reported worldwide to date. Here, we describe the first identification of NDM-5 and OXA-48 co-producing E. coli in Korea. This case has got an exemption (2017-11-0222) from the approval of the Institutional Review Board for Human Research in Yonsei University Wonju Severance Christian Hospital. Informed consent from the patient was not required for this report because the patient was de-identified. A 76-year-old female patient was admitted to the Wonju Severance Christian Hospital for aortic valve replacement surgery due to severe aortic stenosis. The patient had a medical history of recent cerebral infarction, coronary artery occlusion disease, paroxysmal atrial fibrillation, and hypertension. She had no known recent history of travel. Following the surgery, she was treated for pneumonia with cefepime. A few days later, the patient newly developed a fever of 38.2°C. Two aerobic and anaerobic blood culture sets drawn from both arms were incubated in the BacT/Alert 3D system (bioMérieux, Marcy l’Etoile, France), and no organisms were detected from the blood cultures after five days of incubation. The laboratory findings showed an elevated white blood cell count of 11.22×10/L (segmented neutrophils, 67.2%) and serum C-reactive protein level of 224.76 nmol/L (reference range: <28.57 nmol/L). The platelet count decreased to 86×10/L. Urinalysis showed bacteriuria, and urine culture revealed the presence of Enterococcus faecium (>10 CFU/mL). Levofloxacin was administered to the patient, and the

Development of a Rapid Reverse Blot Hybridization Assay for Detection of Clinically Relevant Antibiotic Resistance Genes in Blood Cultures Testing Positive for Gram-Negative Bacteria

Rapid and accurate identification of the causative pathogens of bloodstream infections is crucial for the prompt initiation of appropriate antimicrobial therapy to decrease the related morbidity and mortality rates. The aim of this study was to evaluate the performance of a newly developed PCR-reverse blot hybridization assay (REBA) for the rapid detection of Gram-negative bacteria (GNB) and their extended-spectrum β-lactamase (ESBL), AmpC β-lactamase, and carbapenemase resistance genes directly from the blood culture bottles. The REBA-EAC (ESBL, AmpC β-lactamase, carbapenemase) assay was performed on 327 isolates that were confirmed to have an ESBL producer phenotype, 200 positive blood culture (PBCs) specimens, and 200 negative blood culture specimens. The concordance rate between the results of REBA-EAC assay and ESBL phenotypic test was 94.2%. The sensitivity, specificity, positive predictive value, and negative predictive value of the REBA-EAC assay for GNB identification in blood culture specimens were 100% (95% CI 0.938–1.000, P < 0.001), 100% (95% CI 0.986–1.000, P < 0.001), 100% (95% CI 0.938–1.000, P < 0.001), and 100% (95% CI 0.986–1.000, P < 0.001), respectively. All 17 EAC-producing GNB isolates from the 73 PBCs were detected by the REBA-EAC assay. The REBA-EAC assay allowed easy differentiation between EAC and non-EAC genes in all isolates. Moreover, the REBA-EAC assay was a rapid and reliable method for identifying GNB and their β-lactamase resistance genes in PBCs. Thus, this assay may provide essential information for accelerating therapeutic decisions to achieve earlier appropriate antibiotic treatment during the acute phase of bloodstream infection.

Scoring system for detecting spurious hemolysis in anticoagulated blood specimens.

Background The identification of in vitro hemolysis (IVH) using a hematology analyzer is challenging because centrifugation of the specimens cannot be performed for cell counts. In the present study, we aimed to develop a scoring system to help identify the presence of hemolysis in anticoagulated blood specimens. Methods Thirty-seven potassium EDTA anticoagulated blood specimens were obtained, and each specimen was divided into 3 aliquots (A, B, and C). Aliquots B and C were mechanically hemolyzed by aspirating 2 and 5 times, respectively, using a 27-gauge needle and then tested; aliquot A was analyzed immediately without any hemolysis. After the cells were counted, aliquots B and C were centrifuged and the supernatants were tested for the hemolytic index and lactate dehydrogenase levels. Results The 4 hematologic parameters were selected and scored from 0 to 3 as follows:< 34.0, 34.0-36.2, 36.3-38.4, and ≥38.5 for mean cell hemoglobin concentration (MCHC, g/dL); <0.02, 0.02, 0.03, and ≥0.04 for red blood cell ghosts (1012/L); <0.13, 0.13-0.38, 0.39-1.30, and ≥1.31 for difference value (g/dL) of measured hemoglobin and calculated hemoglobin; and <0.26, 0.26-0.95, 0.96-3.34, and ≥3.35 for difference value (g/dL) of MCHC and cell hemoglobin concentration mean. The hemolysis score was calculated by adding all the scores from the 4 parameters. At the cutoff hemolysis score of 3, the IVH of aliquots B and C were detected as 64.9% and 91.9%, respectively. Conclusions The scoring system might provide effective screening for detecting spurious IVH.

First Case of Pasteurella multocida Pneumonic Bacteremia in Korea

Dear Editor, There are rising concerns related to the high incidence of zoonotic diseases in humans, caused by close encounters with pets and other wild or domestic animals [1]. Pasteurella species are one of the most prevalent commensal and opportunistic infection-causing pathogens found in domestic and wild animals worldwide, and are part of the normal flora of the oral, nasal, and respiratory cavities in many animals such as dogs and cats [2]. Although Pasteurella mostly causes local wound infections in humans following animal bites or scratches, cases of infections including those of the bloodstream or respiratory system have also been reported for this opportunistic pathogen [3, 4]. However, to our knowledge, there is no report of pneumonic bacteremia caused by Pasteurella in Korea. We describe a case of a systemic infection of Pasteurella multocida in the bloodstream and respiratory system of a Korean patient. This study was exempted from review by the Institutional Review Board for Human Research, Yonsei University, Wonju Severance Christian Hospital (2017-12-0145). Informed consent from the patient was not required for this report because de-identified patient data was used. A 70-year-old man was admitted to Wonju Severance Christian Hospital because of abdominal pain and low blood pressure for one day. The patient also complained of coughing, a brownish blood-tinged sputum, rhinorrhea, heating sensation, chills, and chest discomfort. The patient had a medical history of hypertension, stable angina, pulmonary tuberculosis, chronic obstructive pulmonary disease, allergic rhinitis, and asthma. The patient does not breed any animals and did not report any contact with animals in the previous year. He was a chronic alcoholic with a more than 50-year history of heavy drinking, but had quit drinking one year prior to hospital admission and had no history of liver dysfunction. Physical examination revealed a low blood pressure of 76/52 mmHg and crackles on the right lower lung field. Laboratory findings showed an elevated white blood cell count of 21.3×10/L (94% segmented neutrophils) and serum C-reactive protein level (170.0 mg/L, reference: <3.0 mg/L). Chest computerized tomography showed consolidation in the right lower lobe. The patient was diagnosed as having community-acquired pneumonia and was empirically treated with cefoperazone-sulbatam and moxifloxacin. A blood specimen was incubated using two aerobic and anaerobic culture sets in the BacT/Alert 3D system (bioMérieux, Durham, NC, USA). After a 14-hour incubation period, gramnegative coccobacilli grew in the aerobic bottle and were identified as P. multocida by VITEK 2 systems (bioMérieux) using the gram-negative identification card (Bionumber 0001410100040001, bioMérieux). A sputum specimen was also inoculated on 5%

A New Bacterial Growth Graph Pattern Analysis to Improve Positive Predictive Value of Continuous Monitoring Blood Culture System

False positive signals (FPSs) of continuous monitoring blood culture system (CMBCS) cause delayed reporting time and increased laboratory cost. This study aimed to analyze growth graphs digitally in order to identify specific patterns of FPSs and true positive signals (TPSs) and to find the method for improving positive predictive value (PPV) of FPS and TPS. 606 positive signal samples from the BACTEC FX (BD, USA) CMBCS with more than one hour of monitoring data after positive signal were selected, and were classified into FPS and TPS groups using the subculture results. The pattern of bacterial growth graph was analyzed in two steps: the signal stage recorded using the monitoring data until positive signal and the post-signal stage recorded using one additional hour of monitoring data gained after the positive signal. The growth graph before the positive signal consists of three periods; initial decline period, stable period, and steeping period. Signal stage analyzed initial decline period and stable period, and classified the graphs as standard, increasing, decreasing, irregular, or defective pattern, respectively. Then, all patterns were re-assigned as confirmed or suspicious pattern in the post-signal stage. Standard, increasing, and decreasing patterns with both initial decline period and stable period are typical patterns; irregular patterns lacking a smooth stable period and defective patterns without an initial decline period are false positive patterns. The false positive patterns have 77.2% of PPV for FPS. The confirmed patterns, showing a gradually increasing fluorescence level even after positive signal, have 97.0% of PPV for TPS.

The characteristics of transferrin variants by carbohydrate-deficient transferrin tests using capillary zone electrophoresis

Transferrin is the major plasma transport protein for iron. We aimed to investigate the characteristics of transferrin variant by carbohydrate‐deficient transferrin (CDT) test using capillary zone electrophoresis.

Evaluation of Diagnostic Performance of RAPIDEC CARBA NP Test for Carbapenemase-Producing Enterobacteriaceae

Background: Extended-spectrum β-lactamase (ESBL)producing Enterobacteriaceae are resistant to most β-lactam antibiotics except carbapenems. In recent years, infrequently isolated Enterobacteriaceae that produce carbapenemase pose a serious threat in the selection of appropriate therapeutic antibiotics. The rapid detection method of carbapenemase-producing Enterobacteriaceae (CPE) is necessary to prevent the spread of CPE into healthcare facilities. Methods: One hundred clinical Enterobacteriaceae isolates (Klebsiella pneumoniae 40, Escherichia coli 40, others 20) showing susceptibility to carbapenems and positivity in the CLSI ESBL phenotypic test from November 2015 to March 2016 and 59 stocked Enterobacteriaceae isolates harboring resistance genes producing carbapenemase (K. pneumoniae 56, Enterobacter cloacae 2, E. coli 1; types of CPE: KPC 36, GES 12, NDM 6, VIM 2, OXA 2, IMP 1) were subjected to the RAPIDEC CARBA NP test (bioMerieux, France) and CPE phenotypic test using the modified Hodge test (MHT) and carbapenemase inhibition test. Results: All of the 100 Enterobacteriaceae isolates with carbapenem susceptibility and ESBL positivity were negative on the RAPIDEC CARBA NP test and CPE phenotypic test. Of 59 stock CPE isolates, 53 and 42 showed positive results to the RAPIDEC CARBA NP test and MHT, respectively. The sensitivity and specificity of the RAPIDEC CARBA NP test for detecting CPE were 89.8% and 100%, respectively. Conclusion: The RAPIDEC CARBA NP test is simple and produces a result within 3 hr. In conclusion, the test is a useful screen for detecting CPE because it shows high sensitivity and specificity for CPE detection. (Ann Clin Microbiol 2016;19:59-64)