Control of an Outbreak of Middle East Respiratory Syndrome in a Tertiary Hospital in Korea

BACKGROUND

In 2015, a large outbreak of Middle East respiratory syndrome (MERS) occurred in the Republic of Korea. Half of the cases were associated with a tertiary care university hospital.

OBJECTIVE

To document the outbreak and successful control measures.

DESIGN

Descriptive study.

SETTING

A 1950-bed tertiary care university hospital.

PATIENTS

92 patients with laboratory-confirmed MERS and 9793 exposed persons.

MEASUREMENTS

Description of the outbreak, including a timeline, and evaluation of the effectiveness of the control measures.

RESULTS

During the outbreak, 92 laboratory-confirmed MERS cases were associated with a large tertiary care hospital, 82 of which originated from unprotected exposure to 1 secondary patient. Contact tracing and monitoring exposed patients and assigned health care workers were at the core of the control measures in the outbreak. Nontargeted screening measures, including body temperature screening among employees and visitors at hospital gates, monitoring patients for MERS-related symptoms, chest radiographic screening, and employee symptom monitoring, did not detect additional patients with MERS without existing transmission links. All in-hospital transmissions originated from 3 patients with MERS who also had pneumonia and productive cough.

LIMITATIONS

This was a retrospective single-center study. Statistical analysis could not be done. Because this MERS outbreak originated from a superspreader, effective control measures could differ in endemic areas or in other settings.

CONCLUSION

Control strategies for MERS outbreaks should focus on tracing contacts of persons with epidemiologic links. Adjusting levels of quarantine and personal protective equipment according to the assumed infectivity of each patient with MERS may be appropriate.

PRIMARY FUNDING SOURCE

Samsung Biomedical Research Institute.

Oral Macrolide Therapy Following Short-term Combination Antibiotic Treatment of Mycobacterium massiliense Lung Disease

BACKGROUND

Although Mycobacterium massiliense lung disease is increasing in patients with cystic fibrosis and non-cystic fibrosis bronchiectasis, optimal treatment regimens remain largely unknown. This study aimed to evaluate the efficacy of oral macrolide therapy after an initial 2-week course of combination antibiotics for the treatment of M massiliense lung disease.

METHODS

Seventy-one patients received oral macrolides, along with an initial 4-week (n = 28) or 2-week (n = 43) IV amikacin and cefoxitin (or imipenem) treatment. These patients were treated for 24 months (4-week IV group) or for at least 12 months after negative sputum culture conversion (2-week IV group).

RESULTS

Total treatment duration was longer in the 4-week IV group (median, 23.9 months) than in the 2-week IV group (15.2 months; P < .001). The response rates after 12 months of treatment were 89% for symptoms, 79% for CT scanning, and 100% for negative sputum culture results in the 4-week IV group. In the 2-week IV group, these values were 100% (P = .057), 91% (P = .177), and 91% (P = .147), respectively. Acquired macrolide resistance developed in two patients in the 2-week IV group. Genotyping analyses of isolates from patients who did not achieve negative sputum culture conversion during treatment and from those with positive culture results after successful treatment completion revealed that most episodes were due to reinfection with different genotypes of M massiliense.

CONCLUSIONS

Oral macrolide therapy after an initial 2-week course of combination antibiotics might be effective in most patients with M massiliense lung disease.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT00970801; URL: www.clinicaltrials.gov.

Evaluation of three real-time PCR assays for differential identification of Mycobacterium tuberculosis complex and nontuberculous mycobacteria species in liquid culture media

We evaluated the analytical performance of M. tuberculosis complex (MTBC)/nontuberculous mycobacteria (NTM) PCR assays for differential identification of MTBC and NTM using culture-positive liquid media. Eighty-five type strains and 100 consecutive mycobacterial liquid media cultures (MGIT 960 system) were analyzed by a conventional PCR assay (MTB-ID(®) V3) and three real-time PCR assays (AdvanSure™ TB/NTM real-time PCR, AdvanSure; GENEDIA(®) MTB/NTM Detection Kit, Genedia; Real-Q MTB & NTM kit, Real-Q). The accuracy rates for reference strains were 89.4%, 100%, 98.8%, and 98.8% for the MTB-ID V3, AdvanSure, Genedia, and Real-Q assays, respectively. Cross-reactivity in the MTB-ID V3 assay was mainly attributable to non-mycobacterium Corynebacterineae species. The diagnostic performance was determined using clinical isolates grown in liquid media, and the overall sensitivities for all PCR assays were higher than 95%. In conclusion, the three real-time PCR assays showed better performance in discriminating mycobacterium species and non-mycobacterium Corynebacterineae species than the conventional PCR assay.

Clinical Significance of Mycobacterium kansasii Isolates from Respiratory Specimens

The clinical significance of Mycobacterium kansasii respiratory isolates is uncertain. The aims of this study were to determine the clinical relevance of M. kansasii isolates and to identify the clinical features and outcomes of M. kansasii lung disease. We reviewed the medical records of 104 patients from whom at least one respiratory M. kansasii isolate was obtained from January 2003 to July 2014 at Samsung Medical Center, South Korea. Of these 104 patients, 54 (52%) met the diagnostic criteria for nontuberculous mycobacterial lung disease; among them, 41 (76%) patients received antibiotic treatment for a median time of 15.0 months (interquartile range [IQR], 7.0-18.0 months). The remaining 13 (24%) without overt disease progression were observed for a median period of 24.0 months (IQR, 5.0-34.5 months). Patients with M. kansasii lung disease exhibited various radiographic findings of lung disease, including the fibrocavitary form (n = 24, 44%), the nodular bronchiectatic form (n = 17, 32%), and an unclassifiable form (n = 13, 24%). The fibrocavitary form was more common in patients who received treatment (n = 23, 56%), while the nodular bronchiectatic form was more common in patients with M. kansasii lung disease who did not receive treatment (n = 9, 70%). None of the patients with a single sputum isolate (n = 18) developed M. kansasii disease over a median follow-up period of 12.0 months (IQR, 4.0-26.5 months). In total, 52% of all patients with M. kansasii respiratory isolates exhibited clinically significant disease. Moreover, patients with M. kansasii lung disease displayed diverse radiographic findings in addition to the fibrocavitary form. The nodular bronchiectatic form was more common in patients with M. kansasii lung disease with an indolent clinical course. Thus, since the clinical significance of a single M. kansasii respiratory isolate is not definite, strict adherence to recommended diagnostic criteria is advised.

Molecular analysis of clinical isolates previously diagnosed as Mycobacterium intracellulare reveals incidental findings of "Mycobacterium indicus pranii" genotypes in human lung infection

Background

Mycobacterium intracellulare is a major cause of Mycobacterium avium complex lung disease in many countries. Molecular studies have revealed several new Mycobacteria species that are closely related to M. intracellulare. The aim of this study was to re-identify and characterize clinical isolates from patients previously diagnosed with M. intracellulare lung disease at the molecular level.

Methods

Mycobacterial isolates from 77 patients, initially diagnosed with M. intracellulare lung disease were re-analyzed by multi-locus sequencing and pattern of insertion sequences.

Results

Among the 77 isolates, 74 (96 %) isolates were designated as M. intracellulare based on multigene sequence-based analysis. Interestingly, the three remaining strains (4 %) were re-identified as “Mycobacterium indicus pranii” according to distinct molecular phylogenetic positions in rpoB and hsp65 sequence-based typing. In hsp65 sequevar analysis, code 13 was found in the majority of cases and three unreported codes were identified. In 16S–23S rRNA internal transcribed spacer (ITS) sequevar analysis, all isolates of both species were classified within the Min-A ITS sequevar. Interestingly, four of the M. intracellulare isolates harbored IS1311, a M. avium-specific element. Two of three patients infected with “M. indicus pranii” had persistent positive sputum cultures after antibiotic therapy, indicating the clinical relevance of this study.

Conclusions

This analysis highlights the importance of precise identification of clinical isolates genetically close to Mycobacterium species, and suggests that greater attention should be paid to nontuberculous mycobacteria lung disease caused by “M. indicus pranii”.

Intermittent antibiotic therapy for nodular bronchiectatic Mycobacterium avium complex lung disease

RATIONALE

Although intermittent, three-times-weekly therapy is recommended for the initial treatment of noncavitary nodular bronchiectatic Mycobacterium avium complex (MAC) lung disease, supporting data are limited.

OBJECTIVES

To evaluate the clinical efficacy of intermittent therapy compared with daily therapy for nodular bronchiectatic MAC lung disease.

METHODS

A retrospective cohort study of 217 patients with treatment-naive noncavitary nodular bronchiectatic MAC lung disease. All patients received either daily (n = 99) or intermittent therapy (n = 118) that included clarithromycin or azithromycin, rifampin, and ethambutol.

MEASUREMENTS AND MAIN RESULTS

Modification of the initial antibiotic therapy occurred more frequently in the daily therapy group than in the intermittent therapy group (46 vs. 21%; P < 0.001); in particular, ethambutol was more frequently discontinued in the daily therapy group than in the intermittent therapy group (24 vs. 1%; P ≤ 0.001). However, the rates of symptomatic improvement, radiographic improvement, and sputum culture conversion were not different between the two groups (daily therapy vs. intermittent therapy: 75 vs. 82%, P = 0.181; 68 vs. 73%, P = 0.402; 76 vs. 67%, P = 0.154, respectively). In addition, the adjusted proportion of sputum culture conversion was similar between the daily therapy (71.3%; 95% confidence interval, 59.1-81.1%) and the intermittent therapy groups (73.6%; 95% confidence interval, 62.9-82.2%; P = 0.785).

CONCLUSIONS

These results suggest that intermittent three-times-weekly therapy with a macrolide, rifampin, and ethambutol is a reasonable initial treatment regimen for patients with noncavitary nodular bronchiectatic MAC lung disease. Clinical trial registered with www.clinicaltrials.gov (NCT 00970801).

Species-specific difference in antimicrobial susceptibility among viridans group streptococci

Background

Viridans group streptococci (VGS) are both commensal microbes and potential pathogens. Increasing resistance to penicillin in VGS is an ongoing issue in the clinical environment. We investigated the difference in susceptibility and resistance to penicillin among various VGS species.

Methods

In total 1,448 VGS isolated from various clinical specimens were analyzed over a two-yr period. Identification and antimicrobial susceptibility test was performed by the automated VITEK 2 system (bioMerieux, France) or the MicroScan MICroSTREP system (Siemens, Germany).

Results

Among the 1,448 isolates, 412 were isolated from blood (28.4%). Streptococcus mitis group was the most frequently isolated (589 isolates, 40.7%), followed by the S. anginosus group (290 isolates, 20.0%), S. sanguinis group (179 isolates, 12.4%) and S. salivarius group (57 isolates, 3.9%). In total, 314 isolates could not be identified up to the species level. The overall non-susceptibility to penicillin was observed to be 40.0% (resistant, 11.2% and intermediately resistant, 28.8%) with uneven distribution among groups; 40.2% in S. sanguinis group (resistant, 5.0% and intermediately resistant, 35.2%), 60.3% in S. mitis group (resistant, 20.9% and intermediately resistant, 39.4%), 78.9% in S. salivarius group (resistant, 8.8% and intermediately resistant, 70.1%), and 6.2% in S. anginosus group (resistant, 1.7% and intermediately resistant, 4.5%).

Conclusions

Antimicrobial resistance patterns towards penicillin show differences among various VGS; this should be considered while devising an effective antimicrobial treatment against VGS.

Evaluation of the iNtRON VRE vanA/vanB real-time PCR assay for detection of vancomycin-resistant enterococci

BACKGROUND

Recently, the iNtRON VRE vanA/vanB real-time PCR (iNtRON; iNtRON Biotechnology, Korea) assay, a multiplex real-time PCR method, was introduced. In this prospective study, we compared the iNtRON assay with the Seeplex VRE ACE detection kit (Seeplex; Seegene, Korea), a conventional multiplex PCR assay.

METHODS

A chromogenic agar-based culture, in which pre-selected vancomycin-resistant enterococci (VRE) was grown and subsequently plated on blood agar with vancomycin disks, was regarded as the reference method. A total of 304 consecutive rectal swab specimens were tested for VRE by culture and by iNtRON and Seeplex PCR assays. For the PCR assays, specimens were enriched for 16-24 hr before PCR.

RESULTS

VRE were isolated from 44 (14.5%) specimens by chromogenic agar-based culture. The clinical sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the iNtRON assay were 100% (95% confidence interval: 89.8%-100%), 99.2% (96.9%-99.9%), 95.6% (83.6%-99.2%), and 100% (98.2%-100%), respectively, while those of the Seeplex assay were 97.7% (86.2%-99.9%), 99.6% (97.5%-99.9%), 97.7% (86.2%-99.9%), and 99.6% (97.5%-99.9%), respectively. The iNtRON assay had a detection limit of 3,159 copies/µL and 13,702 copies/µL for the vanA and vanB genes, respectively. No cross-reactivity was observed in 11 non-VRE bacterial culture isolates.

CONCLUSIONS

The overall performance of the iNtRON assay was comparable to that of a chromogenic agar-based culture method for prompt identification of VRE-colonized patients in hospitals. This assay could be an alternative or supportive method for the effective control of nosocomial VRE infection.

Performance evaluation of the Xpert MTB/RIF assay according to its clinical application

Background

The Xpert MTB/RIF assay (Xpert assay; Cepheid, Sunnyvale, CA) is becoming the test of choice for the rapid diagnosis of tuberculosis and rifampin (RIF) resistance. The aim of this study was to evaluate the performance of the Xpert assay with respect to its clinical application at a tertiary care hospital in Korea, a country with an intermediate tuberculosis burden and high-resource.

Methods

A total of 303 Xpert assay results from 109 smear-positive and 194 smear-negative respiratory specimens were retrospectively reviewed. Based on patients’ medical records, four categories of clinical applications of the Xpert assay were identified: (1) the diagnosis of pulmonary tuberculosis in patients with a high probability of pulmonary tuberculosis according to their clinical and radiological features; (2) the exclusion of tuberculosis in clinically indeterminate patients for pulmonary tuberculosis; (3) the differentiation of Mycobacterium tuberculsosis (MTB) from nontuberculous mycobacteria in a smear-positive specimen; and (4) the diagnosis of RIF resistance. Standard culture and drug susceptibility tests were used as reference methods.

Results

The sensitivity of the Xpert assay for MTB detection in category 1 was 89.8% (95% confidence interval [CI], 78.5-95.8%), but 66.7% (95% CI, 12.5-98.2%) in category 2. The positive predictive values ranged from 33.3% (95% CI, 6.0-75.9%) in category 2 to 91.3% and 91.7% in categories 1 and 3, respectively. The negative predictive values were over 90% in all categories. The Xpert assay correctly detected RIF resistance in six of the seven (85.7%) isolates tested.

Conclusions

The Xpert assay exhibited variable performance according to its clinical application; this finding cautions that careful interpretation for the results of this assay would be needed according to its intended purpose.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-014-0589-x) contains supplementary material, which is available to authorized users.

Clinical characteristics of Raoultella ornithinolytica bacteremia

PURPOSE

Raoultella ornithinolytica is not well known as a clinical pathogen. We performed a retrospective review of R. ornithinolytica bacteremia to investigate its clinical features, antimicrobial susceptibility, and overall patient outcomes.

METHODS

R. ornithinolytica bacteremia cases were collected from an electronic database of all cases of bacteremia over a 10-year period. Medical records were retrospectively reviewed. Demographic data, clinical information, the presence of underlying comorbidities, the results of antimicrobial susceptibility testing, and the antimicrobial regimen administered were investigated.

RESULTS

R. ornithinolytica was isolated from blood culture specimens in 16 cases. The majority of these patients had an underlying malignant condition of advanced stage (15 patients, 94 %). Seven of these patients had a solid tumor with lesions or metastases that extended to the bile duct or biliary tract. Neutropenic fever following hematologic stem cell transplantation was found in three cases. No resistance to piperacillin/tazobactam or imipenem was found. Four cases showed resistance to cefoxitin, while one of these cases showed resistance to multiple cephalosporins. In overall outcomes, seven patients (44 %) did not recover from the infection and subsequently expired.

CONCLUSIONS

R. ornithinolytica bacteremia occurs mainly in patients with underlying malignancies. The overall outcome was not favorable, despite favorable antimicrobial susceptibility test results. The findings of this study contradict those of other studies that demonstrated that infection from Raoultella species have good prognoses.

First case of nontuberculous mycobacterial lung disease caused by Mycobacterium marseillense in a patient with systemic lupus erythematosus

Mycobacterium marseillense was designated as a new species within Mycobacterium avium complex. We report the first case of M. marseillense lung disease in a patient with systemic lupus erythematosus. All serial isolates were identified as M. marseillense by multilocus sequence analysis, based on hsp65, 16S-23S rRNA internal transcribed spacer, and 16S rRNA fragments.

Incidence and clinical features of herpes simplex viruses (1 and 2) and varicella-zoster virus infections in an adult Korean population with aseptic meningitis or encephalitis

Since there are limited data on the incidence and clinical findings of central nervous system (CNS) infection by three α-herpesviruses including human herpes simplex virus 1 (HSV-1), HSV-2 and varicella-zoster virus (VZV) in Korea, a retrospective analysis of clinical data and polymerase chain reaction (PCR) results was performed in patients who presented with suspicion of acute viral meningitis and/or encephalitis at the emergency department of a tertiary referral hospital in Seoul, Korea. During the 3-year study period, a total of 224 cerebrospinal fluid (CSF) samples from 224 patients were examined. Among the 224 patients, 135 (60.3%) patients were identified as having aseptic meningitis (n = 70, 51.9%), encephalitis (n = 41, 30.4%) or meningoencephalitis (n = 24, 17.8%) at discharge. Twenty-four (17.8%) patients were identified as having VZV meningitis (n = 16, 11.9%), VZV meningoencephalitis (n = 2, 1.5%), HSV-2 meningitis (n = 4, 3.0%), or HSV-1 encephalitis (n = 2, 1.5%). Of the 24 patients infected with the three herpesviruses, immunocompromised patients accounted for 33.3% (n = 8). Skin rashes were observed in half (n = 9) of the patients with VZV, and none with HSV-1 or HSV-2. One patient with VZV meningitis and four patients with brain parenchymal involvement had neurologic sequelae. In conclusion, three herpesviruses are important causative agents of CNS infectious disease with significant morbidity in adults, regardless of the immunologic status. Therefore, CSF should be examined for HSV-1, HSV-2, and VZV using sensitive diagnostic methods in all cases of adult patients with clinical manifestations of CNS disease in order to identify the correct etiology and to determine appropriate therapy.

Comparison of the Anyplex(TM) II RV16 and Seeplex(®) RV12 ACE assays for the detection of respiratory viruses

The Anyplex^TM II RV16 detection kit (RV16; Seegene, Seoul, South Korea) is a multiplex real-time PCR assay based on tagging oligonucleotide cleavage extension. In this prospective study, we evaluated the RV16 assay by comparing with the Seeplex^® RV12 ACE detection kit (RV12; Seegene), a multiplex end-point PCR kit. A total of 365 consecutive respiratory specimens were tested with both RV16 and RV12 assays in parallel and detected 140 (38.4%) and 89 (24.4%) positive cases, respectively. The positive percent agreement, negative percent agreement, and kappa values for the 2 assays were 95.6% (95% confidence interval [CI], 89.4–98.3%), 80.4% (95% CI, 75.3–84.6%), and 0.64 (95% CI, 0.56–0.72), respectively. The monoplex PCR and sequencing for the samples with discrepant results revealed that majority of the results were concordant with the results from RV16 assays. In conclusion, the RV16 assay produces results comparable to the RV12 assay.

The First Korean Case of Nontuberculous Mycobacterial Lung Disease Caused by Mycobacterium abscessus Subspecies bolletii in a Patient with Bronchiectasis

We report the first Korean case of lung diseases caused by Mycobacterium abscessus subsp. bolletii in a previously healthy male, except for a previous history of pulmonary tuberculosis and bronchiectasis. All serial isolates are identified as M. abscessus subsp. bolletii by multi-locus sequence analysis based on the hsp65, rpoB, and 16S rRNA fragments. At the genetic level, the isolate has the erm(41) gene with a T28 sequevar, associated with clarithromycin resistance, and no rrl mutation. The isolate is resistant to clarithromycin. Although the symptoms and radiographic findings have improved after combination of antibiotics, the follow-up sputum cultures are persistently positive.