Continued Upward Trend in Non-Tuberculous Mycobacteria Isolation over 13 Years in a Tertiary Care Hospital in Korea

Purpose@#Despite decreased prevalence of tuberculosis, the incidence of the diseases associated with nontuberculous mycobacteria (NTM) has been increasing in South Korea and around the world. The present retrospective study was conducted to determine longitudinal changes in the epidemiology and distribution of NTM over 13 years at a tertiary care hospital in Korea. @*Materials and Methods@#We retrospectively analyzed data on Mycobacterium species over 13 years (January 2007 to December 2019) by utilizing the laboratory information system. Mycobacterium species were identified using biochemical tests and PCR-restriction fragment length polymorphism and Mycobacteria GenoBlot assays. @*Results@#After excluding duplicates from the initial pool of 17996 mycobacterial isolates, 7674 strains were analyzed and 2984 (38.9%) NTM were isolated. The proportion of NTM continuously increased over the 13-year period, from 17.0% in 2007 to 57.5% in 2019. Among the NTM isolates, the most common species were Mycobacterium intracellulare (50.6%), M. avium (18.3%), M. fortuitum complex (4.9%), M. abscessus (4.5%), M. gordonae (3.3%), M. kansasii (1.1%), M. chelonae (1.0%), and M. massiliense (0.9%).In patients over the age of 70 years, the proportion of NTM among the isolates increased from 26.6% in 2007 to 62.0% in 2019, and that of M. intracellulare isolates among the NTM increased from 13.9% (11/79) in 2007 to 37.4% (175/468) in 2019. @*Conclusion@#The number of NTM isolates continuously increased over the study period, and the increase in the proportion of M. intracellulare in patients aged over 70 years was notable.

Continued Upward Trend in Non-Tuberculous Mycobacteria Isolation over 13 Years in a Tertiary Care Hospital in Korea

Purpose@#Despite decreased prevalence of tuberculosis, the incidence of the diseases associated with nontuberculous mycobacteria (NTM) has been increasing in South Korea and around the world. The present retrospective study was conducted to determine longitudinal changes in the epidemiology and distribution of NTM over 13 years at a tertiary care hospital in Korea. @*Materials and Methods@#We retrospectively analyzed data on Mycobacterium species over 13 years (January 2007 to December 2019) by utilizing the laboratory information system. Mycobacterium species were identified using biochemical tests and PCR-restriction fragment length polymorphism and Mycobacteria GenoBlot assays. @*Results@#After excluding duplicates from the initial pool of 17996 mycobacterial isolates, 7674 strains were analyzed and 2984 (38.9%) NTM were isolated. The proportion of NTM continuously increased over the 13-year period, from 17.0% in 2007 to 57.5% in 2019. Among the NTM isolates, the most common species were Mycobacterium intracellulare (50.6%), M. avium (18.3%), M. fortuitum complex (4.9%), M. abscessus (4.5%), M. gordonae (3.3%), M. kansasii (1.1%), M. chelonae (1.0%), and M. massiliense (0.9%).In patients over the age of 70 years, the proportion of NTM among the isolates increased from 26.6% in 2007 to 62.0% in 2019, and that of M. intracellulare isolates among the NTM increased from 13.9% (11/79) in 2007 to 37.4% (175/468) in 2019. @*Conclusion@#The number of NTM isolates continuously increased over the study period, and the increase in the proportion of M. intracellulare in patients aged over 70 years was notable.

Nosocomial Outbreak Caused by NDM-5 and OXA-181 Carbapenemase Co-producing Escherichia coli / 감염과화학요법

Carbapenemase-producing Enterobacteriaceae (CPE) is an important and increasing threat to global health. From July to September 2017, 20 inpatients at a tertiary care hospital in Korea were either colonized or infected with carbapenem-resistant Escherichia coli strains. All of E. coli isolates co-produced bla(NDM-5) and bla(OXA-181) carbapenemase genes and shared ≥88% clonal relatedness on the basis of a cladistic calculation of the distribution of pulsed-field gel electrophoresis patterns. Rapid detection of CPE is one of the most important factors to prevent CPE dissemination because it takes long time for CPE to become negative.

Globicatella sanguinis Bacteremia in a Korean Patient / 대한임상미생물학회지

Globicatella sanguinis is an unusual pathogen causing bacteremia, meningitis, and urinary tract infection, and can be misidentified as Streptococcus pneumoniae or viridans streptococci due to its colonial morphology. A 76-year-old female patient with hypertension and degenerative arthritis was admitted to the hospital complaining of knee joint pain. Blood culture revealed the presence of Gram-positive cocci, and the isolated organism was equally identified as S. pneumoniae using the MicroScan identification system (Beckman Coulter, USA) and Vitek 2 identification system (bioMérieux, USA). However, the isolate showed optochin resistance based on the optochin disk susceptibility test. The organism was finally confirmed to be G. sanguinis based on 16S rRNA sequencing and hydrogen sulfide production testing. Accurate identification of G. sanguinis isolated from aseptic body fluids including blood is important for appropriate antibiotic selection based on accurate application of interpretative criteria of antimicrobial susceptibility test.

First Case of Pasteurella multocida Pneumonic Bacteremia in Korea

No abstract available.

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

No abstract available.

Trend of Bacteria and Fungi Isolated from Cerebrospinal Fluid Culture in a Tertiary Care Hospital During Recent Two Decades (1997-2016) / 대한임상미생물학회지

BACKGROUND: Meningitis is a clinically important disease because of its high mortality and morbidity. The epidemiology of this disease has changed remarkably due to the introduction of pneumococcal vaccines and Haemophilus influenzae type b (Hib) conjugate vaccine. Therefore, it is required to continuously monitor and research the organisms isolated from cerebrospinal fluid (CSF) cultures. METHODS: We analyzed trends of bacteria and fungi isolates obtained from CSF cultures between 1997 and 2016 in a tertiary care hospital according to year, month, gender, and age. RESULTS: Out of a total of 38,450 samples, we identified 504 (1.3%) isolates. The isolation rate in the first tested decade (1997–2006) ranged from 1.3% to 3.1%, while that in the second decade (2007–2016) ranged from 0.4% to 1.5%. The most common organisms was coagulase-negative staphylococci (CoNS) (31.9%), followed by Staphylococcus aureus (9.5%), Streptococcus pneumoniae (7.5%), Acinetobacter baumannii (5.8%), and Mycobacterium tuberculosis (5.8%). Monthly isolation rates were highest in May and July and lowest in February and December. Male to female ratio was 1.5:1. The isolation rates of S. pneumoniae, Enterococcus faecium, and Escherichia coli were similar in children and adults, but those of S. aureus, E. faecalis, A. baumannii, Pseudomonas aeruginosa, M. tuberculosis, and Cryptococcus neoformans were higher in adults than in children. CONCLUSION: During the last two decades, the isolation rate of CSF culture per year has decreased, with monthly isolation rates being highest in May and July. CoNS, S. aureus, and S. pneumoniae were most common in males, whereas CoNS, S. pneumoniae, and M. tuberculosis were most common in females. While Group B Streptococcus was most common in infants younger than 1 year, S. aureus and C. neoformans were more common in adults.

Trend of Prevalence and Antifungal Drug Resistance of Candida Species Isolated from Candidemia Patients at a Tertiary Care Hospital During Recent Two Decades / 대한임상미생물학회지

BACKGROUND: Candidemia has increased with an increasing number of people in the high risk group and so has become more important. This study was conducted to investigate the isolation rate of Candida species from candidemia patients and the change in rate of antifungal resistance. METHODS: At a single tertiary care hospital, 1,120 blood cultures positive for Candida species from 1997 to 2016 were investigated according to date of culture, gender, age, and hospital department. RESULTS: During the investigation period, the number of candidemia patients increased from 14 in 1997 to 84 in 2016. The most common organism identified during the two decades was Candida albicans (40.8%), followed by Candida parapsilosis (24.1%), Candida tropicalis (13.2%), and Candida glabrata (12.8%). C. glabrata was relatively common in females (45.5%) compared to males. The age group 40-89 years was more frequently infected than other age groups, and the most frequent isolates according to age group were C. albicans in neonate (66.7%), C. parapsilosis in 1-9-year-olds (41.7%), and C. glabrata in those aged ≥60 years (range; 13.3%–20.0%). According to the visited departments, C. albicans, C. glabrata, and Candida haemulonii were more common in medical departments, while C. parapsilosis was more common in surgical departments. In the antifungal susceptibility test, a rising trend of azole resistance among C. albicans and C. glabrata was observed in recent years. CONCLUSION: In this study, it was confirmed that the isolation rate of Candida species in blood is different by age, gender, and hospital department, and the distribution of isolated Candida species changed over time. The resistance patterns of antifungal agents are also changing, and continuous monitoring and proper selection of antifungal agents are necessary.

Vancomycin Resistance due to vanA Gene Expression in an Aerococcus viridans Isolate: First Case in Korea

No abstract available.

Microbiological Characteristics according to Transudative and Exudative Effusion in Pleural Fluid Culture / 대한임상미생물학회지

A total of 1,132 pleural fluid culture results obtained from October 2012 to July 2014 were analyzed to elucidate the microbiological characteristics according to transudative and exudative pleural fluid. The pleural fluid cultures were performed using aerobic and anaerobic blood culture bottles. The blood and pleural fluid for total protein, lactate dehydrogenase, and glucose measurement were submitted to laboratory at the same time with pleural fluid cultures. The rates for culture positivity, anaerobes isolation, and polymicrobials between transudative and exudative pleural fluid were 5.2% vs. 10.4%, 14.8% vs. 7.8%, and 14.8% vs. 10.9%.

Multidrug-Resistant Corynebacterium striatum Bacteremia: First Case in Korea

No abstract available.

Macrolide Resistance Trends in beta-Hemolytic Streptococci in a Tertiary Korean Hospital

PURPOSE: Erythromycin-resistant beta-hemolytic streptococci (BHS) has recently emerged and quickly spread between and within countries throughout the world. In this study, we evaluate the antimicrobial susceptibility patterns and erythromycin resistance mechanisms of BHS during 2003-2004. MATERIALS AND METHODS: The MICs of seven antimicrobials were determined for 204 clinical isolates of BHS from 2003 to 2004. Resistance mechanisms of erythromycin-resistant BHS were studied by the double disk test as well as by polymerase chain reaction (PCR). RESULTS: Compared with our previous study, resistance among Streptococcus pyogenes isolates to a variety of drugs decreased strikingly: from 25.7% to 4.8% in erythromycin; 15.8% to 0% in clindamycin; and 47.1% to 19.0% in tetracycline. The prevalent phenotypes and genotypes of macrolide-lincosamide-streptograminB (MLSB) resistance in Streptococcus pyogenes isolates have been changed from the constitutive MLSB phenotype carrying erm(B) to the M phenotype with mef(A) gene. In contrast with Streptococcus pyogenes, resistance rates to erythromycin (36.7%), clindamycin (43.1%), and tetracycline (95.4%) in Streptococcus agalactiae isolates did not show decreasing trends. Among the Streptococcus dysgalactiae subsp. equisimilis isolates (Lancefield group C, G), resistance rates to erythromycin, clindamycin, tetracycline and chloramphenicol were observed to be 9.4%, 3.1%, 68.8%, and 9.4%, respectively. CONCLUSION: Continual monitoring of antimicrobial resistance among large-colony-forming BHS is needed to provide the medical community with current data regarding the resistance mechanisms that are most common to their local or regional environments.

Antimicrobial Susceptibility Patterns and Macrolide Resistance Genes of beta-Hemolytic Viridans Group Streptococci in a Tertiary Korean Hospital

The aim of this study was to investigate antimicrobial susceptibilities and macrolide resistance mechanisms of beta-hemolytic viridans group streptococci (VGS) in a tertiary Korean hospital. Minimum inhibitory concentrations (MICs) of seven antimicrobials were determined for 103 beta-hemolytic VGS isolated from various specimens. The macrolide resistance mechanisms of erythromycin-resistant isolates were studied by the double disk test and polymerase chain reaction (PCR). The overall resistance rates of beta-hemolytic VGS were found to be 47.5% to tetracycline, 3.9% to chloramphenicol, 9.7% to erythromycin, and 6.8% to clindamycin, whereas all isolates were susceptible to penicillin G, ceftriaxone, and vancomycin. Among ten erythromycin-resistant isolates, six isolates expressed a constitutive MLSB (cMLSB) phenotype, and each of the two isolates expressed the M phenotype, and the inducible MLSB (iMLSB) phenotype. The resistance rates to erythromycin and clindamycin of beta-hemolytic VGS seemed to be lower than those of non-beta-hemolytic VGS in our hospital, although cMLSB phenotype carrying erm(B) was dominant in beta-hemolytic VGS.

A Case of Septicemia by Staphylococcus lugdunensis / 대한임상미생물학회지

Staphylococcus lugdunensis is one of coagulase-negative staphylococci, but rarely causes aggressive and progressive infections similar to Staphylococcus aureus infection. Moreover, agglutination test for clumping factor can be positive, and the colony morphology often resembles that of S. aureus, but S. lugdunensis is usually sensitive to all antimicrobials used against staphylococci. We report a case of septicemia caused by S. lugdunensis in a 71-year-old man with diarrhea, diabetes mellitus, and peripheral neuropathy.

A Case of Clostridium perfringens Septicemia with Fatal Hemolytic Complication / 대한진단검사의학회지

Massive intravascular hemolysis secondary to Clostridium perfringens septicemia is rare but often fatal. We report a case of a fatal clostridial hemolytic complication in a 71-year-old woman with probable refractory anemia. The patient was admitted to the emergency room due to a comatose mental state and a high fever. Laboratory analysis showed massive hemolysis. She died from severe anemia two hours after admission. The next day, blood cultures grew gram positive cocci and boxcarshaped gram positive rods, which were identified as coagulase-negative staphylococci and C. perfringens, respectively.

Correlation of Serotypes and Genotypes of Macrolide-Resistant Streptococcus agalactiae

Despite the necessity for studies of group B streptococci (GBS), due to the increase in serious adult infections, the emergence of new serotypes, and the increased resistance to macrolide antibiotics, such studies have been limited in Korea. The primary purpose of the present study was to determine the frequency trends of GBS serotypes, including serotypes VI, VII, and VIII. The final objective was to elucidate the relationship between the genotypes and serotypes of macrolide-resistant GBS isolates from a Korean population. Among 446 isolates of Streptococcus agalactiae, isolated between January 1990 and December 2002 in Korea, the frequency of serotypes were III (36.5%), Ib (22.0%), V (21.1%), Ia (9.6%), VI (4.3%), II (1.8%), VIII (1.3%), IV (1.1%), and VII (0.9%). The resistance rates to erythromycin, by serotype, were 85% (V), 23% (III), 21% (VI), 3% (Ib), and 2% (Ia). Of 135 erythromycin- resistant S. agalactiae, ermB was detected in 105 isolates, mefA in 20 isolates, and ermTR in seven isolates; most type V isolates harbored the ermB gene, Ib type isolates had an equal distribution of resistance genes, type III isolates accounted for 70% of all isolates carrying mefA genes, and one fourth of type VI isolates had mefA genes.

Two Cases of Leuconostoc Bacteremia / 대한임상미생물학회지

Although Leuconostoc species with intrinsic high-level vancomycin resistance have rarely been isolated from clinical specimens, this organism may cause serious invasive infections such as bacteremia and meningitis in immunocompromised hosts or patients with a wide spectrum of underlying diseases including alcoholic liver diseases and gastrointestinal diseases. Predisposing factors of Leuconostoc bacteremia include intravenous or enteral feeding catheters, other invasive access devices such as tracheostomy, gastrostomy or endotracheal tubes, and previous antimicrobial treatment. This low prevalence may be due, in part, to the inability of automated systems to recognize this organism. It is important that all Leuconostoc isolates obtained from clinical specimens that are related to serious infections should be identified to species level for appropriate antibiotic therapy. We report two cases of Leuconostoc bacteremia occurring in a 65-year-old male with variceal bleeding, and in a 5 month child with ileostomy receiving total parenteral nutrition therapy.

Susceptibility of Fosfomycin against Vancomycin Resistant Enterococci / 감염

BACKGROUND: Vancomycin-resistant enterococci (VRE) were first recovered from clinical isolates in Korea in 1992, and the incidence has been steadily increasing. Alternatives to vancomycin are few because VRE are frequently resistant to commonly used antimicrobial agents. The present study was designed to assess the in-vitro activity of fosfomycin to clinical isolates of VRE. METHODS: For 199 VRE isolates from 1995 to 2000, and 91 enterococcal isolates that were consecutively isolated during the January of 2001 at Wonju Christian Hospital, fosfomycin (200 microgram) disk diffusion test was done by NCCLS method. The number of enterococcal isolates tested for fosfomycin were as follows:58 E. faecalis (42 vancomycin susceptible isolates, 16 vancomycin resistant isolates, and 1 vancomycin intermediate resistance isolate); 210 E. faecium (185 vancomycin resistant and 25 vancomycin susceptible isolates); 15 E. gallinarum, and 6 E. casseliflavus isolates. RESULTS: Among the VRE isolates, the resistance rates of fosfomycin according to enterococcal species were 6.3% in E. faecalis, 4.9% in E. faecium, 0% in E. casseliflavus, and 16.7% in E. gallinarum. CONCLUSION: Fosfomycin could be a potentially useful drug for the treatment of infections caused by VRE.

A Case of Enterococcus casseliflavus Bacteremia / 대한임상미생물학회지

Although Enterococcus casseliflavus with intrinsic low-level vancomycin resistance has rarely been isolated from clinical specimens, this organism may cause serious invasive infections such as endocarditis and bacteremia. This low prevalence may be due, in part, to the inability of automated systems to recognize this organism. Vancomycin may not be effective against E. casseliflavus, despite in vitro results that indicate vancomycin susceptibility. It is important that all E. casseliflavus isolates obtained from clinical specimens that are related to serious infections should be identified to species level for appropriate antibiotic therapy. We report a case of bacteremia caused by E. casseliflavus in a 44-year-old female patient with liver disease.

Distributions of Macrolide-Lincosamide-Streptogramin (MLS) Resistance Types in beta-hemolytic Streptococci / 대한임상미생물학회지

BACKGROUND: Macrolide resistance in beta-hemolytic streptococci has increased during the 1990s, and the proportion of MLS (Macrolide-lincosamide-streptogramin) resistance phenotypes and genotypes of beta-hemolytic streptococci are quite different by geographical variation and study period. The aim of the present study was to determine the distribution of MLS resistance phenotypes and genotypes in beta-hemolytic streptococci isolated from Wonju Christian Hospital. METHODS: The minimal inhibitory concentrations of erythromycin and clindamycin of 426 beta- hemolytic streptococci isolated from clinical specimens between 1990 to 1999 were determined by agar dilution method. MLS resistance phenotypes were determined by double disk diffusion method using erythromycin and clindamycin disk, and genotypes were determined by polymerase chain reaction (PCR). The PCR primers for erm(A), erm(B), erm(C), erm(TR), and mef(A) were used in these study. RESULTS: The proportion of MLS resistance phenotypes of 80 erythromycin-resistant beta-hemolytic streptococci were 60.0% for constitutive phenotype, 23.8% for M phenotype, and 16.2% for inducible phenotype. The proportion of three MLS resistance phenotypes of group A streptococci were nearly equal. About three-fourths of group B streptococci had the constitutive phenotypes, whereas three-fourths (75%) of group G streptococci had the M phenotypes. All MLS resistant strains carried the erm(B) genes in constitutive phenotypes, erm(TR) genes in inducible phenotypes, and mef(A) genes in M phenotypes, respectively. CONCLUSIONS: Mechanisms and phenotype proportions of MLS resistance are different by species in beta-hemolytic streptococci. It is possible that MLS resistance genes have transferred among beta- hemolytic streptococci because the erythromycin resistance genes are the same in beta-hemolytic streptococci.