To assess the mortality dynamics of patients with Pseudomonas aeruginosa bloodstream infections (BSIs) and the influence of OprD deficiencies of the microorganism on early mortality.A prospective multicentre observational study was conducted with 120 patients with P. aeruginosa BSIs occurring between May 2016 and April 2017 in six general hospitals in South Korea. PCR and sequencing were carried out to identify the alterations in oprD and the presence of virulence factors. Cox regression was used to estimate the risk factors for mortality at each timepoint and Kaplan-Meier survival analyses were performed to determine the mortality dynamics.During the 6 week follow-up, 10.8% (13/120) of the patients with P. aeruginosa BSIs died in 2 weeks, 14.2% (17/120) in 4 weeks and 20.0% (24/120) in 6 weeks, revealing a steep decrease in cumulative survival between the fourth and sixth weeks. ICU admission and SOFA score were risk factors for mortality in any weeks after BSI onset and causative OprD-defective P. aeruginosa had a risk tendency for mortality within 6 weeks. Among the 120 P. aeruginosa blood isolates, 14 were XDR, nine produced either IMP-6 or VIM-2 MBL, and 21 had OprD deficiency.BSIs caused by OprD-defective P. aeruginosa resulted in a 2-fold higher 6 week mortality rate (33.3%) than that of BSIs caused by OprD-intact P. aeruginosa (17.2%), likely due to the decreased susceptibility to carbapenems and bacterial persistence in clinical settings.
Our aim was to study the antimicrobial susceptibilities and macrolide resistance mechanisms of viridans group streptococci (VGS) in a Korean tertiary hospital.MICs of five antimicrobials were determined for 106 VGS isolated from blood cultures. The macrolide resistance mechanisms of erythromycin non-susceptible isolates were studied by the double-disc test and PCR.In all, 42.4% of the isolates were susceptible to penicillin. Nine of 61 penicillin non-susceptible isolates were fully resistant (MIC >/= 4 mg/L). Rates of non-susceptibility to erythromycin, clindamycin and ceftriaxone were 33.9%, 17.9% and 9.4%, respectively. Twenty-two (61.1%) of 36 erythromycin non-susceptible isolates expressed constitutive resistance to macrolide-lincosamide-streptogramin B antibiotics (a constitutive MLS(B) phenotype); 13 isolates (36.1%) expressed an M phenotype; and one isolate, a Streptococcus bovis isolate, had an inducible MLS(B) resistance phenotype. erm(B) was found in isolates with constitutive/inducible MLS(B) phenotypes, and mef(A) in isolates with the M phenotype. In three isolates (two isolates with a constitutive MLS(B) phenotype and in one isolate with the M phenotype), none of erm(A), erm(B), erm(C) or mef(A) was detected by PCR.Penicillin non-susceptible VGS were more resistant to erythromycin, clindamycin and ceftriaxone than were penicillin-susceptible isolates. A constitutive MLS(B) phenotype associated with erm(B) was the predominant mechanism of macrolide resistance among erythromycin non-susceptible isolates from this Korean hospital.
Background: Rapid and accurate detection of Mycobacterium tuberculosis (Mtb) is of primary importance for infection control and selection of anti-tuberculosis drugs. However, most clinical laboratories report Mtb complex (MTC) without reporting Mtb because MTC comprising Mtb, Mycobacterium bovis, Mycobacterium africanum, Mycobacterium microti, Mycobacterium caprae, and Mycobacterium pinnipedii have 99.9% similarity at the nucleotide level and identical 16S rRNA sequences. This study was conducted to analyze the species frequency of MTC isolates obtained from clinical specimens. Methods: Of 310 MTC isolates obtained from clinical samples in a tertiary care hospital from February 2017 to August 2018, MolecuTech Real TB-Taq (YD Diagnostics, Korea) real-time polymerase chain reaction (PCR) was performed,specifically to detect Mtb. For DNA showing Mtb negative results by Mtb-specific real-time PCR or pyrazinamide-resistant strains, PCR-based MTC typing, spacer oligonucleotide typing (spoligotyping), and exact tandem repeat D gene sequencing were performed. Results: All the 310 MTC isolates were identified to be Mtb. Two Mtb strains of the East-African-Indian 4-Vietnam genotype, which have not been reported in Korea, were also found. Conclusion: There was no zoonotic tuberculosis in this study. Since we investigated only 310 MTC isolates detected in only one medical institution, a multi-center study is needed to accurately know the prevalence of zoonotic tuberculosis in Korea.
(1) Background: We compared the diagnostic and prognostic performance of serum amyloid A (SAA), procalcitonin (PCT), delta neutrophil index (DNI), and C-reactive protein (CRP) in patients with hematologic diseases; (2) Methods: We retrospectively collected the remaining serum samples from patients with hematologic diseases, analyzed their clinical data, and measured the levels of PCT, DNI, CRP, and SAA. Performances for infection diagnosis were evaluated using a receiver operating characteristic curve analysis, and 90-day mortality was analyzed using Kaplan-Meier estimation; (3) Results: The levels of all markers were significantly higher in the infected group (N = 27) than those in the uninfected group (N = 100) (p < 0.0001 for all markers). The areas under the curve for diagnosing infection for PCT, DNI, CRP, and SAA were 0.770, 0.817, 0.870, and 0.904, respectively. Increased PCT levels were associated with higher mortality (p = 0.0250); this association was not observed with other examined markers; (4) Conclusions: CRP and SAA exhibited greater discriminative power for infection than PCT. However, only PCT levels were positively associated with 90-day mortality. Herein, we evaluated the diagnostic performance of the four markers. Additional studies are needed to confirm the findings of the present study and validate the potential of these markers in clinical practice.
Background The incidence of fungal infections varies among hospitals and between different time periods. We performed a nationwide survey in Korea to in-vestigate the distribution of yeast and mold species recovered from clinical specimens. Methods The distributions of clinical isolates of yeast and mold species obtained from 12 university hospitals between January and December 2011 were evaluated relative to the hospital and specimen type. Results A total of 39,533 fungal isolates (37,847 yeast and 1,686 mold isolates) were obtained. C. albicans was the predominant species (49.4%) among the yeast isolates from all clinical specimens, followed by C. glabrata (7.2%) and C. tropicalis (6.5%). For 5,248 yeast isolates from sterile body fluids, blood was the most common source of yeasts (71.1%), followed by peritoneal fluid (9.4%). Although C. albicans was the predominant species at all but two hospitals, the rate of non-albicans Candida species varied from 71.2% to 40.1%, depending on the hospital. The yeast species recovered most fre-quently from the sterile body fluids was C. albicans (41.7%), followed by C. parapsilosis (17.8%) and C. glabrata (14.4%), while that from non-sterile sites was C. albicans (50.7%), followed by C. glabrata (6.0%) and C. tropicalis (5.5%). For mold-forming fungi, Aspergillus species (62.3%) were most common, followed by Trichophyton species (15.4%). Respiratory specimens were the most common source of molds (39.6%), followed by abscesses/wounds (28.4%) and tissues (17.5%). Conclusion The rank order of distribution for different fungal species varied among hospitals and specimen types. Continual national surveillance programs are essential for identifying possible changes in fungal infection patterns.
Background:The epidemiology of pathogenic bacteria varies according to the socioeconomic status and antimicrobial resistance status.However, longitudinal epidemiological studies to evaluate the changes in species distribution and antimicrobial susceptibility of pathogenic bacteria nationwide are lacking.We retrospectively investigated the nationwide trends in species distribution and antimicrobial susceptibility of pathogenic bacteria over the last 20 years in Korea.Methods: From 1997 to 2016, annual cumulative antimicrobial susceptibility and species distribution data were collected from 12 university hospitals in five provinces and four metropolitan cities in South Korea.Results: The prevalence of Staphylococcus aureus was the highest (13.1%) until 2012 but decreased to 10.3% in 2016, consistent with the decrease in oxacillin resistance from 76.1% in 2008 to 62.5% in 2016.While the cefotaxime resistance of Escherichia coli increased from 9.0% in 1997 to 34.2% in 2016, E. coli became the most common species since 2013, accounting for 14.5% of all isolates in 2016.Pseudomonas aeruginosa and Acinetobacter baumannii rose to third and fifth places in 2008 and 2010, respectively, while imipenem resistance
Salmonella is a major pathogen causing foodborne infections in humans. Salmonella isolates are identified using biochemical and serological tests, including automated systems such as the VITEK2 system. However, there are few reports on Salmonella identification using VITEK MS. Therefore, we aimed to evaluate the usefulness of MALDI-TOF VITEK MS for Salmonella identification. A total of 1389 Salmonella isolates were identified using VITEK MS ver3.0 or ver3.2. All Salmonella isolates were confirmed by serotyping using the Kauffmann-White scheme, and the results were compared with the VITEK MS results. A total of 1389 Salmonella isolates, including 66 serotypes, were correctly identified at the genus level by VITEK MS. However, these systems failed to correctly identify typhoidal Salmonella. Among the five Salmonella enterica ssp. diarizonae isolates, only one was correctly identified, whereas one and three isolates were partially identified and misidentified, respectively. On the other hand, the VITEK2 system successfully identified all typhoidal Salmonella (Typhi and Paratyphi A) and Salmonella enterica ssp. diarizonae isolates. VITEK MS was useful for identifying Salmonella species isolated from clinical specimens; however, additional biochemical tests, such as the VITEK2 System, should be considered to accurately identify Salmonella ser. Typhi, and Salmonella ser. Paratyphi A.
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