ObjectivesThe global spread and increasing incidence of carbapenem non-susceptible Klebsiella pneumoniae (CnSKP) has made its treatment difficult, increasing the mortality. To establish nationwide data on CnSKP spread and carbapenem-resistance mechanisms, we conducted a national surveillance study in Taiwanese hospitals.MethodsWe collected 100 and 247 CnSKP isolates in 2010 and 2012, respectively. The tests performed included antibiotic susceptibility tests; detection of carbapenemase, extended-spectrum β-lactamases (ESBL), and AmpC β-lactamases genes; outer membrane porin profiles; and genetic relationship with pulsed-field gel electrophoresis and multilocus sequence type.ResultsThe resistance rate of CnSKP isolates to cefazolin, cefotaxime, cefoxitin, ceftazidime, and ciprofloxacin was over 90%. Susceptibility rate to tigecycline and colistin in 2010 was 91.0% and 83.0%, respectively; in 2012, it was 91.9% and 87.9%, respectively. In 2010, carbapenemase genes were detected in only 6.0% of isolates (4 bla IMP-8 and 2 bla VIM-1). In 2012, carbapenemase genes were detected in 22.3% of isolates (41 bla KPC-2, 7 bla VIM-1, 6 bla IMP-8, and 1 bla NDM-1). More than 95% of isolates exhibited either OmpK35 or OmpK36 porin loss or both. Impermeability due to porin mutation coupled with AmpC β-lactamases or ESBLs were major carbapenem-resistance mechanisms. Among 41 KPC-2-producing K. pneumoniae isolates, all were ST11 with 1 major pulsotype.ConclusionsIn 2010 and 2012, the major mechanisms of CnSKP in Taiwan were the concomitance of AmpC with OmpK35/36 loss. KPC-2-KP dissemination with the same ST11 were observed in 2012. The emergence and rapid spread of KPC-2-KP is becoming an endemic problem in Taiwan. The identification of NDM-1 K. pneumoniae case is alarming.

Tigecycline is regarded as a last-resort treatment for carbapenem-resistant Klebsiella pneumoniae (CRKP) infections, but increasing numbers of tigecycline-resistant K. pneumoniae isolates have been reported. The tigecycline resistance mechanisms in CRKP are undetermined. This study aimed to elucidate the mechanisms underlying tigecycline resistance in 16 tigecycline-and carbapenem-resistant K. pneumoniae (TCRKP) isolates. Mutations in tigecycline resistance determinant genes [ramR, acrR, oqxR, tet(A), tet(L), tet(X), tet(M), rpsJ]were assessed by PCR amplicon sequencing, and mutations in ramR and tet(A) exhibited high prevalences individually (81%) and in combination (63%). Eight functional ramR mutation profiles reducing tigecycline sensitivity were verified by plasmid complementation of wild-type and mutant ramR. Using a site-specific mutant, the most frequent RamR mutation, A19V (60%), had no significant effect on tigecycline susceptibility or the upregulation of ramA and acrA. Two tet(A) variants with double frameshift mutations, type 1 and type 2, were identified; type 2 tet(A) is novel. A parent strain transformed with a plasmid carrying type 1 or type 2 tet(A) increased the tigecycline MIC by 8-fold or 4-fold, respectively. Synergistic effects were observed in strains harboring no ramR gene and a mutated tet(A), with an 8-fold increase in the tigecycline MIC compared with that in strains harboring only mutated tet(A) being seen. Overall, mutations in the ramR and tet(A) efflux genes constituted the major tigecycline resistance mechanisms among the studied TCRKP isolates. The identification of strains exhibiting the combination of a ramR deficiency and widespread mutated tet(A) is concerning due to the possible dissemination of increased tigecycline resistance in K. pneumoniae.

Severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) has spread rapidly, causing deaths worldwide. In this study, we evaluated the performance of the BD MAX Open System module for identifying viral pathogens, including SARS-CoV-2, in nasopharyngeal specimens from individuals with symptoms of upper respiratory tract infection. We developed and validated a rapid total nucleic acid extraction method based on real-time reverse transcription-polymerase chain reaction (RT-PCR) for the reliable, high-throughput simultaneous detection of common cold viral pathogens using the BD MAX Platform. The system was evaluated using 205 nasopharyngeal swab clinical samples. For assessment of the limit of detection (LoD), we used SARS-CoV-2, influenza A/B, and respiratory syncytial virus (RSV) RNA standards. The BD MAX dual multiplex real-time RT-PCR panel demonstrated a sensitivity comparable to that of the World Health Organization-recommended SARS-CoV-2 assay with an LoD of 50 copies/PCR. The LoD of influenza A/B and RSV was 100-200 copies/PCR. The overall percent agreement between the BD MAX panel and laboratory-developed RT-PCR test on 55 SARS-CoV-2-positive clinical samples was 100%; no cross-reactions were encountered. Among the 55 positive cases of COVID-19 analysed, no coinfection was detected. The BD MAX rapid multiplex PCR provides a highly sensitive, robust, and accurate assay for the rapid detection of SARS-CoV-2, influenza A/B, and RSV. Our assay could accurately identify SARS-CoV-2 and other common respiratory viral infections, shortening the turnaround time, and could thus increase the effectiveness of control and prevention measures for this emerging infectious disease.