Emergence of aac(6')-Ie-aph(2'')-Ia-positive enterococci with non-high-level gentamicin resistance mediated by IS1216V: adaptation to decreased aminoglycoside usage in Taiwan.

OBJECTIVES: To explore the mechanisms mediating the different levels of gentamicin resistance in enterococci. METHODS: Susceptibility testing with gentamicin and PCR of resistance determinants were performed in 149 enterococcal isolates. Genetic relatedness was characterized by MLST and PFGE analysis. Sequences of the aac(6')-Ie-aph(2'')-Ia gene and its surrounding environment were determined by Illumina sequencing. Stability assays of gentamicin resistance were carried out to evaluate the probability of loss of the high-level gentamicin resistance (HLGR) phenotype. RESULTS: A total of 17 (11.4%) aac(6')-Ie-aph(2'')-Ia-positive enterococcal isolates (2 Enterococcus faecalis and 15 Enterococcus faecium) with non-HLGR phenotype were found. MLST analysis revealed that the 2 E. faecalis belonged to ST116 and ST618, while all the 15 E. faecium belonged to clonal complex 17. Sequence analysis demonstrated that IS1216V was inserted into the 5'-end of aac(6')-Ie-aph(2'')-Ia, leading to loss of HLGR phenotype. Three IS1216V insertion types were found, and type II and III were frequently found in E. faecium. Interestingly, a total of 38 aac(6')-Ie-aph(2'')-Ia-positive E. faecium with HLGR phenotype also had type II or type III IS1216V insertion. Sequencing of the aac(6')-Ie-aph(2'')-Ia-positive HLGR E. faecium E37 revealed that an intact aac(6')-Ie-aph(2'')-Ia was located adjacent to IS1216V-disrupted aac(6')-Ie-aph(2'')-Ia. In a non-antibiotic environment, E37 tended to lose HLGR phenotype with a probability of 1.57 × 10-4, which was largely attributed to homologous recombination between the intact and disrupted aac(6')-Ie-aph(2'')-Ia. CONCLUSIONS: This is first study to elucidate that the E. faecium is capable of changing its HLGR phenotype, which may contribute to adaptation to hospital environments with decreased usage of gentamicin.

Assessment of dental personal protective equipment (PPE) and the relationship between manual dexterity and dissemination of aerosol and splatter during the COVID-19 pandemic.

Background/purpose: Asymptomatic COVID-19 patients visit the dental clinic for routine treatment, during which, high-speed handpieces, and third-use sprayers can produce aerosols. We focused on the effect and possible inadequacy of personal protective equipment (PPE) while cleaning teeth and assessed whether doctors' proficiency was related to the range of spraying droplets. Materials and methods: Doctors were divided into three different groups: attending physicians, residents, and intern respectively. Each doctor treated 15 patients; each group comprised 30 patients. The dentists wore leg covers, shoe covers, medical masks, haircaps, full masks, waterproof barrier gowns, and gloves. Each patient was covered with a waterproof hole towel, and the upper edge was fixed to the patient's nose with a medical tape. After cleaning the teeth with water contained red pigment, the spattering distance and range of droplets were calculated. Concurrently, we examined whether there was any droplet contamination on the PPE. Results: With the exception of shoe covers, haircaps, and medical surgical masks, pigment splash marks were found on both the dentist and assistant's PPE. The interns performed cleaning for a significantly longer time than the residents and attending physicians, with a significant statistical difference (P < 0.05). The spatter distance for the interns was significantly larger than the residents (P < 0.05). Conclusion: It is recommended that the hole towel be centered on the patient's nose tip, at least larger than a radius of 54.9-64.5 cm. The dentist's proficiency did cause differences in the duration of teeth cleaning, which further affects the spatter distance.

A Possible Role of Insertion Sequence IS1216V in Dissemination of Multidrug-Resistant Elements MESPM1 and MES6272-2 between Enterococcus and ST59 Staphylococcus aureus.

Sequence type 59 (ST59) is the dominant type of community-associated methicillin-resistant Staphylococcus aureus (MRSA) in Taiwan. Previously, we reported that ST59 MRSA harbors enterococcal IS1216V-mediated multidrug-resistant composite transposons MESPM1 or MES6272-2. The MES were found to have a mosaic structure, largely originating in enterococci and partly native to S. aureus. The current study aimed to track the origin of the MES and how they disseminated from enterococci to ST59 S. aureus. A total of 270 enterococcal isolates were analyzed, showing that two ST64 Enterococcus faecalis isolated in 1992 and 11 clonal complex 17 Enterococcus faecium harbored MESPM1-like and MES6272-2-like structures, respectively. Sequence analysis revealed that ST64 E. faecalis strain N48 acquired the MESPM1-like structure on the plasmid pEflis48. The pEflis48 harbored the enterococci-originated region (erythromycin, kanamycin, and streptomycin resistances) and the S.aureus-originated region (chloramphenicol resistance) of MESPM1 but was separated by the replication region of the plasmid. Homologous recombination between the two direct repeats of IS1216V resulted in excision of the replication region of the plasmid to regenerate MESPM1. The p4780-1 and pV19 of E. faecium carried MES6272-2-like structures with IS1216V, albeit with multiple insertions by other insertion sequences. The findings show that IS1216V plays important roles in bidirectional gene transfer of multidrug resistance between enterococci and S. aureus.

Using groEL as the target for identification of Enterococcus faecium clades and 7 clinically relevant Enterococcus species.

BACKGROUND/PURPOSE: Accurate identification is important for effective treatment because Enterococcus species have talents to cope with various antibiotics either by intrinsic resistance or by acquisition of mobile genetic elements. The groEL gene is a permissive target in identification of bacteria. We aimed to develop simple assays based on groEL for identification of enterococci. RESULTS: We continued our previous work and determined groEL gene sequences of Enterococcus species isolated from clinical specimens. Phylogenetic analysis based on groEL revealed that each strain clustered well with their reference strains (bootstrap value 100%), in which Enterococcusfaecium and Enterococcusgallinarum could be split into two clades. The divergence of E. faecium was coincident with hospital-associated clade, known as clade A, and community-associated clade, known as clade B. A PCR-restriction fragment length polymorphism (PCR-RFLP) assay was therefore designed to differentiate the two E. faecium clades, based on the specific RsaI cutting sites present in the two clades. To differentiate 7 clinical relevant Enterococcus species, the multiplex PCR assay was designed to identify Enterococcusavium, Enterococcuscasseliflavus, Enterococcusfaecalis, E. faecium, E. gallinarum, Enterococcushirae and Enterococcusraffinosus. Specificity was tested with other Enterococcus species including Enterococcuscecorum, Enterococcusdurans and Enterococcusmundtii. None of these bacterial species generated products of similar size to those of the seven Enterococcus species. CONCLUSION: The simple PCR-RFLP and multiplex PCR assays on the basis of groEL gene provided an alternative way to identify Enterococcus species.

The epidemiology, antibiograms and predictors of mortality among critically-ill patients with central line-associated bloodstream infections.

BACKGROUND/PURPOSE: For high risk of central line-associated bloodstream infections (CLABSIs) in patients of intensive care units (ICUs) and scarcely epidemiology and therapeutic recommendations in Asia, we aimed to evaluate the annual change in epidemiology, antibiogram, and risk factors for 14-day mortality. METHODS: A retrospective study of ICUs patients with CLABSIs at a medical center in Taiwan (2010-2016), where central line care bundle implemented since 2014, by reviewing clinical data, pathogens, and the antibiogram. RESULTS: Gram-negative bacteria (59.3%) were main microorganisms of CLABSIs, and 9.0% of all GNB were MDROs. Acinetobacter spp., Enterobacter spp., and Stenotrophomonas maltophilia were the most frequently isolated. In multivariate analysis, malignancy, inadequate empirical antimicrobial therapy, inadequate definite antimicrobial therapy, and infection by fungi or multidrug-resistant organisms (MDROs) were associated with 14-day mortality (all p < 0.05). The CLABSI incidence rate decreased from 5.54 to 2.18 per 1000 catheter-day (from 2014 to 2015) with improved compliance to care bundle. Carbapenem and aminoglycoside were suitable empirical drugs in the hospital setting when GNB is predominant for CLABSI. Significant decreasing susceptibility of ampicillin/sulbactam in Enterobacter spp. (36.7%-0.0%), and ampicillin/sulbactam (12.5%-0.0%), ceftazidime (100.0%-52.9%), and tigecycline (87.5%-35.3%) in Serratia marcescens. CONCLUSION: We identified Gram-negative bacteria as leading pathogens of CLABSIs in a Taiwan medical center, and good compliance to care bundle is associated with reduced CLABSI incidence rate. Malignancy, infection by MDROs or fungi, inadequate empirical or definite antimicrobial therapy are significant factors for 14-day mortality.