Rapid multiplex detection of the resistance genes mecA, vanA and vanB from Gram-positive cocci-positive blood cultures using a PCR-dipstick technique

Introduction. Among the causative agents of bloodstream infections (BSIs), methicillin-resistant Staphylococcus aureus (MRSA) or vancomycin-resistant Enterococcus (VRE) are the key causative pathogens. Their rapid detection directly from Gram-positive cocci-positive blood culture specimens will promote timely treatment and help to implement effective infection control measures.Aim. We aim to develop a PCR-dipstick technique for the rapid detection of MRSA and VRE directly from positive blood culture specimens.Methodology. PCR-dipstick is a PCR-based multiplex detection technique where DNA-DNA hybridization is employed, and the results are interpreted with the naked eye. It was designed to target three drug resistance genes: mecA in MRSA and vanA/vanB in VRE from positive blood culture specimens. A total of 120 clinical isolates were used to evaluate the sensitivity and specificity of PCR-dipstick. Then, PCR-dipstick was examined for MRSA and VRE detection directly from positive blood cultures.Results. PCR-dipstick showed 100 % sensitivity and specificity in detecting mecA, vanA and vanB genes directly from bacterial colonies in comparison with multiplex PCR for genomic DNA followed by agarose gel electrophoresis. Further, it could differentially detect multiple resistant genes in pooled bacterial colonies (n=10). Ultimately, PCR-dipstick could detect MRSA and VRE in positive blood cultures in ~3 h.Conclusion. The results of the current study substantiate that PCR-dipstick can be used as an efficient detection system for MRSA and VRE directly from Gram-positive cocci-positive blood cultures. Its affordability and rapidity indicate that PCR-dipstick can be an effective tool for controlling nosocomial pathogens.

Risk model for severe postoperative complications after total pancreatectomy based on a nationwide clinical database

BACKGROUND

Total pancreatectomy is required to completely clear tumours that are locally advanced or located in the centre of the pancreas. However, reports describing clinical outcomes after total pancreatectomy are rare. The aim of this retrospective observational study was to assess clinical outcomes following total pancreatectomy using a nationwide registry and to create a risk model for severe postoperative complications.

METHODS

Patients who underwent total pancreatectomy from 2013 to 2017, and who were recorded in the Japan Society of Gastroenterological Surgery and Japanese Society of Hepato-Biliary-Pancreatic Surgery database, were included. Severe complications at 30 days were defined as those with a Clavien-Dindo grade III needing reoperation, or grade IV-V. Occurrence of severe complications was modelled using data from patients treated from 2013 to 2016, and the accuracy of the model tested among patients from 2017 using c-statistics and a calibration plot.

RESULTS

A total of 2167 patients undergoing total pancreatectomy were included. Postoperative 30-day and in-hospital mortality rates were 1·0 per cent (22 of 2167 patients) and 2·7 per cent (58 of 167) respectively, and severe complications developed in 6·0 per cent (131 of 2167). Factors showing a strong positive association with outcome in this risk model were the ASA performance status grade and combined arterial resection. In the test cohort, the c-statistic of the model was 0·70 (95 per cent c.i. 0·59 to 0·81).

CONCLUSION

The risk model may be used to predict severe complications after total pancreatectomy.

In Vitro Efficacy of Meropenem-Cefmetazole Combination Therapy against New Delhi Metallo-β-lactamase-producing Enterobacteriaceae

BACKGROUND

Limited treatment options complicate management of infections with New Delhi metallo-β-lactamase (NDM)-producing organisms. The efficacy of combination therapy with meropenem (MEM) and cefmetazole (CMZ) was assessed against NDM-producing Enterobacteriaceae.

MATERIALS AND METHODS

Twelve Escherichia coli clinical isolates harbouring bla_NDM-1 and a positive control E. coli BAA-2469 harbouring bla_NDM-1 were studied. Minimum inhibitory concentrations (MICs) of MEM, ertapenem (ERT) and CMZ were determined by broth microdilution. Checkerboard and time-kill assays were performed to confirm the in vitro efficacy of the MEM/CMZ combination. Scanning electron microscopy, kinetic studies and whole-genome sequence analysis were used to determine the antimicrobial resistance mechanisms.

RESULTS

MICs of MEM, ERT and CMZ in monotherapy ranged from 8 to 32, 16 to 128, and 32 to 512 µg/mL, respectively. In the checkerboard assay, MEM/ERT resulted in no synergy, whereas MEM/CMZ showed a synergistic effect in all the tested isolates. Furthermore, the MIC of MEM in combination decreased by 2- to 8-fold compared with that of MEM alone. The time-kill study revealed a bactericidal effect in 4 of 13 isolates at 24 h. Scanning electron microscopy showed spheroidisation of the bacterial cell in the MEM/CMZ combination; this was not observed in single antibiotic conditions. Kinetic studies indicated CMZ was a better antagonist for NDM-1 than ERT. Whole-genome sequence analysis did not reveal any explainable differences between isolates susceptible and those non-susceptible to combination therapy.

CONCLUSION

In vitro studies showed the potential effectiveness of MEM/CMZ combination therapy against NDM-producing organisms.

Genomic characterization of an emerging blaKPC-2 carrying Enterobacteriaceae clinical isolates in Thailand

The rapidly increasing prevalence of carbapenem-resistant Enterobacteriaceae (CRE) over the past decade has increased concern in healthcare facilities and the impact on public health. The prevalence of bla_KPC (KPC) in Thailand remains very low; only bla_KPC-13 has been described previously. This study is the first to describe the characteristics of bla_KPC-2-carrying Klebsiella pneumoniae, Escherichia coli, and Enterobacter asburiae in Thailand. The prevalence rate of bla_KPC-2-carrying isolates was 0.13% among CRE isolates in our study. Based on carbapenem susceptibility testing, K. pneumoniae C1985 was resistant to meropenem and ertapenem, E. coli C1992 was resistant to meropenem, imipenem, and ertapenem, and E. asburiae C2135 was only resistant to imipenem. K. pneumoniae C1985 carried bla_KPC-2, bla_SHV-11, fosA, oqxA, and oqxB, while E. coli C1992 contained bla_KPC-2 and mdf(A) and E. asburiae C2135 harbored bla_KPC-2, bla_ACT-2, and qnrE1. The genetic features of bla_KPC-2 in the 3 isolates revealed identical rearrangement and flanking regions. Analysis of genomic sequences from these 3 isolates revealed that the sequence types of K. pneumoniae C1985, E. coli C1992, and E. asburiae C2135 were ST4008, ST7297, and ST1249, respectively. The 3 bla_KPC-2 isolates were from individual living cases. Two cases were colonization for K. pneumoniae C1985 and E. asburiae C2135 and the third case was hospital-acquired infection of E. coli C1992. Although the prevalence of bla_KPC-2-carrying CRE is relatively low in this study, continued surveillance and close monitoring are warranted. In addition, prompt or early detection of CRE and strict implementation of infection control are essential to prevent outbreaks or rapid spread in hospitals.

First Identification and genomic characterization of multidrug-resistant carbapenemase-producing Enterobacteriaceae clinical isolates in Malawi, Africa

Purpose. Carbapenemase-producing Enterobacteriaceae (CPE) have become a global concern and a serious threat to human health due to their resistance to multiple antibiotics. In this study, we identified and characterized CPE for the first time in Malawi, southeastern Africa.Methodology. We investigated the possible presence of carbapenemases among a collection of 200 ceftriaxone-nonsusceptible Gram-negative clinical isolates obtained from five Malawian hospitals between January 2016 and December 2017, using both phenotypic and genotypic tests. Molecular typing of CPE was done by PFGE, multilocus sequence typing (ST) or phylogenetic grouping. Resistant plasmids were characterized by S1 PFGE, Southern blotting and conjugation assays.Results. Out of 200 isolates, we detected 16 (8 %) CPE of which all originated from one referral hospital, Kamuzu Central Hospital, in the Central part of Malawi. Of 16 isolates, seven Klebsiella pneumoniae ST340/CC258 carried bla _KPC-2, two Escherichia coli ST636 (phylogroup B2) carried bla _NDM-5, six E. coli ST617 (phylogroup A) and one Klebsiella variicola carried bla _OXA-48. All carbapenemases were plasmid-encoded, but only bla _NDM-5-carrying plasmids could be conjugated. Most isolates co-harboured other β-lactamases and consequently exhibited a wider spectrum of resistance to commonly used antibiotics. We observed indistinguishable genetic profiles between strain types, despite originating from different wards, suggesting acquisition during admission and intra-hospital spread.Conclusion. This report strongly suggests a probable existence of highly resistant various types of CPE organisms in Malawi including KPC-2-producing K. pneumoniae ST340/CC258, a known high-risk epidemic lineage.

P2742Right ventricular stroke volume during dobutamine stress magnetic resonance compared to lung perfusion and peak oxygen uptake after arterial switch operation for transposition of the great arteries

Objectives

Abnormal pulmonary perfusion due to stenosis of the central pulmonary arteries is common after neonatal arterial switch operation (ASO) for transposition of the great arteries (TGA). We conducted a monocentric prospective study in young adults after neonatal ASO for TGA to evaluate the effects of abnormal pulmonary perfusion on the increase of the right ventricular stroke volume (RVSV) during dobutamine stress magnetic resonance (DSMR) and on cardiopulmonary exercise capacity.

Methods

68 unselected patients (age 18–29 years) underwent CMR at rest and under dobutamine stress (10 to 40 μg/kg/min). RVSV, pulmonary blood flow distribution (PBFD) and peak flow velocity were derived from phase contrast mapping in the main, right and left pulmonary artery (PA) at rest and each stress level. A cardiopulmonary exercise test (CPET) was performed at the same day. All patients reached maximal exercise effort according to heart rate and respiratory exchange rate.

Results

PBFD at rest: 9/68 patients (13%, ASO-S) had abnormal pulmonary perfusion at rest, defined as PBFD >2:1 (right/left or left/right) and/or relevant stenosis of the main PA (Vmax >2.5 m/s). 59/68 patients (87%, ASO-N) had normal pulmonary perfusion.

PBFD under DSMR: (1) In the whole patient group, there was no increase of PBFD under stress compared to PBFD at rest. On an individual patient level, no relevant worsening of abnormal PBFD was found.

(2) Under low dose dobutamine, ASO-S had a significantly lower RVSV-increase (RVSVstress/RVSVrest) compared to ASO-N (see figure). However, under high dose dobutamine, this effect was no longer significant (see figure).

(3) The RVSV-increase under low and high dose dobutamine did not correlate with peak oxygen uptake during CPET, neither in the total group nor in the subgroups (see table). Peak oxygen uptake was not significantly different between ASO-N and ASO-S (p=0,72).

RVSV-increase compared to CPET peak VO2% ASO-total ASO-S ASO-N RVSV-increase/peak VO2% RVSV-increase/peak VO2% RVSV-increase/peak VO2% low dose dobu high dose dobu low dose dobu high dose dobu low dose dobu high dose dobu Pearson correlation coefficient −0.02 −0.05 0.01 −0.22 −0.05 −0.04 p-value 0.90 0.71 0.98 0.56 0.71 0.78

Figure 1

Conclusion

(1) Patients with relevant stenosis of main PA and/or abnormal peripheral blood flow distribution (ASO-S) exhibit a reduced RVSV-increase under low dose dobutamine compared to patients without stenosis (ASO-N). This effect was not present under high dose dobutamine stress.

(2) These findings did not correlate with peak oxygen uptake during CPET, an objective parameter of cardiopulmonary exercise capacity.

(3) Therefore, a conservative proceeding rather than surgery or catheter intervention should be considered, especially in asymptomatic adult patients.

Acknowledgement/Funding

Supported by Kinderherzen, Fördergemeinschaft Deutsche Kinderherzzentren e.V.

Contribution to oral and maxillary surgery and surgical technique of osteo-odontokeratoprosthesis in Japan

Osteo-odontokeratoprosthesis (OOKP) is a technique invented by Strampelli in 1963, in which the patient's own tooth root is used to support an optical cylinder. It uses an autologous tooth-bone-periodontal complex to mount an optical cylinder, which is stabilised by overlying autologous buccal mucosa. OOKP involves two, staged procedures done by ophthalmologists and oral surgeons, and the main contribution from the oral surgeon is during the first stage. To date we have done nine first-stage, and completed eight second-stage, OOKP operations in Japan with a mean follow-up of eight years and 11 months by modifying the original method of the oral surgery. All OOKP procedures were unilateral, and canines were selected as the donor teeth. Patients developed ocular blindness as a result of Stevens-Johnson syndrome, ocular cicatricial pemphigoid, and chemical and thermal burns to the cornea and ocular surface. All eight patients who completed the second stage have been stable, and there have been no major perioperative or postoperative oral complications. The patients' visual acuities were stable with no serious complications. Here we report the technical details of the oral contribution to OOKP.

Rapid screening and early precautions for carbapenem-resistant Acinetobacter baumannii carriers decreased nosocomial transmission in hospital settings: a quasi-experimental study

Background

Active surveillance has the potential to prevent nosocomial transmission of carbapenem-resistant Acinetobacter baumannii (CRAB). We assessed whether rapid diagnosis using clinical specimen-direct loop-mediated isothermal amplification (LAMP), a rapid molecular diagnostic assay, and subsequent intervention, could reduce CRAB nosocomial transmission in intensive care units (ICUs).

Methods

A before and after (quasi-experimental) study was conducted in two ICUs at the Mahidol University Faculty of Medicine Ramathibodi Hospital with 3 months of observational period followed by 9 months of interventional period. All patients were screened for CRAB using both the culture and LAMP method from rectal swab and/or bronchial aspirates (intubated patients only) upon admission, weekly thereafter, and upon discharge. During the pre-intervention period, we performed contact precautions based on culture results. In contrast, during the intervention period, we initiated contact precautions within a few hours after sample collection on the basis of LAMP results.

Results

A total of 1335 patients were admitted to the ICUs, of which 866 patients (pre-intervention period: 187; intervention period: 679) were eligible for this study. Incidence rate of CRAB infection decreased to 20.9 per 1000 patient-days in the intervention period from 35.2 in the pre-intervention period (P < 0.02). The calculated hazard ratio of CRAB transmission was 0.65 (95% confidence interval [CI], 0.44–0.97). Risk factors for CRAB acquisition included exposure to carbapenem (hazard ratio, 2.54 [95% CI: 1.61–5.57]).

Conclusions

LAMP screening for CRAB upon ICU admission proved feasible for routine clinical practice. Rapid screening using LAMP followed by early intervention may reduce CRAB transmission rates in ICUs when compared to conventional intervention.

Electronic supplementary material

The online version of this article (10.1186/s13756-019-0564-9) contains supplementary material, which is available to authorized users.

PCR-Dipstick-Oriented Surveillance and Characterization of mcr-1- and Carbapenemase-Carrying Enterobacteriaceae in a Thai Hospital

Colistin is used as an alternative therapeutic for carbapenemase-producing Enterobacteriaceae (CPE) infections which are spreading at a very high rate due to the transfer of carbapenemase genes through mobile genetic elements. Due to the emergence of mcr-1, the plasmid-mediated colistin resistance gene, mcr-1-positive Enterobacteriaceae (MCRPEn) pose a high risk for the transfer of mcr-1-carrying plasmid to CPE, leading to a situation with no treatment alternatives for infections caused by Enterobacteriaceae possessing both mcr-1 and carbapenemase genes. Here, we report the application of PCR-dipstick-oriented surveillance strategy to control MCRPEn and CPE by conducting the PCR-dipstick technique for the detection of MCRPEn and CPE in a tertiary care hospital in Thailand and comparing its efficacy with conventional surveillance method. Our surveillance results showed a high MCRPEn (5.9%) and CPE (8.7%) carriage rate among the 219 rectal swab specimens examined. Three different CPE clones were determined by pulsed-field gel electrophoresis (PFGE) whereas only two MCRPEn isolates were found to be closely related as shown by single nucleotide polymorphism-based phylogenetic analysis. Whole genome sequencing (WGS) and plasmid analysis showed that MCRPEn carried mcr-1 in two plasmids types—IncX4 and IncI2 with ~99% identity to the previously reported mcr-1-carrying plasmids. The identification of both MCRPEn and CPE in the same specimen indicates the plausibility of plasmid-mediated transfer of mcr-1 genes leading to the emergence of colistin- and carbapenem-resistant Enterobacteriaceae. The rapidity (<2 h) and robust sensitivity (100%)/specificity (~99%) of PCR-dipstick show that this specimen-direct screening method could aid in implementing infection control measures at the earliest to control the dissemination of MCRPEn and CPE.

Loop-Mediated Isothermal Amplification for Rapid Identification of Mycobacterium tuberculosis in Comparison with Immunochromatographic SD Bioline MPT64 Rapid® in a High Burden Setting

Loop-mediated isothermal amplification (LAMP) was assessed for rapid identification of Mycobacterium tuberculosis complex (MTC) in comparison with an immunochromatographic test (ICT) using SD Bioline Ag MPT64 Rapid^®. One hundred and fifty-one MGIT cultures positive for acid-fast bacilli were tested for MTC. DNA was extracted from a small portion of culture samples by heat lysis and subjected to LAMP analysis. Of these, 144 were positive and 5 were negative by both tests. One culture that was ICT negative but was LAMP positive was confirmed to have a mutation in the mpt64 gene. The agreement was 98.68% (95% confidence interval [CI]: 94.80-99.77), and the kappa value was 0.83% (95% CI: 0.59-1.00). Good correlation results suggested that LAMP assay is a reliable molecular test for rapid identification of MTC and is practical for use in resource-limited, high burden settings.

Establishment of a dual-wavelength spectrophotometric method for analysing and detecting carbapenemase-producing Enterobacteriaceae

The spread of carbapenemase-producing Enterobacteriaceae (CPE) is an increasing global public health concern. The development of simple and reliable methods for CPE detection is required in the clinical setting. This study aimed to establish a dual-wavelength measurement method using an ultraviolet–visible spectrophotometer to rapidly quantify imipenem hydrolysis in bacterial cell suspensions. The hydrolytic activities of 148 strains including various CPE strains (Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, and Enterobacter aerogenes containing the bla_IMP, bla_KPC, bla_NDM, bla_OXA, and bla_VIM genes) were measured and analysed. A cut-off value was obtained for differentiation between CPE and non-CPE strains, and the method had high sensitivity (100%) and specificity (100%) within 60 min. Our system has potential clinical applications in detecting CPE.

How useful are hemoglobin concentration and its variations to predict significant hemorrhage in the early phase of trauma? A multicentric cohort study

Background

The diagnostic value of hemoglobin (Hb) for detecting a significant hemorrhage (SH) in the early phase of trauma remains controversial. The present study aimed to assess the abilities of Hb measurements taken at different times throughout trauma management to identify patients with SH.

Methods

All consecutive adult trauma patients directly admitted to six French level-1 trauma centers with at least one prehospital Hb measurement were analyzed. The abilities of the following variables to identify SH (≥ 4 units of red blood cells in the first 6 h and/or death related to uncontrolled bleeding within 24 h) were determined and compared to that of shock index (SI): Hb as measured with a point-of-care (POC) device by the prehospital team on scene (POC-Hb_prehosp) and upon patient’s admission to the hospital (POC-Hb_hosp), the difference between POC-Hb_hosp and POC-Hb_prehosp (DeltaPOC-Hb) and Hb as measured by the hospital laboratory on admission (Hb-Lab_hosp).

Results

A total of 6402 patients were included, 755 with SH and 5647 controls (CL). POC-Hb_prehosp significantly predicted SH with an area under ROC curve (AUC) of 0.72 and best cutoff values of 12 g/dl for women and 13 g/dl for men. POC-Hb_prehosp < 12 g/dl had 90% specificity to predict of SH. POC-Hb_hosp and Hb-Lab_hosp (AUCs of 0.92 and 0.89, respectively) predicted SH better than SI (AUC = 0.77, p < 0.001); best cutoff values of POC-Hb_hosp were 10 g/dl for women and 12 g/dl for men. DeltaPOC-Hb also predicted SH with an AUC of 0.77, a best cutoff value of − 2 g/dl irrespective of the gender. For a same prehospital fluid volume infused, DeltaPOC-Hb was significantly larger in patients with significant hemorrhage than in controls.

Conclusions

Challenging the classical idea that early Hb measurement is not meaningful in predicting SH, POC-Hb_prehosp was able, albeit modestly, to predict significant hemorrhage. POC-Hb_hosp had a greater ability to predict SH when compared to shock index. For a given prehospital fluid volume infused, the magnitude of the Hb drop was significantly higher in patients with significant hemorrhage than in controls.

Electronic supplementary material

The online version of this article (10.1186/s13613-018-0420-8) contains supplementary material, which is available to authorized users.

Detection of plasmid-mediated colistin-resistant and carbapenem-resistant genes by multiplex PCR

A multiplex PCR was described to simultaneously detect mcr-1 and frequently occurring carbapenem-resistant genes including bla_KPC, bla_NDM, bla_IMP, and bla_OXA-48-like in a single reaction. The PCR product sizes of these 4 carbapenem-resistant genes were 232 bp, 438 bp, 621 bp, and 798 bp for bla_IMP, bla_OXA-48-like, bla_NDM, and bla_KPC, respectively, whereas mcr-1 revealed 1126 bp of PCR product. This protocol accurately detected those resistant genes in agreement with the reference strains, 127 local carbapenem-resistant Enterobacteriaceae, 8 mcr-1 carrying Enterobacteriaceae, and 62 carbapenem-susceptible Enterobacteriaceae. This method will be useful for laboratory application and surveillance of carbapenem and/or colistin-resistant bacteria.

Genetic characterization of blaNDM-harboring plasmids in carbapenem-resistant Escherichia coli from Myanmar

The bacterial enzyme New Delhi metallo-β-lactamase hydrolyzes almost all β-lactam antibiotics, including carbapenems, which are drugs of last resort for severe bacterial infections. The spread of carbapenem-resistant Enterobacteriaceae that carry the New Delhi metallo-β-lactamase gene, bla_NDM, poses a serious threat to public health. In this study, we genetically characterized eight carbapenem-resistant Escherichia coli isolates from a tertiary care hospital in Yangon, Myanmar. The eight isolates belonged to five multilocus-sequence types and harbored multiple antimicrobial-resistance genes, resulting in resistance against nearly all of the antimicrobial agents tested, except colistin and fosfomycin. Nine plasmids harboring bla_NDM genes were identified from these isolates. Multiple bla_NDM genes were found in the distinct Inc-replicon types of the following plasmids: an IncA/C₂ plasmid harboring bla_NDM-1 (n = 1), IncX3 plasmids harboring bla_NDM-4 (n = 2) or bla_NDM-7 (n = 1), IncFII plasmids harboring bla_NDM-4 (n = 1) or bla_NDM-5 (n = 3), and a multireplicon F plasmid harboring bla_NDM-5 (n = 1). Comparative analysis highlighted the diversity of the bla_NDM-harboring plasmids and their distinct characteristics, which depended on plasmid replicon types. The results indicate circulation of phylogenetically distinct strains of carbapenem-resistant E. coli with various plasmids harboring bla_NDM genes in the hospital.