Expansion of highly stable bla OXA-10 β-lactamase family within diverse host range among nosocomial isolates of Gram-negative bacilli within a tertiary referral hospital of Northeast India

Background

The current study reports dissemination of highly stable bla_OXA-10 family of beta lactamases among diverse group of nosocomial isolates of Gram-negative bacilli within a tertiary referral hospital of the northern part of India.

Methods

In the current study, a total number of 590 Gram negative isolates were selected for a period of 1 year (i.e. 1st November 2011–31st October 2012). Members of Enterobacteriaceae and non fermenting Gram negative rods were obtained from Silchar Medical College and Hospital, Silchar, India. Screening and molecular characterization of β-lactamase genes was done. Integrase gene PCR was performed for detection and characterization of integrons and cassette PCR was performed for study of the variable regions of integron gene cassettes carrying bla_OXA-10. Gene transferability, stability and replicon typing was also carried out. Isolates were typed by ERIC as well as REP PCR.

Results

Twenty-four isolates of Gram-negative bacilli that were harboring bla_OXA-10 family (OXA-14, and OXA16) with fact that resistance was to the extended cephalosporins. The resistance determinant was located within class I integron in five diverse genetic contexts and horizontally transferable in Enterobacteriaceae, was carried through IncY type plasmid. MIC values were above break point for all the tested cephalosporins. Furthermore, co-carriage of bla_CMY-2 was also observed.

Conclusion

Multiple genetic environment of bla_OXA-10 in this geographical region must be investigated to prevent dissemination of these gene cassettes within bacterial population within hospital settings.

Electronic supplementary material

The online version of this article (doi:10.1186/s13104-017-2467-2) contains supplementary material, which is available to authorized users.

An unusual occurrence of plasmid-mediated blaOXA-23 carbapenemase in clinical isolates of Escherichia coli from India

The bla_OXA-23 group was considered as the first group of OXA-type β-lactamases conferring carbapenem resistance and has been reported worldwide in Acinetobacter baumannii, however their presence in Escherichia coli is very rare and unique. This study describes an unusual occurrence of bla_OXA-23 in 14 clinical isolates of E. coli obtained from intensive care unit patients admitted to a tertiary referral hospital in India. The bla_OXA-23 gene was found located within a self-conjugative plasmid of IncF_repB and IncK incompatibility types and simultaneously carrying bla_CTX-M-15, bla_VEB-1, bla_PER-1 and/or bla_NDM-1. The copy number of bla_OXA-23 within the IncK-type plasmid was inversely proportional to increasing concentrations of imipenem, whereas in the case of the IncF_repB-type the result was variable; and increased copy number of the IncK-type plasmid was observed with increasing concentrations of meropenem. Plasmids encoding bla_OXA-23 could be successfully eliminated after single treatment and were found to be not highly stable, as complete loss of plasmids was observed within 5-10 days. This study emphasises that carbapenem stress invariably altered the copy number of two different Inc type plasmids encoding the bla_OXA-23 resistance gene and also highlights a potential threat of clonal expansion of this class D carbapenemase through a heterologous host in this country, which is in second incidence globally.

Occurrence of bla DHA-1 mediated cephalosporin resistance in Escherichia coli and their transcriptional response against cephalosporin stress: a report from India

Background

Treatment alternatives for DHA-1 harboring strains are challenging as it confers resistance to broad spectrum cephalosporins and may further limit treatment option when expressed at higher levels. Therefore, this study was designed to know the prevalence of DHA genes and analyse the transcription level of DHA-1 against different β-lactam stress.

Methods

Screening of AmpC β-lactamase phenotypically by modified three dimensional extract method followed by Antimicrobial Susceptibility and MIC determination. Genotyping screening of β-lactamase genes was performed by PCR assay followed by their sequencing. The bla_DHA-1 transcriptional response was evaluated under different cephalosporin stress by RT PCR. Transferability of bla_DHA gene was performed by transformation and conjugation and plasmid incompatibility typing, DNA fingerprinting by enterobacterial repetitive intergenic consensus sequences PCR.

Results

16 DHA-1 genes were screened positive from 176 Escherichia coli isolates and primer extension analysis showed a significant increase in DHA-1 mRNA transcription in response to cefotaxime at 8 µg/ml (6.99 × 10² fold), ceftriaxone at 2 µg/ml (2.63 × 10³ fold), ceftazidime at 8 µg/ml (7.06 × 10³ fold) and cefoxitin at 4 µg/ml (3.60 × 10⁴ fold) when compared with untreated strain. These transcription data were found significant when analyzed statistically using one way ANOVA. Four different ESBL genes were detected in 10 isolates which include CTX-M (n = 6), SHV (n = 4), TEM (n = 3) and OXA-10 (n = 1), whereas, carbapenemase gene (NDM) was detected only in one isolate. Other plasmid mediated AmpC β-lactamases CIT (n = 9), EBC (n = 2) were detected in nine isolates. All DHA-1 genes detected were encoded in plasmid and incompatibility typing from the transformants indicated that the plasmid encoding bla_DHA-1 was carried mostly by the FIA and L/M Inc group.

Conclusion

This study demonstrates the prevalence of DHA-1 gene in this region and highlights high transcription of DHA-1 when induced with different β-lactam antibiotics. Therefore, cephalosporin treatment must be restricted for the patients infected with pathogen expressing this resistance determinant.

Transcriptional analysis of blaNDM-1 and copy number alteration under carbapenem stress

BACKGROUND

New Delhi metallo beta-lactamase is known to compromise carbapenem therapy and leading to treatment failure. However, their response to carbapenem stress is not clearly known. Here, we have investigated the transcriptional response of blaNDM-1 and plasmid copy number alteration under carbapenem exposure.

METHODS

Three blaNDM-1 harboring plasmids representing three incompatibility types (IncFIC, IncA/C and IncK) were inoculated in LB broth with and without imipenem, meropenem and ertapenem. After each 1 h total RNA was isolated, immediately reverse transcribed into cDNA and quantitative real time PCR was used for transcriptional expression of blaNDM-1. Horizontal transferability and stability of the plasmids encoding blaNDM-1 were also determined. Changes in copy number of blaNDM-1 harboring plasmids under the exposure of different carbapenems were determined by real time PCR. Clonal relatedness among the isolates was determined by pulsed field gel electrophoresis.

RESULTS

Under carbapenem stress over an interval of time there was a sharp variation in the transcriptional expression of blaNDM-1 although it did not follow a specific pattern. All blaNDM-1 carrying plasmids were transferable by conjugation. These plasmids were highly stable and complete loss was observed between 92nd to 96th serial passages when antibiotic pressure was withdrawn. High copy number of blaNDM-1 was found for IncF type plasmids compared to the other replicon types.

CONCLUSION

This study suggests that the single dose of carbapenem pressure does not significantly influence the expression of blaNDM-1 and also focus on the stability of this gene as well as the change in copy number with respect to the incompatible type of plasmid harboring resistance determinant.

Abstract P4-16-01: Evaluation of miracle mouthwash (MMW) plus hydrocortisone or prednisolone mouth rinses as prophylaxis for everolimus-associated stomatitis: Results of a randomized phase II study

Background: Oral stomatitis is a frequent adverse event (AE) associated with mTOR-inhibitor therapy, and can impact adherence. In BOLERO-2, patients (pts) with hormone receptor-positive (HR+) metastatic breast cancer (MBC) treated with exemestane plus everolimus (EVE), the incidence of all-grade (G) stomatitis or related AEs was 67%, with 24%/8% of pts developing G2/G3 stomatitis or related AEs, respectively (Perez et al ASCO 2013 Abs 7029). In BOLERO-2, 24% of pts required EVE dose reduction for stomatitis (Rugo et al Ann Oncol 2014;25:808). This study evaluated 2 steroid-based mouth rinses for the prevention or amelioration of oral stomatitis in pts with MBC treated with EVE. Methods: This prospective randomized phase II study enrolled postmenopausal pts (planned accrual=100) with HR+ MBC within the US Oncology Network who were initiating therapy with an aromatase inhibitor plus EVE (10 mg/day)(AIE). Pts were randomized 1:1 to prophylactic therapy with 1 of 2 oral rinses (ARM 1: MMW 480 ml recipe: 320 mL oral Benadryl, 2 g Tetracycline, 80 mg Hydrocortisone, 40 mL Nystatin suspension, water; or ARM 2: Prednisolone (P) 15mg/5mL oral solution, 1.8% alcohol). Pts were instructed to swish/expectorate 10 ml of the assigned rinse 4x daily starting with D1 of EVE treatment, for a total of 12 wks. The primary objective was to determine the incidence of G≥2 stomatitis or related oral AEs during the first 12 wks of treatment. Based on a historical estimate that ≥37% of pts receiving AIE develop G≥2 stomatitis, 50 pts for each arm were required to detect a reduction of the incidence of G≥2 stomatitis from 37% to <20%, with alpha = 0.05, 80% power, and a 1-sided test. Secondary objectives included assessment of AEs (all grades), determination of the percentage of pts requiring dose interruption/reduction of EVE or discontinuation of therapy due to toxicity, and evaluation of the impact of the oral rinses on the duration and severity of stomatitis. Results: As of 5/30/2016, a total of 104 pts have been randomized and 100 pts have received treatment (49 MMW; 51 P). Median age was 61 yrs (range 31-82 yrs). The incidence of stomatitis and related oral AEs (any grade) during the first 12 wks was 29% (n=14/49) and 27.5% (14/51) in the MMW and P arms respectively. The incidence of G2 oral AEs was 12% (6/49) and 8% (4/51) with MMW and P respectively. There was only 1 G3 oral AE (MMW arm), and no G4 events. There was 1 EVE dose reduction (MMW) and 4 EVE dose delays (3 MMW, 1 P) during the first 12 wks of treatment. No pts stopped the steroid mouth rinse therapy due to mouth rinse-related toxicity. Conclusion: These prospective data provide evidence of a reduced incidence of mTOR-associated oral AEs with prophylactic use of a steroid mouth rinse. The 29%/27.5% incidence of all-grade and 12%/8% incidence of G2 oral AEs, with only 1 G3 event, compare favorably with the 67% and 24%/8% incidence of all-grade and G2/3 stomatitis, respectively, in BOLERO-2. These data also show the safety and tolerability of these 2 steroid mouth rinses. Prophylactic use of steroid mouth rinses substantially decreases the incidence of G2/3 stomatitis and the need for EVE dose modifications.

Citation Format: Jones VE, McIntyre KJ, Paul D, Wilks ST, Ondreyco SM, Sedlacek SM, Melnyk Jr. AM, Oommen SP, Wang Y, O'Shaughnessy JA. Evaluation of miracle mouthwash (MMW) plus hydrocortisone or prednisolone mouth rinses as prophylaxis for everolimus-associated stomatitis: Results of a randomized phase II study [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P4-16-01.

Effect of single-dose carbapenem exposure on transcriptional expression of blaNDM-1 and mexA in Pseudomonas aeruginosa

The therapeutic option of a carbapenem antibiotic is compromised in Pseudomonas aeruginosa owing both to acquired and intrinsic resistance mechanisms. In recent years, New Delhi metallo-β-lactamase has been the focus as a predominant carbapenem resistance determinant. However, it is unclear which of the mechanisms might be adopted by a P. aeruginosa strain possessing both bla_NDM-1 and an overexpressed MexAB-OprM system during carbapenem therapy. This study investigated the interplay of both mechanisms in clinical isolates of P. aeruginosa when exposed to meropenem. Five strains were used: (i) strain overexpressing MexAB-OprM but with no bla_NDM-1; (ii) strain harbouring bla_NDM-1 but expressing MexAB-OprM at basal level; (iii) strain possessing bla_NDM-1 and overexpressing MexAB-OprM; (iv) P. aeruginosa PAO1; and (v) P. aeruginosa K2733-PAO1 (ΔMexAB-OprMΔMexCD-OprJΔMexEF-OprNΔMexXY-OprM) into which bla_NDM-1 was cloned. Strains were incubated in Luria-Bertani broth with and without 1μg/mL meropenem. Total RNA was isolated at 45-min intervals and was immediately reverse transcribed to cDNA. This was repeated for 6h. Quantitative real-time PCR was performed for both resistance mechanisms. Meropenem exposure did not significantly elevate transcription of either the bla_NDM-1 or mexA gene. However, an interesting finding was that upon single-dose exposure to carbapenem, the efflux pump system played a major role in bacterial survival compared with NDM-1. This study gives an insight into the bacterial response to carbapenem antibiotic when two different resistance mechanisms coexist. This type of study would be helpful in designing future antimicrobials.

Metallization and APPJ treatment of bismaleimide

Bismaleimide (BMI) resins are a new breed of thermosetting resins used mainly for high-temperature applications and have major usage in aerospace. Fourier transform infrared (FTIR) studies have shown signatures of imide, C–N–C stretching, maleimide, and N–H stretching. These BMI polymer coatings were deposited on aluminum (Al) and mild steel substrates by sprinkling powers followed by baking. Thermogravimetric analysis and differential scanning calorimetric studies showed the degradation temperature of these polymers around 370°C. Al coatings were deposited on BMI that is previously deposited on Al and mild steel to make a metal–BMI–metal trilayer. These trilayers can solve the problem charging of the aircraft bodies at high altitudes. Atomic force microscopy was done to determine the morphology of the surface. Roughness and thickness measurements of the BMI coatings were carried out by a surface profilometer. Vickers microhardness tests showed an increase in the hardness of the metal–BMI–metal trilayer. FTIR spectrum showed signatures of imides, C–N–C stretching, maleimide, and N–H stretching in BMI. Peak broadening indicates the release of the stress during thermal treatment of the coating. The coating is subject to variable Atmospheric Pressure Plasma Jet (APPJ) conditions, which improves the properties at high temperature. X-ray diffraction studies showed a hint of crystallinity on APPJ treatment.

Occurrence of co-existing bla VIM-2 and bla NDM-1 in clinical isolates of Pseudomonas aeruginosa from India

BACKGROUND

bla VIM-2 harboring Pseudomonas aeruginosa has been reported worldwide and considered as the most prevalent metallo-β-lactamase after NDM which are found horizontally transferable and mostly associated with integron gene cassettes. The present study investigates the genetic background, transmission dynamics as well as stability of bla VIM-2 in clinical isolates of P. aeruginosa harbor bla NDM-1 as well which were collected from October 2012 to September 2013.

METHODS

Two P. aeruginosa strains harboring bla VIM-2 along with bla NDM-1 were isolated from Silchar Medical College and Hospital, India. Genetic environment of these resistance determinants was determined and transferability was checked by transformation and conjugation assay which was further confirmed by Southern hybridization. Replicon typing was performed to determine the incompatibility group of the resistant plasmid and their stability was checked by serial passage method. Antimicrobial susceptibility pattern of the isolates was determined and their clonal relatedness was checked by pulsed field gel electrophoresis.

RESULTS

bla VIM-2 was found to be horizontally transferable through an Inc F type plasmid of approximately 30 kb in size. bla VIM-2 was found to be associated with integron gene cassette and was flanked by two different types of cassette arrays. Both the isolates were co-harboring bla NDM-1 which was carried within Inc N type of plasmid with an approximate 24 kb in size and associated with ISAba125 in their upstream region. Reduced susceptibility rate as well as high MIC range was observed in case of wild strains and transformants carrying bla VIM-2 and bla NDM-1.

CONCLUSIONS

The detection of this co-existence of multiple carbapenem resistance genes in this part of world is worrisome and further investigation is required in order to trace the source and to initiate proper treatment option.

Alanine Aminotransferase and Total Bilirubin Concentration in Preeclampsia and Eclampsia

Eclampsia is an important cause of maternal mortality in developing countries. This cross-sectional comparative study was conducted in the Departments of Clinical Pathology, Bangabandhu Sheikh Mujib Medical University (BSMMU), and Obstetrics and Gynecology, BSMMU, and Dhaka Medical College Hospital, Dhaka, Bangladesh, from March 2012 to February 2013 and was designed to evaluate liver markers to predict preeclampsia. One hundred fifty (150) women with pregnancy of ≥28 weeks, 50 for each normal, preeclampsia and eclampsia group, were enrolled purposively. The protocol was approved by IRB of BSMMU. Consent was taken from each patient. Serum total Bilirubin and ALT were assessed. Data was collected in a questionnaire and analyzed by SPSS-16. Quantitative data were compared by ANOVA or 't' test and qualitative data by chi-square test. P value <0.05 was considered significant. The patients of all groups were similar in age and gravida. The mean±SD serum total bilirubin and ALT were significantly higher in preeclampsia and eclampsia groups than normal pregnancy. However they were similar in preeclampsia and eclampsia group.

Co-Carriage of blaKPC-2 and blaNDM-1 in Clinical Isolates of Pseudomonas aeruginosa Associated with Hospital Infections from India

Global spread of KPC poses to be a serious threat complicating treatment options in hospital settings. The present study investigates the genetic environment of bla_KPC-2 among clinical isolates of Pseudomonas aeruginosa from a tertiary referral hospital of India. The study isolates were collected from different wards and clinics of Silchar Medical College and Hospital, India, from 2012–2013. The presence of bla_KPC was confirmed by genotypic characterization followed by sequencing. Cloning of the bla_KPC-2 gene was performed and the genetic environment of this gene was characterized as well. Transferability of the resistance gene was determined by transformation assay and Southern hybridization. Additionally, restriction mapping was also carried out. Two isolates of P. aeruginosa were found to harbor bla_KPC-2, were resistant towards aminoglycosides, quinolone and β-lactam-β-lactamase inhibitor combination. In both the isolates, the resistance determinant was associated with class 1 integron and horizontally transferable. Both the isolates were co-harboring bla_NDM-1. The first detection of this integron mediated bla_KPC-2 coexisting with bla_NDM-1 in P. aeruginosa from India is worrisome, and further investigation is required to track the gene cassette mediated bla_KPC-2 in terms of infection control and to prevent the spread of this gene in hospitals as well as in the community.

Covariance-based analyses of biological pathways

The use of high-throughput data to study the changing behavior of biological pathways has focused mainly on examining the changes in the means of pathway genes. In this paper, we propose instead to test for changes in the co-regulated and unregulated variability of pathway genes. We assume that the eigenvalues of previously defined pathways capture biologically relevant quantities, and we develop a test for biologically meaningful changes in the eigenvalues between classes. This test reflects important and often ignored aspects of pathway behavior and provides a useful complement to traditional pathway analyses.

Transcriptional Analysis of MexAB-OprM Efflux Pumps System of Pseudomonas aeruginosa and Its Role in Carbapenem Resistance in a Tertiary Referral Hospital in India

Carbapenem resistance presents severe threat to the treatment of multidrug resistant Pseudomonas aeruginosa infections. The study was undertaken to investigate the role of efflux pumps in conferring meropenem resistance and effect of single dose exposure of meropenem on transcription level of mexA gene in clinical isolates of P. aeruginosa from a tertiary referral hospital of India. Further, in this investigation an effort was made to assess whether different components of MexAB-OprM operon expresses in the same manner and the extent of contributions of those components in meropenem resistance in its natural host (P. aeruginosa) and in a heterologous host (E. coli). Out of 83 meropenem nonsusceptible isolates, 22 isolates were found to possess efflux pump activity phenotypically. Modified hodge test and multiplex PCR confirmed the absence of carbapenemase genes in those isolates. All of them were of multidrug resistant phenotype and were resistant to all the carbepenem drug tested. MexAB-OprM efflux pump was found to be overexpressed in all the study isolates. It could be observed that single dose exposure meropenem could give rise to trivial increase in transcription of mexA gene. Different constructs of MexAB-OprM (mexR-mexA-mexB-OprM; mexA-mexB-OprM; mexA-mexB) could be expressed in both its natural (P. aeruginosa PAO1) and heterologous host (E. coli JM107) but transcription level of mexA gene varied in both the hosts before and after single dose exposure of meropenem. Different components of the operon failed to enhance meropenem resistance in E. coli JM107 and P. aeruginosa PAO1. This study could prove that MexAB-OprM efflux pump can significantly contribute to meropenem resistance in hospital isolates of P. aeruginosa where an acquired resistant mechanism is absent. Thus, equal importance should be given for diagnosis of intrinsic resistance mechanism so as to minimize treatment failure. As meropenem could not enhance mexA transcriptions significantly, there might be a possibility that the increase in expression of efflux pump genes does not mediated by single antibiotic but rather by a combination of antipseudomonal drugs which are used during treatments. Early detection of efflux genes will help in selection of proper therapeutic options.

Correlation of Connective Tissue Growth Factor (CTGF/CCN2) with Hepatic Fibrosis in Chronic Hepatitis B

CTGF/CCN2 plays an important role in the formation and development of hepatic fibrosis. This study determined the correlation between serum CTGF/CCN2 and stages of hepatic fibrosis and explored the clinical value of serum CTGF/CCN2 in the assessment of hepatic fibrosis in chronic hepatitis B. This cross sectional study was done in department of Clinical Pathology, Bangabandhu Sheikh Mujib Medical University, Dhaka from March 2012 to February 2013. Serum CTGF was measured by using of a sandwich immunoassay technique. Forty (40) chronic hepatitis B patients were included in this study. The sensitivity of CTGF/CCN2 was 71.6%, specificity 67.5%. Spearman's rank correlation coefficient was 0.652 between serum CTGF/CCN2 and stages of hepatic fibrosis (p<0.001). The area under receiver-operating curve (ROC) was 0.750 for identification of hepatic fibrosis. This present data revealed that serum CTGF/CCN2 in chronic hepatitis B were strongly associated with stages of hepatic fibrosis. CTGF/CCN2 may useful diagnostic tool for assessing the hepatic fibrosis in chronic hepatitis B.