Liver retransplantation in patients with acquired familial amyloid polyneuropathy: a Portuguese center experience

In 1995 Furtado et al performed the first domino transplantation using a donor liver with familial amyloid polyneuropathy (FAP), thereby increasing the pool of donors. Our experience showed that the onset of FAP symptoms occurs earlier in some patients. Patients with FAP acquired by transplantation are candidates for liver retransplantation to minimize the progression of symptoms. Liver retransplantation is considered to be a high-risk procedure and has lower survival compared with the first transplantation. We evaluated the risk of liver retransplantation in patients with acquired FAP. We did a retrospective analysis of these patients based on the records of perioperative data. From 1995 to 2004 we carried out 81 domino transplantations, of which 10 were submitted to liver retransplantation because of acquired FAP. The better outcomes in this group lead us to think that the liver retransplantation in patients with acquired FAP is not associated with the same risks of liver retransplantation in candidates with graft failure.

Phenotypic and genotypic diversity in a multinational sample of drug-resistant Mycobacterium tuberculosis isolates

OBJECTIVE

To develop and evaluate rapid, molecular-based drug susceptibility testing (DST) for extensively drug-resistant tuberculosis (XDR-TB), we assembled a phenotypically and genotypically diverse collection of Mycobacterium tuberculosis isolates from patients evaluated for drug resistance in four high-burden countries.

METHODS

M. tuberculosis isolates from India (n = 111), Moldova (n = 90), the Philippines (n = 96), and South Africa (n = 103) were selected from existing regional and national repositories to maximize phenotypic diversity for resistance to isoniazid, rifampin (RMP), moxifloxacin, ofloxacin, amikacin, kanamycin, and capreomycin. MGIT™ 960 was performed on viable isolates in one laboratory using standardized procedures and drug concentrations. Genetic diversity within drug resistance phenotypes was assessed.

RESULTS

Nineteen distinct phenotypes were observed among 400 isolates with complete DST results. Diversity was greatest in the Philippines (14 phenotypes), and least in South Africa (9 phenotypes). Nearly all phenotypes included multiple genotypes. All sites provided isolates resistant to injectables but susceptible to fluoroquinolones. Many patients were taking drugs to which their disease was resistant.

DISCUSSION

Diverse phenotypes for XDR-TB-defining drugs, including resistance to fluoroquinolones and/or injectable drugs in RMP-susceptible isolates, indicate that RMP susceptibility does not ensure effectiveness of a standard four-drug regimen. Rapid, low-cost DST assays for first- and second-line drugs are thus needed.

Optimization of protein loaded PLGA nanoparticle manufacturing parameters following a quality-by-design approach

This paper explores the development of a multivariate-based regression model for estimating the critical attributes to establish a design-space for poly(lactic-co-glycolic acid) nanoparticles prepared by a double emulsion–solvent evaporation method.

Evaluation of operative risk in de novo familial amyloid polyneuropathy retransplantation

Familial amyloid polyneuropathy (FAP) is the most common hereditary amyloidosis, characterized by progressive peripheral sensory and motor neuropathy. The livers of patients with FAP are used in domino liver transplantation in selected cases to increase the number of grafts available. In our department 10 patients underwent liver retransplantation (ReLTx) in the absence of liver dysfunction by de novo FAP after domino liver transplantation. Our aim was to compare the differences in the consumption of blood products and intraoperative hemodynamic support among patients with FAP undergoing liver transplantation (LTx) and patients with de novo FAP undergoing ReLTx in the same time frame. The anesthetic records of all patients who underwent LTx for FAP and ReLTx for de novo FAP were analyzed, from January 2009 to May 2014. Patients were divided into 2 groups: group 1 patients with FAP, and group 2 patients with de novo FAP. Statistical differences in the value of preoperative creatinine were found. Hemoglobin levels, preoperative international normalized ratio (INR), use of blood products, aminergic support, and surgical time showed no statistical difference. Major bleeding rates would be expected in patients undergoing ReLTx. Changes in renal function, chronic immunosuppressive therapy, and age may contribute to the increase in intraoperative complications. We did not find statistically significant differences, leading us to the conclusion that de novo FAP does not seem to be a predictor of perioperative risk.

Dual-tubed multiplex-PCR for molecular characterization of carbapenemases isolated among Acinetobacter spp. and Pseudomonas spp

AIM

To molecularly characterize clinical isolates of Acinetobacter spp. and Pseudomonas spp. from various clinical samples so as to identify the carbapenemases mechanisms harboured by them.

MATERIALS AND RESULTS

A total of 95 carbapenem-resistant, nonduplicate, multi-drug resistant Gram-negative clinical isolates (53 Acinetobacter spp. and 42 Pseudomonas spp.), were collected between July and December 2012. Modified Hodge test (MHT) for the detection of carbapenemases was performed. Inhibitor-based test, EDTA for the detection of metallo-β-lactamases (MBL) and phenyl boronic acid (PBA) for the detection of Klebsiella pneumoniae carbapenemase (KPC), were performed to distinguish between different classes of β-lactamases. Two-tubed multiplex-PCR was performed for genotypic characterization of different classes of carbapenemases ((blaNDM-1 , blaOXA-48 like , blaKPC , blaVIM , blaIMP ), (blaOXA-23 like , blaOXA-24 like , blaOXA-51 like , blaOXA-58 like )). Eighty-five per cent (81/95) isolates were carbapenemase producers. Among these, 56.7% (44) were multiple carbapenemase producers. Furthermore, 48.14% (39) were MBLs, 35.8% (29) were carbapenem hydrolyzing class D β-lactamases (CHDLs), 16% (13) had MBLs as well as CHDLs and 14.7% (14/95) had none of the targeted resistance mechanisms. The overall rate of concordance between phenotypic and genotypic test was 97% and 98% for the detection of carbapenemases and MBL, respectively.

CONCLUSION

This is the first study from Western India which highlights the presence of multiple carbapenemases in nonfermenters Gram-negative bacilli (NFGNB). Co-existence of multiple carbapenemases along with other resistance mechanisms might result in treatment failure. Molecular characterization of the resistance mechanisms of suspected pathogens would help provide appropriate antimicrobial treatment for good clinical outcome.

SIGNIFICANCE AND IMPACT OF THE STUDY

Dual-tubed multiplex PCR decreases the time of amplification and thus the turnaround time which is crucial in clinical microbiology; this would be helpful in rapid characterization of CHDLs and MBLs.

Survey of tuberculosis drug resistance among Tibetan refugees in India

SETTING

Tuberculosis (TB) is a major health problem among Tibetans living in exile in India. Although drug-resistant TB is considered common in clinical practice, precise data are lacking.

OBJECTIVE

To determine the proportion of drug-resistant cases among new and previously treated Tibetan TB patients.

DESIGN

In a drug resistance survey in five Tibetan settlements in India, culture and drug susceptibility testing (DST) for first-line drugs were performed among all consecutive new and previously treated TB cases from April 2010 to September 2011. DST against kanamycin (KM), ethionamide, para-aminosalicylic acid and ofloxacin (OFX) was performed on multidrug-resistant TB (MDR-TB) isolates.

RESULTS

Of 307 patients enrolled in the study, 264 (193 new and 71 previously treated) were culture-positive and had DST available. All patients tested for the human immunodeficiency virus (n = 250) were negative. Among new TB cases, 14.5% had MDR-TB and 5.7% were isoniazid (INH) monoresistant. Among previously treated cases, 31.4% had MDR-TB and 12.7% were INH-monoresistant. Of the MDR-TB isolates, 28.6% of new and 26.1% of previously treated cases were OFX-resistant, while 7.1% of new cases and 8.7% of previously treated cases were KM-resistant. Three patients had extensively drug-resistant TB.

CONCLUSIONS

MDR-TB is common in new and previously treated Tibetans in India, who also show additional complex resistance patterns. Of particular concern is the high percentage of MDR-TB strains resistant to OFX, KM or both.

Prognostic significance of novel katG mutations in Mycobacterium tuberculosis

BACKGROUND

By using whole genome sequencing (WGS), researchers are beginning to understand the genetic diversity of Mycobacterium tuberculosis (MTB) and its consequences for the diagnosis of multidrug-resistant tuberculosis (MDR-TB) on a genomic scale. The Global Consortium for Drug-resistant TB Diagnostics (GCDD) conducted a genome scale variant analyses of 366 clinical MTB genomes (mostly MDR/XDR [extensively drug resistant]) from four countries in order to inform the development of rapid molecular diagnostics. This project has been extended by performing an evolutionary analysis of isoniazid (INH)-resistant isolates for prognostic purposes.

METHODS

151 (130 INH^R, 21 INH^S) clinical MTB isolates from India (19: 17 INH^R, 2 INH^S), Moldova (48: 42 INH^R, 6 INH^S), the Philippines (26: 20 INH^R, 6 INH^S), and South Africa (58: 51 INH^R, 7 INH^S) were included in this study. INH drug susceptibility was determined by using MGIT 960 and WHO (World Health Organization)-recommended critical concentration of 0.1 mg/L. Isolates were sequenced using PacBio RS WGS platform. A genome-wide variant analysis was conducted using a proprietary pipeline (PacDAP) developed at San Diego State University. To infer the amino acid changes in katG that confer resistance, PAML was utilized to detect sites in silico that are under positive selection. The dN/dS method was used in combination with Bayes empirical Bayes to determine sites under positive selection and Chi-Squared analysis to determine the significance of the selected sites.

RESULTS

PacDAP variant analysis revealed 22 novel catalase-peroxidase (katG product) mutations. Of these, 14 were single nucleotide polymorphisms, while 8 novel mutations appeared in combination with katG S315T and/or with inhA promoter C-15T. These SNPs have not been previously reported. Additionally, 11 previously observed, but uncommon, katG mutations were also observed in these clinical isolates. These results suggest that 17 amino acids in the enzyme are under positive selective pressure; most significantly in South Africa and the Philippines. No selective pressure on codons other than 315 was observed in isolates from Moldova. Due to the low number of isolates from India, the significance of the sites under positive selection was low and no prediction for India could be made based on this study.

CONCLUSIONS

Eleven of the 14 SNPs are resistance conferring, and it is believed that the remaining 8 combinatorial mutations are either compensatory in nature or, in combination with known SNPs, could increase resistance levels. Positive selection results indicate a diversifying evolutionary path to resistance more in line with long tail statistics and therefore indicate a departure from the traditional point mutation (or "hotspot") model that current molecular diagnostics are based on. Positive selection pressures indicate a future with elevated diagnostic and prognostic significance of the "long tail" (i.e., alternative mechanisms of resistance) and potentially diminishing significance of the canonical mutations (especially in South Africa and the Philippines), which could have significant future implications on narrowly targeting molecular diagnostics.

Second-line drug susceptibility breakpoints for Mycobacterium tuberculosis using the MODS assay

OBJECTIVE

To establish breakpoint concentrations for the fluoroquinolones (moxifloxacin [MFX] and ofloxacin [OFX]) and injectable second-line drugs (amikacin [AMK], kanamycin [KM] and capreomycin [CPM]) using the microscopic observation drug susceptibility (MODS) assay.

SETTING

A multinational study conducted between February 2011 and August 2012 in Peru, India, Moldova and South Africa.

DESIGN

In the first phase, breakpoints for the fluoroquinolones and injectable second-line drugs (n = 58) were determined. In the second phase, MODS second-line drug susceptibility testing (DST) as an indirect test was compared to MGIT™ DST (n = 89). In the third (n = 30) and fourth (n = 156) phases, we determined the reproducibility and concordance of MODS second-line DST directly from sputum.

RESULTS

Breakpoints for MFX (0.5 μg/ml), OFX (1 μg/ml), AMK (2 μg/ml), KM (5 μg/ml) and CPM (2.5 μg/ml) were determined. In all phases, MODS results were highly concordant with MGIT DST. The few discrepancies suggest that the MODS breakpoint concentrations for some drugs may be too low.

CONCLUSION

MODS second-line DST yielded comparable results to MGIT second-line DST, and is thus a promising alternative. Further studies are needed to confirm the accuracy of the drug breakpoints and the reliability of MODS second-line DST as a direct test.

Molecular characterization of carbapenem-resistant Enterobacteriaceae at a tertiary care laboratory in Mumbai

Carbapenem-hydrolyzing β-lactamases are increasingly reported worldwide, leading to therapeutic failure. In an era where the drug development pipeline is stagnant, it is crucial to preserve current classes of antibiotics to help fight against infection caused by multidrug-resistant organisms (MDROs), by practicing a rational approach for the use of antibiotics. Identifying the mechanisms of resistance gives us much needed insights in this field. A total of 113 consecutive, non-duplicate carbapenem-resistant clinical isolates were collected from July to December 2012. These isolates were subjected to the modified Hodge test (MHT) for phenotypic detection of carbapenemases, an inhibitor-based test employing EDTA for the detection of metallo-β-lactamase (MBL), and phenylboronic acid for the detection of Klebsiella pneumoniae carbapenemase (KPC). A multiplex polymerase chain reaction (PCR) assay that characterized the five most predominant carbapenemases (bla NDM, bla OXA, bla VIM, bla IMP, bla KPC) was designed. The 113 isolates consisted of Klebsiella spp. (46), Enterobacter spp. (32), Escherichia coli (31), Citrobacter spp. (2), Proteus spp. (1), and Morganella spp. (1). bla NDM-1 was the most prevalent carbapenemase and accounted for 75.22 % (85/113) of the isolates. This was followed by bla OXA [4.42 % (n = 5)]. 18.5 % (21/113) of the isolates possessed dual carbapenemase genes. 98.9 % concordance was observed between the phenotypic tests and the molecular tests for the detection of MBL. In conclusion, patients infected with resistant bacteria require early appropriate antimicrobial treatment for good clinical outcome. Thus, identifying the resistant mechanisms of suspected pathogens becomes crucial. Also, the high incidence of plasmid-mediated bla NDM-1 calls for the implementation of strict infection control and contact isolation precautions in order to prevent the spread of these organisms.

[Endobronchial ultrasound-guided transbronchial needle aspiration for lung cancer diagnosis and staging in 179 patients]

BACKGROUND

Linear endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is an important minimally invasive procedure for non-small cell lung cancer (NSCLC) staging. It is also a valid method for diagnosing extraluminal lesions adjacent to the tracheobronchial tree.

AIM

To evaluate our EBUS-TBNA performance regarding diagnostic yield, safety and learning curve for lung cancer diagnosis and staging.

MATERIAL AND METHODS

All patients undergoing EBUS-TBNA for lung cancer diagnosis or staging were included. They were divided into three different groups: paratracheal and parabronchial masses sent for diagnosis (Group 1); peripheral lung lesions with abnormal mediastinal lymph nodes sent for diagnosis and staging (Group 2); NSCLC patients sent for mediastinal staging (Group 3). The learning curve was assessed for yield, accuracy, procedure time, size and number of lesions punctured per patient.

RESULTS

A total of 179 patients were included and 372 lesions were punctured. The overall yield and accuracy were 88% and 92.7%, respectively. In Group 1, EBUS-TBNA was performed in 48 patients and sensitivity was 86.1% and accuracy was 87.5%. For the 87 patients included in Group 2, yield was 86.7%, accuracy was 93.1% and cancer prevalence was 51.7%. The diagnostic yield and accuracy in Group 3 was 95% and 97.7% respectively. EBUS-TBNA practice led to an increase number of sites punctured per patient in a shorter time, without complications.

CONCLUSION

EBUS-TBNA is an effective method for diagnosing and staging lung cancer patients. The procedure is clearly safe. Handling and performance improves with the number of procedures executed.

Can inhA mutation predict ethionamide resistance?

SETTING

A tertiary care centre in Mumbai, India.

OBJECTIVE

To estimate the extent of association between inhA mutant isoniazid (INH) resistant strains and ethionamide (ETH) resistance.

DESIGN

A total of 140 clinical isolates processed for INH and ETH phenotypic drug susceptibility testing, and molecularly processed with the line-probe assay (LPA) Genotype® MTBDRplus, were considered.

RESULTS

Among the 112 phenotypically determined INH-resistant strains, 69 (61.6%) strains were ETH-resistant. An inhA promoter mutation was identified in 24 (21.4%) INH-resistant isolates, 21 (87.5%) of which were ETH-resistant (P < 0.0001).

CONCLUSION

An inhA promoter mutation could be considered as a marker for the determination of ETH resistance in India, where the use of LPA is being expanded.