Exploring azole antifungal drug resistance in Aspergillus fumigatus with special reference to resistance mechanisms

ABSTRACT: 

Aspergillus fumigatus, a ubiquitously distributed opportunistic pathogen, is the global leading cause of aspergillosis. Azole antifungals play an important role in the management of aspergillosis. However, over a decade, azole resistance in A. fumigatus isolates has been increasingly reported with variable prevalence worldwide and it is challenging the effective management of aspergillosis. The high mortality rates observed in patients with invasive aspergillosis caused by azole-resistant A. fumigatus (ARAF) isolates pose serious challenges to the clinical microbiologist for timely identification of resistance and appropriate therapeutic interventions. The majority of ARAF isolates contain alterations in the cyp51A gene; however, there have been increasing reports on non-cyp51A mutations contributing to azole resistant phenotypes. This review highlights the emergence and various mechanisms implicated in the development of azole resistance in A. fumigatus. We further present recent developments related to the environmental route in the emergence of ARAF isolates and discuss the therapeutic options available.

New clonal strain of Candida auris, Delhi, India

A new clonal strain of Candida auris is an emerging etiologic agent of fungemia in Delhi, India. In 12 patients in 2 hospitals, it was resistant to fluconazole and genotypically distinct from isolates from South Korea and Japan, as revealed by M13 and amplified fragment length polymorphism typing.

Growth inhibitory and adjuvant therapeutic potential of aqueous extract of Triticum aestivum on MCF-7 and HeLa cells

AIM

The purpose of the present study is to evaluate the potent growth inhibitory effects of aqueous wheatgrass extract (AWE) alone and in combination with cisplatin on human breast and cervical cancer cells.

MATERIALS AND METHODS

The cytotoxic potential of AWE alone and in combination with cisplatin was evaluated on human breast and cervical cancer cells (MCF-7 and HeLa) by cell viability assay. Further, the mode of cell death induced by AWE was determined by nuclear morphological examination and cell cycle analysis. These effects were then correlated with the expression of genes involved in apoptosis and proliferation (cyclin D1 and Bax) by RT-PCR.

RESULTS

AWE showed dose- and time dependent selective cytotoxicity towards the cancer highlighting its safe profile. Lower dose combinations of AWE and cisplatin induced increased growth inhibition compared with the individual drugs on both cell lines (combination index < 1) indicating strong synergistic interactions. AWE was found to induce apoptosis and arrested the cells at G0-G1 phase of the cell cycle which correlated with the modulation of expression of bax and cyclin D1 in a time-dependent manner in MCF-7 and HeLa cells.

CONCLUSION

These results suggest that the anti-cancer potential of AWE may be due to apoptosis induction and its anti-proliferative properties. This study also provides the first evidence demonstrating synergism between AWE and cisplatin, which may enhance the therapeutic index of prevention and/or treatment of human breast and cervical cancer.

Multidrug-resistant endemic clonal strain of Candida auris in India

Candida auris is a recently described rare agent of fungemia. It is notable for its antifungal resistance. A total of 15 C. auris isolates, originating from seven cases of fungemia, three cases of diabetic gangrenous foot, and one case of bronchopneumonia from a tertiary care hospital in south India, were investigated. All of the 15 isolates were identified by sequencing and 14 of these along with 12 C. auris isolates previously reported from two hospitals in Delhi, north India, two each from Japan and Korea were genotyped by amplified fragment length polymorphism (AFLP). In vitro antifungal susceptibility testing (AFST) was done by the Clinical and Laboratory Standards Institute (CLSI) broth microdilution method. Candida auris isolates were misidentified as Candida haemulonii by VITEK. All were resistant to fluconazole [geometric mean minimum inhibitory concentration (MIC) 64 μg/ml] and 11 isolates were resistant to voriconazole (MIC ≥1 μg/ml). Forty-seven percent of the C. auris isolates were resistant to flucytosine (MIC ≥64 μg/ml) and 40% had high MIC (≥1 μg/ml) of caspofungin. Breakthrough fungemia developed in 28.6% of patients and therapeutic failure in 4 (66.7%) patients. Interestingly, the 26 Indian C. auris isolates from north and south India were clonal and phenotypically and genotypically distinct from Korean and Japanese isolates. The present study demonstrates that C. auris is a potential emerging pathogen that can cause a wide spectrum of human mycotic infections. The prevalence of a C. auris endemic clonal strain resistant to azoles and other antifungals in Indian hospitals with high rates of therapeutic failure in cases of fungemia is worrisome.

Impacts of increasing ozone on Indian plants

Increasing anthropogenic and biogenic emissions of precursor compounds have led to high tropospheric ozone concentrations in India particularly in Indo-Gangetic Plains, which is the most fertile and cultivated area of this rapidly developing country. Current ozone risk models, based on European and North American data, provide inaccurate estimations for crop losses in India. During the past decade, several ozone experiments have been conducted with the most important Indian crop species (e.g. wheat, rice, mustard, mung bean). Experimental work started in natural field conditions around Varanasi area in early 2000's, and the use of open top chambers and EDU (ethylene diurea) applications has now facilitated more advanced studies e.g. for intra-species sensitivity screening and mechanisms of tolerance. In this review, we identify and discuss the most important gaps of knowledge and future needs of action, e.g. more systematic nationwide monitoring for precursor and ozone formation over Indian region.

Clonal expansion and emergence of environmental multiple-triazole-resistant Aspergillus fumigatus strains carrying the TR₃₄/L98H mutations in the cyp51A gene in India

Azole resistance is an emerging problem in Aspergillus which impacts the management of aspergillosis. Here in we report the emergence and clonal spread of resistance to triazoles in environmental Aspergillus fumigatus isolates in India. A total of 44 (7%) A. fumigatus isolates from 24 environmental samples were found to be triazole resistant. The isolation rate of resistant A. fumigatus was highest (33%) from soil of tea gardens followed by soil from flower pots of the hospital garden (20%), soil beneath cotton trees (20%), rice paddy fields (12.3%), air samples of hospital wards (7.6%) and from soil admixed with bird droppings (3.8%). These strains showed cross-resistance to voriconazole, posaconazole, itraconazole and to six triazole fungicides used extensively in agriculture. Our analyses identified that all triazole-resistant strains from India shared the same TR₃₄/L98H mutation in the cyp51 gene. In contrast to the genetic uniformity of azole-resistant strains the azole-susceptible isolates from patients and environments in India were genetically very diverse. All nine loci were highly polymorphic in populations of azole-susceptible isolates from both clinical and environmental samples. Furthermore, all Indian environmental and clinical azole resistant isolates shared the same multilocus microsatellite genotype not found in any other analyzed samples, either from within India or from the Netherlands, France, Germany or China. Our population genetic analyses suggest that the Indian azole-resistant A. fumigatus genotype was likely an extremely adaptive recombinant progeny derived from a cross between an azole-resistant strain migrated from outside of India and a native azole-susceptible strain from within India, followed by mutation and then rapid dispersal through many parts of India. Our results are consistent with the hypothesis that exposure of A. fumigatus to azole fungicides in the environment causes cross-resistance to medical triazoles. The study emphasises the need of continued surveillance of resistance in environmental and clinical A. fumigatus strains.

Cardioprotective effect of lycopene against isoproterenol-induced myocardial infarction in rats

The present study was designed to evaluate the cardioprotective potential of lycopene (LCP) against isoproterenol (ISP)-induced myocardial infarction (MI), by assessing hemodynamic, biochemical and histopathological parameters. Wistar male albino rats were orally administered with LCP (0.5, 1.0 and 1.5 mg/kg) or with vehicle for 30 days, with concurrent subcutaneous injections of ISP (85 mg/kg) on days 28 and 29. ISP significantly (p < 0.05) decreased systolic, diastolic and mean arterial blood pressure (SAP, DAP and MAP, respectively) and heart rate (HR). ISP also decreased contractility (+LVdP/dt), relaxation (-LVdP/dt) and increased left ventricular end-diastolic pressure (LVEDP). In addition to functional impairment, ISP also caused a significant (p < 0.05) decrease in antioxidants, namely, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSHPx), glutathione (GSH), cardiac injury marker enzymes, creatine phosphokinase-MB (CK-MB) and lactate dehydrogenase (LDH), as well as induced lipid peroxidation, malonaldialdehyde (MDA) and histopathological alterations in heart. However, pretreatment with LCP significantly (p < 0.05) attenuated ISP-induced cardiac dysfunction as evidenced by improved SAP, DAP, MAP, HR, (±)LVdP/dt and reduced LVEDP. Pretreatment with LCP also significantly (p < 0.05) prevented the depletion of antioxidants (SOD, CAT, GSHPx and GSH), myocyte injury marker enzymes (CK-MB and LDH) and inhibited lipid peroxidation and MDA formation in the heart. Furthermore, reduced necrosis, edema and infiltration of inflammatory cells on histopathological examination also depicted the protective effect of LCP against the deleterious effect of ISP. Based on the results, it is suggested that LCP possesses significant cardioprotective potential and may serve as an adjunct in treatment and prophylaxis of MI.

Synthesis and Antimicrobial Activity of Some New 2-(3-(4-Aryl)-1-phenyl-1H-pyrazol-4-yl) Chroman-4-ones

Seven new 2-(3-(4-aryl)-1-phenyl-1H-pyrazol-4-yl) chroman-4-ones (4a-4g) have been synthesized by cyclization of 2-hydroxychalcone analogues of pyrazole 3a-3g using conc. HCl in acetic acid. The structures of the compounds 4a-4g were established by the combined use of (1)HNMR, IR and mass spectra. All the seven compounds were tested in vitro for their antibacterial activity against two Gram positive bacteria namely Staphylococcus aureus and Bacillus subtilis and two Gram negative bacteria Escherichia coli and Pseudomonas aeruginosa. The compounds 4b, 4c, 4e, 4f, 4g have displayed good antibacterial activity when compared with commercially available antibiotic, ciprofloxacin. These compounds also were screened for their antifungal activity against two ear pathogenic fungi, namely Aspergillus Niger and A. flavus. The compounds 4a, 4c, 4d, 4g exhibited good antifungal activity when compared with commercially available antifungal, fluconazole.

Chemical characteristics of aerosols and trace gas distribution over North and Central India

A field campaign on aerosol chemical properties and trace gases measurements was carried out along the Delhi-Hyderabad-Delhi road corridor (spanning about 3,200 km) in India, during February 1-29, 2004. Aerosol particles were collected on quartz and cellulose filters using high volume (PM(10)) sampler at various locations along the route (i.e., urban, semi-urban, rural, and forest areas) and have been characterized for major cations (Na(+), Ca(2+), Mg(2+), K(+), and NH (4) (+)), anions (Cl(-), NO (3)(-), and SO (4)(2-)), and heavy metals (Cu, Cd, Fe, Zn, Mn, and Pb). Simultaneously, we measured NO(2) and SO(2) gases. These species show large spatial and temporal variations. The ambient PM(10) concentration has been observed to be the highest (55 ± 4 μg m(-3)) near semi-urban areas followed by forest areas (48 ± 2 μg m(-3)) and in rural areas (44 ± 22 μg m(-3)). The concentrations of NO( x ) (NO(2)+NO) and SO(2) ranged from 16 to 69 μg m(-3) and 4 to 11 μg m(-3), respectively. Among anions, NO(3)(-) and SO(4) (2-) are the major constituents of PM(10). The urban and semi-urban sites showed enhanced concentrations of Fe, Zn, Mn, Cd, and Pb. This study provide information about atmospheric concentrations of various species in the northern to central India, which may be important for policy makers to better understand the air quality of the region.

Abstract P1-03-01: Generation of a Novel In Vivo Model of Patient-Derived Chemoresistant Breast Cancers

Background: Breast cancer patients who have significant residual cancer after neoadjuvant chemotherapy (NCT) are at high risk of relapse. There is a pressing need to identify novel therapeutics that can be offered to these patients. In vivo models available to test new agents are limited. We hypothesized that tumors from patients with poor response to NCT can be transplanted into nude mice to establish xenografts, providing a novel in vivo model to study therapies for chemoresistant tumors. Materials and Methods: After informed consent, excess tumor was taken from the mastectomy specimens from six patients who had either disease progression during NCT or significant residual disease after NCT. On surgical pathologic evaluation, average tumor size was 8.6 ± 3.2 cm (range 4.5-12 cm), and average number of positive lymph nodes was 6.2 ± 6.8 (range 0-18). Patients had RECIST criteria of partial response (n=2), stable disease (n= 1) or progressive disease (n=3). For each patient, tumors were implanted subcutaneously into the flanks of five nude mice. Tumors were passaged to successive generations when they reached 1.5 cm in diameter. In vivo tumor growth and the ability to serially passage tumors were assessed. Patient and tumor characteristics, and patient outcomes were evaluated.

Results: Three patients had ER+HER2- tumors and three had ER-HER2- tumors. Serially transplanted xenografts were established from all six patients (100%); see Figure 1. Within each group of five mice implanted with the human tumors, 60 ± 26% developed tumor. Time to tumor size of 1.5 cm diameter was 4.2 ± 2.6 months (range 1.5-7.8 months). Two mice also developed tumors at a location distant from the implantation site (Met). These tumors were separately engrafted, also with 100% take, reaching 1.5 cm diameter at 1.5 and 1.7 months. Of the six patients, one had metastatic disease at surgery and underwent palliative mastectomy. Of the other five patients, four (80%) developed metastatic disease 4-8.4 months after surgery. Mice developed passagable tumors at least 2 months before the donor patients developed distant recurrence. The one patient who remains distant disease-free had the longest time to tumor passage (8.4 months).

Figure 1. Time to passage of tumor to next generation of mice. Flank tumors xenografts were derived from patients with chemoresistant breast cancers. When tumors reach 1.5 cm in diameter, they are passaged to the next generation of 5 mice. X-axis depicts time to reach 1.5 cm with each passage.

Discussion: Patients with progression or significant residual disease after NCT are at very high risk of distant relapse. Their chemoresistant tumors can be used to create serially transplantable xenografts. This in vivo model of chemoresistant breast cancer may be utilized to allow individualization of additional adjuvant or metastatic breast cancer treatment.

Molecular variants of HPV-16 associated with cervical cancer in Indian population

Human papilloma virus is a causative factor in the etiology of cervical cancer with HPV16 being the most prevalent genotype associated with it. Intratype variations in oncogenic E6/E7 and capsid L1 proteins of HPV 16 besides being of phylogenetic importance, are associated with risk of viral persistence and progression. The objective of this multicentric study was to identify HPV-16 E6, E7 and L1 variants prevalent in India and their possible biological effects. Squamous cell cervical cancer biopsies were collected from 6 centres in India and examined for the presence of HPV 16. Variants of HPV-16 were characterized by full length sequence analysis of L1, E6 and E7 genes in 412 samples. Similar distribution of the variants was seen from the different centres/regions, with the European variant E350G being the most prevalent (58%), followed by American Asian variant (11.4%). Fifty six changes were seen in E6 region, 31 being nonsynonymous. The most frequent being L83V (72.3%), Q14H (13.1%) and H78Y (12.1%). Twenty-nine alterations were seen in E7 region, with 12 being nonsynonymous. The most frequent being F57V (9%). L1 region showed 204 changes, of which 67 were nonsynonymous. The most frequent being 448insS (100%), and 465delD (100%), H228D (94%), T292A (85%). The identified variants some new and some already reported can disrupt pentamer formation, transcriptional regulation of the virus, L1 protein interface interaction, B and T cell epitopes, p53 degradation, and thus their distribution is important for development of HPV diagnostics, vaccine, and for therapeutic purpose.

Development of methane emission factors for Indian paddy fields and estimation of national methane budget

A state-wise assessment of methane (CH(4)) budget for Indian paddies, based on a decadal measurement data across India is presented for the calendar year (CY) 1994, the base year for India's Initial National Communication (NATCOM) to the United Nations Framework Convention on Climate Change (UNFCCC), along with national trend from CY 1979 to 2006. The NATCOM CH(4) emission factors (EFs) for Indian paddy cultivation areas, generally having less than 0.7% of soil organic carbon (SOC), have been estimated as 17.48+/-4 g m(-2) for irrigated continuously flooded (IR-CF), 6.95+/-1.86 g m(-2) for rain-fed drought prone (RF-DP), 19+/-6 g m(-2) for rain-fed flood prone (RF-FP) and deep-water (DW), 6.62+/-1.89 g m(-2) for irrigated intermittently flooded single aeration (IR-IF-SA) and 2.01+/-1.49 g m(-2) for IR-IF multiple aeration (MA) paddy water regimes. The state-wise study for 1994 has indicated national CH(4) budget estimate of 4.09+/-1.19 Tg y(-1) and the trend from 1979 to 2006 was in the range of 3.62+/-1 to 4.09+/-1.19 Tg y(-1). Four higher emitting or "hot spot" states (West Bengal, Bihar, Madhya Pradesh and Uttar Pradesh) have accounted for 53.9% of total CH(4) emission with RF-FP paddy water regime as the major contributor. CH(4) emissions were enhanced by factors such as SOC ( approximately 1.5 times due to increase in SOC by approximately 1.8 times), paddy cultivars (approximately 1.5 times), age of seedlings (approximately 1.4 times), and seasons (approximately 1.8 times in Kharif or monsoon than in Rabi or winter season).

Right lung agenesis

Congenital pulmonary agenesis or aplasia is extremely rare. Although more than fifty percent of patients die before first five years of age, some individuals may remain asymptomatic throughout their life. A three-month-old female child with right pulmonary agenesis presented to us with severe respiratory distress. She was misdiagnosed as a case of foreign body bronchus at the peripheral health centre. Bronchoscopy confirmed the diagnosis and relieved the symptoms. It is recommended that invasive diagnostic procedures and prophylactic surgery should not be done in asymptomatic cases.

Greenhouse gas emissions from municipal solid waste management in Indian mega-cities: a case study of Chennai landfill sites

Municipal solid waste generation rate is over-riding the population growth rate in all mega-cities in India. Greenhouse gas emission inventory from landfills of Chennai has been generated by measuring the site specific emission factors in conjunction with relevant activity data as well as using the IPCC methodologies for CH4 inventory preparation. In Chennai, emission flux ranged from 1.0 to 23.5mg CH4m(-2)h(-1), 6 to 460microg N2Om(-2)h(-1) and 39 to 906mg CO2m(2)h(-1) at Kodungaiyur and 0.9 to 433mg CH4m(-2)h(-1), 2.7 to 1200microg N2Om(-2)h(-1) and 12.3 to 964.4mg CO2m(-2)h(-1) at Perungudi. CH4 emission estimates were found to be about 0.12Gg in Chennai from municipal solid waste management for the year 2000 which is lower than the value computed using IPCC, 1996 [IPCC, 1996. Report of the 12th session of the intergovernmental panel of climate change, Mexico City, 1996] methodologies.

Trends of greenhouse gas emissions from the road transport sector in India

The road transport sector is the largest consumer of commercial fuel energy within the transportation system in India and accounts for nearly 35% of the total liquid commercial fuel consumption by all sectors. Gasoline and diesel consumption for road transportation have quadrupled between 1980 and 2000 due to about nine times increase in the number of vehicles and four-fold increase in freight and passenger travel demands. The paper elaborates the trends of energy consumption and consequent emissions of greenhouse gases such as CO(2), CH(4) and N(2)O and ozone precursor gases like CO, NO(x) and NMVOC in the road transport sector in India for the period from 1980 to 2000. For the first time, efforts have been made to apportion the fuels, both diesel and gasoline, across different categories of vehicles operating on the Indian roads. In order to generate more comprehensive and complete emission estimates, additionally, other minor fuel types like light diesel oil and fuel oil along with lubricants have also been taken into account. Emission estimates have revealed that nearly 27 Mt of CO(2) were emitted in 1980, increasing to about 105 Mt in 2000. Similar trends have also been observed for other gases. Further scope for improvements in emission estimation is possible by generating country specific emission factors for different vehicle categories and improvement in documentation of fuel consumption at segregated levels by fuel types and vehicle types.