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T. Kowshik - One of the best experts on this subject based on the ideXlab platform.
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seasonal variations in the prevalence of cryptococcus neoformans var grubii and cryptococcus gattii in Decayed Wood inside trunk hollows of diverse tree species in north western india a retrospective study
Medical Mycology, 2011Co-Authors: H S Randhawa, T. Kowshik, Anuradha Chowdhary, Anupam Prakash, Z U KhanAbstract:This study presents a 7-year retrospective analysis of seasonal variations in the prevalence of Cryptococcus neoformans var. grubii and Cryptococcus gattii in Decayed Wood inside trunk hollows of 518 trees belonging to 20 species in north-western India during 2000-2007. Of the 1,439 Wood samples investigated, 406 (28.2%) were found to be positive for the Cryptococcus neoformans species complex which included 247 samples from which C. neoformans var. grubii was recovered and 171 which yielded C. gattii. While both of the pathogens were isolated through all the seasons, the overall prevalence of C. neoformans var. grubii was significantly higher (17.2%) than that of C. gattii serotype B (11.9%, P < 0.0001), indicating that Decayed Wood was as good, if not better, a natural habitat of C. neoformans var. grubii as that of C. gattii. The highest recovery of both yeasts was in the autumn, followed by that in the summer. For C. gattii, the lowest prevalence occurred during the winter and for C. neoformans var. grubii during the rainy season. The low prevalence of C. gattii during winter is similar to that reported from Bogota, Colombia, where C. gattii had a low population density in bark samples but it was not found in Decayed Wood of trunk hollows investigated during the period of January and February. The prevalence of C. neoformans var. grubii was significantly lower in the rainy season than in the other portions of the year. This finding is similar to the reported low isolation frequency (4%) of C. neoformans var. grubii from chicken feces in the rainy season in northern Thailand. Further investigations are warranted to determine the clinical significance of seasonal variations in the prevalence of C. neoformans var. grubii and C. gattii in Decayed trunk Wood of various trees in climatically divergent regions of India.
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the expanding host tree species spectrum of cryptococcus gattii and cryptococcus neoformans and their isolations from surrounding soil in india
Medical Mycology, 2008Co-Authors: H S Randhawa, T. Kowshik, Anuradha Chowdhary, Z U Khan, Preeti K Sinha, Jianping XuAbstract:This study reports the widespread prevalence of Cryptococcus neoformans and Cryptococcus gattii in Decayed Wood inside trunk hollows of 14 species representing 12 families of trees and from soil near the base of various host trees from Delhi and several places in the Indian states of Uttar Pradesh, Haryana, Tamil Nadu and Chandigarh Union Territory. Of the 311 trees from which samples were obtained, 64 (20.5%) were found to contain strains of the C. neoformans species complex. The number of trees positive for C. neoformans var grubii (serotypeA) was 51 (16.3%), for C. gattii (serotype B) 24 (7.7%) and for both C. neoformans and C. gattii 11 (3.5%). The overall prevalence of C. neoformans species complex in Decayed Wood samples was 19.9% (111/556). There was no obvious correlation between the prevalence of these two yeast species and the species of host trees. The data on prevalence of C. gattii (24%) and C. neoformans (26%) in soil around the base of some host trees indicated that soil is another important ecologic niche for these two Cryptococcus species in India. Among our sampled tree species, eight and six were recorded for the first time as hosts for C. neoformans var grubii and C. gattii, respectively. A longitudinal surveillance of 8 host tree species over 0.7 to 2.5 years indicated long term colonization of Polyalthia longifolia, Mimusops elengi and Manilkara hexandra trees by C. gattii and/or C. neoformans. The mating type was determined for 153 of the isolates, including 98 strains of serotype A and 55 of serotype B and all proved to be mating type a (MAT a). Our observations document the rapidly expanding spectrum of host tree species for C. gattii and C. neoformans and indicate that Decayed Woods of many tree species are potentially suitable ecological niches for both pathogens.
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antifungal susceptibility of cryptococcus neoformans and cryptococcus gattii isolates from Decayed Wood of trunk hollows of ficus religiosa and syzygium cumini trees in north western india
Journal of Antimicrobial Chemotherapy, 2007Co-Authors: Zia U Khan, T. Kowshik, Anuradha Chowdhary, H S Randhawa, Rachel ChandyAbstract:Background: We present antifungal susceptibility data on environmental Isolates of Cryptococcus neoformans (serotype A, n = 117) and Cryptococcus gattii (serotype B, n = 65) cultured from Decayed Wood of trunk hollows of Ficus religiosa and Syzygium cumini trees. Methods: Susceptibilities to amphotericin B, fluconazole, ketoconazole, itraconazole and voriconazole were determined by using Etest. The MICs were read after 48 h as per the guidelines provided by the manufacturer. Results: The MIC 90 S and susceptibility ranges for C. neoformans isolates were as follows: 0.094 (0.004-0.25) mg/L for amphotericin B, 4 (0.032-12) mg/L for fluconazole, 0.094 (0.004-0.75) mg/L for itraconazole, 0.064 (0.002-0.19) mg/L for ketoconazole, and 0.047 (0.006-0.125) mg/L for voriconazole, whereas for C. gattii isolates these were 0.125 (0.023-0.5) mg/L for amphotericin B, 8 (0.032-16) mg/L for fluconazole, 0.75 (0.006-2) mg/L for itraconazole, 0.125 (0.003-0.19) mg/L for ketoconazole, and 0.094 (0.004-0.125) mg/L for voriconazole. A comparison of the geometric means of MICs (mg/L) revealed that C. gattii was less susceptible than C. neoformans to amphotericin B (0.075 versus 0.051, P = 0.0003), fluconazole (2.912 versus 2.316, P = 0.003), itraconazole (0.198 versus 0.0344, P< 0.0001), ketoconazole (0.072 versus 0.037, P< 0.0001), and voriconazole (0.045 versus 0.023, P< 0.0001). Conclusions: The antifungal susceptibility data obtained in this study indicate that the occurrence of primary resistance among environmental isolates of C. neoformans serotype A and C. gattii serotype B Is rare, and serotype B isolates are less susceptible than serotype A isolates.
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Distribution of Cryptococcus gattii and Cryptococcus neoformans in Decayed trunk Wood of Syzygium cumini trees in north-western India
Medical mycology, 2006Co-Authors: Harbans S. Randhawa, T. Kowshik, K. Preeti Sinha, Anuradha Chowdhary, Ziauddin Khan, Zhun Yan, Amit KumarAbstract:The aim of this study is to report the regional distribution of Cryptococcus. gattii and Cryptococcus. neoformans in Decayed Wood inside trunk hollows of Syzygium cumini trees (Java plum, Indian black berry) investigated in Amritsar (Panjab), Meerut Cantt. and Bulandshahr (Uttar Pradesh) and Delhi, in north-western India. Two hundred and seventeen Wood samples collected from 74 S. cumini trees were investigated. This includes 7 known positive S. cumini trees in Delhi subjected to a mycological surveillance for perennial colonization by C. gattii and C. neoformans. Cryptococcus gattii showed the highest prevalence (89%) in S. cumini trees in Delhi, followed by 27%, 12.5% and 9% prevalence in Bulandshahr, Amritsar City and Meerut Cantt., respectively. In contrast, C. neoformans had the highest prevalence (54%) in Amritsar, followed by 44% in Delhi, 9% in Bulandshahr and 0% in Meerut Cantt. Furthermore, 44% of the S. cumini trees in Delhi, 9% in Bulandshahr and 8% in Amritsar were concomitantly colonized by ...
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efficacy of swabbing versus a conventional technique for isolation of cryptococcus neoformans from Decayed Wood in tree trunk hollows
Medical Mycology, 2005Co-Authors: H S Randhawa, T. Kowshik, Z U KhanAbstract:The efficacy of swabbing versus a conventional sedimentation technique was evaluated for sampling of Decayed Wood in tree trunk hollows for isolation of Cryptococcus neoformans. Of 52 samples of Decayed Wood, bark or other plant debris originating from 35 living trees, 42 Wood samples yielded C. neoformans. The positive samples included 40 collected from 31 Syzygium cumini trees growing along roadsides in Old Delhi, whereas the remaining two were from inside tree trunk fissures of Ficus religiosa in a New Delhi locality. The number of Wood samples found positive by swabbing was 40 (95%) as opposed to 32 (76%) by the conventional technique, and this difference was statistically significant (P < 0.01). Also, the conventional technique showed 24% false-negative results, which was in striking contrast to only 5% by swabbing. Furthermore, swabbing yielded a significantly higher C. neoformans mean colony count than did the conventional technique (P < 0.005), thus highlighting greater efficacy of the former technique. The overall prevalence of C. neoformans in the S. cumini trees investigated was 84% (26/31 trees) which is the highest as yet reported from any tree species in India. Varietal identification and serotyping was done with 33 of the C. neoformans isolates, 31 of which came from 23 tree trunk hollows of S. cumini and two from the tree trunk fissures of F. religiosa. Among the S. cumini isolates, 26 were identified as C. neoformans var. gattii (all serotype B except two untypeable ones) and five as C. neoformans var. neoformans, serotype A (= C. neoformans var. grubii). Both of the F. religiosa isolates belonged to C. n. var. neoformans, serotype A. Being a more efficacious, simple, less time-consuming and less hazardous technique, swabbing is recommended for wider use in order to further elucidate the ecology of C. neoformans.
Emil Engelund Thybring - One of the best experts on this subject based on the ideXlab platform.
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water relations in untreated and modified Wood under brown rot and white rot decay
International Biodeterioration & Biodegradation, 2017Co-Authors: Emil Engelund ThybringAbstract:Abstract One key requisite for fungal decay of Wood is water within cell walls. While several reviews have focused on the mechanistic relationship between water and decay of Wood, this study is the first review of water relations of Decayed Wood material. Based on a vast compilation of experimental data from several literature sources, the water relations of untreated and modified Wood Decayed by brown-rot and white-rot fungi are examined. The aim is to investigate to what extent observations and assumptions regarding brown-rot and white-rot decay can explain changes in water relations observed during and after decay. Although the available experimental data for modified Wood is scarce, it indicates that brown-rot and white-rot decay of non-resistant modified Wood occurs by similar degradation mechanisms with similar effects on water relations as for untreated Wood. From simplistic, mathematical modelling, it is shown that changes in water relations during decay can be partly explained by accompanying changes in chemical composition and void volume.
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Wood water interactions in brown rot Decayed Wood characterized by low field nuclear magnetic resonance lfnmr
13th annual meeting of the Northern European Network for Wood Science and Engineering (WSE2017), 2017Co-Authors: Sanne Johansson, Emil Engelund Thybring, Maria Fredriksson, Lisbeth Garbrecht ThygesenAbstract:It is a trivial fact that water is needed for decay of Wood by brown rot fungi, but when this is looked at in more detail, there are several fundamental questions concerning water and decay that are not solved. The purpose of this study is to study how the Wood-water interaction is changed during degradation of brown-rot fungi of Norway spruce (Picea abies (L) Karst.) grown at two different parts of Sweden and if it is changed in a way that facilitates further decay. We use Low-Field Nuclear Magnetic Resonance (LFNMR) equipment to measure on water-saturated samples degraded by the brown-rot fungus Postia placenta and exposed to different moisture conditions. With the LFNMR technique, it is possible to distinguish between water in different physical and chemical environments (pore sizes, water-pore wall interactions) and it is therefore possible to study how Wood-water interactions changes with different degree of degradation. This conference proceeding concerns part of a larger experiment which is not completely evaluated and only results from the NMR-study will be shown here. (Less)
H S Randhawa - One of the best experts on this subject based on the ideXlab platform.
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seasonal variations in the prevalence of cryptococcus neoformans var grubii and cryptococcus gattii in Decayed Wood inside trunk hollows of diverse tree species in north western india a retrospective study
Medical Mycology, 2011Co-Authors: H S Randhawa, T. Kowshik, Anuradha Chowdhary, Anupam Prakash, Z U KhanAbstract:This study presents a 7-year retrospective analysis of seasonal variations in the prevalence of Cryptococcus neoformans var. grubii and Cryptococcus gattii in Decayed Wood inside trunk hollows of 518 trees belonging to 20 species in north-western India during 2000-2007. Of the 1,439 Wood samples investigated, 406 (28.2%) were found to be positive for the Cryptococcus neoformans species complex which included 247 samples from which C. neoformans var. grubii was recovered and 171 which yielded C. gattii. While both of the pathogens were isolated through all the seasons, the overall prevalence of C. neoformans var. grubii was significantly higher (17.2%) than that of C. gattii serotype B (11.9%, P < 0.0001), indicating that Decayed Wood was as good, if not better, a natural habitat of C. neoformans var. grubii as that of C. gattii. The highest recovery of both yeasts was in the autumn, followed by that in the summer. For C. gattii, the lowest prevalence occurred during the winter and for C. neoformans var. grubii during the rainy season. The low prevalence of C. gattii during winter is similar to that reported from Bogota, Colombia, where C. gattii had a low population density in bark samples but it was not found in Decayed Wood of trunk hollows investigated during the period of January and February. The prevalence of C. neoformans var. grubii was significantly lower in the rainy season than in the other portions of the year. This finding is similar to the reported low isolation frequency (4%) of C. neoformans var. grubii from chicken feces in the rainy season in northern Thailand. Further investigations are warranted to determine the clinical significance of seasonal variations in the prevalence of C. neoformans var. grubii and C. gattii in Decayed trunk Wood of various trees in climatically divergent regions of India.
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the expanding host tree species spectrum of cryptococcus gattii and cryptococcus neoformans and their isolations from surrounding soil in india
Medical Mycology, 2008Co-Authors: H S Randhawa, T. Kowshik, Anuradha Chowdhary, Z U Khan, Preeti K Sinha, Jianping XuAbstract:This study reports the widespread prevalence of Cryptococcus neoformans and Cryptococcus gattii in Decayed Wood inside trunk hollows of 14 species representing 12 families of trees and from soil near the base of various host trees from Delhi and several places in the Indian states of Uttar Pradesh, Haryana, Tamil Nadu and Chandigarh Union Territory. Of the 311 trees from which samples were obtained, 64 (20.5%) were found to contain strains of the C. neoformans species complex. The number of trees positive for C. neoformans var grubii (serotypeA) was 51 (16.3%), for C. gattii (serotype B) 24 (7.7%) and for both C. neoformans and C. gattii 11 (3.5%). The overall prevalence of C. neoformans species complex in Decayed Wood samples was 19.9% (111/556). There was no obvious correlation between the prevalence of these two yeast species and the species of host trees. The data on prevalence of C. gattii (24%) and C. neoformans (26%) in soil around the base of some host trees indicated that soil is another important ecologic niche for these two Cryptococcus species in India. Among our sampled tree species, eight and six were recorded for the first time as hosts for C. neoformans var grubii and C. gattii, respectively. A longitudinal surveillance of 8 host tree species over 0.7 to 2.5 years indicated long term colonization of Polyalthia longifolia, Mimusops elengi and Manilkara hexandra trees by C. gattii and/or C. neoformans. The mating type was determined for 153 of the isolates, including 98 strains of serotype A and 55 of serotype B and all proved to be mating type a (MAT a). Our observations document the rapidly expanding spectrum of host tree species for C. gattii and C. neoformans and indicate that Decayed Woods of many tree species are potentially suitable ecological niches for both pathogens.
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antifungal susceptibility of cryptococcus neoformans and cryptococcus gattii isolates from Decayed Wood of trunk hollows of ficus religiosa and syzygium cumini trees in north western india
Journal of Antimicrobial Chemotherapy, 2007Co-Authors: Zia U Khan, T. Kowshik, Anuradha Chowdhary, H S Randhawa, Rachel ChandyAbstract:Background: We present antifungal susceptibility data on environmental Isolates of Cryptococcus neoformans (serotype A, n = 117) and Cryptococcus gattii (serotype B, n = 65) cultured from Decayed Wood of trunk hollows of Ficus religiosa and Syzygium cumini trees. Methods: Susceptibilities to amphotericin B, fluconazole, ketoconazole, itraconazole and voriconazole were determined by using Etest. The MICs were read after 48 h as per the guidelines provided by the manufacturer. Results: The MIC 90 S and susceptibility ranges for C. neoformans isolates were as follows: 0.094 (0.004-0.25) mg/L for amphotericin B, 4 (0.032-12) mg/L for fluconazole, 0.094 (0.004-0.75) mg/L for itraconazole, 0.064 (0.002-0.19) mg/L for ketoconazole, and 0.047 (0.006-0.125) mg/L for voriconazole, whereas for C. gattii isolates these were 0.125 (0.023-0.5) mg/L for amphotericin B, 8 (0.032-16) mg/L for fluconazole, 0.75 (0.006-2) mg/L for itraconazole, 0.125 (0.003-0.19) mg/L for ketoconazole, and 0.094 (0.004-0.125) mg/L for voriconazole. A comparison of the geometric means of MICs (mg/L) revealed that C. gattii was less susceptible than C. neoformans to amphotericin B (0.075 versus 0.051, P = 0.0003), fluconazole (2.912 versus 2.316, P = 0.003), itraconazole (0.198 versus 0.0344, P< 0.0001), ketoconazole (0.072 versus 0.037, P< 0.0001), and voriconazole (0.045 versus 0.023, P< 0.0001). Conclusions: The antifungal susceptibility data obtained in this study indicate that the occurrence of primary resistance among environmental isolates of C. neoformans serotype A and C. gattii serotype B Is rare, and serotype B isolates are less susceptible than serotype A isolates.
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efficacy of swabbing versus a conventional technique for isolation of cryptococcus neoformans from Decayed Wood in tree trunk hollows
Medical Mycology, 2005Co-Authors: H S Randhawa, T. Kowshik, Z U KhanAbstract:The efficacy of swabbing versus a conventional sedimentation technique was evaluated for sampling of Decayed Wood in tree trunk hollows for isolation of Cryptococcus neoformans. Of 52 samples of Decayed Wood, bark or other plant debris originating from 35 living trees, 42 Wood samples yielded C. neoformans. The positive samples included 40 collected from 31 Syzygium cumini trees growing along roadsides in Old Delhi, whereas the remaining two were from inside tree trunk fissures of Ficus religiosa in a New Delhi locality. The number of Wood samples found positive by swabbing was 40 (95%) as opposed to 32 (76%) by the conventional technique, and this difference was statistically significant (P < 0.01). Also, the conventional technique showed 24% false-negative results, which was in striking contrast to only 5% by swabbing. Furthermore, swabbing yielded a significantly higher C. neoformans mean colony count than did the conventional technique (P < 0.005), thus highlighting greater efficacy of the former technique. The overall prevalence of C. neoformans in the S. cumini trees investigated was 84% (26/31 trees) which is the highest as yet reported from any tree species in India. Varietal identification and serotyping was done with 33 of the C. neoformans isolates, 31 of which came from 23 tree trunk hollows of S. cumini and two from the tree trunk fissures of F. religiosa. Among the S. cumini isolates, 26 were identified as C. neoformans var. gattii (all serotype B except two untypeable ones) and five as C. neoformans var. neoformans, serotype A (= C. neoformans var. grubii). Both of the F. religiosa isolates belonged to C. n. var. neoformans, serotype A. Being a more efficacious, simple, less time-consuming and less hazardous technique, swabbing is recommended for wider use in order to further elucidate the ecology of C. neoformans.
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Decayed Wood of syzygium cumini and ficus religiosa living trees in delhi new delhi metropolitan area as natural habitat of cryptococcus neoformans
Medical Mycology, 2003Co-Authors: H S Randhawa, T. Kowshik, Z U KhanAbstract:The isolation is reported of Cryptococcus neoformans var. gattii and C. n. var. neoformans from Decayed Wood inside trunk hollows of Syzygium cumini and of C. n. var. neoformans from Ficus religiosa trees in the Delhi/New Delhi metropolitan area. Fourteen of sixty-six (21%) S. cumini trees investigated proved to be positive, seven for each variety. The two varieties never co-occurred in the same hollow. C. n. var. neoformans was also isolated from three of seventeen Ficus religiosa-trees. Two of these isolates originated from Decayed Wood and one from bark. The C. n. var. gattii and C. n. var. neoformans isolates belonged to serotype B and serotype A, respectively. The data strongly supported colonization of S. cumini by both varieties and of F. religiosa trees by C. n. var. neoformans. Evidence of this was found by repeated isolations. For example, in 36/44 (82%) samples for C. n. var. gattii and 22/27 (81%) samples for C. n. var. neoformans, and by a high population density in the tested Wood debris (maximally 6 x 10(5) colony-forming units per gram [c.f.u./g] for C. n. var. gattii and 8 x 10(4) c.f.u./g for C. n. var. neoformans). No eucalypt trees were seen near the positive S. cumini and F. religiosa trees. The densities of C. neoformans in these trees exceeded those found previously in Eucalyptus camaldulensis and in other tree species more rarely reported to be sources of C. neoformans in India. S. cumini and F. religiosa appear not to have been reported to date as sources for either C. n. var. gattii or C n. var. neoformans. Our results add to the recently emerging evidence that the natural habitat of C. n. var. gattii and C. n. var. neoformans is not specific to Woody or other debris of particular tree species, but instead is more generalized.
Z U Khan - One of the best experts on this subject based on the ideXlab platform.
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seasonal variations in the prevalence of cryptococcus neoformans var grubii and cryptococcus gattii in Decayed Wood inside trunk hollows of diverse tree species in north western india a retrospective study
Medical Mycology, 2011Co-Authors: H S Randhawa, T. Kowshik, Anuradha Chowdhary, Anupam Prakash, Z U KhanAbstract:This study presents a 7-year retrospective analysis of seasonal variations in the prevalence of Cryptococcus neoformans var. grubii and Cryptococcus gattii in Decayed Wood inside trunk hollows of 518 trees belonging to 20 species in north-western India during 2000-2007. Of the 1,439 Wood samples investigated, 406 (28.2%) were found to be positive for the Cryptococcus neoformans species complex which included 247 samples from which C. neoformans var. grubii was recovered and 171 which yielded C. gattii. While both of the pathogens were isolated through all the seasons, the overall prevalence of C. neoformans var. grubii was significantly higher (17.2%) than that of C. gattii serotype B (11.9%, P < 0.0001), indicating that Decayed Wood was as good, if not better, a natural habitat of C. neoformans var. grubii as that of C. gattii. The highest recovery of both yeasts was in the autumn, followed by that in the summer. For C. gattii, the lowest prevalence occurred during the winter and for C. neoformans var. grubii during the rainy season. The low prevalence of C. gattii during winter is similar to that reported from Bogota, Colombia, where C. gattii had a low population density in bark samples but it was not found in Decayed Wood of trunk hollows investigated during the period of January and February. The prevalence of C. neoformans var. grubii was significantly lower in the rainy season than in the other portions of the year. This finding is similar to the reported low isolation frequency (4%) of C. neoformans var. grubii from chicken feces in the rainy season in northern Thailand. Further investigations are warranted to determine the clinical significance of seasonal variations in the prevalence of C. neoformans var. grubii and C. gattii in Decayed trunk Wood of various trees in climatically divergent regions of India.
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the expanding host tree species spectrum of cryptococcus gattii and cryptococcus neoformans and their isolations from surrounding soil in india
Medical Mycology, 2008Co-Authors: H S Randhawa, T. Kowshik, Anuradha Chowdhary, Z U Khan, Preeti K Sinha, Jianping XuAbstract:This study reports the widespread prevalence of Cryptococcus neoformans and Cryptococcus gattii in Decayed Wood inside trunk hollows of 14 species representing 12 families of trees and from soil near the base of various host trees from Delhi and several places in the Indian states of Uttar Pradesh, Haryana, Tamil Nadu and Chandigarh Union Territory. Of the 311 trees from which samples were obtained, 64 (20.5%) were found to contain strains of the C. neoformans species complex. The number of trees positive for C. neoformans var grubii (serotypeA) was 51 (16.3%), for C. gattii (serotype B) 24 (7.7%) and for both C. neoformans and C. gattii 11 (3.5%). The overall prevalence of C. neoformans species complex in Decayed Wood samples was 19.9% (111/556). There was no obvious correlation between the prevalence of these two yeast species and the species of host trees. The data on prevalence of C. gattii (24%) and C. neoformans (26%) in soil around the base of some host trees indicated that soil is another important ecologic niche for these two Cryptococcus species in India. Among our sampled tree species, eight and six were recorded for the first time as hosts for C. neoformans var grubii and C. gattii, respectively. A longitudinal surveillance of 8 host tree species over 0.7 to 2.5 years indicated long term colonization of Polyalthia longifolia, Mimusops elengi and Manilkara hexandra trees by C. gattii and/or C. neoformans. The mating type was determined for 153 of the isolates, including 98 strains of serotype A and 55 of serotype B and all proved to be mating type a (MAT a). Our observations document the rapidly expanding spectrum of host tree species for C. gattii and C. neoformans and indicate that Decayed Woods of many tree species are potentially suitable ecological niches for both pathogens.
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efficacy of swabbing versus a conventional technique for isolation of cryptococcus neoformans from Decayed Wood in tree trunk hollows
Medical Mycology, 2005Co-Authors: H S Randhawa, T. Kowshik, Z U KhanAbstract:The efficacy of swabbing versus a conventional sedimentation technique was evaluated for sampling of Decayed Wood in tree trunk hollows for isolation of Cryptococcus neoformans. Of 52 samples of Decayed Wood, bark or other plant debris originating from 35 living trees, 42 Wood samples yielded C. neoformans. The positive samples included 40 collected from 31 Syzygium cumini trees growing along roadsides in Old Delhi, whereas the remaining two were from inside tree trunk fissures of Ficus religiosa in a New Delhi locality. The number of Wood samples found positive by swabbing was 40 (95%) as opposed to 32 (76%) by the conventional technique, and this difference was statistically significant (P < 0.01). Also, the conventional technique showed 24% false-negative results, which was in striking contrast to only 5% by swabbing. Furthermore, swabbing yielded a significantly higher C. neoformans mean colony count than did the conventional technique (P < 0.005), thus highlighting greater efficacy of the former technique. The overall prevalence of C. neoformans in the S. cumini trees investigated was 84% (26/31 trees) which is the highest as yet reported from any tree species in India. Varietal identification and serotyping was done with 33 of the C. neoformans isolates, 31 of which came from 23 tree trunk hollows of S. cumini and two from the tree trunk fissures of F. religiosa. Among the S. cumini isolates, 26 were identified as C. neoformans var. gattii (all serotype B except two untypeable ones) and five as C. neoformans var. neoformans, serotype A (= C. neoformans var. grubii). Both of the F. religiosa isolates belonged to C. n. var. neoformans, serotype A. Being a more efficacious, simple, less time-consuming and less hazardous technique, swabbing is recommended for wider use in order to further elucidate the ecology of C. neoformans.
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Decayed Wood of syzygium cumini and ficus religiosa living trees in delhi new delhi metropolitan area as natural habitat of cryptococcus neoformans
Medical Mycology, 2003Co-Authors: H S Randhawa, T. Kowshik, Z U KhanAbstract:The isolation is reported of Cryptococcus neoformans var. gattii and C. n. var. neoformans from Decayed Wood inside trunk hollows of Syzygium cumini and of C. n. var. neoformans from Ficus religiosa trees in the Delhi/New Delhi metropolitan area. Fourteen of sixty-six (21%) S. cumini trees investigated proved to be positive, seven for each variety. The two varieties never co-occurred in the same hollow. C. n. var. neoformans was also isolated from three of seventeen Ficus religiosa-trees. Two of these isolates originated from Decayed Wood and one from bark. The C. n. var. gattii and C. n. var. neoformans isolates belonged to serotype B and serotype A, respectively. The data strongly supported colonization of S. cumini by both varieties and of F. religiosa trees by C. n. var. neoformans. Evidence of this was found by repeated isolations. For example, in 36/44 (82%) samples for C. n. var. gattii and 22/27 (81%) samples for C. n. var. neoformans, and by a high population density in the tested Wood debris (maximally 6 x 10(5) colony-forming units per gram [c.f.u./g] for C. n. var. gattii and 8 x 10(4) c.f.u./g for C. n. var. neoformans). No eucalypt trees were seen near the positive S. cumini and F. religiosa trees. The densities of C. neoformans in these trees exceeded those found previously in Eucalyptus camaldulensis and in other tree species more rarely reported to be sources of C. neoformans in India. S. cumini and F. religiosa appear not to have been reported to date as sources for either C. n. var. gattii or C n. var. neoformans. Our results add to the recently emerging evidence that the natural habitat of C. n. var. gattii and C. n. var. neoformans is not specific to Woody or other debris of particular tree species, but instead is more generalized.
Anuradha Chowdhary - One of the best experts on this subject based on the ideXlab platform.
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seasonal variations in the prevalence of cryptococcus neoformans var grubii and cryptococcus gattii in Decayed Wood inside trunk hollows of diverse tree species in north western india a retrospective study
Medical Mycology, 2011Co-Authors: H S Randhawa, T. Kowshik, Anuradha Chowdhary, Anupam Prakash, Z U KhanAbstract:This study presents a 7-year retrospective analysis of seasonal variations in the prevalence of Cryptococcus neoformans var. grubii and Cryptococcus gattii in Decayed Wood inside trunk hollows of 518 trees belonging to 20 species in north-western India during 2000-2007. Of the 1,439 Wood samples investigated, 406 (28.2%) were found to be positive for the Cryptococcus neoformans species complex which included 247 samples from which C. neoformans var. grubii was recovered and 171 which yielded C. gattii. While both of the pathogens were isolated through all the seasons, the overall prevalence of C. neoformans var. grubii was significantly higher (17.2%) than that of C. gattii serotype B (11.9%, P < 0.0001), indicating that Decayed Wood was as good, if not better, a natural habitat of C. neoformans var. grubii as that of C. gattii. The highest recovery of both yeasts was in the autumn, followed by that in the summer. For C. gattii, the lowest prevalence occurred during the winter and for C. neoformans var. grubii during the rainy season. The low prevalence of C. gattii during winter is similar to that reported from Bogota, Colombia, where C. gattii had a low population density in bark samples but it was not found in Decayed Wood of trunk hollows investigated during the period of January and February. The prevalence of C. neoformans var. grubii was significantly lower in the rainy season than in the other portions of the year. This finding is similar to the reported low isolation frequency (4%) of C. neoformans var. grubii from chicken feces in the rainy season in northern Thailand. Further investigations are warranted to determine the clinical significance of seasonal variations in the prevalence of C. neoformans var. grubii and C. gattii in Decayed trunk Wood of various trees in climatically divergent regions of India.
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the expanding host tree species spectrum of cryptococcus gattii and cryptococcus neoformans and their isolations from surrounding soil in india
Medical Mycology, 2008Co-Authors: H S Randhawa, T. Kowshik, Anuradha Chowdhary, Z U Khan, Preeti K Sinha, Jianping XuAbstract:This study reports the widespread prevalence of Cryptococcus neoformans and Cryptococcus gattii in Decayed Wood inside trunk hollows of 14 species representing 12 families of trees and from soil near the base of various host trees from Delhi and several places in the Indian states of Uttar Pradesh, Haryana, Tamil Nadu and Chandigarh Union Territory. Of the 311 trees from which samples were obtained, 64 (20.5%) were found to contain strains of the C. neoformans species complex. The number of trees positive for C. neoformans var grubii (serotypeA) was 51 (16.3%), for C. gattii (serotype B) 24 (7.7%) and for both C. neoformans and C. gattii 11 (3.5%). The overall prevalence of C. neoformans species complex in Decayed Wood samples was 19.9% (111/556). There was no obvious correlation between the prevalence of these two yeast species and the species of host trees. The data on prevalence of C. gattii (24%) and C. neoformans (26%) in soil around the base of some host trees indicated that soil is another important ecologic niche for these two Cryptococcus species in India. Among our sampled tree species, eight and six were recorded for the first time as hosts for C. neoformans var grubii and C. gattii, respectively. A longitudinal surveillance of 8 host tree species over 0.7 to 2.5 years indicated long term colonization of Polyalthia longifolia, Mimusops elengi and Manilkara hexandra trees by C. gattii and/or C. neoformans. The mating type was determined for 153 of the isolates, including 98 strains of serotype A and 55 of serotype B and all proved to be mating type a (MAT a). Our observations document the rapidly expanding spectrum of host tree species for C. gattii and C. neoformans and indicate that Decayed Woods of many tree species are potentially suitable ecological niches for both pathogens.
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antifungal susceptibility of cryptococcus neoformans and cryptococcus gattii isolates from Decayed Wood of trunk hollows of ficus religiosa and syzygium cumini trees in north western india
Journal of Antimicrobial Chemotherapy, 2007Co-Authors: Zia U Khan, T. Kowshik, Anuradha Chowdhary, H S Randhawa, Rachel ChandyAbstract:Background: We present antifungal susceptibility data on environmental Isolates of Cryptococcus neoformans (serotype A, n = 117) and Cryptococcus gattii (serotype B, n = 65) cultured from Decayed Wood of trunk hollows of Ficus religiosa and Syzygium cumini trees. Methods: Susceptibilities to amphotericin B, fluconazole, ketoconazole, itraconazole and voriconazole were determined by using Etest. The MICs were read after 48 h as per the guidelines provided by the manufacturer. Results: The MIC 90 S and susceptibility ranges for C. neoformans isolates were as follows: 0.094 (0.004-0.25) mg/L for amphotericin B, 4 (0.032-12) mg/L for fluconazole, 0.094 (0.004-0.75) mg/L for itraconazole, 0.064 (0.002-0.19) mg/L for ketoconazole, and 0.047 (0.006-0.125) mg/L for voriconazole, whereas for C. gattii isolates these were 0.125 (0.023-0.5) mg/L for amphotericin B, 8 (0.032-16) mg/L for fluconazole, 0.75 (0.006-2) mg/L for itraconazole, 0.125 (0.003-0.19) mg/L for ketoconazole, and 0.094 (0.004-0.125) mg/L for voriconazole. A comparison of the geometric means of MICs (mg/L) revealed that C. gattii was less susceptible than C. neoformans to amphotericin B (0.075 versus 0.051, P = 0.0003), fluconazole (2.912 versus 2.316, P = 0.003), itraconazole (0.198 versus 0.0344, P< 0.0001), ketoconazole (0.072 versus 0.037, P< 0.0001), and voriconazole (0.045 versus 0.023, P< 0.0001). Conclusions: The antifungal susceptibility data obtained in this study indicate that the occurrence of primary resistance among environmental isolates of C. neoformans serotype A and C. gattii serotype B Is rare, and serotype B isolates are less susceptible than serotype A isolates.
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Distribution of Cryptococcus gattii and Cryptococcus neoformans in Decayed trunk Wood of Syzygium cumini trees in north-western India
Medical mycology, 2006Co-Authors: Harbans S. Randhawa, T. Kowshik, K. Preeti Sinha, Anuradha Chowdhary, Ziauddin Khan, Zhun Yan, Amit KumarAbstract:The aim of this study is to report the regional distribution of Cryptococcus. gattii and Cryptococcus. neoformans in Decayed Wood inside trunk hollows of Syzygium cumini trees (Java plum, Indian black berry) investigated in Amritsar (Panjab), Meerut Cantt. and Bulandshahr (Uttar Pradesh) and Delhi, in north-western India. Two hundred and seventeen Wood samples collected from 74 S. cumini trees were investigated. This includes 7 known positive S. cumini trees in Delhi subjected to a mycological surveillance for perennial colonization by C. gattii and C. neoformans. Cryptococcus gattii showed the highest prevalence (89%) in S. cumini trees in Delhi, followed by 27%, 12.5% and 9% prevalence in Bulandshahr, Amritsar City and Meerut Cantt., respectively. In contrast, C. neoformans had the highest prevalence (54%) in Amritsar, followed by 44% in Delhi, 9% in Bulandshahr and 0% in Meerut Cantt. Furthermore, 44% of the S. cumini trees in Delhi, 9% in Bulandshahr and 8% in Amritsar were concomitantly colonized by ...
