Begomoviruses: Occurrence and Management in Asia and Africa, 2017
Begomoviruses, a group of whitefly-transmitted single-stranded DNA viruses that are widely spread... more Begomoviruses, a group of whitefly-transmitted single-stranded DNA viruses that are widely spread, cause significant economic losses in several important crops in tropical and subtropical regions of India. Begomoviruses have been known to be associated with and cause many diseases in cucurbitaceous, solanaceous, malvaceous vegetable and legume crops in most parts of the country. However, these viruses have emerged as a major threat to vegetable and legume production in India. Tomato, chillies, cucurbits, cotton, okra, legumes, papaya, and cassava are the most seriously affected crops. In recent decades, the most dramatic emergence of begomoviruses has been observed in tomato, chilli, and cucurbits throughout the country specially in tropical areas. The major factors responsible for the emergence of new viruses and their spread in the ecosystem are introduction of viruses, introduction of susceptible crops or genotypes, change in vector population, recombination in viruses, weather factors, and new intensive agricultural practices. This article presents the current understanding of begomovirus diseases in India and the driving forces for their emergence.
Banana (Musa spp.) is one of the most important staple food crops which provide nutrition and inc... more Banana (Musa spp.) is one of the most important staple food crops which provide nutrition and income for the millions of farmers worldwide, especially in tropical regions. Asia being the major continent for banana production contributes more than half of the world banana production (101.9 million tonnes). Banana is vegetatively propagated using suckers or through tissue culture plants which grow, mature and fruit without seasonality throughout the year. Viral diseases are considered a major concern for banana production because of their effects on yield and quality as well as limitations to germplasm multiplication and the international germplasm exchange. There are many (about 20) different viruses reported to infect banana worldwide. However, the economically most important viruses are: Banana bunchy top virus (BBTV), Banana streak viruses (BSV), Banana bract mosaic virus (BBrMV) and Cucumber mosaic virus (CMV). Among these, BBTV and BSV are major threats for banana production. Of the two, BSV exist as episomal and endogenous forms and more widely spread worldwide than BBTV, though later is so far most economically damaging virus contributing to a yield reduction of up to 100 %. Due to lack of durable virus resistance in the Musa spp., measures such as phytosanitation, use of virus free planting material, strict regulation on movement of infected planting materials are effective means to control viral diseases in banana. Studies of several decades on the biology, epidemiology, survival, spread, sequence integration into the host genome of banana viruses and their integrated management strategies are summarized in this review.
Intravenous device (IVD) associated nosocomial blood stream infections due to staphylococci are m... more Intravenous device (IVD) associated nosocomial blood stream infections due to staphylococci are major cause of morbidity and mortality. The present study was carried out to assess the frequency of staphylococcal IVD associated infections in a paediatric ward of a tertiary case hospital. Prevalence of resistance to commonly used antimicrobials in hospital acquired staphylococcal isolates was also tested. Children admitted in paediatric wards with IVD for more than 48 h were enrolled. Blood, IVD tip at the time of removal, skin swab at the site of insertion of IVD and nasal swab were collected and cultured by standard protocol. All staphylococcal isolates from any source were analyzed for antimicrobial susceptibility by disk diffusion method. Genotyping matching of those staphylococcal isolates was done which were isolated from different sites of the same patient, but were phonotypically similar. Genotype of blood isolate was compared with genotype of isolate from nose/IVD/skin. Staph...
Staphylococci are the main causative agents of nosocomial diseases. Over the last few years, the ... more Staphylococci are the main causative agents of nosocomial diseases. Over the last few years, the increase in the number of meticillin-resistant (MR) staphylococci has become a major clinical problem. Accuracy and promptness in the detection of meticillin resistance are of key importance in ensuring the correct antibiotic treatment in infected patients and control of MR staphylococci in the hospital environment. This study evaluated the accuracy of a cefoxitin disc diffusion (DD) test for the detection of meticillin resistance in staphylococci. A total of 144 clinical isolates [97 Staphylococcus aureus and 47 coagulase-negative staphylococci (CoNS)] were tested using a mecA gene PCR, a DD test (oxacillin, 1 mg disc; cefoxitin, 30 mg disc), determination of oxacillin MIC by agar dilution (AD), and an oxacillin screen agar test at oxacillin concentrations of 4 and 6 mg ml "1. Of the 97 S. aureus and 47 CoNS isolates, 73 (75.26 %) and 30 (63.83 %), respectively, were mecA-positive. The sensitivity and specificity of the cefoxitin DD test were 94.44 and 95.83 %, respectively, for S. aureus and 80 and 100 %, respectively, for CoNS. The oxacillin DD method was 100 % sensitive and 58.33 % specific for S. aureus, and 86.67 % sensitive and 70.59 % specific for CoNS. The AD test was highly sensitive (98.63 %) and specific (98.53 %) for S. aureus and CoNS (83.33 % sensitive and 94.12 % specific). The cefoxitin DD test for meticillin-resistance detection was more specific but less sensitive than the oxacillin DD test. Use of DD tests for both cefoxitin and oxacillin can help in more accurate prediction of meticillin resistance. Centres that are not equipped to carry out PCR can use AD methods for confirmation of meticillin resistance, especially in oxacillin-resistant and cefoxitin-sensitive cases.
To evaluate an in-house dot-enzyme-linked immunosorbent assay (ELISA) for confirmation of clinica... more To evaluate an in-house dot-enzyme-linked immunosorbent assay (ELISA) for confirmation of clinically suspected cases of tuberculous lymphadenitis (TBLN). The study was performed at the postgraduate departments of microbiology and pathology of a tertiary-care teaching hospital in India. Suspected cases of TBLN were prospectively enrolled. Fine needle aspiration was done of enlarged lymph nodes in all patients, and 2 smears were prepared, 1 for acid-fast bacillus (AFB) demonstration and the other for cytologic examination. The remaining material was tested with in-house dot-ELISA and by IS6110 amplification with polymerase chain reaction (PCR), for diagnosis of TBLN. ELISA was more sensitive and detected 93.2% of cases. PCR and fine needle aspiration cytology (FNAC) detected 82.5% and 61.0% cases, respectively. AFB positivity was 33.1%. Application of dot-ELISA was more sensitive but less specific as compared to PCR. PCR, though expensive, should be used in problem cases because of its high specificity.
Begomoviruses: Occurrence and Management in Asia and Africa, 2017
Begomoviruses, a group of whitefly-transmitted single-stranded DNA viruses that are widely spread... more Begomoviruses, a group of whitefly-transmitted single-stranded DNA viruses that are widely spread, cause significant economic losses in several important crops in tropical and subtropical regions of India. Begomoviruses have been known to be associated with and cause many diseases in cucurbitaceous, solanaceous, malvaceous vegetable and legume crops in most parts of the country. However, these viruses have emerged as a major threat to vegetable and legume production in India. Tomato, chillies, cucurbits, cotton, okra, legumes, papaya, and cassava are the most seriously affected crops. In recent decades, the most dramatic emergence of begomoviruses has been observed in tomato, chilli, and cucurbits throughout the country specially in tropical areas. The major factors responsible for the emergence of new viruses and their spread in the ecosystem are introduction of viruses, introduction of susceptible crops or genotypes, change in vector population, recombination in viruses, weather factors, and new intensive agricultural practices. This article presents the current understanding of begomovirus diseases in India and the driving forces for their emergence.
Banana (Musa spp.) is one of the most important staple food crops which provide nutrition and inc... more Banana (Musa spp.) is one of the most important staple food crops which provide nutrition and income for the millions of farmers worldwide, especially in tropical regions. Asia being the major continent for banana production contributes more than half of the world banana production (101.9 million tonnes). Banana is vegetatively propagated using suckers or through tissue culture plants which grow, mature and fruit without seasonality throughout the year. Viral diseases are considered a major concern for banana production because of their effects on yield and quality as well as limitations to germplasm multiplication and the international germplasm exchange. There are many (about 20) different viruses reported to infect banana worldwide. However, the economically most important viruses are: Banana bunchy top virus (BBTV), Banana streak viruses (BSV), Banana bract mosaic virus (BBrMV) and Cucumber mosaic virus (CMV). Among these, BBTV and BSV are major threats for banana production. Of the two, BSV exist as episomal and endogenous forms and more widely spread worldwide than BBTV, though later is so far most economically damaging virus contributing to a yield reduction of up to 100 %. Due to lack of durable virus resistance in the Musa spp., measures such as phytosanitation, use of virus free planting material, strict regulation on movement of infected planting materials are effective means to control viral diseases in banana. Studies of several decades on the biology, epidemiology, survival, spread, sequence integration into the host genome of banana viruses and their integrated management strategies are summarized in this review.
Intravenous device (IVD) associated nosocomial blood stream infections due to staphylococci are m... more Intravenous device (IVD) associated nosocomial blood stream infections due to staphylococci are major cause of morbidity and mortality. The present study was carried out to assess the frequency of staphylococcal IVD associated infections in a paediatric ward of a tertiary case hospital. Prevalence of resistance to commonly used antimicrobials in hospital acquired staphylococcal isolates was also tested. Children admitted in paediatric wards with IVD for more than 48 h were enrolled. Blood, IVD tip at the time of removal, skin swab at the site of insertion of IVD and nasal swab were collected and cultured by standard protocol. All staphylococcal isolates from any source were analyzed for antimicrobial susceptibility by disk diffusion method. Genotyping matching of those staphylococcal isolates was done which were isolated from different sites of the same patient, but were phonotypically similar. Genotype of blood isolate was compared with genotype of isolate from nose/IVD/skin. Staph...
Staphylococci are the main causative agents of nosocomial diseases. Over the last few years, the ... more Staphylococci are the main causative agents of nosocomial diseases. Over the last few years, the increase in the number of meticillin-resistant (MR) staphylococci has become a major clinical problem. Accuracy and promptness in the detection of meticillin resistance are of key importance in ensuring the correct antibiotic treatment in infected patients and control of MR staphylococci in the hospital environment. This study evaluated the accuracy of a cefoxitin disc diffusion (DD) test for the detection of meticillin resistance in staphylococci. A total of 144 clinical isolates [97 Staphylococcus aureus and 47 coagulase-negative staphylococci (CoNS)] were tested using a mecA gene PCR, a DD test (oxacillin, 1 mg disc; cefoxitin, 30 mg disc), determination of oxacillin MIC by agar dilution (AD), and an oxacillin screen agar test at oxacillin concentrations of 4 and 6 mg ml "1. Of the 97 S. aureus and 47 CoNS isolates, 73 (75.26 %) and 30 (63.83 %), respectively, were mecA-positive. The sensitivity and specificity of the cefoxitin DD test were 94.44 and 95.83 %, respectively, for S. aureus and 80 and 100 %, respectively, for CoNS. The oxacillin DD method was 100 % sensitive and 58.33 % specific for S. aureus, and 86.67 % sensitive and 70.59 % specific for CoNS. The AD test was highly sensitive (98.63 %) and specific (98.53 %) for S. aureus and CoNS (83.33 % sensitive and 94.12 % specific). The cefoxitin DD test for meticillin-resistance detection was more specific but less sensitive than the oxacillin DD test. Use of DD tests for both cefoxitin and oxacillin can help in more accurate prediction of meticillin resistance. Centres that are not equipped to carry out PCR can use AD methods for confirmation of meticillin resistance, especially in oxacillin-resistant and cefoxitin-sensitive cases.
To evaluate an in-house dot-enzyme-linked immunosorbent assay (ELISA) for confirmation of clinica... more To evaluate an in-house dot-enzyme-linked immunosorbent assay (ELISA) for confirmation of clinically suspected cases of tuberculous lymphadenitis (TBLN). The study was performed at the postgraduate departments of microbiology and pathology of a tertiary-care teaching hospital in India. Suspected cases of TBLN were prospectively enrolled. Fine needle aspiration was done of enlarged lymph nodes in all patients, and 2 smears were prepared, 1 for acid-fast bacillus (AFB) demonstration and the other for cytologic examination. The remaining material was tested with in-house dot-ELISA and by IS6110 amplification with polymerase chain reaction (PCR), for diagnosis of TBLN. ELISA was more sensitive and detected 93.2% of cases. PCR and fine needle aspiration cytology (FNAC) detected 82.5% and 61.0% cases, respectively. AFB positivity was 33.1%. Application of dot-ELISA was more sensitive but less specific as compared to PCR. PCR, though expensive, should be used in problem cases because of its high specificity.
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