The aim of this investigation was to determine the persistence of biofilm-associated antibiotic r... more The aim of this investigation was to determine the persistence of biofilm-associated antibiotic resistance developed by methicillin-sensitive Staphylococcus aureus (MSSA), of different capsular types, during biofilm formation. Because of superiority of the tissue culture plate (TCP) over the Congo Red Agar (CRA) method for measuring biofilm formation, it was used to determine the persistence of the antibiotic resistance developed by the isolates in biofilms. The antibiotic resistance was found to persist for 3–4 wk post-propagation as planktonic subcultures. Interestingly, some strains even developed resistance to vancomycin and/or teicoplanin. However, no association of either biofilm formation or persistent antibiotic resistance with the major capsular phenotype was observed. These observations highlight the potential significance of (a) determining the antibiograms of S. aureus subcultured from biofilms developed in vitro using the TCP method as well as from planktonic cultures for formulation of an optimal therapeutic strategy, and (b) continuing to identify predominant non-capsular antigens contributing to biofilm formation, regardless of the capsular phenotype for the development of an effective potentially broad-spectrum vaccine for prevention of bovine mastitis caused by S. aureus.
A B S T R A C T Methicillin-resistant Staphylococcus aureus (MRSA) is a serious human pathogen th... more A B S T R A C T Methicillin-resistant Staphylococcus aureus (MRSA) is a serious human pathogen that can cause a wide variety of infections. Comparative genetic analyses have led to the discovery that despite the existence of a vast number of genotypes, outbreak strains of MRSA appear to be limited to certain genotypes, some of which are further restricted to certain geographical locations. Whereas extensive literature is available in several countries, the complexity of the clonal distribution both of healthcare-associated (HA) and community-associated (CA) MRSA in India is only now beginning to be understood. Studies have revealed that MRSA in India is distributed among all of the major staphylococcal cassette chromosome mec (SCCmec) types. The majority of HA-MRSA isolates belong to SCCmec type III and sequence type (ST) 239. By contrast, CA-MRSA mostly belong to ST22 (SCCmec IV), ST772 (SCCmec V) and ST672 (SCCmec V) genotypes. Similar to the global scenario, CA-MRSA is becoming more invasive and transmissible and is increasingly becoming difficult to be differentiated from HA-MRSA. In addition, it is disturbing that some of the HA-MRSA isolates have been reported to be vancomycin-resistant. On the other hand, almost no information is available on the genotypes of livestock-associated MRSA or their potential impact on human infections in India. Concerted efforts are needed to further understand the genetic epidemiology of MRSA in India.
Francisella tularensis (Ft) is a gram-negative intercellular pathogen and category
A biothreat ag... more Francisella tularensis (Ft) is a gram-negative intercellular pathogen and category A biothreat agent. However, despite 15 years of strong government investment and intense research focused on the development of a US Food and Drug Administration-approved vaccine against Ft, the primary goal remains elusive. This article reviews research efforts focused on developing an Ft vaccine, as well as a number of important factors, some only recently recognized as such, which can significantly impact the development and evaluation of Ft vaccine efficacy. Finally, an assessment is provided as to whether a US Food and Drug Administrationapproved Ft vaccine is likely to be forthcoming and the potential means by which this might be achieved. Keywords: Sex
The aim of this investigation was to determine the persistence of biofilm-associated antibiotic r... more The aim of this investigation was to determine the persistence of biofilm-associated antibiotic resistance developed by methicillin-sensitive Staphylococcus aureus (MSSA), of different capsular types, during biofilm formation. Because of superiority of the tissue culture plate (TCP) over the Congo Red Agar (CRA) method for measuring biofilm formation, it was used to determine the persistence of the antibiotic resistance developed by the isolates in biofilms. The antibiotic resistance was found to persist for 3-4 wk post-propagation as planktonic subcultures. Interestingly, some strains even developed resistance to vancomycin and/or teicoplanin. However, no association of either biofilm formation or persistent antibiotic resistance with the major capsular phenotype was observed. These observations highlight the potential significance of (a) determining the antibiograms of S. aureus subcultured from biofilms developed in vitro using the TCP method as well as from planktonic cultures for formulation of an optimal therapeutic strategy, and (b) continuing to identify predominant non-capsular antigens contributing to biofilm formation, regardless of the capsular phenotype for the development of an effective potentially broad-spectrum vaccine for prevention of bovine mastitis caused by S. aureus.
The aim of this investigation was to determine the persistence of biofilm-associated antibiotic r... more The aim of this investigation was to determine the persistence of biofilm-associated antibiotic resistance developed by methicillin-sensitive Staphylococcus aureus (MSSA), of different capsular types, during biofilm formation. Because of superiority of the tissue culture plate (TCP) over the Congo Red Agar (CRA) method for measuring biofilm formation, it was used to determine the persistence of the antibiotic resistance developed by the isolates in biofilms. The antibiotic resistance was found to persist for 3–4 wk post-propagation as planktonic subcultures. Interestingly, some strains even developed resistance to vancomycin and/or teicoplanin. However, no association of either biofilm formation or persistent antibiotic resistance with the major capsular phenotype was observed. These observations highlight the potential significance of (a) determining the antibiograms of S. aureus subcultured from biofilms developed in vitro using the TCP method as well as from planktonic cultures for formulation of an optimal therapeutic strategy, and (b) continuing to identify predominant non-capsular antigens contributing to biofilm formation, regardless of the capsular phenotype for the development of an effective potentially broad-spectrum vaccine for prevention of bovine mastitis caused by S. aureus.
A B S T R A C T Methicillin-resistant Staphylococcus aureus (MRSA) is a serious human pathogen th... more A B S T R A C T Methicillin-resistant Staphylococcus aureus (MRSA) is a serious human pathogen that can cause a wide variety of infections. Comparative genetic analyses have led to the discovery that despite the existence of a vast number of genotypes, outbreak strains of MRSA appear to be limited to certain genotypes, some of which are further restricted to certain geographical locations. Whereas extensive literature is available in several countries, the complexity of the clonal distribution both of healthcare-associated (HA) and community-associated (CA) MRSA in India is only now beginning to be understood. Studies have revealed that MRSA in India is distributed among all of the major staphylococcal cassette chromosome mec (SCCmec) types. The majority of HA-MRSA isolates belong to SCCmec type III and sequence type (ST) 239. By contrast, CA-MRSA mostly belong to ST22 (SCCmec IV), ST772 (SCCmec V) and ST672 (SCCmec V) genotypes. Similar to the global scenario, CA-MRSA is becoming more invasive and transmissible and is increasingly becoming difficult to be differentiated from HA-MRSA. In addition, it is disturbing that some of the HA-MRSA isolates have been reported to be vancomycin-resistant. On the other hand, almost no information is available on the genotypes of livestock-associated MRSA or their potential impact on human infections in India. Concerted efforts are needed to further understand the genetic epidemiology of MRSA in India.
Francisella tularensis (Ft) is a gram-negative intercellular pathogen and category
A biothreat ag... more Francisella tularensis (Ft) is a gram-negative intercellular pathogen and category A biothreat agent. However, despite 15 years of strong government investment and intense research focused on the development of a US Food and Drug Administration-approved vaccine against Ft, the primary goal remains elusive. This article reviews research efforts focused on developing an Ft vaccine, as well as a number of important factors, some only recently recognized as such, which can significantly impact the development and evaluation of Ft vaccine efficacy. Finally, an assessment is provided as to whether a US Food and Drug Administrationapproved Ft vaccine is likely to be forthcoming and the potential means by which this might be achieved. Keywords: Sex
The aim of this investigation was to determine the persistence of biofilm-associated antibiotic r... more The aim of this investigation was to determine the persistence of biofilm-associated antibiotic resistance developed by methicillin-sensitive Staphylococcus aureus (MSSA), of different capsular types, during biofilm formation. Because of superiority of the tissue culture plate (TCP) over the Congo Red Agar (CRA) method for measuring biofilm formation, it was used to determine the persistence of the antibiotic resistance developed by the isolates in biofilms. The antibiotic resistance was found to persist for 3-4 wk post-propagation as planktonic subcultures. Interestingly, some strains even developed resistance to vancomycin and/or teicoplanin. However, no association of either biofilm formation or persistent antibiotic resistance with the major capsular phenotype was observed. These observations highlight the potential significance of (a) determining the antibiograms of S. aureus subcultured from biofilms developed in vitro using the TCP method as well as from planktonic cultures for formulation of an optimal therapeutic strategy, and (b) continuing to identify predominant non-capsular antigens contributing to biofilm formation, regardless of the capsular phenotype for the development of an effective potentially broad-spectrum vaccine for prevention of bovine mastitis caused by S. aureus.
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Papers by R. Sunagar
A biothreat agent. However, despite 15 years of strong government investment and intense
research focused on the development of a US Food and Drug Administration-approved vaccine
against Ft, the primary goal remains elusive. This article reviews research efforts focused on
developing an Ft vaccine, as well as a number of important factors, some only recently recognized
as such, which can significantly impact the development and evaluation of Ft vaccine
efficacy. Finally, an assessment is provided as to whether a US Food and Drug Administrationapproved
Ft vaccine is likely to be forthcoming and the potential means by which this might
be achieved.
Keywords: Sex
A biothreat agent. However, despite 15 years of strong government investment and intense
research focused on the development of a US Food and Drug Administration-approved vaccine
against Ft, the primary goal remains elusive. This article reviews research efforts focused on
developing an Ft vaccine, as well as a number of important factors, some only recently recognized
as such, which can significantly impact the development and evaluation of Ft vaccine
efficacy. Finally, an assessment is provided as to whether a US Food and Drug Administrationapproved
Ft vaccine is likely to be forthcoming and the potential means by which this might
be achieved.
Keywords: Sex