Rahul Mittal - Academia.edu (original) (raw)

Papers by Rahul Mittal

Research paper thumbnail of Tuberculosis of the foot

Journal of Bone and Joint Surgery-british Volume, 1999

I n 44 patients with tuberculosis of the foot we identified five radiological patterns of lesions... more I n 44 patients with tuberculosis of the foot we identified five radiological patterns of lesions; cystic, rheumatoid, subperiosteal, kissing and spina ventosa. Cystic destruction had the best outcome and rheumatoid the poorest. All the patients were cured after antituberculous treatment for 18 months, and none required surgery.

Research paper thumbnail of Effect of macrophage secretory products on elaboration of virulence factors by planktonic and biofilm cells of Pseudomonas aeruginosa

Comparative Immunology Microbiology and Infectious Diseases, 2006

Macrophages, which constitute the first line of defense, pour their secretions in the mileu follo... more Macrophages, which constitute the first line of defense, pour their secretions in the mileu following stimulation with pathogens. These secretory products, referred to as macrophage secretory products (MSPs), can influence ultimate outcome of an infection. In the present investigation, it was observed that different strains of Pseudomonas aeruginosa vary in their ability to stimulate macrophages leading to variability in generation of macrophage secretory products. Cytokine levels, reactive nitrogen intermediates and protein content of macrophage secretory products generated with biofilm cells of P. aeruginosa was found to be more as compared to their planktonic counterparts. The effect of macrophage secretory products produced in response to interaction of macrophages with P. aeruginosa on elaboration of virulence factors produced by planktonic and biofilm cell forms of this pathogen was assessed. Significant enhancement in growth and elaboration of all the virulence determinants by both the cell forms was observed when P. aeruginosa was grown in presence of supernatants with macrophage secretory products. Implications of these findings in relation to urinary tract infections induced by P. aeruginosa have been discussed. q

Research paper thumbnail of Iron dictates the virulence of Pseudomonas aeruginosa in urinary tract infections

Journal of Biomedical Science, 2008

Iron-limiting conditions have been reported to be prevalent in the milieu of urinary tract. In th... more Iron-limiting conditions have been reported to be prevalent in the milieu of urinary tract. In the present investigation, effect of iron on virulence of uropathogenic Pseudomonas aeruginosa in planktonic and biofilm cell mode was studied. Significant enhancement in elaboration of all the virulence traits along with increased adherence to uroepithelial cells and decreased phagocytosis of P. aeruginosa was observed following growth in iron-deplete medium. On the contrary, decrease in all these parameters except phagocytosis was observed when P. aeruginosa was grown in iron-rich medium. In vivo, P. aeruginosa grown in iron-deplete medium showed increased renal bacterial load and tissue pathology in a mouse model of ascending urinary tract infection compared with organisms grown in iron-replete medium. The results of the present study may help in understanding host–parasite interaction and in developing alternative preventive approach against P. aeruginosa induced urinary tract infections.

Research paper thumbnail of Urinary tract infections caused by Pseudomonas aeruginosa: A minireview

Journal of Infection and Public Health, 2009

Urinary tract infections (UTIs) are a serious health problem affecting millions of people each ye... more Urinary tract infections (UTIs) are a serious health problem affecting millions of people each year. Infections of the urinary tract are the second most common type of infection in the body. Catheterization of the urinary tract is the most common factor, which predisposes the host to these infections. Catheterassociated UTI (CAUTI) is responsible for 40% of nosocomial infections, making it the most common cause of nosocomial infection. CAUTI accounts for more than 1 million cases in hospitals and nursing homes annually and often involve uropathogens other than Escherichia coli. While the epidemiology and pathogenic mechanisms of uropathogenic Escherichia coli have been extensively studied, little is known about the pathogenesis of UTIs caused by other organisms like Pseudomonas aeruginosa. Scanty available information regarding pathogenesis of UTIs caused by P. aeruginosa is an important bottleneck in developing effective preventive approaches. The aim of this review is to summarize some of the advances made in the field of P. aeruginosa induced UTIs and draws attention of the workers that more basic research at the level of pathogenesis is needed so that novel strategies can be designed.

Research paper thumbnail of Macrophage inflammatory protein-2, neutrophil recruitment and bacterial persistence in an experimental mouse model of urinary tract infection

Microbes and Infection, 2004

This study analyzed macrophage inflammatory protein-2 (MIP-2) production and neutrophil recruitme... more This study analyzed macrophage inflammatory protein-2 (MIP-2) production and neutrophil recruitment in urinary tract in response to Pseudomonas aeruginosa in an ascending model of urinary tract infection (UTI) in mice. Both planktonic and biofilm cells of P. aeruginosa were used for inducing UTI in mice. MIP-2 levels determined in urine, bladder and kidney showed maximum MIP-2 production 6 h postinfection, which correlated with neutrophil recruitment. Biofilm cells showed significantly more MIP-2 production and neutrophil recruitment. However, no correlation between bacterial numbers and neutrophil recruitment was observed in urine and kidney tissue. The role of MIP-2 and neutrophils in relation to the persistence of P. aeruginosa in the urinary tract of mice is discussed.

Research paper thumbnail of Contribution of Tamm–Horsfall protein to virulence of Pseudomonas aeruginosa in urinary tract infection

Microbes and Infection, 2005

Tamm-Horsfall glycoprotein (THP) is the most abundant protein which is synthesized by renal tubul... more Tamm-Horsfall glycoprotein (THP) is the most abundant protein which is synthesized by renal tubular cells and excreted in urine. Its role in urinary tract infection has yet not been identified. In the present study, the contribution of THP towards adherence of Pseudomonas aeruginosa to uroepithelial cells and murine peritoneal macrophages was studied. Decreased adherence of THP-coated P. aeruginosa to UECs and phagocytes was observed in vitro. In vivo, P. aeruginosa showed increased renal bacterial load and tissue pathology in a mouse model of acute ascending pyelonephritis, when THP-coated P. aeruginosa was used to cause infection. This study shows that THP may not necessarily act as a host defense component; rather, it may help in renal colonization of P. aeruginosa in vivo.

Research paper thumbnail of Contribution of free radicals to Pseudomonas aeruginosa induced acute pyelonephritis

Microbial Pathogenesis, 2008

Pyelonephritis induces an inflammatory process in the renal parenchyma, which may occur as a resu... more Pyelonephritis induces an inflammatory process in the renal parenchyma, which may occur as a result of excessive reactive nitrogen intermediates (RNI) and reactive oxygen species (ROS) and/or impaired antioxidant capacity. In the present investigation, contribution of free radicals to the development of acute pyelonephritis induced by planktonic and biofilm cells of Pseudomonas aeruginosa was studied. Increase in production of RNI and ROS in urine, bladder and renal tissue following infection with P. aeruginosa was observed which correlated with bacterial load, neutrophil recruitment and malondialdehyde (MDA). Evaluation of the data revealed that excessive production of free radicals causes tissue damage leading to bacterial persistence in host's tissues. Treatment of mice with N-acetylcysteine (NAC), a potent antioxidant, lead to significant amelioration of oxidative stress and subsequent decrease in bacterial titer, neutrophil influx, MDA as well as tissue pathology highlighting important role of free radicals in P. aeruginosa induced pyelonephritis. Results of the present study bring out that production of RNI and ROS contributes to the pathophysiology of pyelonephritis. These findings may be relevant for the better understanding of host-parasite interactions and may be of clinical importance in the development of preventive intervention against P. aeruginosa induced pyelonephritis.

Research paper thumbnail of Phenotypic characters of urinary isolates of Pseudomonas aeruginosa & their association with mouse renal colonization

Very few studies regarding production of virulence factors in different predominant serotypes of ... more Very few studies regarding production of virulence factors in different predominant serotypes of uropathogenic Pseudomonas aeruginosa are available and they have not been correlated to in vivo pathogenicity in the urinary tract. This study was carriedout with the objective to analyze the phenotypic characters of uroisolates of P. aeruginosa in vitro and to study the association of these virulence traits with their ability to cause nephropathogenicity in mouse model of ascending urinary tract infection (UTI).

Research paper thumbnail of Experimental Non-obstructive Chronic Renal Infection Model with Planktonic and Biofilm Cells of Pseudomonas Aeruginosa

American Journal of Biomedical Sciences, 2009

Availability of an acceptable animal model, which closely mimics human clinical situations in ter... more Availability of an acceptable animal model, which closely mimics human clinical situations in terms of receptors and route of entry, is of utmost importance to study host parasite interaction. In the present study, Swiss Webster (LACA) strain of female mice was chosen for induction of chronic renal inflammation by planktonic as well as biofilm cells of Pseudomonas aeruginosa. Bacterial inoculum was instilled thrice intrauretherally with the help of catheter. Both the cell forms were able to induce chronic renal inflammation in the experimental animals. However, severity of lesions induced by four day old biofilm cells was more as compared to planktonic cells. The chronic pyelonephritis model holds great promise for understanding the biology and pathogenesis of P. aeruginosa induced urinary tract infections as well as in development of effective preventive strategies.

Research paper thumbnail of Enhanced siderophore production and mouse kidney pathogenicity in Escherichia coli grown in urine

Journal of Medical Microbiology, 1991

Fifteen siderophore producing urinary isolates of Escherichia coli were compared for aerobactin a... more Fifteen siderophore producing urinary isolates of Escherichia coli were compared for aerobactin and enterochelin production in trypticase soy broth and pooled normal human urine. Significant increase in siderophore production (both phenolate and hydroxamate) was observed when organisms were grown in urine. Mouse kidney pathogenic potential of the strains grown in urine was compared with that of bacteria grown in trypticase soy broth in an ascending model of pyelonephritis in female Swiss Webster mice. Organisms grown in urine and instilled into a mouse bladder demonstrated markedly enhanced renal pathogenicity (p less than 0.01). Further information about the influence of urinary constituents on siderophore production could help in understanding the pathogenesis of pyelonephritis.

Research paper thumbnail of Alteration in virulence characteristics of biofilm cells of Pseudomonas aeruginosa in presence of Tamm-Horsfall protein

World Journal of Microbiology & Biotechnology, 2006

Tamm-Horsfall glycoprotein is the most abundant protein in human urine. The present investigation... more Tamm-Horsfall glycoprotein is the most abundant protein in human urine. The present investigation was planned to study the effect of Tamm-Horsfall protein (THP) on elaboration of virulence factors by biofilm cells of Pseudomonas aeruginosa. It was observed that with increase in concentration of THP from 10 to 50 μg/ml there was significant enhancement in elaboration of all the virulence factors by biofilm cells of P. aeruginosa. However, with further increase in concentration of THP from 50 to 70 μg/ml, significant decrease in elaboration of all the virulence traits was observed. Implications of these findings in relation to urinary tract infections caused by P. aeruginosa have been discussed.

Research paper thumbnail of Protective efficacy and immunogenicity of Escherichia coli K13 diphtheria toxoid conjugate against experimental ascending pyelonephritis

Medical Microbiology and Immunology, 2005

In the present study, protective efficacy of Escherichia coli capsular antigen, K13, was evaluate... more In the present study, protective efficacy of Escherichia coli capsular antigen, K13, was evaluated in a mouse model of pyelonephritis. Unconjugated capsular polysaccharide failed to provide any protection. However, coupling of K13 to diphtheria toxoid (DT) enhanced its immunogenicity and led to significant production of anticapsular antibodies in mice. Immunization of animals with K13–DT conjugate also caused significant improvement in cell-mediated immune response as indicated by an increase in lymphoblastogenic response and in the CD4+/CD8+ cell ratio of splenic lymphocytes. Significant decrease in bacterial load and renal severity scores were observed in K13–DT immunized animals. Suitability of K13–DT conjugate as an effective vaccine candidate against urinary tract infections caused by E. coli has been discussed.

Research paper thumbnail of Giant cell tumor of rib – rare location on the anterior aspect

Archives of Orthopaedic and Trauma Surgery, 2000

Giant cell tumor rarely occurs in ribs, where it presents posteriorly. We present a report of a g... more Giant cell tumor rarely occurs in ribs, where it presents posteriorly. We present a report of a giant cell tumor of bone occurring anteriorly in the rib with a review of the literature.

Research paper thumbnail of In Vitro Effect of Urinary Constituents on the Adhesion Ability of Pseudomonas aeruginosa to Human Uroepithelial Cells

Journal of Adhesion Science and Technology, 2009

Abstract Adhesion of uropathogens to epithelial cells is considered as an indispensable prerequis... more Abstract Adhesion of uropathogens to epithelial cells is considered as an indispensable prerequisite for the manifesta-tion of urinary tract infections. This study was carried out to investigate the influence of urinary constituents, such as glucose, lactose, urea and creatinine either alone or in ...

Research paper thumbnail of Contribution of quorum-sensing systems to virulence of Pseudomonas aeruginosa in an experimental pyelonephritis model

Pseudomonas aeruginosa has been reported to monitor its cell density as well as expression of vir... more Pseudomonas aeruginosa has been reported to monitor its cell density as well as expression of virulence determinants by quorum-sensing signal mechanisms operative through autoinducers. In the present investigation, we studied the contribution of quorum-sensing signals during the course of P. aeruginosa-induced pyelonephritis in mice. The standard parent strain of P. aeruginosa (PAO1), possessing functional las and rhl quorum-sensing systems and its isogenic mutant strains, PAO-JP1 (single mutant), harboring a mutated lasI gene and PAO-JP3 (double mutant), harboring mutated lasI and rhlR genes were employed. One uroisolate of P. aeruginosa belonging to serotype O8 and deficient in production of quorum-sensing signals was also used. The parent strain of P. aeruginosa was significantly more virulent compared to its isogenic mutant strains and quorum-sensing negative clinical strain, as assessed by neutrophil influx, malondialdehyde production, renal bacterial load and pathology induced in experimental animals. Quorum-sensing systems play an important role in the pathogenicity of P. aeruginosa in pyelonephritis. Both the las and rhl quorum-sensing systems are important for the virulence of P. aeruginosa in the development of pyelonephritis.

Research paper thumbnail of Effect of pH on production of virulence factors by biofilm cells of Pseudomonas aeruginosa

Folia Microbiologica, 2005

Effect of pH on production of extracellular virulence factors ofPseudomonas aeruginosa grown on c... more Effect of pH on production of extracellular virulence factors ofPseudomonas aeruginosa grown on catheter in biofilm was determined. Alginate and proteinase production was higher at pH 8; in contrast, siderophores (pyochelin and pyoverdin) were synthesized more intensively at pH 5.

Research paper thumbnail of Contribution of Tamm?Horsfall protein to virulence of in urinary tract infection

Microbes and Infection, 2005

Tamm-Horsfall glycoprotein (THP) is the most abundant protein which is synthesized by renal tubul... more Tamm-Horsfall glycoprotein (THP) is the most abundant protein which is synthesized by renal tubular cells and excreted in urine. Its role in urinary tract infection has yet not been identified. In the present study, the contribution of THP towards adherence of Pseudomonas aeruginosa to uroepithelial cells and murine peritoneal macrophages was studied. Decreased adherence of THP-coated P. aeruginosa to UECs and phagocytes was observed in vitro. In vivo, P. aeruginosa showed increased renal bacterial load and tissue pathology in a mouse model of acute ascending pyelonephritis, when THP-coated P. aeruginosa was used to cause infection. This study shows that THP may not necessarily act as a host defense component; rather, it may help in renal colonization of P. aeruginosa in vivo.

Research paper thumbnail of Effect of Osmolarity on Virulence of Uropathogenic Pseudomonas Aeruginosa

American Journal of Biomedical Sciences, 2009

In the milieu of urinary tract, urine is subject to changes in osmolarity depending on host's die... more In the milieu of urinary tract, urine is subject to changes in osmolarity depending on host's diet and clinical condition. The present investigation was planned to study the effect of osmolarity on growth and elaboration of virulence factors by Pseudomonas aeruginosa in planktonic and biofilm cell mode. Significant enhancement in growth and elaboration of all the virulence traits was observed with increase in osmolarity of the growth medium from 100 to 300 mOsmol/l. However, with further increase in osmolarity to 350 mOsmol/l there was significant decrease in growth and production of all the virulence determinants. In addition, organisms grown in 300 mOsmol/l medium showed increased adherence to uroepithelial cells, evade phagocytosis and were more virulent in mouse model of ascending pyelonephritis as indicated by higher bacterial load and tissue damage. The findings of the present study may be relevant for the better understanding of host-parasite interactions and will pave the way for the future development of preventive strategies against urinary tract infections.

Research paper thumbnail of Tuberculosis of the foot

Journal of Bone and Joint Surgery-british Volume, 1999

I n 44 patients with tuberculosis of the foot we identified five radiological patterns of lesions... more I n 44 patients with tuberculosis of the foot we identified five radiological patterns of lesions; cystic, rheumatoid, subperiosteal, kissing and spina ventosa. Cystic destruction had the best outcome and rheumatoid the poorest. All the patients were cured after antituberculous treatment for 18 months, and none required surgery.

Research paper thumbnail of Effect of macrophage secretory products on elaboration of virulence factors by planktonic and biofilm cells of Pseudomonas aeruginosa

Comparative Immunology Microbiology and Infectious Diseases, 2006

Macrophages, which constitute the first line of defense, pour their secretions in the mileu follo... more Macrophages, which constitute the first line of defense, pour their secretions in the mileu following stimulation with pathogens. These secretory products, referred to as macrophage secretory products (MSPs), can influence ultimate outcome of an infection. In the present investigation, it was observed that different strains of Pseudomonas aeruginosa vary in their ability to stimulate macrophages leading to variability in generation of macrophage secretory products. Cytokine levels, reactive nitrogen intermediates and protein content of macrophage secretory products generated with biofilm cells of P. aeruginosa was found to be more as compared to their planktonic counterparts. The effect of macrophage secretory products produced in response to interaction of macrophages with P. aeruginosa on elaboration of virulence factors produced by planktonic and biofilm cell forms of this pathogen was assessed. Significant enhancement in growth and elaboration of all the virulence determinants by both the cell forms was observed when P. aeruginosa was grown in presence of supernatants with macrophage secretory products. Implications of these findings in relation to urinary tract infections induced by P. aeruginosa have been discussed. q

Research paper thumbnail of Iron dictates the virulence of Pseudomonas aeruginosa in urinary tract infections

Journal of Biomedical Science, 2008

Iron-limiting conditions have been reported to be prevalent in the milieu of urinary tract. In th... more Iron-limiting conditions have been reported to be prevalent in the milieu of urinary tract. In the present investigation, effect of iron on virulence of uropathogenic Pseudomonas aeruginosa in planktonic and biofilm cell mode was studied. Significant enhancement in elaboration of all the virulence traits along with increased adherence to uroepithelial cells and decreased phagocytosis of P. aeruginosa was observed following growth in iron-deplete medium. On the contrary, decrease in all these parameters except phagocytosis was observed when P. aeruginosa was grown in iron-rich medium. In vivo, P. aeruginosa grown in iron-deplete medium showed increased renal bacterial load and tissue pathology in a mouse model of ascending urinary tract infection compared with organisms grown in iron-replete medium. The results of the present study may help in understanding host–parasite interaction and in developing alternative preventive approach against P. aeruginosa induced urinary tract infections.

Research paper thumbnail of Urinary tract infections caused by Pseudomonas aeruginosa: A minireview

Journal of Infection and Public Health, 2009

Urinary tract infections (UTIs) are a serious health problem affecting millions of people each ye... more Urinary tract infections (UTIs) are a serious health problem affecting millions of people each year. Infections of the urinary tract are the second most common type of infection in the body. Catheterization of the urinary tract is the most common factor, which predisposes the host to these infections. Catheterassociated UTI (CAUTI) is responsible for 40% of nosocomial infections, making it the most common cause of nosocomial infection. CAUTI accounts for more than 1 million cases in hospitals and nursing homes annually and often involve uropathogens other than Escherichia coli. While the epidemiology and pathogenic mechanisms of uropathogenic Escherichia coli have been extensively studied, little is known about the pathogenesis of UTIs caused by other organisms like Pseudomonas aeruginosa. Scanty available information regarding pathogenesis of UTIs caused by P. aeruginosa is an important bottleneck in developing effective preventive approaches. The aim of this review is to summarize some of the advances made in the field of P. aeruginosa induced UTIs and draws attention of the workers that more basic research at the level of pathogenesis is needed so that novel strategies can be designed.

Research paper thumbnail of Macrophage inflammatory protein-2, neutrophil recruitment and bacterial persistence in an experimental mouse model of urinary tract infection

Microbes and Infection, 2004

This study analyzed macrophage inflammatory protein-2 (MIP-2) production and neutrophil recruitme... more This study analyzed macrophage inflammatory protein-2 (MIP-2) production and neutrophil recruitment in urinary tract in response to Pseudomonas aeruginosa in an ascending model of urinary tract infection (UTI) in mice. Both planktonic and biofilm cells of P. aeruginosa were used for inducing UTI in mice. MIP-2 levels determined in urine, bladder and kidney showed maximum MIP-2 production 6 h postinfection, which correlated with neutrophil recruitment. Biofilm cells showed significantly more MIP-2 production and neutrophil recruitment. However, no correlation between bacterial numbers and neutrophil recruitment was observed in urine and kidney tissue. The role of MIP-2 and neutrophils in relation to the persistence of P. aeruginosa in the urinary tract of mice is discussed.

Research paper thumbnail of Contribution of Tamm–Horsfall protein to virulence of Pseudomonas aeruginosa in urinary tract infection

Microbes and Infection, 2005

Tamm-Horsfall glycoprotein (THP) is the most abundant protein which is synthesized by renal tubul... more Tamm-Horsfall glycoprotein (THP) is the most abundant protein which is synthesized by renal tubular cells and excreted in urine. Its role in urinary tract infection has yet not been identified. In the present study, the contribution of THP towards adherence of Pseudomonas aeruginosa to uroepithelial cells and murine peritoneal macrophages was studied. Decreased adherence of THP-coated P. aeruginosa to UECs and phagocytes was observed in vitro. In vivo, P. aeruginosa showed increased renal bacterial load and tissue pathology in a mouse model of acute ascending pyelonephritis, when THP-coated P. aeruginosa was used to cause infection. This study shows that THP may not necessarily act as a host defense component; rather, it may help in renal colonization of P. aeruginosa in vivo.

Research paper thumbnail of Contribution of free radicals to Pseudomonas aeruginosa induced acute pyelonephritis

Microbial Pathogenesis, 2008

Pyelonephritis induces an inflammatory process in the renal parenchyma, which may occur as a resu... more Pyelonephritis induces an inflammatory process in the renal parenchyma, which may occur as a result of excessive reactive nitrogen intermediates (RNI) and reactive oxygen species (ROS) and/or impaired antioxidant capacity. In the present investigation, contribution of free radicals to the development of acute pyelonephritis induced by planktonic and biofilm cells of Pseudomonas aeruginosa was studied. Increase in production of RNI and ROS in urine, bladder and renal tissue following infection with P. aeruginosa was observed which correlated with bacterial load, neutrophil recruitment and malondialdehyde (MDA). Evaluation of the data revealed that excessive production of free radicals causes tissue damage leading to bacterial persistence in host's tissues. Treatment of mice with N-acetylcysteine (NAC), a potent antioxidant, lead to significant amelioration of oxidative stress and subsequent decrease in bacterial titer, neutrophil influx, MDA as well as tissue pathology highlighting important role of free radicals in P. aeruginosa induced pyelonephritis. Results of the present study bring out that production of RNI and ROS contributes to the pathophysiology of pyelonephritis. These findings may be relevant for the better understanding of host-parasite interactions and may be of clinical importance in the development of preventive intervention against P. aeruginosa induced pyelonephritis.

Research paper thumbnail of Phenotypic characters of urinary isolates of Pseudomonas aeruginosa & their association with mouse renal colonization

Very few studies regarding production of virulence factors in different predominant serotypes of ... more Very few studies regarding production of virulence factors in different predominant serotypes of uropathogenic Pseudomonas aeruginosa are available and they have not been correlated to in vivo pathogenicity in the urinary tract. This study was carriedout with the objective to analyze the phenotypic characters of uroisolates of P. aeruginosa in vitro and to study the association of these virulence traits with their ability to cause nephropathogenicity in mouse model of ascending urinary tract infection (UTI).

Research paper thumbnail of Experimental Non-obstructive Chronic Renal Infection Model with Planktonic and Biofilm Cells of Pseudomonas Aeruginosa

American Journal of Biomedical Sciences, 2009

Availability of an acceptable animal model, which closely mimics human clinical situations in ter... more Availability of an acceptable animal model, which closely mimics human clinical situations in terms of receptors and route of entry, is of utmost importance to study host parasite interaction. In the present study, Swiss Webster (LACA) strain of female mice was chosen for induction of chronic renal inflammation by planktonic as well as biofilm cells of Pseudomonas aeruginosa. Bacterial inoculum was instilled thrice intrauretherally with the help of catheter. Both the cell forms were able to induce chronic renal inflammation in the experimental animals. However, severity of lesions induced by four day old biofilm cells was more as compared to planktonic cells. The chronic pyelonephritis model holds great promise for understanding the biology and pathogenesis of P. aeruginosa induced urinary tract infections as well as in development of effective preventive strategies.

Research paper thumbnail of Enhanced siderophore production and mouse kidney pathogenicity in Escherichia coli grown in urine

Journal of Medical Microbiology, 1991

Fifteen siderophore producing urinary isolates of Escherichia coli were compared for aerobactin a... more Fifteen siderophore producing urinary isolates of Escherichia coli were compared for aerobactin and enterochelin production in trypticase soy broth and pooled normal human urine. Significant increase in siderophore production (both phenolate and hydroxamate) was observed when organisms were grown in urine. Mouse kidney pathogenic potential of the strains grown in urine was compared with that of bacteria grown in trypticase soy broth in an ascending model of pyelonephritis in female Swiss Webster mice. Organisms grown in urine and instilled into a mouse bladder demonstrated markedly enhanced renal pathogenicity (p less than 0.01). Further information about the influence of urinary constituents on siderophore production could help in understanding the pathogenesis of pyelonephritis.

Research paper thumbnail of Alteration in virulence characteristics of biofilm cells of Pseudomonas aeruginosa in presence of Tamm-Horsfall protein

World Journal of Microbiology & Biotechnology, 2006

Tamm-Horsfall glycoprotein is the most abundant protein in human urine. The present investigation... more Tamm-Horsfall glycoprotein is the most abundant protein in human urine. The present investigation was planned to study the effect of Tamm-Horsfall protein (THP) on elaboration of virulence factors by biofilm cells of Pseudomonas aeruginosa. It was observed that with increase in concentration of THP from 10 to 50 μg/ml there was significant enhancement in elaboration of all the virulence factors by biofilm cells of P. aeruginosa. However, with further increase in concentration of THP from 50 to 70 μg/ml, significant decrease in elaboration of all the virulence traits was observed. Implications of these findings in relation to urinary tract infections caused by P. aeruginosa have been discussed.

Research paper thumbnail of Protective efficacy and immunogenicity of Escherichia coli K13 diphtheria toxoid conjugate against experimental ascending pyelonephritis

Medical Microbiology and Immunology, 2005

In the present study, protective efficacy of Escherichia coli capsular antigen, K13, was evaluate... more In the present study, protective efficacy of Escherichia coli capsular antigen, K13, was evaluated in a mouse model of pyelonephritis. Unconjugated capsular polysaccharide failed to provide any protection. However, coupling of K13 to diphtheria toxoid (DT) enhanced its immunogenicity and led to significant production of anticapsular antibodies in mice. Immunization of animals with K13–DT conjugate also caused significant improvement in cell-mediated immune response as indicated by an increase in lymphoblastogenic response and in the CD4+/CD8+ cell ratio of splenic lymphocytes. Significant decrease in bacterial load and renal severity scores were observed in K13–DT immunized animals. Suitability of K13–DT conjugate as an effective vaccine candidate against urinary tract infections caused by E. coli has been discussed.

Research paper thumbnail of Giant cell tumor of rib – rare location on the anterior aspect

Archives of Orthopaedic and Trauma Surgery, 2000

Giant cell tumor rarely occurs in ribs, where it presents posteriorly. We present a report of a g... more Giant cell tumor rarely occurs in ribs, where it presents posteriorly. We present a report of a giant cell tumor of bone occurring anteriorly in the rib with a review of the literature.

Research paper thumbnail of In Vitro Effect of Urinary Constituents on the Adhesion Ability of Pseudomonas aeruginosa to Human Uroepithelial Cells

Journal of Adhesion Science and Technology, 2009

Abstract Adhesion of uropathogens to epithelial cells is considered as an indispensable prerequis... more Abstract Adhesion of uropathogens to epithelial cells is considered as an indispensable prerequisite for the manifesta-tion of urinary tract infections. This study was carried out to investigate the influence of urinary constituents, such as glucose, lactose, urea and creatinine either alone or in ...

Research paper thumbnail of Contribution of quorum-sensing systems to virulence of Pseudomonas aeruginosa in an experimental pyelonephritis model

Pseudomonas aeruginosa has been reported to monitor its cell density as well as expression of vir... more Pseudomonas aeruginosa has been reported to monitor its cell density as well as expression of virulence determinants by quorum-sensing signal mechanisms operative through autoinducers. In the present investigation, we studied the contribution of quorum-sensing signals during the course of P. aeruginosa-induced pyelonephritis in mice. The standard parent strain of P. aeruginosa (PAO1), possessing functional las and rhl quorum-sensing systems and its isogenic mutant strains, PAO-JP1 (single mutant), harboring a mutated lasI gene and PAO-JP3 (double mutant), harboring mutated lasI and rhlR genes were employed. One uroisolate of P. aeruginosa belonging to serotype O8 and deficient in production of quorum-sensing signals was also used. The parent strain of P. aeruginosa was significantly more virulent compared to its isogenic mutant strains and quorum-sensing negative clinical strain, as assessed by neutrophil influx, malondialdehyde production, renal bacterial load and pathology induced in experimental animals. Quorum-sensing systems play an important role in the pathogenicity of P. aeruginosa in pyelonephritis. Both the las and rhl quorum-sensing systems are important for the virulence of P. aeruginosa in the development of pyelonephritis.

Research paper thumbnail of Effect of pH on production of virulence factors by biofilm cells of Pseudomonas aeruginosa

Folia Microbiologica, 2005

Effect of pH on production of extracellular virulence factors ofPseudomonas aeruginosa grown on c... more Effect of pH on production of extracellular virulence factors ofPseudomonas aeruginosa grown on catheter in biofilm was determined. Alginate and proteinase production was higher at pH 8; in contrast, siderophores (pyochelin and pyoverdin) were synthesized more intensively at pH 5.

Research paper thumbnail of Contribution of Tamm?Horsfall protein to virulence of in urinary tract infection

Microbes and Infection, 2005

Tamm-Horsfall glycoprotein (THP) is the most abundant protein which is synthesized by renal tubul... more Tamm-Horsfall glycoprotein (THP) is the most abundant protein which is synthesized by renal tubular cells and excreted in urine. Its role in urinary tract infection has yet not been identified. In the present study, the contribution of THP towards adherence of Pseudomonas aeruginosa to uroepithelial cells and murine peritoneal macrophages was studied. Decreased adherence of THP-coated P. aeruginosa to UECs and phagocytes was observed in vitro. In vivo, P. aeruginosa showed increased renal bacterial load and tissue pathology in a mouse model of acute ascending pyelonephritis, when THP-coated P. aeruginosa was used to cause infection. This study shows that THP may not necessarily act as a host defense component; rather, it may help in renal colonization of P. aeruginosa in vivo.

Research paper thumbnail of Effect of Osmolarity on Virulence of Uropathogenic Pseudomonas Aeruginosa

American Journal of Biomedical Sciences, 2009

In the milieu of urinary tract, urine is subject to changes in osmolarity depending on host's die... more In the milieu of urinary tract, urine is subject to changes in osmolarity depending on host's diet and clinical condition. The present investigation was planned to study the effect of osmolarity on growth and elaboration of virulence factors by Pseudomonas aeruginosa in planktonic and biofilm cell mode. Significant enhancement in growth and elaboration of all the virulence traits was observed with increase in osmolarity of the growth medium from 100 to 300 mOsmol/l. However, with further increase in osmolarity to 350 mOsmol/l there was significant decrease in growth and production of all the virulence determinants. In addition, organisms grown in 300 mOsmol/l medium showed increased adherence to uroepithelial cells, evade phagocytosis and were more virulent in mouse model of ascending pyelonephritis as indicated by higher bacterial load and tissue damage. The findings of the present study may be relevant for the better understanding of host-parasite interactions and will pave the way for the future development of preventive strategies against urinary tract infections.