Limits...
Depolymerase improves gentamicin efficacy during Klebsiella pneumoniae induced murine infection.

Bansal S, Harjai K, Chhibber S - BMC Infect. Dis. (2014)

Bottom Line: Highly significant reduction in neutrophil infiltration and levels of pro-inflammatory and anti-inflammatory cytokines was also observed.In addition, as confirmed through flow cytometry, the hyperimmune sera raised against the enzyme did not neutralize its activity.Moreover, since this decapsulating protein does not possess a lytic activity therefore there would be no chances of development of bacterial resistance against it.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, Panjab University, Sector-14, Chandigarh 160014, India. sanjaychhibber8@gmail.com.

ABSTRACT

Background: Presence of capsule enhances the virulence of bacteria that cause pneumonia, meningitis, cystic fibrosis, dental caries, periodontitis. Capsule is an important virulence factor for Klebsiella pneumoniae and infections due to this pathogen have been associated with high mortality rates. In the present study, use of an Aeromonas punctata derived capsule depolymerase against K. pneumoniae, to reinstate the efficacy of gentamicin during pneumonia and septicemia was investigated.

Methods: Depolymerase was administered in mice intraperitoneally (50 μg) alone as well in combination with gentamicin (1.5 mg/kg), 24 h post infection during acute lung infection and 6 h later during septicemia. Bacterial load, neutrophil infiltration and cytokine levels were estimated. The immunogenicity of protein was also studied.

Results: In comparison to groups treated with gentamicin alone, combination treatment with depolymerase and gentamicin significantly reduced (P < 0.01) bacterial titer in the lungs, liver, kidney, spleen and blood of experimental animals. Highly significant reduction in neutrophil infiltration and levels of pro-inflammatory and anti-inflammatory cytokines was also observed. This indicated an efficient capsule removal by the enzyme, that improved gentamicin efficacy in vivo. Although the enzyme was found to be immunogenic, but no significant reduction in treatment efficacy was observed in the preimmunized as well as naïve mice. In addition, as confirmed through flow cytometry, the hyperimmune sera raised against the enzyme did not neutralize its activity.

Conclusion: The results confirm that administration of enzyme 'depolymerase' along with gentamicin not only checked the virulence of K. pneumoniae in vivo but it also increased its susceptibility to gentamicin at a lower concentration. Such a strategy would help to avoid exposure to higher concentration of gentamicin. Moreover, since this decapsulating protein does not possess a lytic activity therefore there would be no chances of development of bacterial resistance against it. Therefore, it should be studied further for its successful inclusion in our prophylactic/therapeutic regimes.

Show MeSH

Related in: MedlinePlus

Log10CFU/ml on 3rdday in naïve untreated mice (Group 1, G1), naïve treated mice (Group 2, G2) and immunized treated mice (Group 3, G3) challenged with 104 CFU/50 μl K. pneumoniaeB5055.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC4150946&req=5

Fig6: Log10CFU/ml on 3rdday in naïve untreated mice (Group 1, G1), naïve treated mice (Group 2, G2) and immunized treated mice (Group 3, G3) challenged with 104 CFU/50 μl K. pneumoniaeB5055.

Mentions: To address the possibility of antibodies against depolymerase, neutralizing the protective efficacy offered by it, hyperimmune serum was raised against the purified protein in mice. Antibody titer of 1,000 was obtained against depolymerase. Thereafter, mice with antisera against depolymerase were challenged intranasally with 104 CFU/50 μl. These were then treated with 50 μg of depolymerase, 24 h post infection. A count of 8.9 Log10CFU/ml was observed in naïve infected untreated mice on the peak day (day 3) (Figure 6). In contrast, no significant difference (P > 0.01) in bacterial count was observed in immunized treated mice (7 Log10CFU/ml) and naïve treated mice [(6.6 Log10CFU/ml), not previously exposed to the enzyme hence with no antisera] (Figure 6).Figure 6


Depolymerase improves gentamicin efficacy during Klebsiella pneumoniae induced murine infection.

Bansal S, Harjai K, Chhibber S - BMC Infect. Dis. (2014)

Log10CFU/ml on 3rdday in naïve untreated mice (Group 1, G1), naïve treated mice (Group 2, G2) and immunized treated mice (Group 3, G3) challenged with 104 CFU/50 μl K. pneumoniaeB5055.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4150946&req=5

Fig6: Log10CFU/ml on 3rdday in naïve untreated mice (Group 1, G1), naïve treated mice (Group 2, G2) and immunized treated mice (Group 3, G3) challenged with 104 CFU/50 μl K. pneumoniaeB5055.
Mentions: To address the possibility of antibodies against depolymerase, neutralizing the protective efficacy offered by it, hyperimmune serum was raised against the purified protein in mice. Antibody titer of 1,000 was obtained against depolymerase. Thereafter, mice with antisera against depolymerase were challenged intranasally with 104 CFU/50 μl. These were then treated with 50 μg of depolymerase, 24 h post infection. A count of 8.9 Log10CFU/ml was observed in naïve infected untreated mice on the peak day (day 3) (Figure 6). In contrast, no significant difference (P > 0.01) in bacterial count was observed in immunized treated mice (7 Log10CFU/ml) and naïve treated mice [(6.6 Log10CFU/ml), not previously exposed to the enzyme hence with no antisera] (Figure 6).Figure 6

Bottom Line: Highly significant reduction in neutrophil infiltration and levels of pro-inflammatory and anti-inflammatory cytokines was also observed.In addition, as confirmed through flow cytometry, the hyperimmune sera raised against the enzyme did not neutralize its activity.Moreover, since this decapsulating protein does not possess a lytic activity therefore there would be no chances of development of bacterial resistance against it.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, Panjab University, Sector-14, Chandigarh 160014, India. sanjaychhibber8@gmail.com.

ABSTRACT

Background: Presence of capsule enhances the virulence of bacteria that cause pneumonia, meningitis, cystic fibrosis, dental caries, periodontitis. Capsule is an important virulence factor for Klebsiella pneumoniae and infections due to this pathogen have been associated with high mortality rates. In the present study, use of an Aeromonas punctata derived capsule depolymerase against K. pneumoniae, to reinstate the efficacy of gentamicin during pneumonia and septicemia was investigated.

Methods: Depolymerase was administered in mice intraperitoneally (50 μg) alone as well in combination with gentamicin (1.5 mg/kg), 24 h post infection during acute lung infection and 6 h later during septicemia. Bacterial load, neutrophil infiltration and cytokine levels were estimated. The immunogenicity of protein was also studied.

Results: In comparison to groups treated with gentamicin alone, combination treatment with depolymerase and gentamicin significantly reduced (P < 0.01) bacterial titer in the lungs, liver, kidney, spleen and blood of experimental animals. Highly significant reduction in neutrophil infiltration and levels of pro-inflammatory and anti-inflammatory cytokines was also observed. This indicated an efficient capsule removal by the enzyme, that improved gentamicin efficacy in vivo. Although the enzyme was found to be immunogenic, but no significant reduction in treatment efficacy was observed in the preimmunized as well as naïve mice. In addition, as confirmed through flow cytometry, the hyperimmune sera raised against the enzyme did not neutralize its activity.

Conclusion: The results confirm that administration of enzyme 'depolymerase' along with gentamicin not only checked the virulence of K. pneumoniae in vivo but it also increased its susceptibility to gentamicin at a lower concentration. Such a strategy would help to avoid exposure to higher concentration of gentamicin. Moreover, since this decapsulating protein does not possess a lytic activity therefore there would be no chances of development of bacterial resistance against it. Therefore, it should be studied further for its successful inclusion in our prophylactic/therapeutic regimes.

Show MeSH
Related in: MedlinePlus