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Sensitivity to Polymyxin B in El Tor Vibrio cholerae O1 Strain, Kolkata, India.

Samanta P, Ghosh P, Chowdhury G, Ramamurthy T, Mukhopadhyay AK - Emerging Infect. Dis. (2015)

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Since the seventh cholera pandemic, which occurred during the 1960s and 1970s and was caused by El Tor strains, the El Tor biotype had been resistant to polymyxin B, a cationic antimicrobial peptide... However, when cholera strains first appeared in patients in Kolkata, India, in June 2012, V. cholerae O1 was found to be sensitive to polymyxin B... To determine whether this phenomenon occurred earlier, we tested 255 clinical strains isolated from patients in Kolkata during 2003–2014 and found that, from March 2013, polymyxin B–sensitive El Tor strains had replaced resistant strains (Figure, panel A)... The MIC of polymyxin B, determined by Etest (bioMérieux, Marcy l’Etoile, France), confirmed that the El Tor strains were susceptible to this antimicrobial drug (Figure, panel B)... In this assay, the El Tor strain (N16961) was highly resistant to polymyxin B (MIC 96 µg/mL), whereas the variant strains in Kolkata showed a drastic reduction in resistance... To confirm additional changes in biotype attributes in the variant Kolkata isolates during 2003–2014, we used the Voges-Proskauer test to determine production of acetylmethyl carbinol and found that the tested strains produced acetoin and were positive for chicken erythrocytes agglutination... The rtsC gene encoding the activator protein, which is absent from classical biotype strains but present in El Tor strains, was found in all the tested strains of the El Tor biotype... Furthermore, Vibrio seventh pandemic (VSP) gene clusters VSP I and VSP II are unique to El Tor strains of the seventh pandemic... We found presence of VSP I and II encoding genes in all our tested strains, indicating that the strains are El Tor, but with specific classical traits... Analysis of these genes from the newly emerged polymyxin-B–sensitive strains may provide additional useful information... We found that these strains contained Haitian variant ctxB (ctxB7) similar to the classical cholera toxin... Our earlier studies identified many new attributes of Haitian V. cholerae variant strains in Kolkata since 2003... The recent changes in V. cholerae O1 strains should be carefully monitored to determine their clinical and epidemiologic implications.

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Isolation profile of polymyxin B–sensitive Vibrio cholerae strains in Kolkata, India, 2003–2014. A) Yearly occurrence of polymyxin B sensitivity and resistance in V. cholerae O1 El Tor variant strains isolated from Kolkata patients. During the study period, 255 strains were tested; n values indicate the number of strains tested each year. Polymyxin B–sensitive strains first appeared in Kolkata in June 2012. The first isolate in January 2013 was resistant, but, thereafter, all strains isolated during 2013–2014 were sensitive to polymyxin B, a biotyping marker for classical strains. B) MIC of polymyxin B in El Tor variant strains (classical and El Tor). MICs are indicated by white arrows. Polymyxin B sensitivity, a characteristic of classical strains, was displayed by El Tor variant strains. Data represent 3 biologic repetitions.
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Figure 1: Isolation profile of polymyxin B–sensitive Vibrio cholerae strains in Kolkata, India, 2003–2014. A) Yearly occurrence of polymyxin B sensitivity and resistance in V. cholerae O1 El Tor variant strains isolated from Kolkata patients. During the study period, 255 strains were tested; n values indicate the number of strains tested each year. Polymyxin B–sensitive strains first appeared in Kolkata in June 2012. The first isolate in January 2013 was resistant, but, thereafter, all strains isolated during 2013–2014 were sensitive to polymyxin B, a biotyping marker for classical strains. B) MIC of polymyxin B in El Tor variant strains (classical and El Tor). MICs are indicated by white arrows. Polymyxin B sensitivity, a characteristic of classical strains, was displayed by El Tor variant strains. Data represent 3 biologic repetitions.

Mentions: Since the seventh cholera pandemic, which occurred during the 1960s and 1970s and was caused by El Tor strains, the El Tor biotype had been resistant to polymyxin B, a cationic antimicrobial peptide. However, when cholera strains first appeared in patients in Kolkata, India, in June 2012, V. cholerae O1 was found to be sensitive to polymyxin B (6). To determine whether this phenomenon occurred earlier, we tested 255 clinical strains isolated from patients in Kolkata during 2003–2014 and found that, from March 2013, polymyxin B–sensitive El Tor strains had replaced resistant strains (Figure, panel A). The MIC of polymyxin B, determined by Etest (bioMérieux, Marcy l’Etoile, France), confirmed that the El Tor strains were susceptible to this antimicrobial drug (Figure, panel B). In this assay, the El Tor strain (N16961) was highly resistant to polymyxin B (MIC 96 µg/mL), whereas the variant strains in Kolkata showed a drastic reduction in resistance (6,7).


Sensitivity to Polymyxin B in El Tor Vibrio cholerae O1 Strain, Kolkata, India.

Samanta P, Ghosh P, Chowdhury G, Ramamurthy T, Mukhopadhyay AK - Emerging Infect. Dis. (2015)

Isolation profile of polymyxin B–sensitive Vibrio cholerae strains in Kolkata, India, 2003–2014. A) Yearly occurrence of polymyxin B sensitivity and resistance in V. cholerae O1 El Tor variant strains isolated from Kolkata patients. During the study period, 255 strains were tested; n values indicate the number of strains tested each year. Polymyxin B–sensitive strains first appeared in Kolkata in June 2012. The first isolate in January 2013 was resistant, but, thereafter, all strains isolated during 2013–2014 were sensitive to polymyxin B, a biotyping marker for classical strains. B) MIC of polymyxin B in El Tor variant strains (classical and El Tor). MICs are indicated by white arrows. Polymyxin B sensitivity, a characteristic of classical strains, was displayed by El Tor variant strains. Data represent 3 biologic repetitions.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4622255&req=5

Figure 1: Isolation profile of polymyxin B–sensitive Vibrio cholerae strains in Kolkata, India, 2003–2014. A) Yearly occurrence of polymyxin B sensitivity and resistance in V. cholerae O1 El Tor variant strains isolated from Kolkata patients. During the study period, 255 strains were tested; n values indicate the number of strains tested each year. Polymyxin B–sensitive strains first appeared in Kolkata in June 2012. The first isolate in January 2013 was resistant, but, thereafter, all strains isolated during 2013–2014 were sensitive to polymyxin B, a biotyping marker for classical strains. B) MIC of polymyxin B in El Tor variant strains (classical and El Tor). MICs are indicated by white arrows. Polymyxin B sensitivity, a characteristic of classical strains, was displayed by El Tor variant strains. Data represent 3 biologic repetitions.
Mentions: Since the seventh cholera pandemic, which occurred during the 1960s and 1970s and was caused by El Tor strains, the El Tor biotype had been resistant to polymyxin B, a cationic antimicrobial peptide. However, when cholera strains first appeared in patients in Kolkata, India, in June 2012, V. cholerae O1 was found to be sensitive to polymyxin B (6). To determine whether this phenomenon occurred earlier, we tested 255 clinical strains isolated from patients in Kolkata during 2003–2014 and found that, from March 2013, polymyxin B–sensitive El Tor strains had replaced resistant strains (Figure, panel A). The MIC of polymyxin B, determined by Etest (bioMérieux, Marcy l’Etoile, France), confirmed that the El Tor strains were susceptible to this antimicrobial drug (Figure, panel B). In this assay, the El Tor strain (N16961) was highly resistant to polymyxin B (MIC 96 µg/mL), whereas the variant strains in Kolkata showed a drastic reduction in resistance (6,7).

View Article: PubMed Central - PubMed

AUTOMATICALLY GENERATED EXCERPT
Please rate it.

Since the seventh cholera pandemic, which occurred during the 1960s and 1970s and was caused by El Tor strains, the El Tor biotype had been resistant to polymyxin B, a cationic antimicrobial peptide... However, when cholera strains first appeared in patients in Kolkata, India, in June 2012, V. cholerae O1 was found to be sensitive to polymyxin B... To determine whether this phenomenon occurred earlier, we tested 255 clinical strains isolated from patients in Kolkata during 2003–2014 and found that, from March 2013, polymyxin B–sensitive El Tor strains had replaced resistant strains (Figure, panel A)... The MIC of polymyxin B, determined by Etest (bioMérieux, Marcy l’Etoile, France), confirmed that the El Tor strains were susceptible to this antimicrobial drug (Figure, panel B)... In this assay, the El Tor strain (N16961) was highly resistant to polymyxin B (MIC 96 µg/mL), whereas the variant strains in Kolkata showed a drastic reduction in resistance... To confirm additional changes in biotype attributes in the variant Kolkata isolates during 2003–2014, we used the Voges-Proskauer test to determine production of acetylmethyl carbinol and found that the tested strains produced acetoin and were positive for chicken erythrocytes agglutination... The rtsC gene encoding the activator protein, which is absent from classical biotype strains but present in El Tor strains, was found in all the tested strains of the El Tor biotype... Furthermore, Vibrio seventh pandemic (VSP) gene clusters VSP I and VSP II are unique to El Tor strains of the seventh pandemic... We found presence of VSP I and II encoding genes in all our tested strains, indicating that the strains are El Tor, but with specific classical traits... Analysis of these genes from the newly emerged polymyxin-B–sensitive strains may provide additional useful information... We found that these strains contained Haitian variant ctxB (ctxB7) similar to the classical cholera toxin... Our earlier studies identified many new attributes of Haitian V. cholerae variant strains in Kolkata since 2003... The recent changes in V. cholerae O1 strains should be carefully monitored to determine their clinical and epidemiologic implications.

No MeSH data available.


Related in: MedlinePlus