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Infected foot ulcers in male and female diabetic patients: a clinico-bioinformative study.

Shakil S, Khan AU - Ann. Clin. Microbiol. Antimicrob. (2010)

Bottom Line: The residues Asn132, Glu166, Pro167, Val172, Lys234 and Thr235 of CTX-M-15 were found to make important contacts with cefotaxime in the docked-complex.Male diabetic patients with MDRGNB-infected foot ulcers have poor glycemic control and hence they might have higher mortality rates compared to their female counterparts.Since the docking results proved that the amino acid residues Asn132, Glu166, Pro167, Val172, Lys234 and Thr235 of CTX-M-15 (enzyme) make important contacts with cefotaxime (drug) in the 'enzyme-drug complex', researchers are expected to duly utilize this information for designing more potent and versatile CTX-M-inhibitors.

View Article: PubMed Central - HTML - PubMed

Affiliation: Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh, India-202002. shazicool@rediffmail.com

ABSTRACT

Background: The study aimed at (i) characterizing the mode of transmission of bla(CTX-M) and bla(TEM-1) among extended-spectrum-beta-lactamase (ESBL)-producing Escherichia coli strains isolated from infected diabetic foot ulcers, and (ii) identifying the risk factors for "sex-associated multidrug resistant Gram-negative bacterial (MDRGNB)-infection status" of the ulcers.

Methods: Seventy-seven diabetic patients having clinically infected foot ulcers were studied in a consecutive series. The E. coli strains isolated from the ulcers were screened for bla(CTX-M), bla(TEM-1), armA, rmtA and rmtB during the 2-year study-period. PCR amplified bla(CTX-M) genes were cloned and sequenced. Enterobacterial repetitive intergenic consensus (ERIC)-PCR was used for the analysis of genetic relatedness of the ESBL-producers. Risk factors for "sex-associated MDRGNB-infection status" of ulcers were assessed. Modeling was performed using Swiss-Model-Server and verified by Procheck and verify3D programmes. Discovery Studio2.0 (Accelrys) was used to prepare Ramachandran plots. Z-scores were calculated using 'WHAT IF'-package. Docking of cefotaxime with modeled CTX-M-15 enzyme was performed using Hex5.1.

Results: Among 51 E. coli isolates, 14 (27.5%) ESBL-producers were identified. Only 7 Class1 integrons, 2 bla(CTX-M-15), and 1 bla(TEM-1) were detected. Ceftazidime and cefotaxime resistance markers were present on the plasmidic DNA of both the bla(CTX-M-15) positive strains and were transmissible through conjugation. The residues Asn132, Glu166, Pro167, Val172, Lys234 and Thr235 of CTX-M-15 were found to make important contacts with cefotaxime in the docked-complex. Multivariate analysis proved 'Glycemic control at discharge' as the single independent risk factor.

Conclusions: Male diabetic patients with MDRGNB-infected foot ulcers have poor glycemic control and hence they might have higher mortality rates compared to their female counterparts. Plasmid-mediated conjugal transfer, albeit at a low frequency might be the possible mechanism of transfer of bla(CTX-M-15) resistance marker in the present setting. Since the docking results proved that the amino acid residues Asn132, Glu166, Pro167, Val172, Lys234 and Thr235 of CTX-M-15 (enzyme) make important contacts with cefotaxime (drug) in the 'enzyme-drug complex', researchers are expected to duly utilize this information for designing more potent and versatile CTX-M-inhibitors.

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(a) CTX-M-15 enzyme modeled from the blaCTX-M-15 gene sequence [Genbank: FJ997866] of E. coli strain D253. The active site Ω-loop, the SDN loop and the KTG motif are labeled. A = 91.5%, B = 7.8%, C = 0.7%, D = 0.0%, where 'A', 'B', 'C' and 'D' stand for percent amino acid residues in most favored, additional allowed, generously allowed and disallowed regions of the Ramachandran plot respectively. The z-score for the modeled structure was equal to 0.027. (b) Amino acid residues crucial to the interaction between cefotaxime and CTX-M-15.
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Figure 3: (a) CTX-M-15 enzyme modeled from the blaCTX-M-15 gene sequence [Genbank: FJ997866] of E. coli strain D253. The active site Ω-loop, the SDN loop and the KTG motif are labeled. A = 91.5%, B = 7.8%, C = 0.7%, D = 0.0%, where 'A', 'B', 'C' and 'D' stand for percent amino acid residues in most favored, additional allowed, generously allowed and disallowed regions of the Ramachandran plot respectively. The z-score for the modeled structure was equal to 0.027. (b) Amino acid residues crucial to the interaction between cefotaxime and CTX-M-15.

Mentions: Over 90% of the amino acid residues in the protein structures modeled from blaCTX-M-15 genes obtained in this study were found to be present in the most favorable regions as revealed by their respective Ramachandran plots. The Ramachandran Z-score for modeled enzyme from strain D253 was found to be 0.027 (Fig 3a), which further confirms the accuracy of the modeled structure. Cefotaxime was docked into the modeled enzyme-structures. It was found that the strain (D253) having a higher cefotaxime MIC displayed a higher negative binding energy as well (Table 1). Analysis of the docked structures by Discovery Studio2.0 revealed that the amino acid residues Asn132, Glu166, Pro167, Val172, Lys234 and Thr235 make important contacts with cefotaxime (Fig 3b).


Infected foot ulcers in male and female diabetic patients: a clinico-bioinformative study.

Shakil S, Khan AU - Ann. Clin. Microbiol. Antimicrob. (2010)

(a) CTX-M-15 enzyme modeled from the blaCTX-M-15 gene sequence [Genbank: FJ997866] of E. coli strain D253. The active site Ω-loop, the SDN loop and the KTG motif are labeled. A = 91.5%, B = 7.8%, C = 0.7%, D = 0.0%, where 'A', 'B', 'C' and 'D' stand for percent amino acid residues in most favored, additional allowed, generously allowed and disallowed regions of the Ramachandran plot respectively. The z-score for the modeled structure was equal to 0.027. (b) Amino acid residues crucial to the interaction between cefotaxime and CTX-M-15.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2821376&req=5

Figure 3: (a) CTX-M-15 enzyme modeled from the blaCTX-M-15 gene sequence [Genbank: FJ997866] of E. coli strain D253. The active site Ω-loop, the SDN loop and the KTG motif are labeled. A = 91.5%, B = 7.8%, C = 0.7%, D = 0.0%, where 'A', 'B', 'C' and 'D' stand for percent amino acid residues in most favored, additional allowed, generously allowed and disallowed regions of the Ramachandran plot respectively. The z-score for the modeled structure was equal to 0.027. (b) Amino acid residues crucial to the interaction between cefotaxime and CTX-M-15.
Mentions: Over 90% of the amino acid residues in the protein structures modeled from blaCTX-M-15 genes obtained in this study were found to be present in the most favorable regions as revealed by their respective Ramachandran plots. The Ramachandran Z-score for modeled enzyme from strain D253 was found to be 0.027 (Fig 3a), which further confirms the accuracy of the modeled structure. Cefotaxime was docked into the modeled enzyme-structures. It was found that the strain (D253) having a higher cefotaxime MIC displayed a higher negative binding energy as well (Table 1). Analysis of the docked structures by Discovery Studio2.0 revealed that the amino acid residues Asn132, Glu166, Pro167, Val172, Lys234 and Thr235 make important contacts with cefotaxime (Fig 3b).

Bottom Line: The residues Asn132, Glu166, Pro167, Val172, Lys234 and Thr235 of CTX-M-15 were found to make important contacts with cefotaxime in the docked-complex.Male diabetic patients with MDRGNB-infected foot ulcers have poor glycemic control and hence they might have higher mortality rates compared to their female counterparts.Since the docking results proved that the amino acid residues Asn132, Glu166, Pro167, Val172, Lys234 and Thr235 of CTX-M-15 (enzyme) make important contacts with cefotaxime (drug) in the 'enzyme-drug complex', researchers are expected to duly utilize this information for designing more potent and versatile CTX-M-inhibitors.

View Article: PubMed Central - HTML - PubMed

Affiliation: Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh, India-202002. shazicool@rediffmail.com

ABSTRACT

Background: The study aimed at (i) characterizing the mode of transmission of bla(CTX-M) and bla(TEM-1) among extended-spectrum-beta-lactamase (ESBL)-producing Escherichia coli strains isolated from infected diabetic foot ulcers, and (ii) identifying the risk factors for "sex-associated multidrug resistant Gram-negative bacterial (MDRGNB)-infection status" of the ulcers.

Methods: Seventy-seven diabetic patients having clinically infected foot ulcers were studied in a consecutive series. The E. coli strains isolated from the ulcers were screened for bla(CTX-M), bla(TEM-1), armA, rmtA and rmtB during the 2-year study-period. PCR amplified bla(CTX-M) genes were cloned and sequenced. Enterobacterial repetitive intergenic consensus (ERIC)-PCR was used for the analysis of genetic relatedness of the ESBL-producers. Risk factors for "sex-associated MDRGNB-infection status" of ulcers were assessed. Modeling was performed using Swiss-Model-Server and verified by Procheck and verify3D programmes. Discovery Studio2.0 (Accelrys) was used to prepare Ramachandran plots. Z-scores were calculated using 'WHAT IF'-package. Docking of cefotaxime with modeled CTX-M-15 enzyme was performed using Hex5.1.

Results: Among 51 E. coli isolates, 14 (27.5%) ESBL-producers were identified. Only 7 Class1 integrons, 2 bla(CTX-M-15), and 1 bla(TEM-1) were detected. Ceftazidime and cefotaxime resistance markers were present on the plasmidic DNA of both the bla(CTX-M-15) positive strains and were transmissible through conjugation. The residues Asn132, Glu166, Pro167, Val172, Lys234 and Thr235 of CTX-M-15 were found to make important contacts with cefotaxime in the docked-complex. Multivariate analysis proved 'Glycemic control at discharge' as the single independent risk factor.

Conclusions: Male diabetic patients with MDRGNB-infected foot ulcers have poor glycemic control and hence they might have higher mortality rates compared to their female counterparts. Plasmid-mediated conjugal transfer, albeit at a low frequency might be the possible mechanism of transfer of bla(CTX-M-15) resistance marker in the present setting. Since the docking results proved that the amino acid residues Asn132, Glu166, Pro167, Val172, Lys234 and Thr235 of CTX-M-15 (enzyme) make important contacts with cefotaxime (drug) in the 'enzyme-drug complex', researchers are expected to duly utilize this information for designing more potent and versatile CTX-M-inhibitors.

Show MeSH
Related in: MedlinePlus