Prevalence, Molecular Diagnosis and Management of Klebsiella species in Captive Sloth Bears (Melursus ursinus)

Genus Klebsiella from faeces of sloth bears was screened by using culture morphology, Gram’s staining, biochemical tests and polymerase chain reaction. Our results showed that out of 60 samples collected, 22 samples (36.67%) were cultured on Klebsiella Selective Agar Base with Klebsiella Selective Supplement and Gram’s stain revealed rod-shaped Gram-negative organism with purple-magenta colony - like colonies. The biochemical tests of cultured samples revealed negative to indole production and methyl red test, positive to Voges-Proskauer test, positive to Simmon citrate utilization test, negative to H2S production and that produced acid over acid reaction in TSI agar and positive to urea production in cultured samples. All Klebsiella species isolates were sensitive to azithromycin followed by enrofloxacin and resistant to clindamycin and methicillin. The gyrA gene was amplified by PCR for the genus Klebsiella and found to be positive of 36.67%. This study may provide information for developing strategies in the future in the control of Klebsiella species infections in sloth bears

Detecção de resistência às fluoroquinolonas em Campylobacter isolados de frangos de criação orgânica / Detection of fluoroquinolone resistance in Campylobacter strains from organic poultry

Estudos têm revelado que a resistência às quinolonas em cepas de Campylobacter está relacionada à presença da mutação Treonina-86 para Isoleucina. Com o objetivo de investigar a presença dessa mutação em cepas de Campylobacter sensíveis e resistentes à ciprofloxacina e enrofloxacina, o conteúdo cecal de 80 frangos de corte de criação orgânica, abatidos sob Serviço de Inspeção Estadual (S.I.E.) do Estado do Rio de Janeiro, foram coletados e investigados para a presença de Campylobacter. A determinação da resistência à ciprofloxacina e enrofloxacina foi feita pela técnica de difusão em disco e de diluição em ágar para determinação da Concentração Inibitória Mínima (CIM). A detecção da mutação na Região Determinante de Resistencia às Quinolonas (RDRQ) no gene gyrA foi realizada através de sequenciamento. Campylobacter foi isolado a partir de 100% das amostras avaliadas, sendo 68,75% correspondente à C. jejuni e 31,25% à C. coli. No teste de difusão em disco, 100% das cepas foram resistentes à ciprofloxacina e 56,25% das cepas foram resistentes à enrofloxacina. No teste de diluição em ágar, todas as cepas foram resistentes à ciprofloxacina apresentando CIM variando de ≥ 16-64μg/mL, e resistência ou resistência intermediaria à enrofloxacina foi detectada em 42,50% (CIM ≥ 4-32μg/mL) e 38,75% (CIM = 2μg/mL) das cepas, respectivamente. A mutação Tre-86-Ile, foi observada em 100% das cepas analisadas. Além dessa mutação, foram observadas outras mutações não silenciosas (Val-73-Glu, Ser-114-Leu, Val-88-Asp, Ala-75-Asp, Ser-119-Gli, Arg-79-Lis) e mutações silenciosas (His-81-His, Ser-119-Ser, Ala-120-Ala, Fen-99-Fen, Ala-122-Ala, Gli-74-Gli, Ile-77-Ile, Ala-91-Ala, Leu-92-Leu, Val-93-Val, Ile-106-Ile, Tre-107-Tre, Gli-113-Gli, Ile-115-Ile, Gli-110-Gli). A observação de que cepas sensíveis à enrofloxacina pelos testes fenotípicos apresentavam a substituição Tre-86 para Ile sugere que outros mecanismos podem contribuir para a resistência à enrofloxacina em Campylobacter...

Studies have shown that resistance to quinolones in Campylobacter strains is related with Threonine-86-Isoleucine mutation. In order to investigate the presence of this mutation in sensitive and resistant Campylobacter strains to ciprofloxacin and enrofloxacin, the cecal contents of 80 broilers from organic raising chickens, slaughtered under State Inspection Service (S.I.S) of the State of Rio de Janeiro, were collected and tested for the presence of Campylobacter. The determination of ciprofloxacin and enrofloxacin susceptibility was done by disk diffusion and agar dilution methods for determining the Minimum Inhibitory Concentration (MIC). The detection of mutation in Quinolone Resistance Determinant Region (QRDR) in gyrA gene was done by sequencing. Campylobacter was isolated from 100% of the samples, being 68.75% C. jejuni and 31.25% C. coli. By the disk diffusion method, resistance to ciprofloxacin was observed in all isolates and 56.25% of the strains were resistant to enrofloxacin. By agar dilution method, all strains were resistant to ciprofloxacin (MIC ≥ 16μg/mL to ≥ 64μg/mL) and full and intermediate resistance to enrofloxacin was detected in 42.50% (MIC ≥ 4-32μg/mL) and 38.75% (MIC =2μg/mL) of the strains, respectively. Mutation Thr-86-Ile was observed in 100% of the isolates investigated. In addition to this mutation, others no silent mutations (Val-73-Glu, Ser-114-Leu, Val-88-Asp, Ala-75-Asp, Gly-119-Ser, Arg-79-Lys) and silent mutations (His-81-His, Ser-119-Ser, Ala-120-Ala, Phe-99-Phe, Ala-122-Ala, Gly-74-Gly, Ile-77-Ile, Ala-91-Ala, Leu-92-Leu, Val-93-Val, Ile-106-Ile, Thr-107-Thr, Gly-113-Gly, Ile-115-Ile, Gly-110-Gly) were detected. All the enrofloxacin-sensitive strains by the phenotypic methods had the Thr-86 to Ile substitution, which suggests other mechanisms contributing to enrofloxacin resistance in Campylobacter...

Novel restriction enzyme SSiI for the detection of mutation in GyrA gene of Salmonella enterica serovar Typhi.

Aim: Enteric fever is an ongoing problem in the developing nations. Resistance and reduced susceptibility to ciprofloxacin narrows the therapeutic options in enteric fever. The present study was carried out with the objective of determining molecular basis of resistance to fluoroquinolone among the clinical isolates of Salmonella enterica serovar Typhi from different parts of India. Materials and Methods: A total of 60 S.Typhi clinical isolates were subjected to antimicrobial susceptibility testing and determination of minimum inhibitory concentration (MIC) to ciprofloxacin and nalidixic acid. Polymerase chain reaction (PCR) for GyrA gene followed by restriction fragment length polymorphism (RFLP) with restriction enzyme (RE) SSiI was performed to detect mutation at position Ser83. Further confirmation of mutation was done by nucleotide sequencing of GyrA gene. Results: Isolates showed 100% sensitivity to first-line drugs ampicillin, chloramphenicol, and cotrimoxazole. Twelve of the 60 isolates (18%) were susceptible to nalidixic acid (NASST) and the remaining 48 (82%) were resistant to nalidixic acid (NARST). Of these 48 NARST strains, 46 (97.5%) had reduced susceptibility to ciprofloxacin (MIC 0.25-1.0 μg/mL), whereas 2 strains (2.75%) were resistant to ciprofloxacin (MIC 4.0 μg/mL). In RFLP analysis, all the NASST strains showed 3 fragments, whereas all the NARST strains showed 2 fragments due to the loss of 1 restriction site as a result of mutation. All the NARST strains with reduced susceptibility to ciprofloxacin (n = 46) had a single mutation in gyrA gene (Ser 83→Tyr or Ser 83→Phe), whereas double mutations (Ser 83→Phe and Asp 87→Asn) were found in each of the 2 ciprofloxacin-resistant strains. None of the NASST strains (n = 12) revealed any mutation. Conclusion: Our study exemplifies the correlation between nalidixic acid screening test, MIC values, and the detection of mutation in GyrA gene by PCR-RFLP with a novel RE SSiI.This was further confirmed by nucleotide sequencing.

A study on gyrA mutant in Levofloxacin-resistant Brucella melitensis induced resistant strains in vitro / 中国地方病学杂志

Objective To study on the drug-resistance mechanism of Brucella resistance to Quinolone antibiotics to guide the selection and use of antimicrobial agents in clinical practice. Methods Six strains of Brucella melitensis(Bru1, Bru2, Bru3, Bru4, Bru5, Bru6) were selected to be induced resistance to levofloxacin in vitro respectively. The MICs of the 6 strains of Brucella melitensis and induced resistant strains were measured by agar dilution method. The sensitivity to Quinolone antibiotics (Levofloxacin, Ciprofloxacin, Lomefloxacin, Norfloxacin, Fleroxacin, Ofloxaein) of 6 strains of Brucella melitensis and induced resistant strains was measured by K-B method. The gyrA of the 6 strains of Brucella melitensis and induced resistant strains was amplified by PCR, then the nucleotide sequence of the genes were analyzed. Results The MICs of Bru1,Bru2,Bru3,Bru4, Bru6 were 0.50 μg/ml and Bru5 was 0.25 μg/ml. The strains Bin3, Bru4 were induced into drug-resistant strains by Levofloxacin, then were named LEVR3 and LEVR4 respectively. The MICs of LEVR3 and LEVR4 were 64,128 μg/ml with 128 and 256 times higher than that of the parental strains. The 6 strains of Brucella melitensis were sensitive to Quinolone antibiotics, LEVR3 and LEVR4 were resistant to Quinolone antibiotics. Neucleotide sequence analysis and comparison of the derived amino acid sequence revealed that Quinolone resistance-determing region of GyrA had a substitution at position Ala87 and Asp91 in laboratory resistant strains. Conclusion The results of in vitro experiments show that acquired resistance of Brucella melitensis strains to Levofloxacin could beinduced when exposed to high level of some antibacterial agents for short term. Two drug-resistant strains occur mutations in gyrA and have cross-resistance to other Quinolones.

Mutaciones en genes gyrA y gyrB en cepas de bacilos Gram negativos aisladas en hospitales chilenos y su relación con la resistencia a fluoroquinolonas / Mutations in gyrA and gyrB genes among strains of Gram-negative bacilli isolated from Chilean hospitals and their relation with resistance to fluoroquinolones

Background: A progressive frequency of resistance to fluorquinolones is observed among Gram-negative bacilli. Aim: To investigate the mechanism of resistance to fluoroquinolones mediated by mutations affecting gyrA and gyrB genes in strains of Gram negative bacüli isolated from CMean hospitals. Material and method: Minimal inhibitory concentration of fluoroquinolones was determined in 91 randomly selected nalidixic acid-resistant strains of Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii and Pseudomonas aeruginosa, isolated from hospitals of 12 Chilean cities. Quinolone resistance determining region (QRDR) was amplified by PCR and mutations were determined by restriction fragment length polymorphism (RFLP) and DNA sequencing. Results: Strains with mutation in codon 83 of gyrA showed decreased susceptibility to ciprofloxacin with MICs ranging from 0.25 to 1024 fig/ml. The sequencing of PCR products for gyrA indicated amino acid changes in the QRDR region. One strain ofE. coli presented a double mutation, in codon 83 Ser to Leu as well as in codon 87 Asp to Asn. In strains ofK. pneumoniae, however, the change of codon 83 was Ser to Tyr, in A. baumannii was Ser to Leu and in P. aeruginosa was Thr to He. No strains with mutations affecting gyrB were found. Conclusions: Mutations in codon 83 of gyrA is a frequent genetic event involved in the mechanism leading to decreased susceptibility to fluoroquinolone in strains of Gram-negative bacilli.

Relationship Between gyrA Gene Mutations in Clinical Isolates of Pseudomonas Aeruginosa and Quinolone Resistance / 中国药房

OBJECTIVE:To observe the relationship between gyrA gene mutations of the clinical isolates of Pseudomonas aeruginosa and quinolone resistance and to evaluate the feasibility of analyzing gyrA gene mutations using PCR-RFLP-SSCP.METHODS:With gyrA gene order of the clinical isolates of Pseudomonas aeruginosa taken as target sequence,gyrA gene mutations in strain ATCC 27853 and 16 clinical isolates of Pseudomonas aeruginosa were analyzed contrastively using PCR,PCR-RFLP,PCR-SSCP,and DNA sequencing.RESULTS:Of the total 8 ciprofloxacin resistant Pseudomonas aeruginosa,6 strains showed single point ACC→ ATC mutation in the gyrA gene at codon 83,leading to amino acid substitution of Thr83→Ile.SacⅡ digestion fragment of the PCR amplified products in gyrA gene was in line with the sequencing results.SSCP showed that the banding patterns of all strains were different from that of strain ATCC 27853 except 2 strains.CONCLUSION:The molecular mechanism of the quinolone resistant Pseudomonas aeruginosa isolated from clinics was manifested as mutations in the gyrA gene at codon 83.The results showed that PCR-RFLP-SSCP is a rapid and accurate method for the detection of basyl variation in gyrA in quinolone resistant Pseudomonas aeruginosa.

gyrA and parC genes mutations in quinolone-resistant clinical isolates of Pseudomonas aeruginosa / 中国药理学通报

Aim To study gyrA and parC mutations of clinical Pseudomonas aeruginosa strains. Methods MIC values of 55 clinical P.aeruginosa isolates were determined by agar dilution test and 1 sensitive strain and 8 resistant strains were selected with standard sensitive strain ATCC27853 as control, the quinolone determining region (QRDR) of the gyrA and parC genes were amplified by PCR, the lengths of PCR products were 351 bp and 397 bp. The gyrA PCR products(351 bp) were digested with enzyme sacⅡ. The gyrA and parC gene were sequenced. Results In this study, gyrA genes of all resistant strains had an ACC to ATC mutation in codon 83, leading to the amino acid substitution of an isoleucine for a threonine, and three high level resistant strains also showed a GAC to GGC mutation in codon 87, leading to the substitution of a glycine for an aspartic acid. In addition, four resistant strains also had an TCG to TTG mutation in codon 87 of parC gene, leading to the amino acid substitution of a serine for a leucine. The strains with both gyrA and parC mutations were two to sixteen times more resistant than the strains which had only gyrA mutations. At the same time, a silent mutation (CAC to CAT) in codon 132 of gyrA gene and a silent mutation(GCT to GCG) in codon 115 of parC gene occured, which did not lead to amino acid change. Conclusion The mutations of 83 and 87 codons of gyrA and the mutatations of 87 codon of parC gene were related to fluroquinolone resistance, and the mutations of the 83 codon of gyrA gene were more important.