16 Thirty-three Salmonella Typhi blood isolates from Lima, Peru (2008-2012), were fully 17 susceptible to trimethoprim-sulfamethoxazole, chloramphenicol, ceftriaxone, and 18 tetracycline; 8/33 (24.2%) showed intermediate susceptibility to ciprofloxacin carrying 19 mutations in the quinolone resistance-determining region of the gyrA gene (Ser83-Phe and 20 Asp87-Asn); and in the gyrB gene (Ser464...

Fluoroquinolones remain the most commonly used antimicrobials for the prevention and management of bacterial endophthalmitis. Coagulase-negative staphylococci are the most frequently recovered pathogens. Increasing resistance among this group has paralleled the presence of methicillin resistance. From 2005 to 2010, we recovered 38 methicillin-susceptible Staphylococcus epidermidis (MSSE) isolat...

We have analyzed genetically three clinical isolates (3180, 3870, and 1244) of Streptococcus pneumoniae with high-level ciprofloxacin resistance. Isolates 3180 and 3870 were atypical because of their insolubility in deoxycholate. However, they hybridized specifically with pneumococcal autolysin and pneumolysin gene probes and have typical pneumococcal atpC and atpA gene sequences. Analysis of t...

To investigate the mechanism of resistance in the isolates, fragments of gyrA (847 bp) and parC (822 bp) genes were amplifi ed by using primers gyrA1F (5′-gttttcccagtcacgacgttgtaATGA CCGACGCAACCATCCGCCAC-3′) and gyrA-1R (5′-ttgtgagcggataacaattt cCCAGCTTGGCTTTGTTGACCTG ATAG-3′), and parC-1F (5′-gttttcccag tcacgacgttgtaATGAATACGCAAGC GCACGCCCCA-3′) and parC-1R (5′ttgtgagcggataacaatttcGGAATTGGC GT...

In order to study the interactions between Escherichia coli DNA gyrase and the gyrase interacting protein QnrB in vivo, we constructed a gyrB-gyrA fusion and validated its ability to correct the temperature-sensitive growth of gyrA and gyrB mutants. Like wild-type gyrA, the gyrB-gyrA fusion complemented a quinolone-resistant gyrA mutant to increase susceptibility. It functioned as an active typ...

Thirty-three Salmonella enterica serovar Typhi blood isolates from Lima, Peru (2008 to 2012), were fully susceptible to trimethoprim-sulfamethoxazole, chloramphenicol, ceftriaxone, and tetracycline; 8/33 (24.2%) showed intermediate susceptibility to ciprofloxacin carrying mutations in the quinolone resistance-determining region of the gyrA gene (Ser83-Phe and Asp87-Asn) and in the gyrB gene (Se...

Discovery of genotypic markers associated with increased transmissibility in Mycobacterium tuberculosis would represent an important step in advancing mycobacterial virulence studies. M. tuberculosis strains may be classified into one of three genotypes on the basis of the presence of specific nucleotide substitutions in codon 463 of the katG gene (katG-463) and codon 95 of the gyrA gene (gyrA-...

Fluoroquinolones form drug-topoisomerase-DNA complexes that rapidly block transcription and replication. Crystallographic and biochemical studies show that quinolone binding involves a water/metal-ion bridge between the quinolone C3-C4 keto-acid and amino acids in helix-4 of the target proteins, GyrA (gyrase) and ParC (topoisomerase IV). A recent cross-linking study revealed a second drug-bindi...

Quinolone susceptibility was analyzed in 17 clinical isolates of Corynebacterium striatum and 9 strains of Corynebacterium amycolatum by the E-test method in Mueller-Hinton agar plates. The C. striatum ATCC 6940 strain was used as a control strain. The amplified quinolone resistance determining regions of the gyrA genes of C. amycolatum and C. striatum were characterized. Four in vitro quinolon...