Azithromycin uptake by tissue cultured epithelial cells

clinical condition of the patient improved and he was discharged several days later. R esistance to the newer quinolones in H. influenz ae is rare. In a large Canadian study in 1992 and 1993, all of 1688 strains were susceptible to ciprofloxacin. 2 Jones found 1% of 7961 H. influenz ae isolates to be moderately susceptible, 3 and 1% resistant to lomefloxacin. Barriere & H indler 4 and G ould et al. 5 described quinolone-resistant H. influenz ae from patients with chronic respiratory tract infections. In an ongoing electronic surveillance in D utch public health laboratories, only 0.19% of 2678 single isolates were resistant to ciprofloxacin (MIC 1 mg/L). Therefore, strain 24482is one of the first ciprofloxacin-resistant H. influenz aeisolates in the Netherlands. Since mutations in the D NA gyrase (gyrA) gene are the most common mechanism of fluoroquinolone resistance in other bacterial species, 6 we sequenced the corresponding region of the gyrA gene of the H. influenz ae strains R d and 24482. D NA was extracted by heating a suspension of cells (10 6 cfu/mL) for 15 min at 100 C and 10 L of each sample was subjected to a 'touchdown' PCR 7 with an annealing temperature ranging from 61 C to 50 C. Based on the gyrA sequence present in G enBank (accession number U 32806) primers were developed corresponding to residues 43 to 25 (For; 5-A TG CTA TA A TCCG C-CA CA A-3) and 536–515 (R ev; 5-A TCCCCA CCG CA-A TA CCA G A A G-3) of the gyrA gene. D NA sequencing of both strands of the PCR products was performed in duplicate with an A BI 373A D NA sequencer according to the instructions provided by the manufacturer (A pplied Biosystems, Foster City, CA , U SA) using the same primers. The sequence of the R d strain (positions 1–510) was identical to the sequence obtained from the database. The sequence of the quinolone-resistant isolate (positions 1–510, deposited in G enBank, accession number Z 73213) differed in 11 bases. E ight of these replacements were silent and only three mutations resulted in amino acid substitutions, in codon 84 (TCC TTA ; Ser Leu) and codon 88 (G A T TA T; A sp Tyr). H omologous double mutations have been found in codons 83 and 87 of several isolates of ciprofloxacin-resistant E scherichia coli. 6 These identical substitutions in E. coli …