Article Figures & Data
Figures
- Fig 1
Alignment of PBP 2 sequences from strains of Neisseria gonorrhoeae with different penA alleles. M32091, wild-type PBP 2; XXXIV, penA mosaic allele previously described (27, 33); CI, penA mosaic allele of F89; XXVI (27, 36) and XXX (27, 51), the only previously reported true penA mosaic alleles containing an A501 alteration (27); C, penA mosaic allele of H041, which is the first high-level ceftriaxone-resistant strain found in Japan (27); and XIII and XVIII, previously described nonmosaic penA alleles that contain A501V (most prevalent) and A501T alterations (27, 51). Identical amino acids are designated by a dot, and alterations from the wild-type sequence are shown with a single capital letter. The three active-site motifs are marked by dashed boxes, while the location of amino acid Ala501 (position 502 in the alignment due to the D345 insertion) is marked with a solid box.
- Fig 2
MICs of a set of recipient strains transformed with the full-length penA allele (penA-CI) from the high-level cefixime- and ceftriaxone-resistant Neisseria gonorrhoeae strain F89 (donor). The MICs of cefixime and ceftriaxone and the number and type of resistance determinants (e.g., mtrR, penB, and ponA) in the recipient strains varied. The MICs of cefixime (A) and ceftriaxone (B) were determined using the Etest method, and the values shown are the means of three transformation experiments (the bars give only whole-MIC steps), with the exact mean MICs in parentheses. The ratios of the MICs of the transformant to the recipient strain (T/R) are indicated.
Tables
- Table 1
Susceptibilities of high-level cefixime- and ceftriaxone-resistant N. gonorrhoeae strain F89 to various antimicrobials
Class, subclass, and antimicrobial MIC Etesta (S, I, or R)b,c CDS (mm)d β-Lactams, penicillins Penicillin G 1 (I)b,c 5 (I) Ampicillin 0.5 NDe Amdinocillin 128 ND Oxacillin 64 ND Piperacillin 0.125 ND Piperacillin-tazobactam 0.016 ND β-Lactams, monobactams, aztreonam 64 ND β-Lactams, cephalosporins Cefuroxime 16 (R)b ND Cefpodoxime 16 (R)b 6 (R) Ceftazidime 16 (R)b ND Cefotaxime 4 (R)b,c ND Cefixime 4 (R)b,c ND Ceftriaxone 2 (1)a (R)b,c 3 (R) Cefepime 16 (R)b ND β-Lactams, carbapenems Ertapenem 0.016 ND Meropenem 0.016 ND Imipenem 0.5 ND Fluoroquinolones Ciprofloxacin >32 (R)b,c 4 (R) Levofloxacin 8 ND Moxifloxacin 4 ND Macrolides Azithromycin 1 (R)c ND Erythromycin 2 ND Aminoglycosides Gentamicin 8 ND Kanamycin 16 ND Tobramycin 8 ND Aminocyclitol, spectinomycin 16 (S)b,c 13 (S) Tetracyclines, tetracycline 2 (R)c ND Glycylcycline, tigecycline 0.5 ND Folic acid antagonists, trimethoprim-sulfamethoxazole 1 ND Rifamycins, rifampin 0.5 ND Chloramphenicol 4 ND Nitrofurantoin 1 ND Fusidic acid 2 ND ↵a MICs were determined using the Etest method (AB bioMérieux, Solna, Sweden) according to the instructions from the manufacturer. Agar dilution was additionally performed for ceftriaxone (the result is in parentheses) according to the method described by the Clinical Laboratory and Standards Institute (CLSI) (9). The Etest method is capable of providing half-MIC steps; however, in accordance with the interpretation of the agar dilution method described by the CLSI (9), only whole-MIC steps are given.
↵b Where available, interpretative criteria (S, susceptible; I, intermediate susceptible; R, resistant) from the CLSI (9) were used.
↵c Interpretative criteria (susceptible, intermediate susceptible, resistant) from the European Committee on Antimicrobial Susceptibility Testing (EUCAST; available online at www.eucast.org/Clinical breakpoints [accessed 20 November 2011]) are also reported where available.
↵d The calibrated dichotomous sensitivity (CDS) disc diffusion method (40; http://web.med.unsw.edu.au/cdstest) is used for antimicrobial resistance testing in many countries in the World Health Organization (WHO) Western Pacific Region.
↵e ND, not determined.
- Table 2
Neisseria gonorrhoeae strains with different cefixime MICs and ceftriaxone MICs and containing different resistance determinants used as recipients in transformation experiments of full-length penA gene from F89
Strain MLST STa NG-MAST STb MIC (μg/ml)c Genotype Cefixime Ceftriaxone penAd mtrRe penBf ponAg WHO F New ST3303 <0.016e <0.002e penA XV (WT) WTh WT WT WHO M ST7367 ST3304 <0.016 0.016e penA II (A345a) A-del Yes L421P WHO K ST7363 ST1424 0.5 0.064 penA X (Mosaic) A-del Yes L421P 35/02 ST7363 ST326 0.5 0.125 penA XXVIII (Mosaic) A-del Yes L421P WHO L ST1590 ST1422 0.25 0.125 penA VII (A501V) A-del Yes L421P ↵a MLST, multilocus sequencing typing (29).
↵b NG-MAST, Neisseria gonorrhoeae multiantigen sequence typing (44).
↵c The Etest method reads also half-MIC steps; however, in accordance with the interpretation of the agar dilution method described by the Clinical Laboratory and Standards Institute (CLSI) (9), only whole-MIC steps are given. MICs of <0.002 μg/ml and <0.016 μg/ml were calculated as 0.001 μg/ml and 0.008 μg/ml, respectively, in the MIC ratios in Fig. 2.
↵d penA mosaic allele encodes a mosaic penicillin-binding protein 2 (PBP 2) that causes a decreased susceptibility to extended-spectrum cephalosporins (ESCs) (21, 27, 36, 41, 43, 58).
↵e A-del, a characteristic single-nucleotide (A) deletion in the inverted repeat of the promoter region of mtrR that causes overexpression of the MtrCDE efflux pump, resulting in a further decreased susceptibility to ESCs (21, 27, 41, 58).
↵f Yes, the presence of the alterations of amino acids 101 and 102 in porin PorB (penB determinant) that cause a decreased intake of ESCs and, accordingly, a further decreased susceptibility to ESCs (21, 27, 41, 58).
↵g The alteration of amino acid 421 in PBP 1 (encoded by ponA) causes decreased susceptibility to penicillins (21, 34, 58).
↵h WT, wild type.
