Correspondence 5. Hammerschlag MR. Activity of gemifloxacin and other new quinolones against Chlamydia pneumoniae: a review. J Antimicrob Chemother 2000; 45 Suppl 1: 35 – 9.
Journal of Antimicrobial Chemotherapy doi:10.1093/jac/dkm333 Advance Access publication 30 August 2007
Gemifloxacin once daily for 5 days versus 7 days for the treatment of community-acquired pneumonia: a randomized, multicentre, double-blind study—authors’ response T. M. File1,2*, L. A. Mandell3 and G. Tillotson4† 1
Northeastern Ohio Universities College of Medicine, Rootstown, OH, USA; 2Summa Health System, 75 Arch Street, Suite 105, Akron, OH 44304, USA; 3McMaster University School of Medicine, 711 Concession Street, Hamilton, Ontario L8V1C3, Canada; 4Oscient Pharmaceuticals Corporation, 1000 Winter Street, Suite 2200, Waltham, MA 02451, USA
Ortho-McNeil, Oscient, Pfizer, Schering Plough and Wyeth. Further, he does not own stocks in any company that might be financially affected by the conclusions of this article. L. A. M. has received research funding from Bayer, Pfizer, Sanofi-Aventis and Wyeth, is a consultant to AstraZeneca, Aventis, Bayer, Pfizer, Sanofi-Aventis and Wyeth and is on the Speakers’ Bureau of Aventis, Bayer, Oscient, Pfizer and Sanofi-Aventis. G. S. T. was an employee of Oscient Pharmaceuticals at the time of the study and is currently an employee of Replidyne Pharmaceuticals, Louisville, CO, USA.
References 1. Hammerschlag MR. Comment on: Gemifloxacin once daily for 5 days versus 7 days for the treatment of community-acquired pneumonia: a randomized, multicentre, double-blind study. J Antimicrob Chemother 2007; 60: 902–903. 2. File TM, Mandell LA, Tillotson G et al. Gemifloxacin once daily for 5 days versus 7 days for the treatment of community-acquired pneumonia: a randomized, multicentre, double-blind study. J Antimicrob Chemother 2007; 60: 112–20.
Journal of Antimicrobial Chemotherapy doi:10.1093/jac/dkm283 Advance Access publication 25 July 2007
Keywords: Chlamydophila, microbiological efficacy, clinical cure
Complete nucleotide sequence of a small qnrS1carrying plasmid from Salmonella enterica subsp. enterica Typhimurium DT193
*Corresponding author. Tel: þ1-330-375-3894; Fax: þ1-330-375-6680; E-mail:
[email protected] †Present address. Replidyne Pharmaceuticals, Louisville, CO, USA.
Corinna Kehrenberg1, Katie L. Hopkins2, E. John Threlfall2 and Stefan Schwarz1*
Sir, We are in agreement with Dr Hammerschlag1 that assessment for Chlamydophila pneumoniae as an aetiology of respiratory infections is difficult; and we share her call for a consistent regulatory policy on acceptable criteria for determining microbiological efficacy. Since serological methods were the only means by which an atypical aetiology was assessed in our paper, we acknowledge this as a potential limitation, but felt that we should include this information to give the reader some impression of the pattern of aetiological agents found in our cases. We would like to stress that the primary purpose of our paper was to demonstrate the clinical efficacy of a shorter 5 day course of gemifloxacin therapy for mild-to-moderate community-acquired pneumonia with the possible benefits which may accrue. We feel that we have demonstrated this in our paper.2
Transparency declarations T. M. F. has received recent research funding from Abbott, Arpida AG, AstraZeneca, Bristol –Myers Squibb, Bayer, Binax Incorporated, Cubist, Genzyme, GlaxoSmithKline, OrthoMcNeil, Oscient, Pfizer, Sanofi-Aventis and Wyeth, is a consultant to Sanofi-Aventis, Bayer, GlaxoSmithKline, Ortho-McNeil, Merck, Oscient, Pfizer and Wyeth and is on the Speakers’ Bureau of Abbott, Sanofi-Aventis, GlaxoSmithKline, Merck,
1
Institut fu¨r Tierzucht, Bundesforschungsanstalt fu¨r Landwirtschaft (FAL), Ho¨ltystr. 10, 31535 NeustadtMariensee, Germany; 2Salmonella Reference Unit, Laboratory of Enteric Pathogens, Health Protection Agency Centre for Infections, 61 Colindale Avenue, London NW9 5EQ, UK Keywords: quinolone resistance, mobilization, recombination, enteric pathogens *Corresponding author. Tel: þ49-5034-871-241; Fax: þ495034-871-246; E-mail:
[email protected] Sir, In a recent study on transferable quinolone resistance among Salmonella enterica strains isolated in the UK, qnrS1 genes were identified on plasmids in the four serotypes Typhimurium, Stanley, Virchow and Virginia.1 Since no complete sequence of a qnrS1-carrying plasmid has been available so far, we decided to sequence completely the smallest type of qnrS1-carrying plasmid to gain insight into the structure and putative origin of this plasmid. The plasmid chosen, TPqnrS-1a, was obtained from a multiresistant Salmonella Typhimurium DT193 strain and previously shown to mediate only decreased susceptibility to ciprofloxacin.1
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Correspondence The plasmid was subjected to extended restriction analyses using the enzymes BglII, ClaI, DraI, EcoRI, EcoRV, HindIII, HpaI, KpnI, PstI, PvuI, PvuII and SmaI in single and double digests. On the basis of these results, a restriction map was constructed. The four HindIII fragments of 1.0, 2.0, 2.6 and 4.4 kb were cloned into pBluescript II SKþ (Stratagene, Amsterdam, The Netherlands) and the recombinant plasmids transformed into Escherichia coli JM109. The different fragments were sequenced on both strands by primer walking. Initial sequence analyses were conducted with standard M13 universal and reverse primers and completed with primers derived from the sequences obtained with the standard primers (MWG, Ebersberg, Germany). Sequence analysis was performed with the BLAST programs blastn and blastp (http://www.ncbi.nlm. nih.gov/BLAST) and with the ORF Finder program (http://www. ncbi.nlm.nih.gov/gorf/gorf.html). The nucleotide sequence of the plasmid TPqnrS-1a has been deposited in the EMBL database under accession number AM746977. With a size of 10 066 bp, plasmid TPqnrS-1a proved to be slightly smaller than initially estimated1 and consisted of two different segments (Figure 1). The initial 4666 bp exhibited 89% nucleotide sequence identity to the 4669 bp plasmid pEC278 isolated from a pathogenic E. coli strain (accession no. AY589571). Within this region, three partially overlapping reading frames were detected, which code for the mobilization proteins MobA, MobB and MobC. The gene mobA codes for a 516-amino-acid protein, which showed 92% identity to the 499amino-acid MobA protein of pEC278. The 161-amino-acid MobB and the 107-amino-acid MobC proteins exhibited 93% and 94% identity, respectively, to the same-sized MobB and
MobC proteins of pEC278. Upstream of the mobC gene, an origin of replication similar to that of the E. coli plasmid p15A (accession no. V00309) was found. The adjacent 2830 bp showed 99% identity to plasmid pINF5 from Salmonella Infantis2 and included the qnrS1 resistance gene area, a truncated IS2 insertion sequence and an incomplete Tn5058-related resolvase gene. Further downstream, another 2044 bp region with 98% identity to pINF5 was detected. This region was orientated in the opposite direction in TPqnrS-1a when compared with the Salmonella Infantis plasmid. Between these two pINF5-homologous segments, a 526 bp region without significant homology to database entries was detected (Figure 1). Poirel et al. 3 recently also observed the aforementioned inversion in the qnrS1 downstream region of plasmid pS5-1 from Enterobacter cloacae. The qnrS1 gene of TPqnrS-1a codes for a 218-amino-acid protein indistinguishable from the QnrS1 proteins previously detected in the S. enterica serovars Infantis (accession no. CAJ84117), Bovismorbificans (accession no. ABF47469), Stanley (accession nos ABI63549 and ABI63550), Virchow (accession nos ABI63552 and ABI63553) and Virginia (accession no. ABI63554) and also from those of Shigella flexneri (accession nos BAD88772 and BAD88776), Klebsiella pneumoniae (accession no. ABG56870) as well as Proteus mirabilis (accession no. ABP88832). Identity to the two so far known QnrS2 proteins from S. enterica serovar Anatum (accession no. ABF47470) and to that of the 8469 bp plasmid pGNB2 obtained from unknown activated sludge bacterium (accession no. ABE98197) was 92%. It should be noted that the qnrS2-carrying plasmid pGNB24 and the qnrS1-carrying
Figure 1. Comparison of the sequenced parts of plasmids pAH0376 from S. flexneri 6 and pINF5 from Salmonella Infantis2 with the complete plasmids TPqnrS-1a from Salmonella Typhimurium DT193 and pEC278 from E. coli. A distance scale in kb is presented below each map. The reading frames are shown as arrows with the arrowhead indicating the direction of transcription. The arrows marked as 213, 259, 213 and 196 in the map of pINF5 indicate reading frames for hypothetical proteins of 213, 259, 213 and 196 amino acids, respectively. The 5 bp direct repeats at the boundaries of the Tn3 elements in pAH0376 and pINF5 as well as the 4 bp direct repeats at the outside boundaries of the truncated IS26 are shown in boxes. The black, striped and stippled boxes indicate the terminal inverted repeats of Tn3, IS26 and IS2, respectively. The areas of homology between plasmids pAH0376, pINF5 and/or TPqnrS-1a as well as between TPqnrS-1a and pEC278 are shown by grey shading.
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Correspondence plasmid TPqnrS-1a do not share any obvious structural similarities. A comparison between the TPqnrS-1a-associated QnrS1 protein and the 218-amino-acid proteins from Vibrio splendidus (accession no. EAP95542) and Vibrio spp. (accession no. EAQ55748)—the latter two considered as a natural reservoir of qnrS genes5—revealed 83% and 82% amino acid identity, respectively, and 91% amino acid similarity. Previous studies revealed that the qnrS1 gene is often located on large plasmids that carry additional resistance genes.1 – 3,6 Although plasmids pAH0376 from S. flexneri 6 and pINF5 from Salmonella Infantis2 carried a complete Tn3 with a blaTEM-1 b-lactamase gene, recently discovered plasmids of E. cloacae identified the qnrS1 gene in close proximity to the novel b-lactamase gene blaLAP-1.3 In the present study, we characterized a comparatively small plasmid that carried the qnrS1 gene as the sole resistance gene. To the best of our knowledge, plasmid TPqnrS-1a is the first qnrS1-carrying plasmid for which the complete sequence is available. A detailed sequence analysis of this plasmid suggested that it has most likely derived from an interplasmid recombination event between a qnrS1-carrying plasmid such as pINF5 from Salmonella Infantis2 or pS5-1 from E. cloacae 3 and a small mobilizable plasmid similar to pEC278 from E. coli. The identification of qnrS1 genes on structurally diverse plasmids points towards the dissemination of these genes and their adaptation in new hosts as relevant factors in the emergence of transferable quinolone resistance.7
Acknowledgements We thank Vera No¨ding for excellent technical assistance.
Funding This study was financially supported by internal funding provided by the Institut fu¨r Tierzucht (FAL).
Transparency declarations None to declare.
References 1. Hopkins KL, Wootton L, Day MR et al. Plasmid-mediated quinolone resistance determinant qnrS1 found in Salmonella enterica strains isolated in the UK. J Antimicrob Chemother 2007; 59: 1071–5. 2. Kehrenberg C, Friederichs S, de Jong A et al. Identification of the plasmid-borne quinolone resistance gene qnrS in Salmonella enterica serovar Infantis. J Antimicrob Chemother 2006; 58: 18 – 22. 3. Poirel L, Cattoir V, Soares A et al. Novel Ambler class A b-lactamase LAP-1 and its association with the plasmid-mediated quinolone resistance determinant QnrS1. Antimicrob Agents Chemother 2007; 51: 631–7. 4. Bo¨nemann G, Stiens M, Puhler A et al. Mobilizable IncQ-related plasmid carrying a new quinolone resistance gene, qnrS2, isolated from the bacterial community of a wastewater treatment plant. Antimicrob Agents Chemother 2006; 50: 3075– 80. 5. Cattoir V, Poirel L, Mazel D et al. Vibrio splendidus as the source of plasmid-mediated QnrS-like quinolone resistance determinants. Antimicrob Agents Chemother 2007; 51: 2650– 1. 6. Hata M, Suzuki M, Matsumoto M et al. Cloning of a novel gene for quinolone resistance from a transferable plasmid in Shigella flexneri 2b. Antimicrob Agents Chemother 2005; 49: 801 –3.
7. Nordmann P, Poirel L. Emergence of plasmid-mediated resistance to quinolones in Enterobacteriaceae. J Antimicrob Chemother 2005; 56: 463–9.
Journal of Antimicrobial Chemotherapy doi:10.1093/jac/dkm288 Advance Access publication 6 August 2007
Activity of iclaprim against Legionella pneumophila Ian Morrissey1* and Stephen Hawser2 1
GR Micro Ltd, 7-9 William Road, London NW1 3ER, UK; ARPIDA AG, Du¨ggingerstrasse 23, Reinach CH-4153, Switzerland
2
Keywords: RTIs, atypical, L. pneumophila *Corresponding author. Tel: þ44-20-7380-4463; Fax: þ44-207388-7324; E-mail:
[email protected] Sir, Legionella pneumophila is an ‘atypical’ pathogen associated with lower respiratory tract infections (RTIs) such as community-acquired pneumonia (CAP).1 Organizations such as the Infectious Diseases Society of America recommend that empirical treatment of CAP should cover atypical pathogens such as L. pneumophila and Chlamydophila (Chlamydia) pneumoniae.2 At present, macrolides and fluoroquinolones are the most active options against atypical pathogens. On the contrary, b-lactams are inactive against these pathogens. Iclaprim is a new dihydrofolate reductase inhibitor, which recently completed enrolment in two Phase III trials of complicated skin and skin structure infections treated via intravenous administration and has recently successfully completed Phase I investigations of an oral formulation. Currently, the only clinically available antibiotic targeting dihydrofolate reductase is trimethoprim. This antibiotic can be used in combination with sulphonamides such as sulfamethoxazole, although rarely these days due to concerns over toxicity with sulfamethoxazole. At present, data on the activity of iclaprim against L. pneumophila have not been published. Iclaprim (Arpida AG, Reinach, Switzerland), trimethoprim, sulfamethoxazole, trimethoprim/sulfamethoxazole (19:1 ratio), clarithromycin and levofloxacin (all from Sigma, Poole, UK) were investigated against 56 L. pneumophila isolates. The isolates were derived mostly from clinical material examined in hospitals or reference centres worldwide. MICs were determined using an agar dilution method. The agar consisted of 1% yeast extract (Oxoid Ltd, Basingstoke, UK), 1.3% Bacteriological Agar No. 1 (Oxoid), 5% water-lysed horse blood (Oxoid) and legionella growth supplement (Oxoid). The inoculum used was 104 cfu of each isolate contained in a volume of 1 mL. After 48 – 72 h of incubation in air at 358C, MIC was determined as the lowest concentration of antimicrobial tested that inhibited growth of the inoculum, disregarding a single persisting colony or a faint haze caused by inoculation. Summary MIC data are presented in Table 1. Iclaprim was very active, with 16-fold lower MIC50 or MIC90 values than
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