Trimethoprim resistance mediated by the Staphylococcus aureus multi-resistance plasmid pSK1 is encoded by a structure with characteristics of a composite transposon which we have designated Tn4003. Nucleotide sequence analysis of Tn4003 revealed it to be 4717 bp in length and to contain three copies of the insertion element IS257 (789-790 bp), the outside two of which are flanked by directly repeated 8-bp target sequences. IS257 has imperfect terminal inverted repeats of 27-28 bp and encodes for a putative transposase with two potential alpha-helix-turn-alpha-helix DNA recognition motifs. IS257 shares sequence similarities with members of the IS15 family of insertion sequences from Gram-negative bacteria and with ISS1 from Streptococcus lactis. The central region of the transposon contains the dfrA gene that specifies the S1 dihydrofolate reductase (DHFR) responsible for trimethoprim resistance. The S1 enzyme shows sequence homology with type I and V trimethoprim-resistant DHFRs from Gram-negative bacteria and with chromosomally encoded DHFRs from Gram-positive and Gram-negative bacteria. 5' to dfrA is a thymidylate synthetase gene, designated thyE.

Restriction endonuclease and DNA hybridization analyses of the Staphylococcus aureus plasmid pSK1, which encodes resistance to ethidium bromide (Eb), quaternary ammonium compounds, gentamicin (Gm), kanamycin (Km), tobramycin (Tm) and trimethoprim (Tp), identified three copies of a directly repeated DNA sequence of approx. 1 kb located in the proximity of the Tp‐resistance‐encoding region of the plasmid. Directly repeated sequences homologous to those detected on pSK1 were also identified on S. aureus heavy‐metal resistance (β‐lactamase) plasmids and the S. aureus chromosome; in both, these repeats flank related, but not identical, mercury (Hg)‐resistance‐encoding regions. The chromosomal Hg‐resistance region mapped adjacent to an integrated tetracycline (Tc)‐resistance plasmid equivalent to pT181, which was also flanked by copies of the repeated sequences, and to a DNA segment associated with methicillin (Mc) resistance.

Background Gonorrhoea is usually managed in community sexual health or general practice, but a proportion of cases present to hospital settings. In this study, we examined how gonorrhoea was managed through a large hospital network and what the implications may be for public health management. Methods: A retrospective chart review was performed of the management of patients with Neisseria gonorrhoeae infection diagnosed at a large Australian healthcare network from January 2015 to May 2018. Documentation rates of five parameters of care were assessed: (1) the presence (or absence) of previous sexually transmissible infections (STIs); (2) recent travel; (3) discussion of HIV testing; (4) contact tracing; and (5) public health notification. Results: In all, 110 cases (48 male, 62 female) were analysed. Most cases were in the 15–39 years age group; 98 cases (89%) were symptomatic, and 12 (11%) were screening tests. The most common presenting syndromes were pelvic inflammatory disease (32%; 31/98 symptomatic cases), urethritis (26%; 25/98) and epididymo-orchitis (13%; 13/98). None of the five parameters assessed were documented in most cases. Documentation was most likely to occur in patients admitted to hospital. When HIV testing was performed, no new cases of HIV were identified. Conclusion: Infections with gonorrhoea present on a regular basis to hospital practice, but overall management is suboptimal. Automated prompts for other recommended tests, including HIV testing when testing for other sexually transmissible diseases is ordered, may improve management. Better awareness of best practice is needed, which can be facilitated with ongoing education. However, the greatest benefit is likely achieved by linking patients back to community-based services, which are best placed to provide ongoing long-term care.