France Recherche Nord & Sud Sida-HIV Hépatites (ANRS) and Bill & Melinda Gates Foundation.

Two different strains of Escherichia coli exhibiting unusual patterns of resistance to beta-lactam antibiotics were isolated from patients at Cochin Hospital. Both isolates showed a low level of resistance to amoxycillin, ticarcillin and ureidopenicillins but were susceptible to cephalosporins, aztreonam and imipenem; beta-lactamase inhibitors potentiated the activities of the beta-lactams to only a limited extent. All resistance characteristics of the strains were transferable by conjugation to E. coli K12. Resistance was shown to be due to beta-lactamases of pI 5.20 and relative molecular masses of 24,000. The hydrolytic and inhibition profiles of these enzymes were similar to each other but differed from those of broad-spectrum beta-lactamases (TEM-1). The rates of hydrolysis (Vmax) of amoxycillin (c. 200%) were higher than that for TEM-1 (84%). Ticarcillin, ureidopenicillins and cephaloridine were hydrolyzed slowly. However, as for TEM-1, no hydrolysis was observed with cefoxitin, third generation cephalosporins, aztreonam and imipenem. The high Km values demonstrated the poor affinity of these enzymes for their substrates. Unlike TEM-1, they were poorly inhibited by beta-lactamase inhibitors. These two enzymes differed from each other as follows: (i) the concentrations of clavulanic acid required for 50% beta-lactamase inhibition were 31 mumol/L for one enzyme (E-SAL) and 9.4 mumol/L for the other (E-GUER); (ii) p-chloromercuribenzoate was a more active inhibitor of E-SAL then E-GUER. The titration curve method and DNA-DNA hybridization studies demonstrated that both enzymes were structurally related to TEM-1. The novel plasmid-encoded enzymes produced by the two isolates of E. coli appeared to be almost identical and to be derived from TEM-enzymes. On the basis of their presumed phylogeny and their biological properties, we propose that these beta-lactamases be given the generic name TRI (TEM Resistant to beta-lactamase Inhibitors).

Background Mycoplasma genitalium (MG) is an emerging pathogen among men who have sex with men (MSM) with raising rates of antibiotic resistance. In this study, we assessed the prevalence and incidence of MG infection in MSM enrolled in the open-label phase of the ANRS IPERGAY trial with on demand TDF/FTC for HIV prevention and the impact of doxycycline post-exposure prophylaxis (PEP). Methods 210 subjects were tested at baseline and at 6 months by real-time PCR assays for MG detection in urine samples, oro-pharyngeal and anal swabs. Resistance to azithromycin (AZM), to fluoroquinolones (FQ) and to doxycycline were investigated in the French National Reference Centre of bacterial STI. Results The all-site prevalence of MG at baseline was 10.5% [6.3% in urine samples, 4.3% in anal swabs and 0.5% in throat swabs] and remained unchanged at 6 months whether or not PEP was used: 9.9% overall, 10.2% with PEP and 9.6% without. The overall rate of MG resistance (prevalent and incident cases) to AZM and FQ was 67.6% and 9.1%, respectively, with no difference between arms. An in vivo mutation of the MG 16S rRNA which could be associated with tetracycline resistance was observed in 12.5% of specimens tested. Conclusions The prevalence of MG infection among MSM on PrEP was high and its incidence was not decreased by doxycycline prophylaxis with a similar high rate of AZM- and FQ-resistance, raising challenging issues for the treatment of this STI and supporting current recommendations to avoid testing or treatment of asymptomatic MG infection.

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