Emma M. Johansson

Antimicrobial susceptibility and genetic characteristics of Neisseria gonorrhoeae isolates from Vietnam, 2011

BackgroundAntimicrobial resistance (AMR) in Neisseria gonorrhoeae is a major public health concern worldwide. In Vietnam, knowledge regarding N. gonorrhoeae prevalence and AMR is limited, and data concerning genetic characteristics of N. gonorrhoeae is totally lacking. Herein, we investigated the phenotypic AMR (previous, current and possible future treatment options), genetic resistance determinants for extended-spectrum cephalosporins (ESCs), and genotypic distribution of N. gonorrhoeae isolated in 2011 in Hanoi, Vietnam.MethodsN. gonorrhoeae isolates from Hanoi, Vietnam isolated in 2011 (n = 108) were examined using antibiograms (Etest for 10 antimicrobials), Neisseria gonorrhoeae multi-antigen sequence typing (NG-MAST), and sequencing of ESC resistance determinants (penA, mtrR and penB).ResultsThe levels of in vitro resistance were as follows: ciprofloxacin 98%, tetracycline 82%, penicillin G 48%, azithromycin 11%, ceftriaxone 5%, cefixime 1%, and spectinomycin 0%. The MICs of gentamicin (0.023-6 mg/L), ertapenem (0.002-0.125 mg/L) and solithromycin (<0.016-0.25 mg/L) were relatively low. No penA mosaic alleles were found, however, 78% of the isolates contained an alteration of amino acid A501 (A501V (44%) and A501T (34%)) in the encoded penicillin-binding protein 2. A single nucleotide (A) deletion in the inverted repeat of the promoter region of the mtrR gene and amino acid alterations in MtrR was observed in 91% and 94% of the isolates, respectively. penB resistance determinants were detected in 87% of the isolates. Seventy-five different NG-MAST STs were identified, of which 59 STs have not been previously described.ConclusionsIn Vietnam, the highly diversified gonococcal population displayed high in vitro resistance to antimicrobials previously recommended for gonorrhoea treatment (with exception of spectinomycin), but resistance also to the currently recommended ESCs were found. Nevertheless, the MICs of three potential future treatment options were low. It is essential to strengthen the diagnostics, case reporting, and epidemiologic surveillance of gonorrhoea in Vietnam. Furthermore, the surveillance of gonococcal AMR and gonorrhoea treatment failures is imperative to reinforce. Research regarding novel antimicrobial treatment strategies (e.g., combination therapy) and new antimicrobials is crucial for future treatment of gonorrhoea.

Elevated CO2 and nitrogen influence exudation of soluble organic compounds by ectomycorrhizal root systems

Root and mycelial exudation contributes significantly to soil carbon (C) fluxes, and is likely to be altered by an elevated atmospheric carbon dioxide (CO(2)) concentration and nitrogen (N) deposition. We quantified soluble, low-molecular-weight (LMW) organic compounds exuded by ectomycorrhizal plants grown under ambient (360 p.p.m.) or elevated (710 p.p.m.) CO(2) concentrations and with different N sources. Scots pine seedlings, colonized by one of five different ectomycorrhizal or nonmycorrhizal fungi, received 70 muM N, either as NH(4)Cl or as alanine, in a liquid growth medium. Exudation of LMW organic acids (LMWOAs), dissolved monosaccharides and total dissolved organic carbon were determined. Both N and CO(2) had a significant impact on exudation, especially of LMWOAs. Exudation of LMWOAs was negatively affected by inorganic N and decreased by 30-85% compared with the organic N treatment, irrespective of the CO(2) treatment. Elevated CO(2) had a clear impact on the production of individual LMWOAs, although with very contrasting effects depending on which N source was supplied.

Quantitative analysis of root and ectomycorrhizal exudates as a response to Pb, Cd and As stress

We examined exudation of low molecular weight (LMW) organic compounds of ectomycorrhizal (ECM) and non-mycorrhizal (NM) seedlings in relation to metals. Scots pine seedlings, either colonized by one of six different ECM fungi or NM, were grown in Petri dishes containing glass beads and liquid growth medium and exposed to elevated concentrations of Pb, Cd and As. Exudation of LMW organic compounds (LMW organic acids (LMWOAs), amino acids and dissolved monosaccharides) and dissolved organic carbon (DOC) was determined qualitatively and quantitatively and exudation rates were calculated. Metals had a significant impact on exudation, especially of oxalate. For Pb and Cd treatments, exudation of oxalate and total LMWOAs generally increased by 15–45% compared to nutrient controls. Production of amino acids, dissolved monosaccharides and DOC was not significantly stimulated by exposure to metals; however, there were non-significant trends towards increased exudation. Finally, exudation generally increased in the presence of mycorrhizal seedlings compared to NM seedlings. The results suggest that ECM fungi may reduce the toxicity of metals to plants through significant increases in the production of organic chelators. Axenic conditions are required to assess the full potential for production of these molecules but their overall significance in soil ecosystems needs to be determined using additional experiments under more ecologically realistic conditions.

Evaluation of the new AmpliSens multiplex real-time PCR assay for simultaneous detection of Neisseria gonorrhoeae, Chlamydia trachomatis, Mycoplasma genitalium, and Trichomonas vaginalis.

In this study, we performed an evaluation of the new CE‐marked multiplex real‐time AmpliSens N.gonorrhoeae/C.trachomatis/M.genitalium/T.vaginalis‐MULTIPRIME‐FRT PCR assay compared to APTIMA tests, i.e., APTIMA COMBO 2 assay, APTIMA Trichomonas vaginalis assay (FDA‐approved), and two different APTIMA Mycoplasma genitalium assays (research use only; one of them only used for discrepancy analysis). Vaginal swabs (n = 209) and first‐void urine (FVU) specimens from females (n = 498) and males (n = 554), consecutive attendees (n = 1261) at a dermatovenerological clinic in Sweden, were examined. The sensitivity of the AmpliSens PCR assay for detection of C. trachomatis (6.3% prevalence), M. genitalium (5.7% prevalence), N. gonorrhoeae (0.3% prevalence), and T. vaginalis (0.08% prevalence) was 97.5% (95% confidence interval (CI): 91.2–99.6%), 81.9% (95% CI: 70.7–89.7%), 100% (95% CI: 40.2–100%) and 100% (95% CI: 16.5–100%), respectively. The specificity of the AmpliSens PCR assay was 100% (95% CI: 99.6–100%) for all agents. The analytical sensitivity and specificity for N. gonorrhoeae detection was excellent, i.e., 55 international gonococcal strains detected and 135 isolates of 13 non‐gonococcal Neisseria species were negative. In conclusion, the multiplex real‐time AmpliSens N.gonorrhoeae/C.trachomatis/M.genitalium/T.vaginalis‐MULTIPRIME‐FRT PCR assay demonstrated high sensitivity and excellent specificity for the detection of C. trachomatis, N. gonorrhoeae, and T. vaginalis, and excellent specificity but suboptimal sensitivity for M. genitalium detection.

Prevalence, phenotypic and genetic characteristics of prolyliminopeptidase-negative Neisseria gonorrhoeae isolates in Sweden during 2000-2007.

Johansson E, Fredlund H, Unemo M. Prevalence, phenotypic and genetic characteristics of prolyliminopeptidase‐negative Neisseria gonorrhoeae isolates in Sweden during 2000–2007. APMIS 2009; 117: 900–4.