Ranmini Kularatne

The Southern African Journal of HIV Medicine is focused on HIV/AIDS treatment, prevention and related topics relevant to clinical and public health practice. The purpose of the journal is to disseminate original research results and support high-level learning related to HIV Medicine. It publishes original research articles, editorials, case reports/case series, reviews of state-of-the-art clinical practice and correspondence.

The Southern African Journal of HIV Medicine is focused on HIV/AIDS treatment, prevention and related topics relevant to clinical and public health practice. The purpose of the journal is to disseminate original research results and support high-level learning related to HIV Medicine. It publishes original research articles, editorials, case reports/case series, reviews of state-of-the-art clinical practice and correspondence.

Treponema pallidum macrolide resistance and clinical treatment failure have emerged rapidly within communities where macrolides have been used as convenient, oral therapeutic alternatives to benzathine penicillin G for syphilis or for other clinical indications. Macrolides are not included in the South African syndromic management guidelines for genital ulcer disease; however, in 2015, a 1-g dose of azithromycin was incorporated into treatment algorithms for genital discharge.

Neisseria gonorrhoeae is the predominant cause of male urethral discharge in South Africa, and escalating prevalence of gonococcal antimicrobial resistance (AMR) is a major health concern both in-country and globally. We analyzed the demographic, behavioral, and clinical characteristics of 685 men presenting with gonococcal urethral discharge to sentinel surveillance clinics over a 3-year period (2017 to 2019) to determine the burden of factors that are known to be associated with N. gonorrhoeae AMR to first-line therapy (defined as group 1 isolates exhibiting resistance or reduced susceptibility to extended-spectrum cephalosporins or azithromycin).

Syphilis is an important sexually transmitted infection caused by the bacterium Treponema pallidum subspecies pallidum . The last two decades have seen syphilis incidence rise in many high-income countries, yet the evolutionary and epidemiological relationships that underpin this are poorly understood, as is the global T. pallidum population structure. We assembled a geographically and temporally diverse collection of clinical and laboratory samples comprising 726 T. pallidum genomes. We used detailed phylogenetic analysis and clustering to show that syphilis globally can be described by only two deeply branching lineages, Nichols and SS14. We show that both of these lineages can be found circulating concurrently in 12 of the 23 countries sampled. To provide further phylodynamic resolution we subdivided Treponema pallidum subspecies pallidum into 17 distinct sublineages. Importantly, like SS14, we provide evidence that two Nichols sublineages have expanded clonally across 9 countries contemporaneously with SS14. Moreover, pairwise genome analysis showed that recent isolates circulating in 14 different countries were genetically identical in their core genome to those from other countries, suggesting frequent exchange through international transmission pathways. This contrasts with the majority of samples collected prior to 1983, which are phylogenetically distinct from these more recently isolated sublineages. Bayesian temporal analysis provided evidence of a population bottleneck and decline occurring during the late 1990s, followed by a rapid population expansion a decade later. This was driven by the dominant T. pallidum sublineages circulating today, many of which are resistant to macrolides. Combined we show that the population of contemporary syphilis in high-income countries has undergone a recent and rapid global expansion.

Background: In South Africa, Neisseria gonorrhoeae (NG) is the predominant cause of male urethritis syndrome (MUS). The national MUS treatment guidelines recommend gentamicin as salvage therapy for ceftriaxone treatment failures. We ascertained and compared gentamicin MICs obtained by agar dilution and Etest for clinical isolates of NG. Methods: Gentamicin MICs for NG culture isolates obtained from 272 MUS cases in 2017 were determined using agar dilution, as per CLSI agar dilution methods, and Etest (R) (bioMerieux, Marcy-l'Etoile, France). Previously published interpretive criteria were used: MIC >= 4 mg/L, susceptible (S); MIC 8-16 mg/L, intermediately resistant (IR); and MIC >= 32 mg/L, resistant (R). WHO 2008 NG reference strains were used as comparison standards. Results: Gentamicin agar dilution versus Etest MIC results (mg/L) were as follows: MIC50 = 16 versus 4; MIC90 = 16 versus 8; minimum MIC = 4 versus 1; and maximum MIC = 32 versus 16. Interpretive categories for agar dilution versus Etest were as follows: S, 4.4% versus 86.8%; IR, 86.0% versus 13.4%; and R, 9.6% versus 0%. The gentamicin MIC50 by agar dilution was significantly higher than by Etest (sign test P value <0.001); overall MIC agreement was 7.4% [kappa statistic (kappa) = -0.014 (95% CI-0.039 to 0.010)]. Correlation with expected MICs for WHO reference strains was consistently better with Etest than with agar dilution. Conclusions: There was a significant discordance between NG gentamicin MICs by agar dilution versus Etest. NG gentamicin AST methodology must be standardized and interpretive criteria established to optimize the monitoring of susceptibility trends.

Antimicrobial resistance in Mycoplasma genitalium is rising globally with resultant clinical treatment failure. We investigated the prevalence of mutations in the macrolide and fluoroquinolone resistance-determining regions of M. genitalium in Johannesburg, South Africa, and ascertained their association with HIV serostatus. Stored M. genitalium positive specimens, collected from STI and HIV patients enrolled in the Gauteng STI National Microbiological Surveillance programme (2007–2014) and a large HIV outpatient clinic-based study (2007) in Johannesburg, were tested for antimicrobial resistance. We determined the prevalence of 23S rRNA gene mutations conferring macrolide resistance and mutations in the quinolone resistance-determining regions (QRDR) of the gyrA and parC genes in 266 M. genitalium positive DNA extracts. No macrolide resistance-associated mutations were detected in any of the specimens analysed. QRDR mutations with known M. genitalium-associated fluoroquinolone resistance were not detected in gyrA, however, one specimen (0.4%) contained a D87Y amino acid alteration in parC, which has been linked to fluoroquinolone treatment failure. The most common parC amino acid change detected, of unknown clinical significance, was P62S (18.8%). We found no significant association between QRDR mutations in M. genitalium and HIV-infection. Ongoing antimicrobial resistance surveillance in M. genitalium is essential, as macrolide resistance may emerge given the recent incorporation of azithromycin into the 2015 South African national STI syndromic management guidelines.

Extra-genital Neisseria gonorrhoeae and Chlamydia trachomatis infections are mostly asymptomatic, and important reservoir sites of infection as they often go undetected and may be more difficult to eradicate with recommended therapeutic regimens. Commercial nucleic acid amplification tests (NAATs) have not received regulatory approval for the detection of N. gonorrhoeae and C. trachomatis in extra-genital specimens. The HOLOGIC® APTIMA Combo2 assay for N. gonorrhoeae and C. trachomatis has performed well in evaluations using extra-genital specimens. We assessed the performance of an in-house real-time duplex PCR assay for the detection of N. gonorrhoeae and C. trachomatis in urine and extra-genital specimens using the HOLOGIC® APTIMA assays as gold standard comparators. Urine, oropharyngeal and ano-rectal specimens were collected from each of 200 men-who-have-sex-with-men (MSM) between December 2011 and July 2012. For N. gonorrhoeae detection, the in-house PCR assay showed 98.5–100% correlation agreement with the APTIMA assays, depending on specimen type. Sensitivity for N. gonorrhoeae detection was 82.4% for ano-rectal specimens, 83.3% for oropharyngeal specimens, and 85.7% for urine; and specificity was 100% with all specimen types. The positive predictive value (PPV) for N. gonorrhoeae detection was 100% and the negative predictive value (NPV) varied with sample type, ranging from 98.5–99.5%. For C. trachomatis detection, correlation between the assays was 100% for all specimen types. The sensitivity, specificity, PPV and NPV of the in-house PCR assay was 100% for C. trachomatis detection, irrespective of specimen type. The in-house duplex real-time PCR assay showed acceptable performance characteristics in comparison with the APTIMA® assays for the detection of extra-genital N. gonorrhoeae and C. trachomatis.

Introduction: Antimicrobial resistant bacterial infections are widespread globally and increases in antimicrobial resistance presents a major threat to public health. Pseudomonas aeruginosa is an opportunistic healthcare-associated pathogen with high rates of morbidity and mortality and an extensive range of resistance mechanisms. This study describes the antibiotic susceptibility profiles of P. aeruginosa isolates from patients with bacteraemia submitted by sentinel laboratories in South Africa from 2014 to 2015. Methodology: Organism identification and antimicrobial susceptibility testing were done using automated systems. Molecular methods were used to detect common resistance genes and mechanisms. Results: Overall the susceptibility was high for all antibiotics tested with a decrease over the two-year period. There was no change in the MIC50 and MIC90 breakpoints for all antibiotics from 2014 to 2015. The MIC50 was within the susceptible breakpoint range for most antibiotics and the MIC90 was within the susceptible breakpoint range for colistin only. Phenotypically carbapenem non-susceptible isolates harboured the following plasmid-mediated genes: blaVIM (n = 81, 12%) and blaGES (n = 6, 0.9%); blaNDM (n = 4, 0.6%) and blaOXA-48 and variants (n = 3, 0.45%). Porin deletions were observed in one meropenem non-susceptible isolate only, and multi-drug resistance efflux pumps were expressed in the majority of the non-susceptible isolates investigated. BlaVEB-1, blaIMP and blaKPC were not detected. Conclusion: The prevalence of resistance to commonly used antibacterial agents was low for P. aeruginosa isolates and similarly, tested resistance mechanisms were detected in a relatively small proportion of isolates. Findings in this study represent baseline information for understanding antimicrobial susceptibility patterns in P. aeruginosa isolates from blood. Our surveillance report may assist in contributing to hospital treatment guidelines.