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Can laboratory-guided treatment of gonorrhoea with ciprofloxacin help to stem the emergence of resistance to ceftiaxone?

28 Jun, 17 | by Leslie Goode, Blogmaster

With antimicrobial-resistant gonorrhoea now an urgent health threat, requiring improved antibiotic stewardship, one option frequently proposed is laboratory-guided recycling of older antibiotics (Lewis (STI); Ison & Unemo (STI); A new kind of treatment for gonorrhoea? (STI/blogs)).  Lewis (STI) alludes to the potential use of floroquinolone therapy – specifically in respect to the oropharyngx, which is the site at which treatment failure is most likely to occur.  Epidemiological typing to detect markers associated with antibiotic resistance makes this kind of intervention a real possibility (Graham & Jennison (STI).

Lao-Tzu & Klausner (L&K) have recently reported a trial that claims to demonstrate the feasibility of just the kind of therapy envisaged by Lewis.  The researchers at University of California Los Angeles (UCLA) Health Clinical Microbiology Laboratory developed and implemented a molecular assay for the prediction of gonorrhoea (Ng) ciprofloxacin susceptibility.  Over the period from November 2015 to July 2016 all Ng positive specimens were subjected to the assay, and treatment recommendations issued on that basis.  In the final two months (June-July 2016) electronic reminder notifications were introduced – and it was only at that point that the intervention had any substantial impact on the treatment of patients.

Of the 176 infections detected, 121 (69%) were successfully genotyped.  Of the latter, 72 (60%) showed wild-type gyrA (the gene associated with antimicrobial resistance, 49 (40%) were mutant.  In the final successful two-month phase of assay implementation, this enabled 9 out of 11 (82%) of Ng infections to be treated with ciprofloxacin. The authors claim this shows the potential for laboratory-guided treatment of floroquinolones to limit recourse to ceftriaxone – and thereby slow the emergence of antibiotic resistant Ng.  Clearly, the trial needs to be run again, but this time using electronic reminder notifications from the start.

When it comes to the more specific issue of antimicrobial resistance to Ng at the oropharyngeal site, the results of the study are less promising. The proportion of gyrA mutant Ng infections did not vary significantly by site (pharyngeal 33%; rectal 45.7%; vaginal/cervical 57%; urine 39%); but of the 62 pharyngeal infections, most (40) could not be genotyped.  So laboratory-guided ciprofloxacin treatment would be of limited usefulness in key populations – such as MSM.

 

 

HPTN 071 attempts universal home-based HIV testing in sub-Saharan Africa: scaling the mountainous challenge of UNAIDS 90-90-90 target

9 Jun, 17 | by Leslie Goode, Blogmaster

Estimates of 96% for the preventative efficacy of ART against HIV transmission, reported in 2011 by Myron & Cohen (M&C), appeared at last to place long-term containment of the epidemic in our hands.  In the wake of this, UNAIDS: 90-90-90 proposed ambitious targets: 90% of those living with HIV to know their status; 90% of known HIV+ individuals to undergo ART initiation; 90% of ART initiated to achieve viral suppression.  Yet – for all the promise of known ART efficacy – the question remains how easy it will be to realize these targets in practice, especially in those settings (e.g. sub-Saharan Africa) where the impact of the epidemic is at its most severe.

Perhaps less easily than one might imagine, suggest Hayes & Fidler (H&F) – a first (one year in) report of results from HPTN-071.  This is a large cluster-randomized study of home-based HIV testing and treatment in 21 Zambian and S. African communities.  The results derive specifically from four of the seven ‘intervention’ communities situated in Zambia.  Of the c.100,000 consenting to the intervention, and visited by pairs of Community HIV Care Providers (CHiPs), 77% of men and 85% of women ended up knowing their status.  (The rest were presumably not reached, or refused testing.)  The estimated proportion of known HIV positive individuals who then went on to initiate ART was 42% within six months and 53% within 12 months.  Over the first year, the estimated overall percentage of HIV+ adults in the four communities who were on ART rose from 44% to 61%.  Obviously, these results reflect only the first year of the intervention, and CHiPs will revisit participants.  At this stage no estimate of the third UNAIDS target (viral suppression) is possible.  Nevertheless, the results reported by this paper give us a sense of the very considerable challenge that the achievement of the UNAIDS target represents in practice.  Among the difficulties, H&F refer specifically to the difficulty of accessing male participants at their homes, and the very slow rates of initiation to ART.

There are various ways of delivering testing.  Home-based testing has been trialled in populations that would otherwise be very difficult to access – e.g. in indigenous Amazonia (Ribeiro & Benzaken (STIs) (R&B); Benzaken & Peeling (STIs) (B&P).  In the case of HPTN-071, its attraction seems to be the possibility of most easily achieving quasi universal coverage.  At 90-90-90, achieved rates of viral suppression would be 73%; at 80-80-80, they would only be 43% – and the preventive efficacy of ART would be correspondingly reduced.  Yet even the latter target seems ambitious.  So far as the testing is concerned, however, the 90% is within reach – at least in Zambia.  The real challenge will be second (and probably also the third) stage of the cascade.  Other studies indicate that HPTN-071 is not unique in seeing large fall out at this point (see Schwartz & Baral (STIs)).  R&B and B&P point to further problem likely to arise at the stage of rolling out this kind of preventative ART intervention – namely that of maintaining the quality of POCT testing (Benzaken & Peeling (STIs)).

 

Sexually transmitted infections are amongst the fastest spreading high-incidence notifiable diseases in China

31 May, 17 | by Leslie Goode, Blogmaster

Sexually transmitted infections emerge from a recent epidemiological study as a particularly pressing concern for Chinese public health at the present time.  Yang & Li (Y&L) assess trends in incidence and mortality in 45 notifiable infectious diseases across China over the decade since the SARS tragedy in 2003 brought important changes in Chinese public health strategies (2003-2013). The main interest of the authors is to investigate the effectiveness of the new strategies.  But, for readers of this journal, what will be especially interesting about this study is the unique profile of three sexually transmitted – or potentially sexually transmitted – diseases: syphilis, HCV and HIV.

In terms of current incidence these three occupy 6th, 8th, and 15th place among the 45, with yearly incidence per 100,000 of, respectively, 20.75, 9.33, and 3.11.  In respect to mortality, HIV far outstrips all the others (even TB), with 48,199 deaths over the ten year period.  However, syphilis, HCV and HIV differ from other high-incidence diseases – hepatitis B, TB, mumps and bacterial dysentery (respectively, 2nd to 5th in the incidence table) – in that their year-on-year incidence is increasing, and at an impressive rate (estimated at a yearly 16.3%, 19.2% and 16.3% averaged over the decade).  These increases are unparalled except in the case of hand, foot and mouth.  The trend in STI incidence emerges particularly strongly against the background of overall trends in the other notifiable diseases. These have, on the whole, been towards stabilization in the latter half of the decade (2009-2013), following an earlier rise likely due in part to technological progress in laboratory detection and case identification (2003-2009).

This raises the questions whether, in the case of STIs, there are particular social factors at work.

For the authors of the study, syphilis, HCV and HIV fall into the category of those diseases whose recent spread can be attributed to the enormous demographic upheavals that have brought over 10% of the population from poor rural areas to the big urban centres in search of economic opportunities, and to ‘augmented human connectivity’.  As regards population mobility, the opinion of Y&L is corroborated by Chen & Tucker (STIs), and – in the case of MSM populations – by Yu & Shang (STIs).  Interestingly, Y&S identify a class of ‘recent migrants’ to the big cities, whose risk profile appears to differ very considerably from that of longer-term residents. Young FSM – many of them also recent migrants to urban centres – appear to represent another high-risk group (Zhang & Luchters (STIs)).  As for the related factor of ‘augmented human connectivity’, this has also been strongly corroborated (Tang & Tucker (STIs)).  Other studies, however, have traced regional outbreaks in these infections – syphilis, HCV and HIV – to causes that are less obviously linked to recent demographic change.  Zhang & Tang (STIs), for example, emphasize the part played in Guangxi by female sex workers who are patronized by older rural workers.  Epidemiological factors, especially over such a vast area, will obviously be complex and multifactorial.

 

Health vulnerability of peri-natally HIV-infected youth: a growing problem throughout the world

3 May, 17 | by Leslie Goode, Blogmaster

Mother-to-child, or ‘vertical’, transmission of HIV is not just a problem for developing countries; even in countries like the US and the UK, peri-natal transmission has probably not been eliminated.  But, with routine ‘opt-out’ ante-natal testing (BHIVA guidelines on HIV testing), cases are increasingly likely to involve births that have taken place overseas or before parental diagnosis (CHIVA guidelines on child testing) – cases that, for various reasons, may be difficult for health services to access (Editorial: ‘Don’t Forget the Children’ (STI)). Yet, even with such events becoming less frequent, and the increasing survival of peri-natally HIV-infected youth (PHIVY) beyond infancy, there remains the problem of managing those already infected, as they transition, in growing numbers, from childhood into adolescence and young adulthood. 

               Such problems are very considerable, according to Nailan & Ciaranello (N&C) – especially for adolescents (13-17yrs) and young adults (18-30yrs).  This recent study offers an analysis of data of PHIVY aged 7-30 years from two cohort studies in the US, the Pediatric HIV/AIDS Cohort Study (PHACS) and the International Maternal Pediatric Adolescent AIDS Clinical Trials study (IMPAACT).  As compared with the younger group (7-13 yrs), adolescents (13-18yrs) and young adults (18-30yrs) are likely to spend considerably more time with inadequate viral suppression (5% and 18% vs 2% with CD4 count <200/µL; 30% and 44% vs 22% with a viral load of 400 copies/mL), and to suffer correspondingly greater mortality (c.1 per 100 person-years amongst young adults) as well as HIV related events (c. 2 and 4 per 100 py. for CDC C and B category events amongst 18-30 yrs; c. 1 and 3 per 100 py. for CDC C and B category events amongst 13-18yrs).  The authors attribute inadequate viral suppression, and high mortality/morbidity, to poor adherence and retention in care. 

               The vulnerability of PHIVY as a group to poor health outcomes is not a problem unique to the US.  In the UK c.1,950 PHIVY are monitored through the Collaborative HIV Pediatric Study (CHIPS) cohort, and the data indicate comparable problems of inadequate viral suppression (around one in ten (CHIVA guidelines on transition)).  In some developing countries the health problems of this group are still more evident.  De Matos & dal Fabbro (STI), analysing the data for a cohort of 78 patients, aged 11-15 in 2009, from a municipality in Brazil, report five deaths, amongst other serious health events.  More generally, the UNAIDS 2016 Report (The ‘life-cycle’ approach (STI/blogs) points, in the case of sub-Saharan Africa, to the recent tripling in peri-natally infected 15-19 yr olds who now account for 40% of all HIV-infected 15-19 yr olds in the region.  Not only does poor adherence pose problems for PHIVY themselves; Nailan & Ciaranello also draw attention to the danger they represent for society at large, given rates of pregnancy and risky sex that appear no lower than in the general population, along with heightened transmission risk resulting from poor viral suppression, and, in some cases, emerging drug resistance.

Bacterial vaginosis-associated bacterium (Gardnerella) may after all have a role in the aetiology of non-gonococcal urethritis

28 Apr, 17 | by Leslie Goode, Blogmaster

The question of the aetiology of ‘non-gonococcal’ or ‘non-specific’ urethritis (NGU/NSU) has been a hot topic of debate in this journal and its predecessors since before 1951, when it was officially acknowledged in the Chief Medical Officer’s report as an independent category of infection (Oriel (STI)). More recently, a number of infectious agents have been recognized as potentially responsible (Hallen & Wallin (STIs); Moi & Moghaddam (STIs)).  But it would be misleading to suggest that, even today, the aetiological question has been altogether resolved.

The controversial hypothesis that bacterial vaginosis (BV) associated bacteria (i.e. Gardnerella) might have a role – proposed in 2001 in an STI editorial by a former editor (Shamanesh (STIs)) – seems to have raised its head once again in a recent animal-based study, Gilbert & Lewis (G&A). Results from studies that have tested for the presence of these – amongst other – bacterial agents seem not to have been particularly favourable to the hypothesis (Manhart & Fredericks (STI); Froelund & Jensen (STIs)).  It must be borne in mind, however, that ‘fastidious growth requirements make G. vaginalis unrecoverable, or at least unidentifiable, under conditions most often used by clinical microbiology labs for the culture and identification of potential uropathogens’ (G&A, p.11).

G&A hypothesize G. vaginalis operates indirectly in the case of NSU by triggering the emergence of Escherichia coli from reservoirs in the bladder of the pre-infected individual.  In this way repeated sexual contact could, they suggest, lead to recurrent UTI infections by an infection that is not itself sexually transmitted.  This theory of ‘covert pathogenesis’ is tested by exposing mice with latent E-coli infection – i.e. mice that had been transurethrally pre-infected but were now negative for bacteriuria – to repeated doses of G. vaginalis or Lactobacillus crispatus.  It was found that double exposure to G.v. triggered E-coli bacteriuria while exposure to L.c.  did not.  Furthermore, G.v. exposed mice had neutrophilic infiltrates, confirming the presence of active UTI.  In sacrificed mice, G.v. was also found to have induced bladder epithelial exfoliation and apoptosis in the bladder epithelium.

The theory of covert pathogenesis is intriguing – not least because it overrides any hard-and-fast distinction been sexually-related and non-sexually-related UTIs.  But, assuming it turns out to be correct, it also has practical implications.  The conventional paradigm assumes that the pathogen present at time of clinical presentation is the main driver of disease.  Given the alarming rise of multi-drug resistant E-coli, the authors point to the potential benefit of preventing UTI and sequelae (e.g. pyelonephritis) by targeting the organism that triggers the infection (i.e. G. vaginalis) rather than the pathogen that causes the symptoms.

 

Harms of HSV-2 may include association of latent infection with autism as well as transfer of active infection to the neonate

11 Apr, 17 | by Leslie Goode, Blogmaster

Mahic & Lipkin (M&L) draw attention to a wholly new health concern in relation to Herpes Simplex Virus 2.

The condition is highly contagious, and the symptoms may be very unpleasant especially during the ‘primary outbreak’, the virus is not, in itself, a major public health concern.  Indeed, up until the 1980s, it was rarely mentioned in this journal – perhaps because it was less common before the 1970s, or maybe because the condition was insufficiently severe to warrant much discussion.

HSV-2 owes its status as a serious health problem to two issues that are independent of its impact on the everyday sufferers.  The first concerns the potentially devastating consequences of transmission of HSV-2 to the neonate (generally in the course of birth rather than in utero) (Preventing neonatal herpes (STIs)).  These are so severe as to have led to a considerable debate on the cost-effectiveness of screening in various parts of the world (Mindel & Cunningham (STIs) (Australia);  Barnabas & Garnett (STIs) (US); Sudfeld & Mensch (STIs) (Malawi)).  The second concerns the links between HSV infection and HIV transmission.  This is an issue discussed primary in the sub-Saharan African context, where HSV is particularly prevalent and its treatment could potentially impact the HIV epidemic (White and Glynn (STIs); Lurie & Matthews (STI)) – though also in the Indian context (Foss & Watts (STI)).

To these two serious concerns Mahic & Lipkin, in a paper recently appearing in the microbiology journal mSphere, have added a third of as yet uncertain importance – the possibility of an association with male autism.  Basing their investigation on data from the Norwegian Autism Birth Cohort (comprising mothers, fathers and infants recruited over the period 1999-2008), the researchers compared maternal immunoglobulin (IgG) antibodies to HSV-2 (amongst other viruses), which had been measured in 442 mothers of male offspring with ASD mid-term, against a frequency-matched control of 464 mothers of ASD unaffected offspring.  An increase in HSV-2 IgG levels from 240 to 640 arbitrary units/ml was found to be associated with a doubling (RR=2.07) in the odds of ASD.  This was not replicated in the case of antibodies to other viruses that were tested for.

The authors suggest that it is the ‘impact of immune activation and inflammation on a vulnerable developing nervous system’ which is likely to be the mechanism here rather than ‘the specific pathogen per se’ – maybe the transfer of maternally produced antibodies and cytokines across the placenta, or the exposure of the fetus to inflammatory molecules produced by the placenta and deciduas in relation to viral shedding.

The question posed by this outcome – should it be confirmed by subsequent research – is whether this third potential harm, when added to the well-established harm of neo-natal infection, might contribute to tipping the balance in favour serological monitoring and suppressive therapy during pregnancy – at least in certain contexts (cf. Barnabas & Garnett (STIs) (US)).

 

Health interventions can change systemic and cultural determinants of STI/HIV transmission

30 Mar, 17 | by Leslie Goode, Blogmaster

The causal pathway linking intimate partner violence (IPV) and health may be two-way.  We are used to thinking of IPV as a determinant of STI; but sexual health also has an impact on IPV.  This, at any rate, is the conclusion of a recently issued working-paper from the US National Bureau of Economic Research uniting a highly interdisciplinary team of researchers from a range of US universities and medical institutions.  The researchers seek to demonstrate that health is kind of human capital, and that a technological advance in medicine can affect ‘some of the most frustratingly persistent social problems’.  This finding will be particularly interesting to readers of this journal.  Health, in the context of this study, happens to be sexual health, and the technological advance is the introduction of HAART in 1996.

Papageorge & Pollack (P&P) base their work on data from the Women’s Intra-Agency HIV Study (WIHS), and compare a cohort of HIV+ women who were, in 1996, just beginning to experience immune system deterioration, with two control cohorts, using a ‘difference in difference’ approach.  One control consisted in HIV+ women not experiencing such effects, another in HIV- women included in the same WIHS data.  Much of the researchers’ task consists in establishing the relative dependence/independence of causal pathways linking IPV with drug use, perceived mental and physical health, and employment.  Their headline finding is a c.10% reduction in IPV a c.15% reduction in IDU attributable to HAART introduction.

The idea that the causative link could flow from STIs to IPV, as well as from IPV to STIs, may not be new to our readers.  Indeed, an ongoing concern for sexual health interventions has been that STI/HIV disclosure (a potentially important element of risk reduction) could result in domestic violence (Partner delivered STI self-testing (STI/blogs)).  This has not prevented other studies from pointing to a potentially positive role for sexual health clinics in relation to IPV (Lockart & McNulty (STIs); Decker and Silverman I (STIs); Decker & Silverman II (STIs)).  The nature of IPV itself is not always well understood, and probably varies with social and cultural context.  For example, it is not restricted to short-term or casual relationships (Silverman & Raj (STIs)), and may be reciprocal (Norris & Hindin (STIs)) as well as man-on-woman.  The nature of the causal link with HIV/STI might be expected to vary with the nature of the IPV itself.

So there is nothing new about the idea that a change in respect to sexual health could influence IPV.  What P&P contribute to the debate is genuinely encouraging, for all that.  Recent characterizations of the global efforts to curb the HIV epidemic (e.g. UNAIDS: On the Fast Track) make a two-fold classification of interventions into, on the one hand, biomedical interventions such as PrEP or cART, and, on the other, vaguer, and longer-term non-biomedical interventions such as legislative or attitudinal change.  The latter correspond to systemic or cultural determinants of sexual health that can seem to mark the ultimate limits on sexual health interventions rather than realistic targets for those interventions.  However, P&P point in this report to the case of a biomedical intervention that would, for once, seem to have achieved something more than an immediate biomedical impact.  HAART introduction, on P&P’s interpretation, effectively provided an additional ‘source of human value’ – an enhancement of women’s social ‘capital’.  Thereby, it would seem to have impacted the fundamental social and cultural determinants of sexual health – those ‘frustratingly persistent social problems’ that constitute the constraints within which sexual health is normally compelled to operate.

‘Scoping’ location: the role of ‘place’/’space’ as an influence on HIV outcomes amongst young MSM

14 Mar, 17 | by Leslie Goode, Blogmaster

Bauermeister & Stephenson (B&S) is a scoping review addressing the impact of location – ‘space’ and ‘place’ – on HIV prevention and care outcomes for young MSM (YMSM).  It owes much to Diaz & Ayala and their concern to view human behaviour in terms of ‘social location’ ‘within a context of social oppressive factors’ rather than in terms of ‘individual identity’.  It focuses on 17 studies, selected for inclusion much as in a systematic review, but analyzed according to scoping methodology (i.e. with a view to mapping out the investigative territory rather than addressing a specific question).  Social location is translated by this study into concepts of ‘space’ and ‘place’.  Space here refers to the physical and geographical aspects of location such as proximity to services and transportation, and place to more socially constructed aspects – ‘the interpersonal exchanges and dynamics that result in physical and social resources in space’.

It is perhaps on account of the breadth of these goals and the methodology of scoping that no very conclusive findings emerge.  Where location assumes the more geographically defined characteristics of ‘space’, the findings underscore the importance of geographic information system (GIS) approaches (see also: Simms & Petersen (STIs editorial); Petersen & Simms (STIs)).  But elsewhere – especially where the concept of location shades into less physical definitions of context (i.e. ‘place’) – the evidence is more contradictory and sometimes appears counter-intuitive.   For example, there are studies that find a positive correlation between social disadvantage and higher levels of adherence to HIV prevention and care recommendations.  Apparently, however, income inequality (as measured by Gini ratio or male-to-female ratio of earnings) stands out across studies as an indicator of poorer YMSM outcomes.

In discussing the limitations of their study, the authors make the interesting point that in a field of investigation as hard to define and as open to fresh hypotheses as this, the tendency for studies reporting an insignificant or null finding not to make their way into the literature could contribute to a serious distortion of our understanding (i.e. ‘publication bias’).  As is evident from their discussion of the review findings, well-conducted studies reporting non-significant findings on the influence of location can make a valuable contribution to the debate (such as, for example,  Haley & Cooper (STIs), a paper published online on the related issue of influence of location on STIs).

A second intriguing question is raised by this review, even if it is perhaps not adequately discussed in it: whether social context is always translatable in terms of ‘geospatial’ location.  Does the concept of ‘place’, for example, really extend to the case of ‘virtual space’ – or does virtual space effectively break free of any geospatial definition?  The question is, of course, very pertinent, given the importance for this population in particular, of dating apps.  Interestingly, Yu & Shang (STIs), in a paper published online, make a case for characterizing an important category of YMSM (occupying a specific ‘place’ in contemporary China society) in terms of extreme geospatial mobility.  One would like to know how B&S would accommodate the paradoxical existence of social ‘places’ defined by the loss of geospatial definition.  Are we still really talking about place?

The PrEP ‘care continuum/cascade’: how would it look?

8 Mar, 17 | by Leslie Goode, Blogmaster

We take for granted the value of the care continuum (or ‘cascade’), now increasingly seen as the key measure of health system response to HIV (Cassell (STIs editorial)).   The application of this model to HIV has provided a benchmark for evaluation in contexts as diverse as Moscow (Wirtz & Beyrer (STIs)), South Africa (Schwartz & Baral (STIs)) or the Netherlands (van Veen & van der Sande (STIs)).   But could the same model also offer a means of evaluation in the case of other complex sexual health interventions such as PrEP (Pre-Exposure Prophylaxis)?

An on-line soon-to-be-published paper by Nunn & Chan (N&C), building on an earlier attempt by Kelley & Rosenberg (K&R), does precisely this.  An important difference from the earlier paper seems to be the more concrete definition of a larger number of steps (nine as against five) – especially in the central area of ‘uptake’ and engagement in care.  Here K&R define three stages: ‘need for awareness of PrEP and willingness to use it’, ‘need for good access to healthcare’, and ‘need for a prescription for PrEP.  N&C replace these with a more concrete conceptualization of the process in five stages involving: an occasion where PrEP access is facilitated (4); an appointment arising from that occasion where the assessment is performed (5); the prescription of PrEP, where indicated (6); the actual initiation of PrEP (i.e. when the client starts taking the pills) (7).  Also important is N&C’s substitution of two final steps – adherence (8)) then retention (9) for K&R’s single final step of ‘adherence’.  N&C point out that, whereas, with ART, ‘adherence’ is once-and-for-all and secures the ultimate goal of viral suppression, in the case of PrEP, we can envisage multiple trajectories depending on whether PrEP continues to be indicated (e.g. the client may no longer be exposed to risk).  Finally, K&R’s first step – ‘identifying at risk MSM’ – gives way to three: identifying at risk individuals (1), enhancing HIV awareness (2), enhancing PrEP awareness (3).

Is this nine-stage definition of a PrEP cascade overly “complex” (EECAAC2018)?

Answering such a question requires us to reflect on the function that the ‘cascade model’ is called upon to perform.  If the model divides up the total course of an intervention into a series of staged tasks, this is presumably because the health benefit depends on the completion of the whole intervention, yet the accomplishment of each step is necessary to the achievement of subsequent ones.  The idea of the cascade can provide a fair way of evaluating the progress of an intervention before its potential health benefits have been delivered – and can also identify the precise points at which the intervention is failing (i.e. where clients become ‘disengaged’).

It follows that each step should correspond to a potential outcome that is not inferable from previous or later outcomes but is worthy of independent evaluation.  If everyone who accesses PrEP (4) also attends an appointment at which suitability of PrEP is discussed (5), or everyone who adheres to PrEP (8) is also retained in PrEP (9), then steps (4) and (5), or steps (8) and (9), can be merged.  This is not stated in so many words by the authors of the model.  However, I would assume that it must lie at the basis of their thinking.

BASHH Centenary Vignette series: Culture of the gonococcus – some historical details

28 Feb, 17 | by flee

Culture of the gonococcus – some historical details

The 43 year period between two BJVD articles1, 2 incubated improvements in the diagnosis of gonorrhoea by laboratory culture. The following 47 gave birth to alternative tests (NAATs), more simple to administer, but whose automation brought loss of personnel and possibly skills: perhaps in microscopy, perhaps in laboratory culture.

In 1927 Colonel Harrison wrote1: “There are differences of opinion as to the value of cultures in the diagnosis of gonorrhoea. Personally I think them indispensable in the case of women and often valuable in male urethritis” (my emphasis).

Laboratory culture of Neisseria gonorrhoeae has always lacked 100% sensitivity. Sampling from multiple sites, on multiple occasions, was necessary to diagnose, to exclude, and, importantly, to monitor any advances, or fluctuations, in the efficiency of laboratory culture. The use of repeated tests to analyse the sensitivity of culture is now impossible, with the universal adoption of epidemiological treatment (before/without diagnosis).

more…

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