Trachoma: an update on prevention, diagnosis, and treatment

An ophthalmologist fought against trachoma in Turkey and his books from an archive: Dr Nuri Fehmi Ayberk and The Development of Ophthalmology in Turkey

Dr Nuri Fehmi Ayberk is an influential figure in the Turkish ophthalmology in training new specialists in the field and contributing to the fight against trachoma. This article includes his short biography, studies, information and cover pictures of some of his works from the original archive of Ege University Faculty of Medicine, Department of History of Medicine and Ethics, Fatma-Ömer Ekimci Library. He took an active role in the establishment of the Turkish Ophthalmological Association in our country (1928) and served as a founding member. Conducting such studies on the biographies and rare books subgroup of the history of medicine is an important contribution to ensure that the biographies of physicians who have left their mark in the past and have achieved success in different specialties are narrated, remembered, and the information and cover pictures of their works in different archives meet with the reader.

WHO's essential medicines and AWaRe: recommendations on first- and second-choice antibiotics for empiric treatment of clinical infections

The WHO Model List of Essential Medicines (EML) prioritizes medicines that have significant global public health value. The EML can also deliver important messages on appropriate medicine use. Since 2017, in response to the growing challenge of antimicrobial resistance, antibiotics on the EML have been reviewed and categorized into three groups: Access, Watch, and Reserve, leading to a new categorization called AWaRe. These categories were developed taking into account the impact of different antibiotics and classes on antimicrobial resistance and the implications for their appropriate use. The 2023 AWaRe classification provides empirical guidance on 41 essential antibiotics for over 30 clinical infections targeting both the primary health care and hospital facility setting. A further 257 antibiotics not included on the EML have been allocated an AWaRe group for stewardship and monitoring purposes. This article describes the development of AWaRe, focussing on the clinical evidence base that guided the selection of Access, Watch, or Reserve antibiotics as first and second choices for each infection. The overarching objective was to offer a tool for optimizing the quality of global antibiotic prescribing and reduce inappropriate use by encouraging the use of Access antibiotics (or no antibiotics) where appropriate. This clinical evidence evaluation and subsequent EML recommendations are the basis for the AWaRe antibiotic book and related smartphone applications. By providing guidance on antibiotic prioritization, AWaRe aims to facilitate the revision of national lists of essential medicines, update national prescribing guidelines, and supervise antibiotic use. Adherence to AWaRe would extend the effectiveness of current antibiotics while helping countries expand access to these life-saving medicines for the benefit of current and future patients, health professionals, and the environment.

Acceptability and perceived utility of different diagnostic tests and sample types for trachoma surveillance in the Bijagos Islands, Guinea Bissau

BACKGROUND

Trachoma is the leading infectious cause of blindness worldwide and is nearing elimination as a public health problem in Guinea Bissau. It is imperative that elimination is followed by a successful postvalidation surveillance programme. The aim of this study was to determine the acceptability and perceived utility of different diagnostic tests and sample types that could be used for postvalidation trachoma surveillance in the Bijagos Islands, Guinea Bissau.

METHODS

Semistructured interviews with community members and stakeholders involved in trachoma elimination were followed by focus group discussions with community members, covering experiences with trachoma and views on trachoma diagnostic methods and sample types.

RESULTS

In this setting, all diagnostic tests and sample types used for trachoma surveillance were generally considered acceptable by communities. A preference for laboratory-based testing and finger-prick blood samples was expressed as these results were considered more accurate and applicable to a range of diseases beyond trachoma.

CONCLUSIONS

Appropriate community and stakeholder engagement and communication regarding the purpose and processes around diagnostic practice prior to trachoma programme implementation are crucial for long-term successful disease-elimination efforts.

Mass Azithromycin Distribution and Community Microbiome: A Cluster-Randomized Trial

BACKGROUND

Mass distributions of oral azithromycin have long been used to eliminate trachoma, and they are now being proposed to reduce childhood mortality. The observed benefit appears to be augmented with each additional treatment, suggesting a possible community-level effect. Here, we assess whether 2 biannual mass treatments of preschool children affect the community's gut microbiome at 6 months after the last distribution.

METHODS

In this cluster-randomized controlled trial, children aged 1-60 months in the Dossa region of Niger were randomized at the village level to receive a single dose of azithromycin or placebo every 6 months. Fecal samples were collected 6 months after the second treatment for metagenomic deep sequencing. The prespecified primary outcome was the Euclidean PERMANOVA of the gut microbiome, or effectively the distance between the genus-level centroid at the community level, with the secondary outcome being the Simpson's α diversity.

RESULTS

In the azithromycin arm, the gut microbial structures were significantly different than in the placebo arm (Euclidean PERMANOVA, P < .001). Further, the diversity of the gut microbiome in the azithromycin arm was significantly lower than in the placebo arm (inverse Simpson's index, P = .005).

CONCLUSIONS

Two mass azithromycin administrations, 6 months apart, in preschool children led to long-term alterations of the gut microbiome structure and community diversity. Here, long-term microbial alterations in the community did not imply disease but were associated with an improvement in childhood mortality.

CLINICAL TRIALS REGISTRATION

NCT02048007.

An eye for azithromycin: review of the literature

Azithromycin is used widely in clinical practice and recently it is available in topical solution for ophthalmic use. The purpose of the current publication is to summarize the newest information on azithromycin’s clinical usefulness over ocular diseases. A PubMed (National Library of Medicine) and a ScienceDirect search was conducted using the key phrases ‘azithromycin’, ‘meibomian’, ‘blepharitis’, ‘trachoma’, ‘toxoplasmosis’ from 2010 to 2017. Articles were limited to articles published in English or at least having an English abstract. There were no restrictions on age, ethnicity, or geographic locations of patients. Topical azithromycin was found effective and safe in various ocular surface infections, in meibomian gland dysfunction and in trachoma. Also, it may substitute fluoroquinolones in corneal UV cross-linking. The World Health Organization targets for trachoma elimination are being reached only after 3 years of annual mass drug administration. Oral azithromycin can participate in combination regiments for toxoplasmosis, mainly because of its very good safety profile and may play a significant role in toxoplasmosis in pregnancy. Azithromycin is one of the safest antibiotics, well tolerated, and with special pharmacokinetic properties. Also, it is characterized by a broad antimicrobial spectrum. Azithromycin is efficacious for the treatment of a lot of ocular diseases and may be included as monotherapy or in combination therapy in new treatment protocols for more ocular infections. However, more research is needed to determine this.

Koala immunology and infectious diseases: How much can the koala bear?

Infectious diseases are contributing to the decline of the iconic Australian marsupial, the koala (Phascolarctos cinereus). Infections with the obligate intracellular bacteria, Chlamydia pecorum, cause debilitating ocular and urogenital-tract disease while the koala-retrovirus (KoRV) has been implicated in host immunosuppression and exacerbation of chlamydial pathogenesis. Although histological studies have provided insight into the basic architecture of koala immune tissues, our understanding of the koala immune response to infectious disease has been limited, until recently, by a lack of species-specific immune reagents. Recent advances in the characterisation of key immune genes have focused on advancing our understanding of the immune response to Chlamydia infection, revealing commonalities in disease pathologies and immunity between koalas and other hosts and paving the way for the development of a koala Chlamydia vaccine. This review summarises these recent findings and highlights key aspects of the koala immune system requiring further attention with particular regard to their most prominent infectious diseases.

Replication-dependent size reduction precedes differentiation in Chlamydia trachomatis

Chlamydiatrachomatis is the most common cause of bacterial sexually transmitted infection. It produces an unusual intracellular infection in which a vegetative form, called the reticulate body (RB), replicates and then converts into an elementary body (EB), which is the infectious form. Here we use quantitative three-dimensional electron microscopy (3D EM) to show that C. trachomatis RBs divide by binary fission and undergo a sixfold reduction in size as the population expands. Conversion only occurs after at least six rounds of replication, and correlates with smaller RB size. These results suggest that RBs only convert into EBs below a size threshold, reached by repeatedly dividing before doubling in size. A stochastic mathematical model shows how replication-dependent RB size reduction produces delayed and asynchronous conversion, which are hallmarks of the Chlamydia developmental cycle. Our findings support a model in which RB size controls the timing of RB-to-EB conversion without the need for an external signal.

The vegetative forms of chlamydiae (RBs) replicate within infected cells and then convert into infectious forms (EBs). Here, the authors use quantitative 3D electron microscopy and computer modeling to show that RB size decreases with replication, and conversion into EBs correlates with an RB size threshold.

Mycoplasma hominis, Ureaplasma urealyticum and Chlamydia trachomatis Respiratory Colonization in Malaysian Preterm Infants

This prospective observational study aims to determine the incidence, predictors and clinical features of Mycoplasma hominis (MH), Ureaplasma urealyticum (UU) and Chlamydia trachomatis (CT) respiratory colonization in infants <37 weeks of gestation. A total of 200 preterm newborns admitted to a tertiary center in Malaysia between 2013 and 2015 for increased breathing effort had their respiratory secretions tested for these bacteria by polymerase chain reaction. Fifteen of the 200 (7.5%) infants were detected to have these organisms in their respiratory tracts. Preterm prelabor rupture of membrane was associated with positive detection (odds ratio: 3.7; 95% confidence interval: 1.2-11.3). Seventy-three of the 200 (36.5%) infants were given macrolide for presumed infection but only 4.1% (3 of 73) were positive for these organisms. The incidence of UU respiratory colonization among preterm infants in our center is lower than other published reports, while the frequency of MH and CT isolation is comparable with many studies. There should be judicious use of empirical antibiotics for presumed UU, MH and CT infection in preterm infants.

Chlamydial eye infections: Current perspectives

Chlamydia trachomatis, an obligate intraocular bacteria causing trachoma, adult and neonatal inclusion conjunctivitis, was the leading cause of blindness in the last century worldwide. Improvement in socioeconomic and living conditions, availability of antibiotics, and introduction of National Trachoma Control Programmes reduced the prevalence in developed countries, but it persisted in resource-poor settings of Africa and Asia, including India. In 2016, as per the WHO report, trachoma is restricted to 42 countries, causing blindness/visual impairment in ~1.9 million people. India is one of the five countries with nearly half of total active trachoma patients. Introduction of Global Elimination of Trachoma 2020 program by the WHO, using SAFE strategy (surgery for trachomatous trichiasis; Antibiotics for C. trachomatis; Facial cleanliness; and environmental improvement) greatly reduced the prevalence, but trachoma still persists in India. Global increase in the reproductive tract infection by C. trachomatis urogenital serotypes (D-K) has led to concurrent increase in C. trachomatis eye infections. Therefore, kerato eye infections due to chlamydial infections continue to be seen in hospitals. Over the years, there have been advances in laboratory diagnostics, in understanding the pathogenesis, tissue tropism, C. trachomatis genomics, and treatment modalities. Due attention and research is still needed for the study of C. trachomatis eye infections.

Optimal Proliferation and Differentiation of Chlamydia Trachomatis

Chlamydia trachomatis is a bacterium that causes eye infection and blindness in humans. It has an unusual life cycle involving two developmental forms. Within a cytoplasmic inclusion, the reticulate body (RB) repeatedly divides by binary fission and asynchronously differentiates into the infectious elementary body (EB). Upon the death of the mammalian cell that host many such inclusions, only the EB form of the bacteria survive and proceed to infect other cells. Given the bacteria's fast spreading infection, conventional wisdom would have the few initial EB turn into RB, divide and proliferate first, and then eventually start converting in order to maximize the terminal EB population upon host cell lysis. Several biological processes are seen as possible mechanisms for implementing such a conversion strategy. However, the optimality of an instinctual strategy with a period of proliferate without conversion prior to the onset of differentiation has never been substantiated theoretically or justified mathematically. This paper formulates three relatively simple models that capture the essential features of the Chlamydia life cycle. When the initial infection is caused by the endocytosis of a small EB population well below the carrying capacity of the host cell, the Maximum Principle requires for these models an optimal conversion strategy that confirms and rigorously justifies the prevailing view of no conversion at the early stage of the host cell infection. However, the conventional supposition is found to be inappropriate for an initial EB (-to-RB) population near or above the carrying capacity. Previously suggested and new biological mechanisms are examined for their role in implementing the different optimal conversion strategies associated with models investigated herein.

[Lymphogranuloma venereum: the first Hungarian cases]

Lymphogranuloma venereum is a sexually transmitted infection caused by the Chlamydia trachomatis serovars L1-3. It has been found to be endemic in tropical countries. In the last decades several cases have been reported in Western Europe, particularly in men who have sex with men population infected with human immunodeficiency virus. The authors present three cases of lymphogranuloma venereum infections, observed at their department in 2013 and 2014. The three human immunodeficiency virus infected patients who belonged to men who have sex with men population had casual sexual contacts in Western Europe. The symptoms included urethral discharge, discomfort and inguinal lymphadenomegaly in two patients, and rectal pain, discharge and perianal ulceration in one patient. The diagnosis was confirmed by nucleic acid amplification test performed in samples obtained from urethral discharge and exudate of perianal ulcer; lymphogranuloma venereum 2b serovars were demonstrated in two patients and serovar 2 in one patient. Doxycyclin (daily dose of two times 100 mg for 21 days) resolved the symptoms in all cases. The authors conclude that lymphogranuloma venereum is a diagnostic challenge in Hungary, too. It is important to be aware of the altered clinical features of this disease to prevent complications and spreading.

Draft Genome Sequence of High-Temperature-Adapted Protochlamydia sp. HS-T3, an Amoebal Endosymbiotic Bacterium Found in Acanthamoeba Isolated from a Hot Spring in Japan

Here, we report the draft genome sequence of high-temperature-adapted Protochlamydia sp. strain HS-T3, an environmental chlamydia. This bacterium is an amoebal endosymbiont, found in Acanthamoeba isolated from a hot spring in Japan. Strain HS-T3 readily grew in mammalian cells at 37°C, a characteristic not previously reported for environmental chlamydiae.

Inhibitory activity of the isoflavone biochanin A on intracellular bacteria of genus Chlamydia and initial development of a buccal formulation

Given the established role of Chlamydia spp. as causative agents of both acute and chronic diseases, search for new antimicrobial agents against these intracellular bacteria is required to promote human health. Isoflavones are naturally occurring phytoestrogens, antioxidants and efflux pump inhibitors, but their therapeutic use is limited by poor water-solubility and intense first-pass metabolism. Here, we report on effects of isoflavones against C. pneumoniae and C. trachomatis and describe buccal permeability and initial formulation development for biochanin A. Biochanin A was the most potent Chlamydia growth inhibitor among the studied isoflavones, with an IC₅₀ = 12 µM on C. pneumoniae inclusion counts and 6.5 µM on infectious progeny production, both determined by immunofluorescent staining of infected epithelial cell cultures. Encouraged by the permeation of biochanin A across porcine buccal mucosa without detectable metabolism, oromucosal film formulations were designed and prepared by a solvent casting method. The film formulations showed improved dissolution rate of biochanin A compared to powder or a physical mixture, presumably due to the solubilizing effect of hydrophilic additives and presence of biochanin A in amorphous state. In summary, biochanin A is a potent inhibitor of Chlamydia spp., and the in vitro dissolution results support the use of a buccal formulation to potentially improve its bioavailability in antichlamydial or other pharmaceutical applications.

Host defense at the ocular surface

Microbial infections of the cornea frequently cause painful, blinding and debilitating disease that is often difficult to treat and may require corneal transplantation. In addition, sterile corneal infiltrates that are associated with contact lens wear cause pain, visual impairment and photophobia. In this article, we review the role of Toll-Like Receptors (TLR) in bacterial keratitis and sterile corneal infiltrates, and describe the role of MD-2 regulation in LPS responsiveness by corneal epithelial cells. We conclude that both live bacteria and bacterial products activate Toll-Like Receptors in the cornea, which leads to chemokine production and neutrophil recruitment to the corneal stroma. While neutrophils are essential for bacterial killing, they also cause tissue damage that results in loss of corneal clarity. These disparate outcomes, therefore, represent a spectrum of disease severity based on this pathway, and further indicate that targeting the TLR pathway is a feasible approach to treating inflammation caused by live bacteria and microbial products. Further, as the P. aeruginosa type III secretion system (T3SS) also plays a critical role in disease pathogenesis by inducing neutrophil apoptosis and facilitating bacterial growth in the cornea, T3SS exotoxins are additional targets for therapy for P. aeruginosa keratitis.

Will the SAFE strategy be sufficient to eliminate trachoma by 2020? Puzzlements and possible solutions

Since the inception of (the Global Elimination of Blinding Trachoma) GET 2020 in 1997 and the implementation of the SAFE strategy a year later, much progress has been made toward lowering the prevalence of trachoma worldwide with elimination of the disease in some countries. However, high recurrence of trichiasis after surgery, difficulty in controlling the reemergence of infection after mass distribution of azithromycin in some communities, the incomplete understanding of environment in relation to the disease, and the difficulty in establishing the prevalence of the disease in low endemic areas are some of the issues still facing completion of the GET 2020 goals. In this narrative review, literature was searched from 1998 to January 2013 in PubMed for original studies and reviews. Reasons for these ongoing problems are discussed, and several suggestions are made as avenues for exploration in relation to improving the SAFE strategy with emphasis on improving surgical quality and management of the mass treatment with antibiotics. In addition, more research needs to be done to better understand the approach to improve sanitation, hygiene, and environment. The main conclusion of this review is that scale-up is needed for all SAFE components, and more research should be generated from communities outside of Africa and Asia.