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Acanthamoeba castellanii interactions with Streptococcus pneumoniae and Streptococcus pyogenes

Siddiqui R, Yee Ong TY, Jung SY, Khan NA

Exp Parasitol, 2017 Dec;183:128-132.
PMID: 28823705 DOI: 10.1016/j.exppara.2017.08.005

Among the genus Streptococcus, S. pyogenes and S. pneumoniae are the major causes of pharyngitis, impetigo, pneumonia and meningitis in humans. Streptococcus spp. are facultative anaerobes that are nutritionally fastidious, yet survive in the environment and target the predisposed population. Antibacterial disinfectants have been partially effective only, indicating the need for novel preventative measures and to understand mechanisms of bacterial resistance. Acanthamoeba is a free-living protist that is known to harbour microbial pathogens, provide shelter, and assist in their transmission to susceptible population. The overall aim of this study was to determine whether S. pyogenes and S. pneumoniae can interact with A. castellanii by associating, invading, and surviving inside trophozoites and cysts. It was observed that both S. pyogenes and S. pneumoniae were able to associate as well as invade and/or taken up by the phagocytic A. castellanii trophozoite. Notably, S. pyogenes and S. pneumoniae survived the encystation process, avoided phagocytosis, multiplied, and exhibited higher recovery from the mature cysts, compared with the trophozoite stage (approximately 2 bacteria per amoebae ratio for cyst stage versus 0.02 bacteria per amoeba ration for trophozoite stage). As Acanthamoeba cysts are resilient and can disperse through the air, A. castellanii can act as a vector in providing shelter, facilitating growth and possibly genetic exchanges. In addition, these interactions may contribute to S. pyogenes and S. pneumoniae survival in harsh environments, and transmission to susceptible population and possibly affecting their virulence. Future studies will determine the molecular mechanisms associated with Acanthamoeba interactions with Streptococcus and the evolution of pathogenic bacteria and in turn expedite the discovery of novel therapeutic and/or preventative measures.
Status of the effectiveness of contact lens disinfectants in Malaysia against keratitis-causing pathogens

Abjani F, Khan NA, Jung SY, Siddiqui R

Exp Parasitol, 2017 Dec;183:187-193.
PMID: 28919333 DOI: 10.1016/j.exppara.2017.09.007

The aim of this study was (i) to assess the antimicrobial effects of contact lens disinfecting solutions marketed in Malaysia against common bacterial eye pathogens and as well as eye parasite, Acanthamoeba castellanii, and (ii) to determine whether targeting cyst wall would improve the efficacy of contact lens disinfectants. Using ISO 14729 Stand-Alone Test for disinfecting solutions, bactericidal and amoebicidal assays of six different contact lens solutions including Oxysept®, AO SEPT PLUS, OPTI-FREE® pure moist®, Renu® fresh™, FreshKon® CLEAR and COMPLETE RevitaLens™ were performed using Manufacturers Minimum recommended disinfection time (MRDT). The efficacy of contact lens solutions was determined against keratitis-causing microbes, namely: Pseudomonas aeruginosa, Methicillin-resistant Staphylococcus aureus, Streptococcus pyogenes, Streptococcus pneumoniae, and Acanthamoeba castellanii. In addition, using chlorhexidine as an antiamoebic compound and cellulase enzyme to disrupt cyst wall structure, we determined whether combination of both agents can enhance efficacy of marketed contact lens disinfectants against A. castellanii trophozoites and cysts, in vitro. The results revealed that all contact lens disinfectants tested showed potent bactericidal effects exhibiting 100% kill against all bacterial species tested. In contrast, none of the contact lens disinfectants had potent effects against Acanthamoeba cysts viability. When tested against trophozoites, two disinfectants, Oxysept Multipurpose and AO-sept Multipurpose showed partial amoebicidal effects. Using chlorhexidine as an antiamoebic compound and cellulase enzyme to disrupt cyst wall structure, the findings revealed that combination of both agents in contact lens disinfectants abolished viability of A. castellanii cysts and trophozoites. Given the inefficacy of contact lens disinfectants tested in this study, these findings present a significant concern to public health. These findings revealed that targeting cyst wall by using cyst wall degrading molecules in contact lens disinfecting solutions will enhance their efficacy against this devastating eye infection.
Production of a monoclonal antibody against a mannose-binding protein of Acanthamoeba culbertsoni and its localization

Kang AY, Park AY, Shin HJ, Khan NA, Maciver SK, Jung SY

Exp Parasitol, 2018 Sep;192:19-24.
PMID: 30031120 DOI: 10.1016/j.exppara.2018.07.009

Amoebae from the genus Acanthamoeba are facultative pathogens of humans and other animals. In humans they most frequently infect the eye causing a sight threatening infection known as Acanthamoeba keratitis (AK), and also cause an often fatal encephalitis (GAE). A mannose-binding protein (MBP) has been identified as being important for Acanthamoeba infection especially in AK. This lectin has previously been characterized from Acanthamoeba castellanii as consisting of multiple 130 kDa subunits. MBP expression correlates with pathogenic potential and is expressed in a number of Acanthamoeba species. Here we report the purification of a similar lectin from Acanthamoeba culbertsoni and the production of a monoclonal antibody to it. The A. culbertsoni MBP was isolated by affinity chromatography using α-D-mannose agarose and has an apparent molecular weight of 83 kDa. The monoclonal antibody is an IgM that is useful in both western blots and immunofluorescence. We expect that this antibody will be useful in the study of the pathology of A. culbertsoni and in its identification in clinical samples.
Fulltext Feasibility of monitoring Global Breast Cancer Initiative Framework key performance indicators in 21 Asian National Cancer Centers Alliance member countries

Ong SK, Haruyama R, Yip CH, Ngan TT, Li J, Lai D, et al.

EClinicalMedicine, 2024 Jan;67:102365.
PMID: 38125964 DOI: 10.1016/j.eclinm.2023.102365

BACKGROUND: The Global Breast Cancer Initiative (GBCI) Framework, launched by the World Health Organisation (WHO) in 2023, emphasises assessing, strengthening, and scaling up services for the early detection and management of breast cancer. This study aims to determine the feasibility of monitoring the status of breast cancer control in the 21 Asian National Cancer Centers Alliance (ANCCA) countries based on the three GBCI Framework key performance indicators (KPIs): stage at diagnosis, time to diagnosis, and treatment completion.
METHODS: We reviewed published literature on breast cancer control among 21 ANCCA countries from May to July 2023 to establish data availability and compiled the latest descriptive statistics and sources of the indicators using a standardised data collection form. We performed bivariate Pearson's correlation analysis to measure the strength of correlation between stage at diagnosis, mortality and survival rates, and universal health coverage.
FINDINGS: Only 12 (57%) ANCCA member countries published national cancer registry reports on breast cancer age-standardised incidence rate (ASIR) and age-standardised mortality rate (ASMR). Indonesia, Myanmar, and Nepal had provincial data and others relied on WHO's Global Cancer Observatory (GLOBOCAN) estimates. GLOBOCAN data differed from the reported national statistics by 5-10% in Bhutan, Indonesia, Iran, the Republic of Korea, Singapore, and Thailand and >10% in China, India, Malaysia, Mongolia, and Sri Lanka. The proportion of patients diagnosed in stages I and II strongly correlated with the five-year survival rate and with the universal health coverage (UHC) index. Three countries (14%) reported national data with >60% of invasive breast cancer patients diagnosed at stages I and II, and a five-year survival rate of >80%. Over 60% of the ANCCA countries had no published national data on breast cancer staging, the time interval from presentation to diagnosis, and diagnosis to treatment. Five (24%) countries reported data on treatment completion. The definition of delayed diagnosis and treatment completion varied across countries.
INTERPRETATION: GBCI's Pillar 1 KPI correlates strongly with five-year survival rate and with the UHC index. Most ANCCA countries lacked national data on cancer staging, timely diagnosis, and treatment completion KPIs. While institutional-level data were available in some countries, they may not represent the nationwide status. Strengthening cancer surveillance is crucial for effective breast cancer control. The GBCI Framework indicators warrant more detailed definitions for standardised data collection. Surrogate indicators which are measurable and manageable in country-specific settings, could be considered for monitoring GBCI indicators. Ensuring UHC and addressing health inequalities are essential to early diagnosis and treatment of breast cancer.
FUNDING: Funding for this research article's processing fee (APC) will be provided by the affiliated institution to support the open-access publication of this work. The funding body is not involved in the study design; collection, management, analysis and interpretation of data; or the decision to submit for publication. The funding body will be informed of any planned publications, and documentation provided.