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Parasitology Research Sep 2021Acanthamoeba spp. are among the most worldwide prevalent protozoa. It is the causative agent of a disease known as Acanthamoeba keratitis, a painful and severe... (Review)
Review
Acanthamoeba spp. are among the most worldwide prevalent protozoa. It is the causative agent of a disease known as Acanthamoeba keratitis, a painful and severe sight-threatening corneal infection that can lead to blindness. In recent years, the prevalence of Acanthamoeba keratitis has rapidly increased, growing its importance to human health. This systematic review aims to assess the distribution of Acanthamoeba sp. genotypes causing keratitis around the world, considering the sample collected type and the used identification method. Most of the cases were found in Asia and Europe. Not surprisingly, the T4 genotype was the most prevalent worldwide, followed by T3, T15, T11, and T5. Furthermore, the T4 genotype contains a higher number of species. Given the differences in pathology, susceptibility to treatment, and clinical outcome between distinct genotypes, it is essential to genotype isolates from Acanthamoeba keratitis cases to help to establish a better correlation between in vitro and in vivo activities, resulting in better drug therapies and successful treatment in cases of this important ocular infection.
Topics: Acanthamoeba; Acanthamoeba Keratitis; Cornea; Genotype; Humans
PubMed: 34351492
DOI: 10.1007/s00436-021-07261-1 -
Scientific Reports Jun 2021Infectious keratitis (IK) is the 5th leading cause of blindness globally. Broad-spectrum topical antimicrobial treatment is the current mainstay of treatment for IK,... (Meta-Analysis)
Meta-Analysis
Infectious keratitis (IK) is the 5th leading cause of blindness globally. Broad-spectrum topical antimicrobial treatment is the current mainstay of treatment for IK, though adjuvant treatment or surgeries are often required in refractory cases of IK. This systematic review aimed to examine the effectiveness and safety of adjuvant amniotic membrane transplantation (AMT) for treating IK. Electronic databases, including MEDLINE, EMBASE and Cochrane Central, were searched for relevant articles. All clinical studies, including randomized controlled trials (RCTs), non-randomized controlled studies and case series (n > 5), were included. Primary outcome measure was time to complete corneal healing and secondary outcome measures included corrected-distance-visual-acuity (CDVA), uncorrected-distance-visual-acuity (UDVA), corneal vascularization and adverse events. A total of twenty-eight studies (including four RCTs) with 861 eyes were included. When compared to standard antimicrobial treatment alone, adjuvant AMT resulted in shorter mean time to complete corneal healing (- 4.08 days; 95% CI - 6.27 to - 1.88; p < 0.001) and better UDVA (- 0.26 logMAR; - 0.50 to - 0.02; p = 0.04) at 1 month follow-up in moderate-to-severe bacterial and fungal keratitis, with no significant difference in the risk of adverse events (risk ratio 0.80; 0.46-1.38; p = 0.42). One RCT demonstrated that adjuvant AMT resulted in better CDVA and less corneal vascularization at 6 months follow-up (both p < 0.001). None of the RCTs examined the use of adjuvant AMT in herpetic or Acanthamoeba keratitis, though the benefit was supported by a number of case series. In conclusion, AMT serves as a useful adjuvant therapy in improving corneal healing and visual outcome in bacterial and fungal keratitis (low-quality evidence). Further adequately powered, high-quality RCTs are required to ascertain its therapeutic potential, particularly for herpetic and Acanthamoeba keratitis. Future standardization of the core outcome set in IK-related trials would be invaluable.
Topics: Amnion; Animals; Disease Management; Disease Susceptibility; Humans; Keratitis; Randomized Controlled Trials as Topic; Treatment Outcome
PubMed: 34155280
DOI: 10.1038/s41598-021-92366-x -
Expert Review of Anti-infective Therapy Nov 2021: encompasses several species of free-living ameba encountered commonly throughout the environment. Unfortunately, these species of ameba can cause opportunistic...
: encompasses several species of free-living ameba encountered commonly throughout the environment. Unfortunately, these species of ameba can cause opportunistic infections that result in keratitis, granulomatous amebic encephalitis, and occasionally systemic infection.: This review discusses relevant literature found through PubMed and Google scholar published as of January 2021. The review summarizes current common keratitis treatments, drug discovery methodologies available for screening potential anti- compounds, and the anti- activity of various azole antifungal agents.: While several biguanide and diamidine antimicrobial agents are available to clinicians to effectively treat keratitis, no singular treatment can effectively treat every keratitis case.Efforts to identify new anti-Acanthamoeba agents include trophozoite cell viability assays, which are amenable to high-throughput screening. Cysticidal assays remain largely manual and would benefit from further automation development. Additionally, the existing literature on the effectiveness of various azole antifungal agents for treating keratitis is incomplete or contradictory, suggesting the need for a systematic review of all azoles against different pathogenic strains.
Topics: Acanthamoeba; Acanthamoeba Keratitis; Amebicides; Azoles; Drug Evaluation, Preclinical; Humans
PubMed: 33929276
DOI: 10.1080/14787210.2021.1924673 -
The Cochrane Database of Systematic... Feb 2015Acanthamoeba are microscopic, free-living, single-celled organisms which can infect the eye and lead to Acanthamoeba keratitis (AK). AK can result in loss of vision in... (Review)
Review
BACKGROUND
Acanthamoeba are microscopic, free-living, single-celled organisms which can infect the eye and lead to Acanthamoeba keratitis (AK). AK can result in loss of vision in the infected eye or loss of eye itself; however, there are no formal guidelines or standards of care for the treatment of AK.
OBJECTIVES
To evaluate the relative effectiveness and safety of medical therapy for the treatment of AK.
SEARCH METHODS
We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (2015, Issue 1), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to January 2015), EMBASE (January 1980 to January 2015), PubMed (1948 to January 2015), Latin American and Caribbean Health Sciences Literature Database (LILACS) (1982 to January 2015), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic search for trials. We last searched the electronic databases on 9 January 2015.
SELECTION CRITERIA
We included randomized controlled trials (RCTs) of medical therapy for AK, regardless of the participants' age, sex, or etiology of disease. We included studies that compared either anti-amoeba therapy (drugs used alone or in combination with other medical therapies) with no anti-amoeba therapy or one anti-amoeba therapy with another anti-amoeba therapy.
DATA COLLECTION AND ANALYSIS
Two authors independently screened search results and full-text reports, assessed risk of bias, and abstracted data. We used standard methodological procedures as set forth by the Cochrane Collaboration.
MAIN RESULTS
We included one RCT (56 eyes of 55 participants) in this review. The study compared two types of topical biguanides for the treatment of AK: chlorhexidine 0.02% and polyhexamethylene biguanide (PHMB) 0.02%. All participants were contact lens wearers with a median age of 31 years. Treatment duration ranged from 51 to 145 days. The study, conducted in the UK, was well-designed and had low risk of bias overall.Outcome data were available for 51 (91%) of 56 eyes. Follow-up times for outcome measurements in the study were not reported. Resolution of infection, defined as control of ocular inflammation, relief of pain and photosensitivity, and recovery of vision, was 86% in the chlorhexidine group compared with 78% in the PHMB group (relative risk (RR) 1.10, 95% confidence intervals (CI) 0.84 to 1.42). In the chlorhexidine group, 20 of 28 eyes (71%) had better visual acuity compared with 13 of 23 eyes (57%) in the PHMB group at final follow-up (RR 1.26, 95% CI 0.82 to 1.94). Five participants required therapeutic keratoplasty: 2 in the chlorhexidine group compared with 3 in the PHMB group (RR 0.55, 95% CI 0.10 to 3.00). No serious adverse event related to drug toxicity was observed in the study.
AUTHORS' CONCLUSIONS
There is insufficient evidence to evaluate the relative effectiveness and safety of medical therapy for the treatment of AK. Results from the one included study yielded no difference with respect to outcomes reported between chlorhexidine and PHMB. However, the sample size was inadequate to detect clinically meaningful differences between the two groups as indicated by the wide confidence intervals of effect estimates.
Topics: Acanthamoeba Keratitis; Anti-Infective Agents, Local; Biguanides; Chlorhexidine; Humans; Randomized Controlled Trials as Topic
PubMed: 25710134
DOI: 10.1002/14651858.CD010792.pub2 -
The Journal of International Medical... Mar 2021keratitis (AK) is a rare but severe ocular infection with a significant risk of vision loss. Contact lens use is the main risk factor for AK. The orthokeratology (OK)...
keratitis (AK) is a rare but severe ocular infection with a significant risk of vision loss. Contact lens use is the main risk factor for AK. The orthokeratology (OK) lens, a specially designed contact lens, has been used worldwide as an effective method of myopia control. However, the OK lens is associated with an increased risk of infection. Many primary practitioners are concerned about this infection because of its relative rarity, the lack of promising therapeutic medications, and the need for referral. We herein report two cases of AK associated with OK lenses, present a systematic review of such cases, and discuss the possible reasons for the higher incidence rate of this infection in patients who wear OK lenses. We combined the clinical knowledge and skills of corneal specialists and lens experts with the sole objective of addressing these OK lens-related AK cases. We found that the most common risk factors were rinsing the lenses or lens cases with tap water. Prompt and accurate diagnosis along with adequate amoebicidal treatment are essential to ensure desirable outcomes for OK lens wearers who develop AK. Appropriate OK lens parameters and regular checkups are also important.
Topics: Acanthamoeba Keratitis; Contact Lenses; Cornea; Humans; Myopia; Risk Factors
PubMed: 33752507
DOI: 10.1177/03000605211000985 -
Annals of Parasitology 2018Acanthamoeba, an opportunistic protozoan parasite, is distributed in the environment globally, causes serious human infections, including a fatal encephalitis and... (Meta-Analysis)
Meta-Analysis
Acanthamoeba, an opportunistic protozoan parasite, is distributed in the environment globally, causes serious human infections, including a fatal encephalitis and keratitis. The purpose of this study was to evaluate the prevalence and genotyping of Acanthamoeba spp. from different water and soil sources in Iran. Six English language and four Persian language databases were searched to identify studies published from March 2005 to October 2016. Random effect model and Stats Direct statistical software was used for the meta-analysis. This review resulted in a total 34 articles meeting the including criteria. The overall prevalence rate of Acanthamoeba spp. among the 1850 water and soil samples in Iran with using random-effect model was estimated 42.7%. The genotyping results of the Acanthamoeba isolates showed that T4 (81.2%) was a predominant strain in Iran. In addition, other genotypes, T2, T3, T4, T5, T6, T11, T13, T15, mixed T3/T4 and mixed T2/T6, were obtained in the environmental samples of Iran. This study may be the first systematic review and meta-analysis of Acanthamoeba prevalence and genotyping in different environmental sources of Iran. Knowledge about wide distribution of Acanthamoeba T4 in the environmental sources may help physicians to manage the patients and susceptible persons in Iran.
Topics: Acanthamoeba; Acanthamoeba Keratitis; Genotype; Humans; Iran; Soil; Water
PubMed: 30710471
DOI: 10.17420/ap6404.163 -
Asian Pacific Journal of Tropical... Sep 2017To verify phylogeography and genetic structure of Acanthamoeba populations among the Iranian clinical isolates and natural/artificial environments distributed in various... (Review)
Review
OBJECTIVE
To verify phylogeography and genetic structure of Acanthamoeba populations among the Iranian clinical isolates and natural/artificial environments distributed in various regions of the country.
METHODS
We searched electronic databases including Medline, PubMed, Science Direct, Scopus and Google Scholar from 2005 to 2016. To explore the genetic variability of Acanthamoeba sp, 205 sequences were retrieved from keratitis patients, immunosuppressed cases and environmental sources as of various geographies of Iran.
RESULTS
T4 genotype was the predominant strain in Iran, and the rare genotypes belonged to T2, T3, T5 (Acanthamoeba lenticulata), T6, T9, T11, T13 and T15 (Acanthamoeba jacobsi). A total of 47 unique haplotypes of T4 were identified. A parsimonious network of the sequence haplotypes demonstrated star-like feature containing haplogroups IR6 (34.1%) and IR7 (31.2%) as the most common haplotypes. In accordance with the analysis of molecular variance, the high value of haplotype diversity (0.612-0.848) of Acanthamoeba T4 represented genetic variability within populations. Neutrality indices of the 18S ribosomal RNA demonstrated negative values in all populations which represented a considerable divergence from neutrality. The majority of genetic diversity belonged to the infected contact lens and dust samples in immunodeficiency and ophthalmology wards, which indicated potential routes for exposure to a pathogenic Acanthamoeba sp. in at-risk individuals. A pairwise fixation index (F) was from low to high values (0.02433-0.41892). The statistically F points out that T4 is genetically differentiated between north-west, north-south and central-south metapopulations, but not differentiated between west-central, west-south, central-south, and north-central isolates.
CONCLUSIONS
An occurrence of IR6 and IR7 displays that possibly a gene flow of Acanthamoeba T4 occurred after the founder effect or bottleneck experience through ecological changes or host mobility. This is the first systematic review and meta-analysis providing new approaches into gene migration and transmission patterns of Acanthamoeba sp, and targeting at the high-risk individuals/sources among the various regions of Iran.
PubMed: 29080613
DOI: 10.1016/j.apjtm.2017.08.011 -
Journal of Ophthalmic Inflammation and... May 2013Collagen cross linking (CXL) of the cornea has been developed recently as a new treatment for multidrug-resistant infectious keratitis. The aim of this study is to...
BACKGROUND
Collagen cross linking (CXL) of the cornea has been developed recently as a new treatment for multidrug-resistant infectious keratitis. The aim of this study is to summarize the previously published data and evaluate the effectiveness of this treatment.
RESULTS
The search identified 12 articles. The number of eyes was 104. The infectious keratitis was associated with bacteria in 58 eyes (57f%): Gram-positive bacteria in 44 (43%; 4 of which were infected with Mycobacterium (3.6%)) and Gram-negative bacteria in 14 eyes (13%), fungus in 13 eyes (12%), and Acanthamoeba in 7 eyes (7%). In 26 eyes (25%), the microbiological culture was negative or not performed. The mean time of re-epithelization after CXL was 20.7±28.1 days (minimum of 3, maximum of 145). Sixteen eyes underwent deep or lamellar keratoplasty. The pooled analysis suggested that CXL has a favorable effect on the block of corneal melting in 85% (95%; CI 0.77, 0.91) of eyes.
CONCLUSION
Although randomized controlled trials are needed, the available evidence supports the use of CXL in the treatment of infectious keratitis.
PubMed: 23718849
DOI: 10.1186/1869-5760-3-47 -
Memorias Do Instituto Oswaldo Cruz 2022Free-living amoeba (FLA) group includes the potentially pathogenic genera Acanthamoeba, Naegleria, Balamuthia, Sappinia, and Vermamoeba, causative agents of human...
Free-living amoeba (FLA) group includes the potentially pathogenic genera Acanthamoeba, Naegleria, Balamuthia, Sappinia, and Vermamoeba, causative agents of human infections (encephalitis, keratitis, and disseminated diseases). In Brazil, the first report on pathogenic FLA was published in the 70s and showed meningoencephalitis caused by Naegleria spp. FLA studies are emerging, but no literature review is available to investigate this trend in Brazil critically. Thus, the present work aims to integrate and discuss these data. Scopus, PubMed, and Web of Science were searched, retrieving studies from 1974 to 2020. The screening process resulted in 178 papers, which were clustered into core and auxiliary classes and sorted into five categories: wet-bench studies, dry-bench studies, clinical reports, environmental identifications, and literature reviews. The papers dating from the last ten years account for 75% (134/178) of the total publications, indicating the FLA topic has gained Brazilian interest. Moreover, 81% (144/178) address Acanthamoeba-related matter, revealing this genus as the most prevalent in all categories. Brazil's Southeast, South, and Midwest geographic regions accounted for 96% (171/178) of the publications studied in the present work. To the best of our knowledge, this review is the pioneer in summarising the FLA research history in Brazil.
Topics: Acanthamoeba; Amoeba; Brazil; Cell Movement; Encephalitis; Humans
PubMed: 35792751
DOI: 10.1590/0074-02760210373