Bottled mineral waters polluted by protozoa in Mexico

Isolation and molecular identification of free-living amoebae (Naegleria spp., Acanthamoeba spp. and Vermamoeba spp.) from mineral springs in Guilan Province, northern Iran

Free-living amoebae (FLA) include many genera which cause serious diseases such as sight-threatening keratitis, cutaneous ulcers and fatal encephalitis. This study was conducted due to the lack of research regarding genotypes Acanthamoeba, Naegleria and Vermamoeba in mineral springs of Guilan Province in northern Iran. Twenty-five water samples were collected from mineral springs in Guilan Province. After filtration through nitrocellulose membrane, samples were cultured on non-nutrient agar plates. The morphological key of Page was used to identify free-living amoebae (FLA) using an inverted microscope. Positive cultures were analyzed by polymerase chain reaction (PCR) and genotypes based on the NCBI database. Eleven (44%) samples were positive for Acanthamoeba, Naegleria and Vermamoeba. By sequencing the positive isolates, the strains were shown to belong to Acanthamoeba castellanii (three case isolates belonged to T4 genotype), three cases of Vermamoeba vermiformis, and two cases of N. australiensis, two cases of N. pagei and one case of N. gruberi. According to our research the occurrence of Acanthamoeba, Naegleria spp. and Vermamoeba spp. in mineral springs could be hazardous for high risk persons. Regular monitoring and posting warning signs of these waters by health planners could prevent free-living amoebae mediated diseases.

The impact of vinegar on pathogenic Acanthamoeba astronyxis isolate

Acanthamoeba keratitis (AK) is a severe corneal disease that was reported by WHO as the second most common infectious cause of blindness after trachoma; contact lens wear is considered one of the main risk factors in its transmission. Thus, the treatment of AK is crucial but, the inability of medical agents to completely eradicate the resistant cyst, together with their toxic effects, suggest that new agents are needed. Vinegar has been known long ago as a simple and available disinfectant with antimicrobial effects, so the present study aimed to test the effect of different concentrations of vinegar solution on Acanthamoeba astronyxis isolate, along the period of 1 h in comparison to parasite and chlorhexidine controls. Post hoc test analysis revealed a highly significant difference between the vinegar-treated parasites and both controls, as regards the viable and non-viable mean cysts count. Vinegar concentration of 5% exhibited the highest mean of non-viable cysts along the time intervals, while the lowest was shown with 0.04% where also, no viable cysts were detected at 60 min. All tested concentrations behaved in a time-dependent manner. There was a positive correlation with a significant outcome between the different concentrations and the mean of the non-viable parasites along time. Transmission electron microscopy of treated cysts revealed corrugated altered cell wall with loss of ridges and detachment and shrinkage of content. Treated trophozoites showed flattening of the acanthopodia with thinned out plasma membrane and degenerated cytoplasmic content. The study highlighted the potential use of vinegar as an adjuvant in the prevention and treatment of AK.

The many lives of nontuberculous mycobacteria

Nontuberculous mycobacteria (NTM) include species that colonize human epithelia, as well as species that are ubiquitous in soil and aquatic environments. NTM that primarily inhabit soil and aquatic environments include the Mycobacterium avium complex (MAC, M. avium and Mycobacterium intracellulare) and the Mycobacterium abscessus complex (MABSC, M. abscessus subspecies abscessus, massiliense, and bolletii), and can be free-living, biofilm-associated, or amoeba-associated. Although NTM are rarely pathogenic in immunocompetent individuals, those who are immunocompromised - due to either an inherited or acquired immunodeficiency - are highly susceptible to NTM infection (NTMI). Several characteristics such as biofilm formation and the ability of select NTM species to form distinct colony morphotypes all may play a role in pathogenesis not observed in the related, well-characterized pathogen Mycobacterium tuberculosis The recognition of different morphotypes of NTM has been established and characterized since the 1950s, but the mechanisms that underlie colony phenotype change and subsequent differences in pathogenicity are just beginning to be explored. Advances in genomic analysis have led to progress in identifying genes important to the pathogenesis and persistence of MAC disease as well as illuminating genetic aspects of different colony morphotypes. Here we review recent literature regarding NTM ecology and transmission, as well as the factors which regulate colony morphotype and pathogenicity.

Free-living amoebae in the water resources of Iran: a systematic review

Free-living amoebae (FLA) are a group of protozoa with the capabilities of growth in the environment and invasion to the human body which have been isolated from different water sources. Acanthamoeba, Naegleria, and Balamuthia are the most important FLA. These cause a variety of severe complications of eye and central nervous system. Despite the fact that various studies have demonstrated the prevalence of FLA in different parts of Iran, there is no comprehensive evaluation and conclusion regarding the pollution of various water sources in Iran. This review was carried out to achieve the prevalence pattern of FLA in water resources across Iran to design appropriate health strategies. For this purpose, 8 online databases in English and Persian and also graduate thesis and national parasitology congresses were studied. The key words such as "free living amoebae", "Acanthamoeba", "Naegleria", "Hartmannella", "Balamuthia", "Sappinia", "Vermamoebae", "Valkampfia", "water resources", "water" and "Iran" were used to search articles between 1990 to 2017. From a total of 236 articles found, 38 reliable articles were included in the study. From the total number of investigated studies, the estimated prevalence was obtained as 36% among 2430 samples. Although Acanthamoeba prevalence has been considered as a priority, most kinds of free-living amoebae were found in all kinds of water resources. Due to the lack of free-living amoebae prevalence in more than a quarter of the Iranian provinces, more studies are recommended to achieve a better perspective to make comprehensive decisions to improve the hygiene of water resources.

Isolation and molecular characterization of Acanthamoeba genotypes in recreational and domestic water sources from Jamaica, West Indies

Free living amoebae (FLA) are amphizoic protozoa that are ubiquitous in nature. Infection with FLA may result in neurological, ocular and skin infections. Exposure to Acanthamoeba occurs frequently through water contact and knowledge of the presence of the organisms in water sources is important in understanding transmission dynamics. The distribution of Acanthamoeba was studied in recreational and domestic water samples collected from across Jamaica. Morphological assessment and polymerase chain reaction revealed Acanthamoeba spp. isolates in 50.6% (42/83) and 17.3% (14/81) of recreational and domestic water, respectively. Sequencing of the DF3 region of the 18S rDNA resulted in the identification of genotypes T3, T4, T5, T10 and T11 corresponding to Acanthamoeba spp: A. griffini, A. triangularis, A. lenticulata, A. culbertsoni and A. hatchetti. Moreover, T4 was the most frequently isolated genotype in both recreational and domestic water. Thermotolerance and osmotolerance assays indicated that most isolates were potentially pathogenic. This is the first report of T3 and T10 genotypes in the Caribbean and the first report of these Acanthamoeba spp. in Jamaican waters. The study shows that there is potential risk of infection to contact wearers who practise poor lens care. Further, Acanthamoeba should be considered as a cause of neurological infections in Jamaica.

Morphological Features and In Vitro Cytopathic Effect of Acanthamoeba griffini Trophozoites Isolated from a Clinical Case

Light and transmission electron microscopy observations are reported on the structure and in vitro cytopathic effect of Acanthamoeba griffini trophozoites isolated from a clinical case. Live trophozoites were moderately active with a remarkable pleomorphism which changed from ovoid to quite elongated shapes. When moving, amoebae formed cytoplasmic projections such as wide lamellae and acanthopodia of diverse size and thickness which contain a significant amount of actin. Ultrastructurally, the cytoplasm showed the main organelles found in other free-living amoebae. Coincubation of trophozoites with MDCK cell monolayers resulted in a local damage to target cells after 24 h of interaction, suggesting that the cytopathic effect is contact-dependent. By transmission electron microscopy, amoebae appeared to engulf small portions of the MDCK cells; however, the cells that were not in contact with trophozoites had an unaltered morphology. When epithelial monolayers were incubated with conditioned medium for 24 h, small areas of cell injury were also observed. The phylogenetical analysis as well as the sequencing of the acquired amplified product for the DF3 region of the amoebae isolate confirmed that it belongs to genotype T3, which includes other pathogenic amoebae; besides the activity of two drugs currently used against Acanthamoeba was tested on A. griffini.

Reevaluating the role of Acanthamoeba proteases in tissue invasion: observation of cytopathogenic mechanisms on MDCK cell monolayers and hamster corneal cells

The morphological analysis of the cytopathic effect on MDCK cell monolayers and hamster cornea and qualitative and quantitative analyses of conditioned medium and proteases were evaluated and compared between two strains of Acanthamoeba genotype T4. Further than highlighting the biological differences found between both strains, the most important observation in this study was the fact that proteases both in total extracts and in conditioned medium are apparently not determinant in tissue destruction. An interestingly finding was that no lysis of corneal tissue was observed as it was previously suggested. These results, together with previous studies, allow us to conclude that the invasion and disruption of corneal tissue is performed by the penetration of the amoebae through cell junctions, either by the action of proteases promoting cellular separation but not by their destruction and/or a mechanical effect exerted by amoebae. Therefore, contact-dependent mechanisms in Acanthamoeba pathogenesis are more relevant than it has been previously considered. This is supported because the phagocytosis of recently detached cells as well as those attached to the corneal epithelium leads to the modification of the cellular architecture facilitating the migration and destruction of deeper layers of the corneal epithelium.

Modulation of corneal and stromal matrix metalloproteinase by the mannose-induced Acanthamoeba cytolytic protein

The involvement of the mannose-induced Acanthamoeba cytopathic protein (MIP-133) in tissue injury and activation of metalloproteinase of corneal and stromal cells was examined in vitro. Activation of MMP-1, MMP-2, MMP-3, and MMP-9 induced by MIP-133 on human corneal epithelial and stromal cell cultures was examined by reverse transcriptase polymerase chain reaction (RT-PCR) and ELISA. MMP-1, MMP-2, MMP-3, and MMP-9 mRNA were expressed in both cultured human corneal epithelial and stromal cells. When the epithelial cells were exposed to MIP-133 protein, the mRNA expression for MMP-1 and MMP-9 was unchanged. However, the transcript for MMP-2 and MMP-3 was decreased by 2-fold. By contrast, the expression of MMP-2 and MMP-3 was significantly upregulated (2- to 4-fold) in the corneal stromal cells 1, 4, and 8h after MIP-133 stimulation. At the protein level, there was no significant difference in the level of MMPs between the corneal epithelial cells before and after stimulation with MIP-133. By contrast, the levels of MMP-2 and MMP-3 were significantly higher in the corneal stromal cells stimulated with MIP-133. The supernatants from corneal stromal cells stimulated with MIP-133 were incubated with PMSF and MIP-133 antibody and the level of MMP-2 was measured by ELISA. Activation of MMP-2 by MIP-133 was inhibited in the supernatants pretreated with the serine protease inhibitor, PMSF, and anti-MIP-133. Supernatants pretreated with the cysteine protease inhibitor E6 or control antibody produced the same amount of MMP-2 as the untreated supernatants. To verify possible homology between MMPs and Acanthamoeba castellanii proteases, the mRNA from A. castellanii was prepared and analyzed for the expression of MMP genes by PT-PCR. The results showed that A. castellanii did not express mRNA for MMP-1, MMP-2, MMP-3, or MMP-9. Thus, A. castellanii mRNA does not cross-react with human MMPs. Furthermore, ELISA was used to determine the cross-reactivity of MMP antibodies with the MIP-133 protein. Monoclonal antibodies against MMPs did not cross-react with either the MIP-133 protein or BSA (negative control antigen). The results indicate that the MIP-133 protein modulates MMP-2 and -3 expression differently in human corneal epithelial and stromal cells.

In vitro evaluation of the amoebicidal activity of garlic (Allium sativum) extract on Acanthamoeba castellanii and its cytotoxic potential on corneal cells

Free-living protozoa of the genus Acanthamoeba can cause one of the most severe, potentially sight-threatening infections of the eye, the so-called A. keratitis. A. keratitis is difficult to treat because, under adverse conditions, the amoeba encyst and medical therapy is often less effective against cysts than against trophozoites. The aim of this study was to investigate evaluate the in vitro effect of the nonpolar subfraction of the methanol extract of garlic (Allium sativum) on the growth of A. castellanii trophozoites and cysts and also its cytotoxicity on corneal cells in vitro. Extract was evaluated for its amoebicidal activity, using an inverted light microscope. The effect of the nonpolar extract with the concentrations, ranging from 0.78 to 62.5 mg/mL on the proliferation of A. castellanii trophozoites and cysts, were examined in vitro. For the determination of cytotoxicity of the extract on corneal cells, agar diffusion tests were performed. The present study demonstrates the in vitro effectiveness of the garlic against the A. castellanii growth curve. Evaluations revealed that garlic inhibits trophozoite growth in dose- and time-dependent ways. In the case of the cyctotoxic acitivities, it showed no cytotoxicity for the cornea cells in the concentration of 3.90 mg/mL. These findings indicate that nonpolar subfraction of the methanol extracts of garlic has amoebicidal, as well as its cysticidal, properties on Acanthamoeba trophozoites and cysts. Garlic alone, and in combination with other amoebicidal agents, may be used in clinical practices after further investigations.

Chemical, microbial and physical evaluation of commercial bottled waters in greater Houston area of Texas

Due to the increased demand and consumption of bottled water in the United States, there has been a growing concern about the quality of this product. Retail outlets sell local as well as imported bottled water to consumers. Three bottles for each of 35 different brands of bottled water were randomly collected from local grocery stores in the greater Houston area. Out of the 35 different brands, 16 were designated as spring water, 11 were purified and/or fortified tap water, 5 were carbonated water and 3 were distilled water. Chemical, microbial and physical properties of all samples were evaluated including pH, conductivity, bacteria counts, anion concentration, trace metal concentration, heavy metal and volatile organics concentration were determined in all samples. Inductively coupled plasma/mass spectrometry (ICPMS) was used for elemental analysis, gas chromatography with electron capture detector (GCECD) as well as gas chromatography mass spectrometry (GCMS) were used for analysis of volatile organics, ion chromatography (IC) and selective ion electrodes were used for the analysis of anions. Bacterial identification was performed using the Biolog software (Biolog, Inc., Hayward, Ca, USA). The results obtained were compared with guidelines of drinking water recommended by the International Bottled Water Association (IBWA), United States Food and Drug Administration (FDA), United States Environmental Protection Agency (EPA) and the World Health Organization (WHO) drinking water standard. The majority of the analyzed chemicals were below their respective drinking water standards for maximum admissible concentrations (MAC). Volatile organic chemicals were found to be below detection limits. Four of the 35 brands of the bottled water samples analyzed were found to be contaminated with bacteria.

Amebic meningoencephalitis

Amebic meningoencephalitis is an uncommon infection of the central nervous system (CNS), the consequences of which are devastating in the vast majority of patients. Although it is fortunate that few individuals are affected by the infection, with such a low incidence of the disease it has been difficult to develop and test treatment approaches that, with the appropriate implementation, could be broadly effective. As might be expected, the currently available information suggests the possibility that early diagnosis and treatment can result in improved survival and possible recovery. It is also possible that some ameba families and strains may be less pathogenic than others. In order to initiate potentially effective interventions during the early stages, it is necessary to be aware of the clinical and epidemiologic features that distinguish primary from secondary CNS amebic infection and of the various organisms that are associated with these forms of disease. This is not only true for patients with the more classical presentations of these infectious syndromes but also for those who are "culture negative" for common human CNS pathogens. Such information would assist greatly in further delineating the etiopathogenesis and spectrum of disease that is associated with amebic infection of the CNS, as well as potentially effective therapies.

Traveller's diarrhoea

Traveller's diarrhoea affects over 50% of travellers to some destinations and can disrupt holidays and business trips. This review examines the main causes and epidemiology of the syndrome, which is associated with poor public health infrastructure and hygiene practices, particularly in warmer climates. Although travellers may be given common sense advice on avoidance of high-risk foods and other measures to prevent traveller's diarrhoea, adherence to such advice is sometimes difficult and the evidence for its effectiveness is contradictory. However, non-antimicrobial means for prevention of traveller's diarrhoea are favoured in most settings. A simple stepwise approach to the management of traveller's diarrhoea includes single doses or 3-day courses of antimicrobials, often self administered. The antibiotics of choice are currently fluoroquinolones or azithromycin, with an emerging role for rifaximin. In the long term, there will be greater benefit and effect on the health of local inhabitants and travellers from improving public health and hygiene standards at tourist destinations.

Factors contributing to the public health and economic importance of waterborne zoonotic parasites

This is the first of a series of review articles in a Special Issue publication on waterborne zoonotic parasites. A brief historical overview of the occurrence and importance of waterborne parasites, dating from early civilization is presented. The article considers the diversity of parasites including protozoa, nematodes, cestodes and trematodes and the related zoonotic organism microsporidia. Many of the life cycle stages and their characteristics, which make parasites environmentally resistant and suitable for waterborne transmission are discussed. Surfaces of transmission stages consist of multiple layers of proteins, lipids, chitin or other substances capable of withstanding a variety of physical and chemical treatments. Delivery of waterborne parasites is facilitated by various mass distribution systems to consumers, and by transport and intermediate hosts such as fish and filter-feeding invertebrates which are consumed by humans. The article discusses the trends in global warming and climate change and potential for concurrent rise in waterborne disease outbreaks due to parasites. Impacts of technological modernization and globalization on the transmission of zoonotic waterborne zoonotic parasites are considered, including the effects of large-scale agricultural practices, rapid transportation of goods, and widespread movement of individuals and animals. Finally, transmission features and parasite attributes which contribute to concerns about accidental or orchestrated waterborne disease outbreaks are discussed.

Induction of morphological and electrophysiological changes in hamster cornea after in vitro interaction with trophozoites of Acanthamoeba spp

Acanthamoeba castellani and Acanthamoeba polyphaga are free-living amebae that cause keratitis and granulomatous encephalitis in humans. We have analyzed the early morphological and electrophysiological changes occurring during the in vitro interaction of cultured amebae with intact or physically damaged corneas obtained from hamsters. Both species of Acanthamoeba produced similar cytopathic changes, as seen by light microscopy and scanning electron microscopy. After adhesion to the epithelial surface, trophozoites formed clumps and migrated toward the cell borders, causing the separation of adjacent cells at 1 h of coculture. At later stages (2 to 4 h), some amebae were found under desquamating epithelial cells whereas others were seen associated with damaged cells or forming amebostome-like structures to ingest detached epithelial cells. Control corneas incubated in culture medium conditioned with amebae showed a cytoplasmic vacuolization and blurring of the epithelial-stromal junction. The early stages of corneal epithelial damage caused by amebae were also analyzed by measuring the transepithelial resistance changes in corneas mounted in Ussing chambers. Both species of Acanthamoeba caused a rapid decrease in electrical resistance. The present observations demonstrate that under in vitro conditions, Acanthamoeba trophozoites rapidly cause significant damage to the corneal epithelium. Furthermore, in our experimental model, previous physical damage to the corneas was not a prerequisite for the development of amebic corneal ulcerations.

Survival of Cryptosporidium parvum oocysts after prolonged exposure to still natural mineral waters

The survival kinetics of purified Cryptosporidium parvum oocysts of both human and ovine origin, immersed in four still natural mineral waters (total dissolved salts ranging from 91 mg/liter to 430 mg/liter) and reverse osmosis water was assessed by inclusion or exclusion of the fluorogenic vital dyes 4',6-diamidino-2-phenylindole and propidium iodide over a 12-week period. Semipermeable chambers were used to contain the oocysts while immersed in each mineral water type, permitting both intimate interactions between oocysts and matrices and straightforward sampling for viability assessments. The viability of both oocyst types, assessed at weekly intervals, remained unaltered after 12 weeks at 4 degrees C, whereas a progressive decline in the viability of both oocyst isolates was observed when immersed in mineral waters at 20 degrees C. At 20 degrees C, approximately 30% of oocysts remained viable after 12 weeks incubation. Here, temperature was the major factor that adversely affected oocyst survival, although higher mineral content was also proportionally and significantly associated with this increased oocyst inactivation. The prolonged survival of oocysts at 4 degrees C in our studies indicates that they could survive for prolonged periods of time in U.K. groundwaters (average temperature approximately 10 degrees C) and thus represent a potential public health hazard if contamination of mineral water sources by viable oocysts were to occur.

Health effects of Acanthamoeba spp. and its potential for waterborne transmission

Risk from Acanthamoeba keratitis is complex, depending upon the virulence of the particular strain, exposure, trauma, or other stress to the eye, and host immune response. Bacterial endosymbionts may also play a factor in the pathogenicity of Acanthamoeba. Which factor(s) may be the most important is not clear. The ability of the host to produce IgA antibodies in tears may be a significant factor. The immune response of the host is a significant risk factor for GAE infection. If so, then a certain subpopulation with an inability to produce IgA in the tears may be at greatest risk. There was no sufficient data on the occurrence or types of Acanthamoeba in tapwater in the U.S. Published work on amoebal presence in tapwater does not provide information on the type of treatment the water received or the level of residual chlorine. Assessment of the pathogenicity by cell culture and molecular methods of Acanthamoeba in tapwater would also be useful in the risk assessment process for drinking water. The possibility that Acanthamoeba spp. might serve as vectors for bacterial infections from water sources also should be explored. The bacterial endosymbionts include an interesting array of pathogens such as Vibrio cholerae and Legionella pneumophila, both of which are well recognized waterborne/water-based pathogens. Work is needed to determine if control of Acanthamoeba spp. is needed to control water-based pathogens in water supplies.

Identification of Cryptosporidium spp. oocysts in United Kingdom noncarbonated natural mineral waters and drinking waters by using a modified nested PCR-restriction fragment length polymorphism assay

We describe a nested PCR-restriction fragment length polymorphism (RFLP) method for detecting low densities of Cryptosporidium spp. oocysts in natural mineral waters and drinking waters. Oocysts were recovered from seeded 1-liter volumes of mineral water by filtration through polycarbonate membranes and from drinking waters by filtration, immunomagnetizable separation, and filter entrapment, followed by direct extraction of DNA. The DNA was released from polycarbonate filter-entrapped oocysts by disruption in lysis buffer by using 15 cycles of freeze-thawing (1 min in liquid nitrogen and 1 min at 65 degrees C), followed by proteinase K digestion. Amplicons were readily detected from two to five intact oocysts on ethidium bromide-stained gels. DNA extracted from Cryptosporidium parvum oocysts, C. muris (RN 66), C. baileyi (Belgium strain, LB 19), human-derived C. meleagridis, C. felis (DNA from oocysts isolated from a cat), and C. andersoni was used to demonstrate species identity by PCR-RFLP after simultaneous digestion with the restriction enzymes DraI and VspI. Discrimination between C. andersoni and C. muris isolates was confirmed by a separate, subsequent digestion with DdeI. Of 14 drinking water samples tested, 12 were found to be positive by microscopy, 8 were found to be positive by direct PCR, and 14 were found to be positive by using a nested PCR. The Cryptosporidium species detected in these finished water samples was C. parvum genotype 1. This method consistently and routinely detected >5 oocysts per sample.

Microbial quality of domestic and imported brands of bottled water in Trinidad

A cross-sectional study was conducted to determine the microbial quality of domestic and imported brands of bottled water available in Trinidad, purchased from six geographical regions in Trinidad, and representing the whole island. A sample size of 344 bottles of water was determined by using a precision rate of 2% and a Type 1 error of 5%. The membrane filter technique was used with cultures grown on m-Endo agar and m-FC agar for total coliforms and thermotolerant coliforms, respectively. Aerobic plate count (APC) was determined on nutrient agar; Pseudomonas aeruginosa was detected on MacConkey agar, Escherichia coli was isolated on eosin methylene blue (EMB) and Salmonella spp. was assayed by using standard methods. Of the 344 water samples tested, 262 (76.2%) and 82 (23.8%) were domestic and imported brands, respectively. Eighteen (5.2%) of the 344 samples contained coliforms with a mean count of 0.88+/-6.38 coliforms per 100 ml, while 5 (1.5%) samples contained E. coli. The prevalence of total coliforms in domestic brands of bottled water was 6.9% (18 of 262) as compared with 0.0% (0 of 82) detected in imported brands. The difference was statistically significant (p=0.004). Similarly, the prevalence of aerobic bacteria in domestic brands of bottled water (33.6%) was significantly higher (p=0.001) than was found in imported brands (14.8%). Twenty-six (7.6%) of the total samples of water contained Pseudomonas species, but all were negative for thermotolerant coliforms and Salmonella spp. It was concluded that based on the recommended zero tolerance for coliforms in potable water, 5% of bottled water sold in Trinidad could be considered unfit for human consumption.

Resistance of Acanthamoeba castellanii cysts to physical, chemical, and radiological conditions

Resistance of Acanthamoeba castellanii cysts to disinfection agents, antimicrobial agents, heat, freeze-thawing, ultraviolet radiation (UV), gamma irradiation, and cellulase were evaluated in vitro. Following exposure to different agents, the cysts were removed and cultured for A. castellanii trophozoites for 3-14 days. Solutions containing 20% isopropyl alcohol or 10% formalin effectively killed A. castellanii cysts. Hydrogen peroxide (3%, AOSept Disinfectant) effectively killed A. castellanii cysts after 4 hr of exposure. Polyhexamethylene biguanide (0.02%), clotrimazole (0.1%), or propamidine isethionate (Brolene) were effective in killing A. castellanii cysts in vitro. Acanthamoeba castellanii cysts were resistant to both 250 K rads of gamma irradiation and 800 mJ/cm2 of UV irradiation. Excystment of trophozoites was accelerated after exposure to 10, 100, and, 1,000 units of cellulase. These results suggest that A. castellanii cysts benefit by enhanced survival because of their resistance to very harsh environmental conditions.

Tear IgA and serum IgG antibodies against Acanthamoeba in patients with Acanthamoeba keratitis

PURPOSE

Exposure to Acanthamoebaspecies appears to be ubiquitous, as 50% to 100% of healthy human subjects display anti-Acanthamoebaantibodies. However, the presence of specific anti-Acanthamoebaantibodies in the serum and tears of patients has not been investigated. The prevalence of serum immunoglobulin G (IgG) and tear IgA against three species of Acanthamoebawas assessed in healthy subjects and patients with Acanthamoebakeratitis.

METHODS

The level of specific serum IgG and tear IgA against A. castellanii, A. astronyxis, and A. culbertsoniin the sera of 23 patients and 25 healthy subjects was tested by enzyme-linked immunosorbent assays. Total serum IgM, IgG, and IgA concentrations were measured by nephelometry. Acanthamoebakeratitis was diagnosed clinically and confirmed by in vivo confocal microscopy. In some patients, corneal biopsies were also performed and trophozoites were cultured on lawns of Escherichia colion non-nutrient agar.

RESULTS

All healthy subjects and patients with Acanthamoebakeratitis had detectable serum IgG antibodies against all Acanthamoebaantigens. However, patients with Acanthamoebakeratitis had significantly higher anti-AcanthamoebaIgG antibody titers than healthy subjects. In contrast, Acanthamoeba-specific tear IgA was significantly lower in patients with Acanthamoebakeratitis in comparison with healthy subjects. Total serum immunoglobulins did not differ significantly between healthy subjects and patients with Acanthamoebakeratitis.

CONCLUSIONS

The results suggest that a low level of anti-AcanthamoebaIgA antibody in the tears appears to be associated with Acanthamoebakeratitis.

Effect of contact lens preservatives on Acanthamoeba

Single preservatives used in contact lens solutions were evaluated for their effectiveness in killing Acanthamoeba castellanii and Acanthamoeba polyphaga trophozoites and cysts. Preservatives were tested against amoebae at intervals varying from 30 minutes to 24 hours. The preservatives were tested with axenically and nonaxenically grown organisms. Chlorhexidine (0.001% and 0.005%), polyaminopropyl biguanide (0.0015%), benzalkonium chloride (0.001% and 0.004%), and hydrogen peroxide (3%) were very effective preservatives. Lower concentrations of these same preservatives were less effective. Thimerosal (0.001% and 0.004%), sorbic acid (0.1%), potassium sorbate (0.13%), EDTA (0.1%), polyaminopropyl biguanide (0.00005%), and polyquaternium-1 (0.001%) were not effective as tested. However, thimerosal 0.004% when combined in solution with EDTA was effective. Preservatives were more effective when tested against axenically prepared organisms than when tested against co-cultured organisms.

The effect of currently available contact lens disinfection systems on Acanthamoeba castellanii and Acanthamoeba polyphaga

Contact lens disinfection systems were evaluated for their effectiveness in killing Acanthamoeba castellanii and Acanthamoeba polyphaga trophozoites and cysts. Amoebae were inoculated into commercially available contact lens cleaning and soaking solutions. At intervals varying from 30 minutes to 24 hours, solutions were filtered. The filters were removed and cultured for Acanthamoeba organisms. Striking differences were observed in the abilities of the different disinfecting solutions to kill the organisms. Solutions containing chlorhexidine were effective at very short exposure times. Solutions containing benzalkonium chloride required slightly longer exposure times but were faster than solutions containing only thimerosal. Solutions containing sorbate, polyaminopropyl biguanide, or polyquaternium-1 were not effective at killing Acanthamoeba organisms in the time allotted for the experiment. Solutions containing hydrogen peroxide were quite effective if the agent was not prematurely catalyzed. A. polyphaga generally required longer exposure to disinfectants than did A. castellanii for complete inhibition to occur.

Microbial contamination of contact lens care systems

We examined the contact lens care systems of 100 asymptomatic patients who used hard or soft contact lenses for correction of refractive errors for the presence of bacteria, fungi, Acanthamoeba, and endotoxin. Of 100 patients, 52 had contaminated contact lens care systems. Sixteen of 126 bottles (13%) of commercial contact lens care solutions were contaminated. Contaminated commercial solutions were opened and used for a longer period of time than uncontaminated solutions. Contamination was not found in bottles of preserved commercial solutions that were opened and used for less than 21 days. All 12 bottles of homemade saline were contaminated with bacteria, and Acanthamoeba was isolated from two of these bottles. Pseudomonas was found in the care systems of 12 patients. Bacillus species, which form spores resistant to heat, were found in the care systems of seven patients. Endotoxin, which is also resistant to heat, was detected in nine of 35 care systems (26%) tested. Potential pathogens were isolated from the conjunctiva of six patients.

Pathogenic and free-living protozoa cultured from the nasopharyngeal and oral regions of dental patients

Protozoa of nose, mouth, and pharynx of 30 randomly chosen female caries patients at an odontological clinic of the National Autonomous University of Mexico, were surveyed by culture from swabs. Culture tubes of swabs from each patient were observed every other day during 5 weeks. Pathogenic protozoa found included Entamoeba histolytica Schaudinn, 1903; Naegleria fowleri Carter, 1970; Acanthamoeba castelanii Douglas, 1930; Acanthamoeba culbertsoni Singh & Das, 1970; and Balantidium coli (Malmsten, 1857) Stein, 1862. This isolation of pathogens suggests that healthy patients may be healthy carriers of cysts of protozoa, mainly amoebae, responsible for several diseases, including primary amoebic meningoencephalitis. Small pathogenic free-living amoebae have not been isolated before from females in Mexico. Many species of free-living protozoa were also cultured from swabs from the patients.

Primary amoebic meningoencephalitis in a young male from northwestern Mexico

Primary meningoencephalitis caused by Naegleria fowleri was documented in a 16-year-old male from Mexicali in the state of Baja California in Mexico. In August 1978, seven days after sustaining moderate head trauma while swimming in a shallow, stagnant irrigation ditch on a hot summer day, the patient presented an acute illness with severe headache, fever and convulsions rapidly progressing into a comatose state. Actively moving trophozoites were observed in the spinal fluid on admission. The patient died shortly after admission to hospital on the third day of symptoms. Post-mortem examination revealed a meningoencephalitis with extensive destruction, haemorrhage and numerous parasites involving structures of the posterior fossa. Immunoperoxidase strains of trophozoites in meningeal and cerebellar tissue were positive for N. fowleri KUL and negative for N. gruberi, N. australiensis and Acanthamoeba rhysodes. This appears to be the first documented case of the disease in Mexico.

A survey of pathogenic and free-living amoebae inhabiting swimming pool water in Mexico City

A survey of pathogenic and free-living amoebae in swimming pool waters of Mexico City was performed. Among the organisms isolated those which have public health importance were Naegleria fowleri Carter and Acanthamoeba castellanii Douglas. Amoebae of the genera Acanthamoeba, Naegleria, and Vahlkampfia were recovered in their cystic stage while those specimens of the genera Amoeba, Entamoeba, Thecamoeba, and Vanella were recovered only in their trophic stage during this study. Amoebae were concentrated through filtration procedures and subsequently cultured in different culture media. Nonpathogenic amoebae also isolated by culture included: Amoeba proteus (Pallas) Leidy, Amoeba striata Penard, Paratetramitus jugosus Page, Acanthamoeba astronyxis Ray and Hayes, Vahlkampfia avara Page, Vahlkampfia inornata Page, Thecamoeba verrucosa Ehrenberg, and Vanella mira Schaeffer. Trophozoites of Entamoeba gingivalis Gros, were also recovered, both directly and by culture. Most commonly found were amoebae of the species Naegleria gruberi Schardinger (59.02%), N. fowleri (16.77%), and A. castellanii (7.64%). Least-frequently found amoebae belonged to the species Thecamoeba verrucosa (0.12%). All isolated strains of N. fowleri and A. castellanii were thermophilic at 45 and 40 degrees C, respectively, and also pathogenic when inoculated into white mice. More populated by amoebae were those swimming pools of the indoor type with an inner side garden. It was also shown that the free residual chloride values of 0.50 to 1.5 mg/liter, ordinarily used in pool waters, are not adequate for elimination of amoebae.

[Isolation of free-living amoebas from bottled mineral water]

Foram isoladas amebas dos gêneros Vahlkampfia, Glaeseria, Acanthamoeba, Filamoeba, Amoeba, Platyamoeba e Hartmanella de dez diferentes marcas de água mineral engarrafadas, servidas no Rio de Janeiro, RJ (Brasil). Somente uma das marcas foi negativa para protozoários, enquanto que de todas as outras foram isoladas amebas de vida livre. O significado desses resultados é discutido como um indicador de qualidade da água mineral usada comercialmente, destacando-se o fato de que alguns desses microorganismos são potencialmente patogênicos.