Interaction between Acanthamoeba and Staphylococcus.

Free-living amoebae of the genus Acanthamoeba are infected by various bacteria in nature, and thus bacteria can protect themselves from adverse environmental conditions. Contrary to this ameba-bacteria relationship whether Acanthamoeba has antibacterial effects on bacteria is the different aspect of the relationship between these microorganisms. In this study, we investigate various Acanthamoeba strains have antibacterial effects on various Staphylococcus strains. Three environmental Acanthamoeba strains, isolated from various aquatic environments in Turkey, and Acanthamoeba castellanii ATCC 50373 standard strains were used in the study. The antistaphylococcal effect of cell-free supernatant (CFS) obtained from these amoebae against 12 different Staphylococcus bacteria was investigated by colony counting method. In addition, the pathogenicity of the tested Acanthamoeba strains was determined using osmotolerance and thermotolerance tests. CFSs obtained from Acanthamoeba were found to have varying degrees of antistaphylococcal effects on various Staphylococcus strains (0%-100%). It was determined that the CFS of the standard Acanthamoeba strain showed 100% inhibitory effect against one clinical methicillin-resistant Staphylococcus aureus strain (M2). Also, CFS of Ugöl strain showed 99.97% inhibitory effect against one clinical methicillin-sensitive Staphylococcus epidermidis strain (L3). It was determined that all Acanthamoeba isolates had no pathogenic potential. According to the results, it has been observed that Acanthamoeba produces antibacterial substance(s) against Staphylococcus bacteria and that the ameba-bacteria relationship may also result in the detriment of the bacteria. Furthermore, the current study indicates that new and natural antimicrobial agents from Acanthamoeba can be used as an alternative to infections caused by Staphylococcus.

Challenges and advances in the medical treatment of granulomatous amebic encephalitis.

Granulomatous amebic encephalitis, caused by the free-living amebae Balamuthia mandrillaris or Acanthamoeba species, is a rare and deadly infectious syndrome with a current mortality rate of >90%. Much work remains to define the optimal treatment for these infections. Here, we provide a comprehensive overview of the supporting evidence behind antimicrobials currently recommended by the Centers for Disease Control and Prevention (CDC) with updated statistics on survival rates and medication usage from the CDC Free-Living Ameba Database. We also discuss promising treatments, especially the emerging therapeutic agent nitroxoline, and provide recommendations for the next steps in this area.

Primary amebic meningoencephalitis: a review of Naegleria fowleri and analysis of successfully treated cases.

Primary amebic meningoencephalitis (PAM) is a necrotizing and hemorrhagic inflammation of the brain and meninges caused by Naegleria fowleri, a free-living thermophilic ameba of freshwater systems. PAM remains a neglected disease that disproportionately affects children in tropical and subtropical climates, with an estimated mortality rate of 95-98%. Due to anthropogenic climate change, the average temperature in the USA has increased by 0.72 to 1.06 °C in the last century, promoting the poleward spread of N. fowleri. PAM is often misdiagnosed as bacterial meningitis or viral encephalitis, which shortens the window for potentially life-saving treatment. Diagnosis relies on the patient's history of freshwater exposure and the physician's high index of suspicion, supported by cerebrospinal fluid studies. While no experimental trials have been conducted to assess the relative efficacy of treatment regimens, anti-amebic therapy with adjunctive neuroprotection is standard treatment in the USA. We performed a literature review and identified five patients from North America between 1962 and 2022 who survived PAM with various degrees of sequelae.

High-Throughput Screen of Microbial Metabolites Identifies F1FO ATP Synthase Inhibitors as New Leads for Naegleria fowleri Infection.

Primary amebic meningoencephalitis (PAM), a brain infection caused by a free-living ameba Naegleria fowleri, leads to an extensive inflammation of the brain and death within 1-18 (median 5) days after symptoms begin. Although natural products have played a significant role in the development of drugs for over a century, research focusing on identifying new natural product-based anti-N. fowleri agents is limited. We undertook a large-scale ATP bioluminescence-based screen of about 10,000 unique marine microbial metabolite mixtures against the trophozoites of N. fowleri. Our screen identified about 100 test materials with >90% inhibition at 50 µg/mL and a dose-response study found 20 of these active test materials exhibiting an EC50 ranging from 0.2 to 2 µg/mL. Examination of four of these potent metabolite mixtures, derived from our actinomycete strains CNT671, CNT756, and CNH301, resulted in the isolation of a pure metabolite identified as oligomycin D. Oligomycin D exhibited nanomolar potency on multiple genotypes of N. fowleri, and it was five- or 850-times more potent than the recommended drugs amphotericin B or miltefosine. Oligomycin D is fast-acting and reached its EC50 in 10 h, and it was also able to inhibit the invasiveness of N. fowleri significantly when tested on a matrigel invasion assay. Since oligomycin is known to manifest inhibitory activity against F1FO ATP synthase, we tested different F1FO ATP synthase inhibitors and identified a natural peptide leucinostatin as a fast-acting amebicidal compound with nanomolar potency on multiple strains.

Fatal Primary Amebic Meningoencephalitis due to Naegleria fowleri: The First Imported Case in Korea.

Primary amebic meningoencephalitis (PAM) is a rare, but almost always fatal, central nervous system infection caused by Naegleria fowleri, which are thermophilic free-living amoeba. Here, we report the first case of PAM detected in South Korea, probably imported from Thailand. Despite antimicrobial treatment for N. fowleri infection with a combination of intravenous liposomal amphotericin B, fluconazole, azithromycin, and oral rifampin, the patient died 13 days after the onset of symptoms. Clinicians in South Korea treating severe meningoencephalitis, especially in individuals returning from tropical areas, are encouraged to include PAM in the differential diagnoses, given the accelerated global warming and increased overseas trips.

Right basal bronchial fistula due to amebic infection: a case report.

BACKGROUND: Pleuropulmonary amebiasis is the second most common form of extraintestinal invasive amebiasis, but cases that include bronchopleural fistula are rare. CASE PRESENTATION: A 43-year-old male was referred to our hospital for liver abscess, right pleural effusion, and body weight loss. He was diagnosed with a bronchopleural fistula caused by invasive pleuropulmonary amebiasis and human immunodeficiency virus (HIV) infection. After initial medical treatment for HIV infection and invasive amebiasis, he underwent pulmonary resection of the invaded lobe. Intraoperative inspection revealed a fistula of the right basal bronchus in the perforated lung abscess cavity, but the diaphragm was intact. The patient was discharged on postoperative day 3 and was in good condition at the 1-year follow-up. CONCLUSIONS: Clinicians should be aware that pleuropulmonary amebiasis can cause a bronchopleural fistula although it is very rare.

Multi-institutional 10-year retrospective review of amoeba diagnosed on cytologic evaluation of anal pap tests: what is the significance?

INTRODUCTION: Intestinal amoebae are usually transmitted via ingestion of amoebic cysts in fecally contaminated water or food. However, other modes of transmission include sexual contact through anal-oral sex. While the primary role of anal cytology is the detection of anal cancer and precursor lesions, organisms can also be identified. Despite this, assessment of the clinical significance of cytologic identification of amoebae is lacking in the literature. MATERIALS AND METHODS: A 10-year retrospective review of the pathology archives of 2 institutions in Boston, Massachusetts was conducted. Anal Pap tests that identified amoeba were reviewed and correlated with the medical records for investigation into clinical parameters and patient management. RESULTS: A total of 46 cases were identified between the 2 sites. The majority of patients were male (95.7%) and endorsed having sex with men (84.8%). Only a minority endorsed recent travel (6.5%). Most of the patients were also HIV (human immunodeficiency virus)-positive (71.1%) with all of these patients being well-controlled on antiretroviral therapy. Most patients were asymptomatic (87.0%). On review of the anal Pap tests, the average organism number per case was 35.4. In the majority of cases, follow-up microbiology testing for confirmation and/or speciation was not performed (89.1%) and were not treated (93.5%). CONCLUSIONS: While identification of amoeba is possible on anal cytology, the clinical significance remains unclear as most patients were asymptomatic and not treated in this series. Ultimately, the clinical setting likely plays an important role in determination of management.

The Epidemiology and Clinical Features of Non-Keratitis Acanthamoeba Infections in the United States, 1956-2020.

Background: Acanthamoeba is a free-living ameba that can cause severe disease affecting the central nervous system, skin, sinuses, and other organs, particularly in immunocompromised individuals. These rare but severe infections are often fatal, yet incompletely described. Methods: Cases included were either reported to the Centers for Disease Control and Prevention (CDC) Free-Living Ameba program or published in scientific literature. Characteristics of all patients in the United States with laboratory-confirmed non-keratitis Acanthamoeba infections were described using descriptive statistics, and associations with survival were determined using χ2 and Fisher exact tests. Results: Of 173 patients identified, 71% were male and the median age was 44 years (range, 0-87 years). Of these, 26 (15%) survived. Most patients (88%) had at least 1 immunocompromising condition, most commonly human immunodeficiency virus (39%), cancer (28%), and solid organ or hematopoietic stem cell transplant (28%). Granulomatous amebic encephalitis (GAE) was the most common disease presentation (71%). Skin (46%), sinuses (29%), lungs (13%), and bone (6%) were also involved. Nearly half of patients (47%) had involvement of >1 organ system. Survival was less frequent among those with GAE (3%, P < .001) compared with cutaneous disease, rhinosinusitis, or multiorgan disease not including GAE. Of 7 who received the currently recommended treatment regimen, 5 (71%) survived. Conclusions: Non-keratitis Acanthamoeba infections occur primarily in immunocompromised individuals and are usually fatal. Survival may be associated with disease presentation and treatment. Providers who care for at-risk patients should be aware of the various disease manifestations to improve early recognition and treatment.

Successful Treatment of Balamuthia mandrillaris Granulomatous Amebic Encephalitis with Nitroxoline.

A patient in California, USA, with rare and usually fatal Balamuthia mandrillaris granulomatous amebic encephalitis survived after receiving treatment with a regimen that included the repurposed drug nitroxoline. Nitroxoline, which is a quinolone typically used to treat urinary tract infections, was identified in a screen for drugs with amebicidal activity against Balamuthia.

Identificación de amebas de vida libre en tanques de almacenamiento de agua de edificios del área metropolitana de Ambato / Identification of free-living amoebas in water storage tanks of buildings in the metropolitan area of Ambato

Naegleria fowleri, Acanthamoeba spp. y Balamuthia mandrillaris, son especies de ameba de vida libre (AVL) que causan enfermedades en el sistema nervioso central grave y puede ser fatal en humanos y otros animales. Todos los géneros de AVL tienen dos etapas: quiste y trofozoíto. Los trofozoítos se dividen por fisión binaria, se alimentan activamente y es la etapa infecciosa del organismo. En el medio ambiente, los acanthopodios permiten que los trofozoítos se adhieran a las superficies de las bacterias, hongos, algas y detritos en los que se encuentran su alimento. Acanthamoeba spp. Parecen mantener una relación endosimbiótica con algunas de las bacterias que consumen. Muchas de estas bacterias, como la Legionella, Pseudomonas, Vibrio y algunas micobacterias parecen adquirir factores de virulencia mientras están viviendo dentro de las amebas, lo que les permite sobrevivir y prosperar dentro de otras células fagocíticas (por ejemplo, macrófagos humanos). La tenacidad de AVL para proliferar en ecosistemas hostiles y sobrevivir a la desecación o desinfección hace de estos organismos una fuente potencial transmitida por el agua, por los alimentos y el aire. Conocidos por su ubicuidad, los AVL han sido aislados de diversas matrices ambientales, como suelo, agua dulce y salobre, aguas residuales, aguas termales, polvo y otros. En función de lo antes comentado, este trabajo tiene como objetivo identificar amebas de vida libre en tanques de almacenamiento de agua de edificios del área metropolitana de la ciudad de Ambato (Ecuador), con el fin de aplicar soluciones correctivas en cualquiera de sus puntos. Según el sitio de muestreo, el género de AVL identificado con mayor frecuencia en la superficie fue Balamuthia sp (70,59%) y Acanthamoeba sp., con un 37,78 %. El fondo estuvo caracterizado por Naegleria sp. con un 44,44%(AU)

Naegleria fowleri, Acanthamoeba spp. and Balamuthia mandrillaris are species of free-living amoeba (FLA) that cause severe central nervous system disease and can be fatal in humans and other animals. All genera of FLA have two stages: cyst and trophozoite. Trophozoites divide by binary fission, actively feed, and is the infective stage of the organism. In the environment, acanthopods allow trophozoites to adhere to the surfaces of bacteria, fungi, algae, and detritus on which their food is found. Acanthamoeba spp. they appear to maintain an endosymbiotic relationship with some of the bacteria they consume. Many of these bacteria, such as Legionella, Pseudomonas, Vibrio, and some mycobacteria appear to acquire virulence factors while living inside amoebas, allowing them to survive and thrive inside other phagocytic cells (eg, human macrophages). FLA's tenacity to proliferate in hostile ecosystems and survive desiccation or disinfection makes these organisms a potential waterborne, foodborne, and airborne source. Known for their ubiquity, FLAs have been isolated from various environmental matrices, such as soil, fresh and brackish water, wastewater, hot springs, dust, and others. Based on the aforementioned, this work aims to identify free-living amoebas in water storage tanks of buildings in the metropolitan area of the city of Ambato (Ecuador), in order to apply corrective solutions at any of its points. According to the sampling site, the FLA genus most frequently identified on the surface was Balamuthia sp (70.59%) and Acanthamoeba sp., with 37.78 %. The background was characterized by Naegleria sp. with 44.44%(AU)

Corrigendum: The first molecular genotyping of Naegleria fowleri causing primary amebic meningoencephalitis in Thailand with epidemiology and clinical case reviews.

[This corrects the article DOI: 10.3389/fcimb.2022.931546.].

Amebic infections of the central nervous system.

The report of death of a person from amebic meningoencephalitis, the proverbial "brain-eating ameba," Naegleria fowleri, acquired in a state park lake in Iowa in July 2022 has once again raised the seasonal alarms about this pathogen. While exceptionally rare, its nearly universal fatality rate has panicked the public and made for good copy for the news media. This review will address free-living ameba that have been identified as causing CNS invasion in man, namely, Naegleria fowleri, Acanthamoeba species, Balamuthia mandrillaris, and Sappinia diploidea (Table 1). Of note, several Acanthamoeba spp. and Balamuthia mandrillaris may also be associated with localized extra-CNS infections in individuals who are immunocompetent and disseminated disease in immunocompromised hosts. These ameba are unique from other protozoa in that they are free-living, have no known insect vector, do not result in a human carrier state, and are typically unassociated with poor sanitation. Table 1 Free-living ameba that have been identified as causing CNS invasion in man, namely, Naegleria fowleri, Acanthamoeba species, Balamuthia mandrillaris, and Sappinia diploidea Entity Pathogenic ameba Predisposing disorders Portal of entry Incubation period Clinical features Radiographic findings CSF finding Diagnostic measures Primary amebic meningoencephalitis Naegleria fowleri; N. australiensis; N. italica Previously healthy children or young adults Olfactory epithelium 2-14 days (average 5 days) Headache, fever, altered mental status, meningeal signs; seizures Brain edema; meningeal enhancement; hydrocephalus; basal ganglia infarctions Increased opening pressure; neutrophilic pleocytosis (~ 1000 cells/cu mm); low glucose Brain biopsy, CSF wet prep, IIF culture or PCR Granulomatous amebic encephalitis Acanthamoeba spp.; Balamuthia mandrillaris; Sappinia diploidea Typically, immunocompromised individual Skin sinuses; olfactory epithelium respiratory tract Weeks to months Headache; altered mental status seizures, focal neurological findings Focal parenchymal lesions with edema; hemorrhagic infarctions; meningeal enhancement Generally, LP contraindicated; when performed lymphocytic pleocytosis; increased protein; low glucose Brain biopsy, CSF culture, wet prep, IIF, or PCR IIF indirect immunofluorescence, LP lumbar puncture, PCR polymerase chain reaction.

The First Molecular Genotyping of Naegleria fowleri Causing Primary Amebic Meningoencephalitis in Thailand With Epidemiology and Clinical Case Reviews.

Primary amebic meningoencephalitis (PAM) is a rare and fatal central nervous system infection caused by Naegleria fowleri, a free-living amoeba found in the environment. To date, eight pathogenic N. fowleri genotypes have been reported worldwide. We aimed to explore the genotypes of N. fowleri that cause primary amebic meningoencephalitis in Thailand. In 2021, the 17th PAM case was reported, and a retrospective literature search of PAM cases in Thailand from 1982 through April 2021 was performed. Phylogenetic and genotyping analyses of the two mitochondrial (12S rRNA and 16S rRNA) and nuclear (ITS1 and 5.8s rRNA) genes of N. fowleri were performed on four available clinical isolates. Based on the mitochondrial and nuclear genes, N. fowleri genotype T3 was found to cause PAM in three out of four cases. However, disagreement between the genotype based on the mitochondrial and nuclear genes was found in one of the PAM cases, in which the 12S rRNA locus suggested the causative genotype as T1, while the ITS1 implied genotype T4. The discrepancy between the mitochondrial and nuclear genome was previously observed, which suggests the possible horizontal gene transfer among N. fowleri species. Based on the ITS1 gene, two N. fowleri genotypes, T3 and T4, were found to be the genotypes causing PAM in this study. In addition, N. fowleri genotype T2 was previously reported in a traveler who was infected in Thailand. Thus, at least three genotypes (T2, T3, and T4) of N. fowleri are found to be associated with PAM in Thailand.

Treatment of Cutaneous Balamuthia mandrillaris Infection With Diminazene Aceturate: A Report of 4 Cases.

Four cases of cutaneous Balamuthia mandrillaris infection were treated with diminazene aceturate. One patient was cured with mainly monotherapy, 2 patients were cured with diminazene aceturate and excision, and 1 patient died of drug-induced liver damage. This is the first report of B. mandrillaris infection treated with diminazene aceturate.

An autopsy case of granulomatous amebic encephalitis caused by Balamuthia mandrillaris involving prior amebic dermatitis.

An 82-year-old man, who was healthy and had worked as a farmer, experienced worsening neurological symptoms over a seven-month period, which eventually caused his death. Multiple fluctuating brain lesions were detected radiographically. Clinically, sarcoidosis was ranked high among the differential diagnoses because of the presence of skin lesions showing granulomatous inflammation, confirmed by biopsy. The patient's cerebrospinal fluid was also examined, but no definitive diagnosis was made while he was alive. An autopsy revealed multiple granulomatous amebic encephalitis lesions in the brain. Genetic and immunohistochemical analyses identified Balamuthia (B.) mandrillaris, a free-living ameba, which resides in soil and fresh water, as the causative organism. A retrospective examination revealed B. mandrillaris in the biopsied skin as well as cerebrospinal fluid, strongly suggesting that the ameba had spread into the brain percutaneously. Few studies have detailed the cutaneous pathology of B. mandrillaris infections. In general, granulomatous amebic encephalitis is extremely difficult to diagnose without autopsy, but the present case provides a clue that could allow similar cases to be diagnosed earlier; that is, the presence of skin lesions.

Evaluation of Amebicidal and Cysticidal Activities of Antifungal Drug Isavuconazonium Sulfate against Acanthamoeba T4 Strains.

Acanthamoeba species of amebae are often associated with Acanthamoeba keratitis, a severe corneal infection. Isavuconazonium sulfate is an FDA-approved drug for the treatment of invasive aspergillosis and mucormycosis. This prodrug is metabolized into the active isavuconazole moiety. Isavuconazole was previously identified to have amebicidal and cysticidal activity against Acanthamoeba T4 strains, but the activity of its prodrug, isavuconazonium sulfate, against trophozoites and cysts remains unknown. Since it is not known if isavuconazonium can be metabolized into isavuconazole in the human eye, we evaluated the activities of isavuconazonium sulfate against trophozoites and cysts of three T4 genotype strains of Acanthamoeba. Isavuconazonium displayed amebicidal activity at nanomolar concentrations as low as 1.4 nM and prevented excystation of cysts at concentrations as low as 136 µM. We also investigated the cysticidal activity of isavuconazonium sulfate in combination with a currently used amebicidal drug polyhexamethylene biguanide (PHMB). Although combination of isavuconazonium with PHMB did not elicit an obvious synergistic cysticidal activity, the combination did not cause an antagonistic effect on the cysts of Acanthamoeba T4 strains. Collectively, these findings suggest isavuconazonium retains potency against Acanthamoeba T4 strains and could be adapted for Acanthamoeba keratitis treatment.

Balamuthia mandrillaris: An opportunistic, free-living ameba - An updated review.

Balamuthia mandrillaris is an opportunistic, free-living ameba that is pathogenic to humans. It has a worldwide distribution but is mainly detected in warmer regions. Balamuthia infections are rare but have been reported in both immunocompetent and immunocompromised individuals of all ages. B. mandrillaris can enter through wounds on the skin or the nose and cause cutaneous lesions and the usually fatal Balamuthia amebic encephalitis (BAE). Infection usually spreads from the lungs or through nerve fibers, and attacks the central nervous system, forming granulomatous lesions and necrosis in the brain. Balamuthia infection is usually chronic, and patients initially present with nonspecific symptoms, including headache, nausea, myalgia, and low-grade fever. As the disease progresses, the patient becomes paralyzed and comatose, often leading to death. Lack of knowledge of predisposing factors, specific treatment, and standardized detection tools have resulted in a nearly cent percent fatality rate. Although only about 200 cases have been reported worldwide since its characterization in the 1990s, the number of reported cases has increased over the years. BAE is an emerging disease and a major health concern. Few patients have survived Balamuthia infections with antimicrobial treatment that has largely been empirical. Early diagnosis is the key and requires familiarity with the disease and a high degree of suspicion on the part of the diagnostician. There are currently no specific treatment and prevention recommendations. This review highlights our current understanding of B. mandrillaris in terms of its pathogenicity, genomics, and novel diagnostic and therapeutic approaches against BAE infections.

Encefalitis por ameba de vida libre: reporte de caso / Free-living amoeba encephalitis: case report

La encefalitis amebiana granulomatosa es una enfermedad considerada atípica debido a la baja incidencia desde que fue descubierta. Sin embargo, conforme han avanzando los métodos diagnósticos, en retrospectiva, se ha descrito la presencia de esta enfermedad desde principios del siglo XX, identificando a Acanthamoeba spp y Balamuthia mandrillaris como agentes más comunes.Es una enfermedad de difícil diagnóstico debido al amplio abanico clínico que puede presentar, siendo el sitio anatómico dentro del sistema nervioso central quien determinará estas características. El conocimiento y sospecha de la misma permitirá un abordaje terapéutico oportuno aunque, en la mayoría de los casos, con un desenlace fatal para el paciente.A continuación se presenta el caso clínico de un paciente masculino de 26 años de edad originario de la ciudad de Durango, México, sin antecedentes de importancia, de ocupación ladrillero, quien sufre golpe con ladrillo en región naso-orbitaria, ingresando al hospital al tercer día del evento con diagnóstico de celulitis periorbitaria izquierda y nasal, cefalea de leve intensidad, rinorrea abundante, hemiparesia fasciocorporal izquierda, parestesia de extremidad superior izquierda, diplopía y vértigo postural. Los estudios imagenológicos revelaron lesiones heterogéneas en el lóbulo occipital, hemisferio cerebeloso izquierdo y tallo cerebral. Se realizó escisión de lesión tumoral cerebelar, con estudio anatomopatológico, reportando encefalitis granulomatosa por presencia de ameba de vida libre. El paciente evolucionó hacia deterioro rostro-caudal declarándose su fallecimiento a los 16 días de su estancia intrahospitalaria.En el Estado de Durango, México, no se cuenta con casos reportados por infección de ameba de vida libre

Granulomatous amoebic encephalitis is a disease considered atypical due to the low incidence since it was discovered. However, as diagnostic methods have progressed, in retrospect, the presence of this disease has been described since the beginning of the 20th century, identifying Acanthamoeba spp. and Balamuthia mandrillaris as the most common agents.A disease that is difficult to diagnose due to the wide clinical range that it can present, being the anatomical site within the central nervous system that will determine these characteristics. The knowledge and suspicion of it will allow a timely therapeutic approach although, in most cases, with a fatal outcome for the patient.The clinical case is presented below of a 26 year old male patient from the city of Durang, México, with no significant history, of brick occupation, who suffers a blow with a brick in the naso-orbital region, follows, entering our hospital on the third day of the event with a diagnosis of left periorbital and nasal cellulitis, mild headache, profuse rhinorrhea, left fasciocorporeal hemiparesis, left upper limb parestesia, diplopia, and postural vertigo.Imaging studies were performed observing heterogeneous lesions in the occipital lobe, left cerebellar hemisphere and brain stem; excision of the cerebellar tumor lesion being carried out, with pathological study, reporting granulomatous encephalitis due to the presence of free-living amoeba. The patient progresses to face-caudal deterioration, declaring his death after 16 days of hospital stay.Within the state of Durango, Mexico, there are no reported cases of free-living amoeba infection

Death From Primary Amebic Meningoencephalitis After Recreational Water Exposure During Recent Travel to India-Santa Clara County, California, 2020.

BACKGROUND: In February 2020, a man returned to the United States after an 11-day trip to India and died of primary amebic meningoencephalitis (PAM), caused by nasal exposure to the free-living ameba Naegleria fowleri found in warm water. We identified potential exposures, confirmed etiology, and described the molecular epidemiology of the infection. METHODS: We reviewed medical records to describe his clinical course and interviewed his family to determine water exposures. Genotyping was performed on the N. fowleri strain and compared with North American strains through repetitive nonpolymorphic nuclear loci analysis to identify differences. We reviewed N. fowleri strains in the National Center for Biotechnology Information database (GenBank) to determine genotypes present in India. RESULTS: The patient became acutely encephalopathic 3 days after returning; the only known nasal water exposure was at an indoor swimming pool in India 5 days earlier. Cerebrospinal fluid (CSF) testing demonstrated neutrophil-predominant pleocytosis and low glucose, but negative gram stain and culture. CSF microscopy revealed trophozoites; N. fowleri was detected by real-time polymerase chain reaction. Classical genotyping confirmed genotype I, common in the United States and among Indian strains in GenBank. The North American N. fowleri strains and the patient's strain varied at 5 nonpolymorphic loci. CONCLUSIONS: A man died from PAM after likely exposure at a vacation rental pool in India. We recommend including PAM in the differential diagnosis when CSF studies suggest bacterial meningitis but gram stain is negative. Genotyping can advance our understanding of N. fowleri molecular epidemiology and support future investigations.