Ophthalmic manifestations of Cryptococcus gattii species complex:a case series and review of the literature

AIM:To report 4 cases of Cryptococcus gattii(C.gattii)species complex infection with diverse ophthalmic manifestations,and to review the literature to examine pathobiology of disease,classical ophthalmic presentations and outcomes,and treatment modalities for this emerging pathogen.METHODS:Cases of C.gattii meningoencephalitis with ophthalmic manifestations were identified via chart review at two institutions in Australia and one institution in the mid-west region of the United States and are reported as a case series.Additionally,a MEDLINE literature review was conducted to identify all reported cases of C.gattii with ophthalmic manifestations from 1990-2020.Cases were reviewed and tabulated,together with our series of patients,in this report.RESULTS:Four cases of C.gattii with ophthalmic manifestations are presented;three from Australia and one from the USA.A literature review identified a total of 331 cases of C.gattii with visual sequelae.The majority of cases occurred in immunocompetent individuals.Blurred vision and diplopia were the most common presenting symptoms,with papilloedema the most common sign,reported in 10%-50%of cases.Visual loss was reported in 10%-53%of cases,as compared to rates of visual loss of 1%-9%in C.neoformans infection.Elevated intracranial pressure,cerebrospinal fluid(CSF)fungal burden,and abnormal neurological exam at presentation correlated with poor visual outcomes.The mainstays of treatment are anti-fungal agents and aggressive management of intracranial hypertension with serial lumbar punctures.CSF diversion procedures should be considered for refractory cases.Acetazolamide and mannitol are associated with high complication rates,and adjuvant corticosteroids have demonstrated higher mortality rates;these treatments should be avoided.CONCLUSION:Permanent visual loss represents a devastating yet potentially preventable sequelae of C.gattii infection.Intracranial hypertension needs to be recognised early and aggressively managed.Referral to an ophthalmologist/neuro-ophthalmologist in all cases of cryptococcal infection independent of visual symptoms at time of diagnosis is recommended.

Meningitis secondary to Cryptococcus gattii,an emerging pathogen affecting immunocompetent hosts

BACKGROUND:Meningitis continues to be one of the most important infections diagnosed and treated by emergency physicians.Despite the advent of anti-infective therapy,meningitis carries a mortality rate of 20%-40%.In this study,we describe the first reported emergency medicine case of meningitis associated with Cryptococcus gattii to alert providers of this insidious,emerging global pathogen infecting immunocompetent individuals.METHODS:We provided a case report and accompanying review of the literature.A MEDLINE search for the term Cryptoccocus gattii was performed to obtain background information on Cryptococcus gattii.RESULTS:After two months of hospitalization,the patient was eventually discharged neurologically intact except for a continued mild bilateral hearing deficit.CONCLUSION:Cryptococcus gattii is an emerging world pathogen,which affects otherwise healthy,immunocompetent patients and requires timely identification and treatment in order to prevent severe neurological sequelae.

Taxonomic analysis of cryptococcus species complex strain $8012 revealed Cryptococcus gattii with high heterogeneity on the ~enetics

Background Initially, Cryptococcus （C.） neoformans was previously divided into two varieties comprising C. neoformans var. neoformans and C. neoformans var. gattii. Currently, taxonomic studies defined C. neoformans as C. species complex, which contains C. neoformans var. neoformans （serotype D）, the hybrid isolates （serotype AD）, C. neoformans var. grubfi （serotype A） and C. gattii （serotypes B and C）. However, Liao and his team once isolated a unique C. gattii isolate, namely strain S8012 with unique phenotype from cerebrospinal fluid （CSF） of a 43-year-old male patient in the Shanghai Changzheng Hospital and described as C. neoformans var. shanghaiensis in 1980s. The aim of this study was to explore the genetic background and polymorphism of Chinese clinical C. gattii isolates. Methods S8012 was analyzed as representative strain using the M13-polymerase chain reaction （PC R） fingerprinting pattern and multilocus sequence analysis including internal transcribed spacers of rDNA （ITS region）, the intergenic spacer 1 regions （IGS1）, RPB1, RPB2, CNLACl, and TEF1 genes. Results The PCR fingerprinting pattern results showed strain S8012 belonged to molecular types VGI, and phylogenetic analysis suggested strain S8012 was grouped into the cluster of C. gattii environmental isolates originated from Eucalyptus camaldulensis trees in Australia. Conclusion C. gattii isolates from Chinese patients expresses high polymorphism on the phenotype, and molecular type VGI isolates from China have a close genetic relationship with the C. gattii isolates from Australia.

Cryptococcus gattii infections in China： extent of the problem？

Approximately 70 species are accepted in the genus Cryptococcus; however, only two species,Cryptococcus neoformans （ C. neoformans, AD and D） and C. gattii （serotypes B responsible for almost all human infections,2,3 and resulted in over 1 million cryptococcosis in the world each year with casualties.4 It is generally assumed that serotypes A, and C） are cryptococcal new cases of over 600000 cryptococcal infections are acquired by inhalation of fungal spores, desiccated cells, or poorly encapsulated yeasts from environmental niches, such as decayed wood debris of certain tree species or bird droppings.5 Epidemiological surveys have shown that C. neoformans caused about 80% of cryptococcosis cases globally each year, particularly in immunocompromised persons, such as human immunodeficiency virus （HIV）-infected people and acquired immunodeficiency syndrome （AIDS） patients,2＇3 while C. gattii primarily infects apparently immunocompetent hosts, and is mainly responsible for the remaining cases of cryptococcosls6,7

Ecological surveys of the Cryptococcus species complex in China

Background Despite recent reports on the molecular epidemiology of cryptococcal infections in China,clinical isolates have been mostly reported from human immunodeficiency virus （HIV）-negative patients,and environmental isolates from China have rarely been included.The aim of this study was to investigate the ecological profile of Cryptococcus （C.）neoformans and C.gattii in China.Methods A survey was performed in 10 cities from 20°N （North latitude） to 50°N and in a Eucalyptus （E.） camaldulensis forestry farm at the Guixi forestry center,China.Results Six hundred and twenty samples of pigeon droppings from 10 cities and 819 E.camaldulensis tree samples were collected and inoculated on caffeic acid cornmeal agar （CACA）.The brown-colored colonies were recultured to observe their morphology,growth on canavanine-glycine-bromothymol-blue （CGB） medium,phenol oxidase and urease activities,serotype and mating type.There were obvious differences in the positive sample rates of C.neoformans in pigeon droppings collected from the different cities,ranging from 50% in the cities located at latitudes from 30°N-40°N,29% at 20°N-30°N and 13% at 40°N-50°N.Conclusions There were no differences in positive bevy rates （approximately 80%） among the three grouped cities.Mycological tests of 101 isolates purified from pigeon droppings revealed that they were C.neoformans var.grubii.We also observed variable capsular size around the C.neoformans cells in colonies with variable melanin production and the bio-adhesion of the natural C.neoformans cells with other microorganisms.One urease-negative C.neoformans isolatewas isolated from pigeon droppings in Jinan city.No C.gattiiwas isolated in this study.

Advanced approach for antifungal susceptibility and characterization of resistance properties in clinical and environmental isolates of Cryptococcus species complex

Background:Meningitis due to Cryptococcus neoformans/gattii is a fatal infection affecting immunocompromised population worldwide.Amphotericin B(AmB),fluconazole(FLC)and 5-flucytosine are the drugs of choice to treat the infection.We studied antifungal susceptibility pattern of clinical and environmental cryptococcal species using newer approach and analyze their resistant characteristics.Methods:Eighty clinical(54 C.neoformans and 26 C.gattii)and 18 environmental(14 C.neoformans and 4 C.gattii)isolates were subjected to antifungal susceptibility testing by automated(VITEK2C)method.Minimum inhibitory concentrations(MIC)were analyzed statistically.Genomic DNA of FLC resistant isolates was extracted and amplified to detect presence of CnAFR1 gene.Results:C.neoformans showed 1.85%and 21.4%AmB resistance,and 1.85%and 28.5%FLC-resistance,whereas C.gattii showed 25%and 50%FLC-resistance among clinical and environmental isolates respectively.MIC values were significantly(p<0.05)different for the isolates from 2 sources.CnAFR1 gene sequence analysis revealed phylogenetic relationship among the resistant isolates.Conclusions:This pioneering study provides an insight into the sensitivity patterns of clinical and environmental cryptococcal isolates from south India.The recent emergence of AmB-resistance may transpire as a challenge for the clinicians.As the clinical and environmental isolates are phylogenetically evolved from CnAFR1 gene of Filobasidiella neoformans,the resistance is most probably an inherent attribute.This study emphasizes the need for speciation and antifungal susceptibility testing of cryptococcal isolates from clinical sources to institute appropriate antifungal therapy and to reduce the mortality and morbidity.