RT Book, Section
A1 Azar, Marwan M.
A1 Bahr, Nathan C.
A1 Malo, Joshua
A1 Hage, Chadi A.
A2 Grippi, Michael A.
A2 Antin-Ozerkis, Danielle E.
A2 Dela Cruz, Charles S.
A2 Kotloff, Robert M.
A2 Kotton, Camille Nelson
A2 Pack, Allan I.
SR Print(0)
ID 1195016004
T1 Cryptococcosis and the Endemic Mycoses: Histoplasma, Blastomyces, and Coccidioides
T2 Fishman’s Pulmonary Diseases and Disorders, 6e
YR 2023
FD 2023
PB McGraw-Hill Education
PP New York, NY
SN 9781260473988
LK accessmedicine.mhmedical.com/content.aspx?aid=1195016004
RD 2024/04/16
AB The  dimorphic  fungi  Histoplasma  capsulatum,  Blastomyces  dermatitidis,  and  Coccidioides  immitis/posadasii  and  the  yeast  Cryptococcus  neoformans  share  important  epidemiologic,  mycologic,  and  clinical  characteristics.  With  the  exception  of  Cryptococcus  neoformans  var.  neoformans,  which  exhibits  no  strong  geographic  predilection,  these  fungi  are  found  in  the  soil  and  other  environmental  niches  of  certain  endemic  regions  within  the  United  States,  particularly  the  Mississippi  and  Ohio  River  valleys  for  H.  capsulatum  and  B.  dermatitidis,  the  Southwestern  United  States  for  C.  posadasii/immitis,  and  the  Pacific  Northwest  for  Cryptococcus  neoformans  var.  gattii  (Fig.  133-1).  Beyond  the  United  States,  areas  of  high  endemicity  have  been  established  across  all  six  inhabited  continents,  lending  global  significance  to  these  fungal  pathogens  (Fig.  133-1).1  Additionally,  due  to  global  warming,  anthropomorphic  land  utilization,  and  a  world  that  is  increasingly  interconnected  by  the  mass  migration  of  people  and  goods,  the  geographic  extent  and  epidemiology  of  endemic  fungi  are  changing.  Infection  most  commonly  follows  inhalation  of  aerosolized  infectious  particles  when  sites  containing  the  organism  are  disturbed.  Within  the  human  host,  these  pathogens  exist  in  yeast  form  and  must  be  distinguished  from  other  pathogenic  yeast  and  from  one  another  based  on  mycologic  characteristics  including  size,  wall  thickness,  and  presence  and  type  of  budding,  among  others  important  features.  Unlike  many  other  fungi  that  cause  disease  only  in  immunocompromised  hosts  or  in  those  with  disrupted  mucosal  or  skin  barriers,  the  dimorphic  fungi  and  Cryptococcus,  especially  Cryptococcus  neoformans  var.  gattii,  can  lead  to  local  and  disseminated  disease  in  the  immunocompetent  host.  Indeed,  the  majority  of  those  hospitalized  due  to  infection  with  endemic  mycoses  in  the  United  States  and  up  to  20%  of  HIV-negative  patients  with  Cryptococcus  infection  have  no  identifiable  immunologic  deficits.2  In  endemic  areas,  dimorphic  fungal  pathogens  account  for  up  to  30%  of  community-acquired  pneumonia  and  respiratory  manifestations  mimic  those  of  bacterial  pneumonia  leading  to  antibiotic  misuse,  diagnostic  delays,  and  increased  morbidity  and  mortality.3  Both  Cryptococcus  and  the  endemic  fungi  can  lead  to  a  wide  spectrum  of  pulmonary  manifestations  ranging  from  subclinical  and  mild  respiratory  symptoms  to  acute,  subacute,  and  chronic  pneumonias,  mediastinal  involvement,  and  acute  respiratory  failure  as  well  as  a  variety  of  pulmonary  infiltrates,  including  nodules,  consolidations,  cavities,  and  ground-glass  opacities  among  others.  These  presentations  must  be  distinguished  from  other  infectious  and  noninfectious  pulmonary  processes  such  as  bacterial  pneumonia,  tuberculosis,  lung  cancer,  and  sarcoidosis  that  may  present  similarly.  Dissemination  outside  the  lungs  occurs  more  commonly  in  immunosuppressed  hosts  and  is  associated  with  high  mortality.  In  the  United  States,  direct  healthcare  costs  from  histoplasmosis,  blastomycosis,  and  coccidioidomycosis  alone  approach  $500  million  annually,  emphasizing  the  devastating  impact  of  endemic  mycoses  and  the  need  for  increased  awareness,  early  diagnosis,  and  effective  treatment  modalities.4