1092 



MANUAL OF DETERMINATIVE BACTERIOLOGY 



genus Rickettsoides da Rocha-Lima {loc. 

 cit.). 



6. Rickettsia akari Huebner, Jellison 

 and Pomerantz. (Pub. Health Pi.ept.,ffi, 

 1946, 1682.) From ^-1 car as, a genus of 

 mites . 



Minute diplobacilli, occurring intra- 

 cellularly and extracellularly, and bi- 

 polarly stained rods. Resemble typical 

 rickettsiae morphologically. Non-mo- 

 tile. 



Stain well by Machiavello's method, 

 the organisms appearing bright red 

 against a blue background. Stain poorly 

 with methylene blue. Gram-negative. 

 Occur intracytoplasmically and have 

 been seen intranuclearly in yolk sac cells. 



Cultivation : In the yolk sac of the 

 chick embryo. No growth on artificial 

 culture media. 



Immunology : Guinea pigs recovered 

 from rickettsialpox are immune to infec- 

 tion with strains isolated from infected 

 mites. 



Serology : Antigens prepared from in- 

 fected yolk sacs are highly specific except 

 for cross i-eactions with Rocky Mountain 

 spotted fever antigens. Sera from con- 

 valescent patients fixed complement with 

 the homologous antigen and usually with 

 Rocky Mountain spotted fever antigens 



though at a lower titer. Does not have 

 a common antigenic factor with Proteus 

 strains except that low titers were ob- 

 tained in a few recovered cases in agglu- 

 tination tests with Proteus 0X19. 



Pathogenicity : Pathogenic for man 

 with focal initial erythematous lesion 

 and adenopathy, followed by fever and 

 appearance of macular rash. No mortal- 

 ity. Experimental infections have been 

 produced in white mice and guinea pigs 

 by the inoculation of infected blood (ir- 

 regularly), and of infected liver and 

 spleen suspensions, infected brain, in- 

 fected lymph nodes, tunica washings of 

 infected animals and by infected yolk 

 sacs. Sjnnptoms in mice include inac- 

 tivity, accelerated respiration, ruffled 

 fur, with occasional deaths; in guinea 

 pigs, fever and marked scrotal reactions. 

 Infected embryos are killed in 4 to 7 

 days. It has not been found pathogenic 

 for monkeys, distinguishing it from 

 Rickettsia conorii. It is also probably 

 more pathogenic for white mice than 

 Rickettsia conorii. 



Source : Blood of a human case of 

 rickettsialpox in New York City. 



Habitat : Blood of human cases and an 

 ectoparasite of rodents, the mite {Allo- 

 dermaniissus sanguineus Hirst). The 

 etiological agent of human rickettsialpox. 



Genus II. Coxiella Bengtson, gen. nov. 



(Subgenus Coxiella Philip, Amer. Jour. Hyg., 37, 1943, 306; generic status recom- 

 mended by Steinhaus, Insect Microbiology, 1946, 263.) Named for Herald R. Cox 

 who first described the organism in guinea pigs inoculated with infected ticks col- 

 lected in Montana. 



Small, pleomorphic, rod-shaped and coccoid organisms, occurring intracellularly 



in the cytoplasm and extracellularly in infected ticks. Stain lightly with aniline 



dyes. Gram-negative. They are filterable. Have not been cultivated in cell-free 



media. Parasites of man and animals which include the etiological agent of Q fever. 



The type species is Coxiella burnetii (Derrick) Bengtson. 



1. Coxiella burnetii (Derrick) Bengt- 

 son comb. nov. (Rickettsia burneli Der- 

 rick, Med. Jour. Australia, 1, 1939, 14; 

 Rickettsia diaporica Cox, Pub. Health 

 Rep., 54, 1939, 1826; Rickettsia burneti 



var. americana, Anon., Brit. Med. Jour., 

 2, lS\\\,r:>'S^; Rickettsia (Coxiella) burneti 

 Philip, Amer. Jour. Hyg., 37, 1943, 306.) 

 Named for F. M. Burnet who discovered 

 the organism in Australia. 



