View source for Rhodococcus hoagii

==Background==
===Microbiology===

*Facultative intracellular, non-spore-forming, [[Stain::Gram-positive]], weakly acid-fast [[Shape::coccobacillus]]
**More coccoid when grown on solid media, and more bacillary with varying lengths (often beaded) when grown in liquid media
*Within the family [[Nocardiaceae]] and order [[Actinomycetes]]
*Obligate aerobic and facultatively intracellular
*Found in dry and dusty soil
*Makes red pigment, hence the name

===Epidemiology===

*Infects domesticated animals: [[Horses]] (and in foals it causes pneumonia), [[Goats]], [[Pigs]], [[Sheep]], and [[Cattle]]
*Most commonly infects people with cell-mediated immunodeficiency, particularly [[HIV]], with or without a notable infectious exposure

===Risk Factors===

*HIV accounts for 65% of cases
*Solid organ and hematopoietic stem cell transplantation
*Diabetes
*Alcohol abuse
*Chronic renal failure
*Leukemia, lymphoma, lung cancer
*Sarcoidosis
*Preterm infants

==Clinical Manifestations==

*[[Necrotizing pneumonia]] is usual presentation, as well as [[Lung nodules|nodules]], [[Cavitary lung disease|cavitation]], [[pleural effusion]], and [[lung abscess]]
**Typically subacute onset with fever, cough, and fatigue, as well as pleuritic chest pain
*Specifically in immunocompromised patients, it can cause a [[cavitary lung disease]] and is on the differential with [[Mycobacterium species|mycobacteria]] and [[nocardiosis]]
*Extrapulmonary disease can occur with or without pulmonary involvement
**In conjunction with other infections, can have abscesses in liver, spleen, thyroid, kidney, psoas, bone, prostate, intraabdominal cavity, and paraspinous tissue
*Extrapulmonary disease without pulmonary involvement has three main presentations:
**Localized infection following traumatic inoculation, causing wound infection, traumatic septic arthritis, or endophthalmitis
**Isolated bacteremia with fever, typically recently after chemotherapy causing neutropenia
**Gastrointestional inoculation followed by lymphatic dissemination, causing peritonitis, pelvic masses, and mesenteric adenitis
**Others include otitis media with mastoiditis, colonic polyp infection, and osteomyelitis

== Diagnosis ==

* May be misidentified as [[Corynebacterium]] in blood culture or [[Kocuria]] on Vitek

==Management==

*Recommend using at least two agents given increasing rates of resistance
**First-line: combination of [[macrolide]] or [[fluoroquinolone]] plus [[rifampin]]
**First-line: combination of [[macrolide]] or [[fluoroquinolone]] plus two of: [[vancomycin]], [[imipenem]], [[linezolid]], or an [[aminoglycoside]]
**Doses are:
***[[Azithromycin]] 500 mg PO/IV once followed by 250 mg PO/IV daily
***Fluoroquinolones:  [[moxifloxacin]] 400 mg PO daily (preferred), [[levofloxacin]] 500 mg PO daily, or [[ciprofloxacin]] 750 mg PO BID
***[[Rifampin]] 600 mg PO once daily
**Increasing resistance to [[doxycycline]], [[rifampin]], and [[TMP-SMX]]
*Treatment usually 6 months or longer
{{DISPLAYTITLE:''Rhodococcus hoagii''}}
[[Category:Gram-positive bacteria]]