Rhodococcus - Indian Coins

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Transcript Rhodococcus - Indian Coins

Chetan Jinadatha MD, MPH
• Rarely produces infection in humans
• First reported case in 1967
• Increased incidence as an oppurtunistic
• Originally was names a Corynebacterium
• Was orginally isolated from foals with
Rhodococcus Scientific classification
Kingdom: Bacteria
Phylum: Actinobacteria
Order: Actinomycetales
Suborder: Corynebacterineae
Family: Nocardiaceae
Genus: Rhodococcus
• Aerobic and grows on non selective media at
• Non sporulating
• Non motile
• Gram positive can be acid fast
• Rod-to-coccus growth cycle variation
• Presence of tuberculostearic acid and cell wall
mycolic acids
• Large, smooth, irregular, highly mucoid colonies
develop by 48 hours
• Initially colorless
• After 4-7 days they may develop salmon pink
colored colonies
• Solid media: cocci
• Liquid media: long rods
• May be acid fast
• LJ media may promote it
Catalase positive
Urease positive
Oxidase negative
Equi factors interact with the products of other
organisms, including the beta toxin of
Staphylococcus aureus, to produce hemolysis
(CAMP test)
• Commercial panels: API Rapid CORYNE®,
bioMérieux Vitek Inc., Hazelwood, MO
• Granulomatous reaction: macrophages filled
with granular cytoplasm that is periodic acid
Schiff (PAS) stain-positive and may contain large
numbers of gram-positive coccobacillary forms
• Malacoplakia: chronic granulomatous
inflammation characterized by aggregates of
PAS positive histiocytes containing lamellated
iron and calcium inclusions named MichaelisGutmann bodies.
Clinical Manifestations
• Adults and children can be affected
• Mostly affects immunocompromised
population especially HIV
• Can cause pulmonary, blood, CNS, skin
and soft tissue, bone and joints, vitreous
fluid, indwelling devices, and ENT.
Pulmonary Infections
• Most common form of human disease
• Accompanying extrapulmonary infection ~
18 percent
• Extrapulmonary sites without evidence of
pulmonary involvement ~ 24 percent
• Usually a chronic infection
• Can occur in immunocompetant host
Pulmonary Infections
• High fever, cough with/without phlegm,
fatigue, chest pain, +/- hemoptysis.
• Cavitation ~ 50%
• Pleural effusion ~20%
• Recurrent pneumothorax can occur
• Multiple pulmonary nodules can occur
Extra-pulmonary Infection
• Most common sites: Brain and subcutaneous tissue
• Wound infections — Septic arthritis, cellulitis, meningitis;
endophthalmitis following corneal lacerations.
• Peritoneal catheter-related infections
• Fever and isolated bacteremia: in patients with central
venous catheters, neutropenia, or recent chemotherapy
associated with underlying malignancies
• Cervical or mesenteric lymphadenitis, peritonitis, and
pelvic and/or paraspinous masses
• High index of suspicion
• Gram positive coccobacillus or acid fast
organism from an immunocompromised
patient with cavitary lung disease should
raise suspicion for R. equi infection
• commonly causes
• May evolve to a thickwalled cavity
• Slightly lower rate of
• Frequently produces
a cavitary lesion in
• Higher rate of
• Frequently resistant to a number of agents
• In vitro susceptibilities methods of this pathogen
to antibiotics are not standardized
• Combination antimicrobial therapy should be
used in immunocompromised hosts.
• Usually susceptible to erythromycin and
extended spectrum macrolides, rifampin,
fluoroquinolones, aminoglycosides,
glycopeptides, amp-sulbatum and imipenem
• 2/3rd are susceptible to clindamycin,
chloramphenicol, tetracyclines, and
• Most human isolates are resistant in vitro to
penicillins and cephalosporins
• Beta-lactams probably should be avoided, even
if initial susceptibility testing is favorable, since
resistance has been shown to develop during
• The emergence of resistance during treatment
has also been demonstrated with doxycycline,
rifampin, and TMP-SMX
• In vitro susceptibility findings should guide selection
(excluding penicillins and cephalosporins); in vitro
studies of synergy/antagonism of combinations can be
• In immunocompetent persons, single agent therapy may
be sufficient, probably best provided with an extendedspectrum macrolide or fluoroquinolone.
• In immunocompromised persons, two or more agents
should be initiated, at least one of which should have
excellent penetration into macrophages.
CNS Treatment
• Vanc penetrates CNS variably, so we may
need to measure vanc levels in CSF
• Rifabutin instead of Rifampin in HIV
patients on PI’s
• Multiple agents with good CNS
penetrations should be used
Therapy Duration
• Initial therapy in immunocompromised persons: at least
two months secondary to frequent relapses following
shorter courses
• Longer initial therapy with persistence of radiographic or
clinical evidence of infection
• Initially IV, PO can be used in cases where the initial
response was good (still 2 or more months)
• surgical resection of infected tissue combined with
antimicrobial therapy has improved survival
• secondary prophylaxis for persistently
immunosuppressed patients
• www.sciencedaily.com/images/2008/02/080226115618large.jpg
• http://labmed.bwh.harvard.edu/microbiology/teaching/ca
• http://path.upmc.edu/cases/case146/images/micro19.jpg
• http://wever.files.wordpress.com/2008/02/rha1.jpg
• http://www.scielo.br/img/revistas/jbpneu/v32n5/e06f3.jpg
• http://www.scielo.br/img/revistas/clin/v62n6/20f2.jpg
• http://www.aids-images.ch/slides/1085,700,600,0,0.jpg
• www.uptodate.com
• www.wikipedia.com