Nocardiosis occur due to an aerobic actinomycete in the “genus Nocardia”, an unusual gram +ve bacteria. It is most commonly seen in im/m. (immunocomp
1) Nocardiosis occur due to an aerobic actinomycete in the “genus Nocardia”, an unusual gram +ve bacteria. It is most commonly seen in im/m. (immunocompromised) ptns, e.g., kidney transplant recipients.
2) Three locations are most commonly involved: the lungs, central nervous system (CNS), & the skin. There’re no pathognomonic Sns or Sms for nocardiosis. It should be suspected in any ptn presenting with brain, soft tissue, or cutaneous involvement and a concurrent or recent pulmonary affection.
3) The lungs are commonly the primary location of nocardial infection in more than 2/3rd of ptns. Onset of pulmonary nocardiosis could be acute, subacute, or chronic and cannot be recognized by any particular Sns or Sms.
4) Radiographic criteria of pulmonary affection are variable and may include single or multiple nodular lesions, lung mass (with or with no cavitation), reticulo-nodular infiltration, interstitial infiltrates, lobar consolidated lesions, sub-pleural plaque, & pleural effusion.
5) CNS involvement accounts for about 20 % of Nocardia ptns and most often results from disseminated infection coming from pulmonary or cutaneous locations. However, the hallmark of CNS Nocardial infection is the formation of parenchymal abscesses that can be observed in any zone of the brain tissues.
6) 4 patterns of skin involvement can be seen: primary cutaneous, lymphocutaneous, cutaneous involvement from a disseminated focus, & mycetoma.
7) Most cutaneous lesions develop owing to the direct traumatic inoculation of the pathogen into the skin.
8) Disseminated nocardial infection can be defined as 2 or more non-contiguous locations of affection that may or may not involve lung focus.
(1) Final diagnosis of nocardial infection needs isolation + identification of the pathogen from a clinical sample.
(2) To establish a Dgx of nocardiosis is somehow problematic as an invasive intervention is usually warranted to get an adequate sampling and recovering of Nocardia in the lab is somehow difficult owing to its slowly growing nature.
(3) With the prompt clinical subset, a presumptive Dgx of nocardial disease can be established if the partial acid-fast filamentous branched rods are detected in clinical sampling.
(4) Nocardial pathogens in the routine aerobic culture usually need about 5-21 d to grow.
(5) Précised speciation & susceptibility tests of clinical specimen is crucial as resistant patterns vary by species varieties.
(6) PCR can provide more accurate & rapid result for the Dgx of nocardial infection as compared to the conventional techniques but it is not currently available in most clinical labs.
(7) Isolated Nocardia are usually referred to a reference lab for precise recognition & susceptibility testing.
(8) Regarding of the higher affinity of Nocardia pathogen to induce CNS infection, an urgent brain imaging is currently mandated for ALL im/m. ptns and in ALL ptns with pulmonary nocardial disease.
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