Comment on a Primary Cutaneous Nocardiosis of the Hand.

Nocardia spp. are gram-positive, partially acid-fast bacteria which are lives in environmental sources and cause of various infection that called nocardiosis in animals and humans. Identification of this group of bacteria was important due to accurate diagnosis, patient management and prevention of antibiotic resistant among of bacteria. Molecular methods including PCR-RFLP and sequencing using housekeeping genes such as 16S rRNA, hsp65, rpoB and gyrB are recommended to accurate and reliable identification of nocardiosis.

Dear Editor,

Camozzota et al., recently published their report on A Primary Cutaneous Nocardiosis of the Hand [1]. Nocardia spp. is opportunistic environmental bacteria which are saprophytic lives in hospital environmental resources that through to the human body via inhalation of environment aerosols and cutaneous traumatic inclusion which cause of nocardiosis in immune disorder patients and even healthy individuals [2][3].

Nocardia species are identified using conventional test and molecular methods that phenotypic tests are laborious, time-consuming, expensive and need to expertise technicians while molecular methods such as direct sequencing of the hsp65 (using pair primers of TB11: 5′-ACCAACGATGGTGTGTCCAT-3′ and TB12: 5′-CTTGTCGAACCGCATACCCT-3′) and 16S rRNA (whit primers 27f (5′-AGAGTTTGATCMTGGCTCAG-3′ and 1525r (5′-AAGGAGGTGWTCCARCC-3′) and PCR-RFLP are reliable, accurate and rapid for identification of nocardial infections especially in emergency cases for example in nocardial disseminated infections that necessary to urgent identifying Nocardia spp. before death of patients [3][4][5]. Based on the literatures, antimicrobial drug susceptibility of Nocardia species are different.

Also in many countries, Trimethoprim-sulfamethoxazole (TMP-SXT) is first choice for treatment of nocardiosis infection whereas reports have showed that high mortality rate of patients with brain abscess and disseminated which treated with sulfonamides alone [3]. Therefore, due to final diagnosis, appropriate treatment of patients Nocardia should be identified to the species level [3][6].

I’m request the authors attend to the following questions.

According to reports other aerobic actinomycetes including Mycobacterium tuberculosis, non-tuberculosis mycobacteria (NTM), Gordonia, Rhodococcus and Tsukamurella are similar to Nocardia spp. are same phenotypic features (microscopic evaluation and colony morphology); and can cause of cutaneous infections in human [7]. Please explain the Nocardia isolation method, which was not mentioned in the report.

Please clarify how Nocardia was identified to the species level.