Corynebacterium striatum infecting a malignant cutaneous lesion: the emergence of an opportunistic pathogen

Corynebacterium striatum infectando lesão cutânea maligna: a emergência de um patógeno oportunista

CASE REPORT

Corynebacterium striatum infecting a malignant cutaneous lesion: the emergence of an opportunistic pathogen

Corynebacterium striatum infectando lesão cutânea maligna: a emergência de um patógeno oportunista

Silvana Vargas Superti^I; Daniela de Souza Martins^I; Juliana Caierão^I; Fabiana Soares^I; Taísa Prochnow^I; Vlademir Vicente Cantarelli^II; Alexandre Prehn Zavascki^III

^ILaboratory of Microbiology, Hospital São Lucas da Pontifícia Universidade Católica do Rio Grande do Sul, RS, Brazil

^IIWeinmann Laboratório Ltda., Microbiology and Molecular Biology Sections, Centro Universitário Feevale, RS, Brazil

^IIIInfectious Diseases Service, Hospital São Lucas da Pontifícia Universidade Católica do Rio Grande do Sul, RS, Brazil

^{Correspondence to}

SUMMARY

We described a case of a 27-year old male patient with skin and soft tissue infection of a neoplastic lesion caused by Corynebacterium striatum, an organism which has been rarely described as a human pathogen. Identification was confirmed by DNA sequencing. Successful treatment with penicillin was achieved. The role of the C. striatum as an emerging opportunistic pathogen is discussed.

Keywords:Corynebacterium striatum; Immunocompromised patients; Oportunistic infections.

RESUMO

Descrevemos infecção de lesão neoplásica em paciente masculino de 27 anos, envolvendo pele e partes moles, causada por Corynebacterium striatum, um microrganismo raramente descrito como patógeno humano. A identificação foi confirmada por seqüenciamento de DNA. O paciente foi tratado com penicilina, com sucesso. O papel do C. striatum como patógeno oportunista é discutido.

INTRODUCTION

Corynebacterium species are widely disseminated in the environment and constitute part of the normal skin and mucous membrane flora³. The pathogenicity potential of coryneform bacteria has for a long time been underestimated³. However, owing to the increasing number of immunocompromised patients, some corynebacteria species have turned clinically relevant⁹. Notably, C. amycolatum, C. jeikeium and C. urealyticum are currently recognized as important pathogens^3,5,6,8-11.

Although some reports previously described C. striatum as a causative agent of infections specially in immunocompromised patients, its role as a human pathogen is poorly understood^5,9,11. We described a case of C. striatum skin and soft tissue infection of a malignant cutaneous lesion and emphasized its role as an emerging opportunistic human pathogen.

CASE REPORT

A 27-year-old male patient with a progressive ulcerative lesion which started two months before his hospitalization for investigation. The lesion had approximately 20 cm in its larger diameter at the left cervical region and shoulder and presented elevated erythematous irregular borders, with a clean base. Local edema surrounding the lesion was present. A non-fetid purulent secretion was present in the latter 15 days, when pain at the lesion was also referred. Cervical and submandibular painful lymph nodes were noted. Fever was sporadic (up to 38.5 ºC) during the course of the disease. There were no other complains. Complete blood count was within the normal range. The patient was submitted to lymph node and skin lesion biopsy. Multiple fragments from distinct sites of the skin lesion were removed. Ziehl-Neelsen and Grocott stains were negative. Gram staining of the lesion fragments revealed multiple gram-positive coryneform bacteria, some of them within polymorphonuclear neutrophils. The fragments were cultured aerobically on sheep blood agar (bioMérieux, Brazil) for 48 hours at 36 ºC. The organism grew in pure culture on sheep agar plate, consisting of gram-positive, catalase-positive, non-spore-forming, rod shaped organism. Preliminary identification was performed following standard procedures for Corynebacterium spp³. Further biochemical identification was achieved using the API Coryne system (bioMérieux Marcy-l'Etoile, France), according to the manufacturer's instructions. The code number achieved was 2111125, being the isolate identified as a C. striatum/amycolatum. Genomic DNA was extracted from a bacterial suspension using QIAamp DNA minikit (QIAGEN, Germany) according to the manufacturer's instructions, and then the 16S rRNA gene was amplified by PCR with the following primers: 8FLP (AGT.TTG.ATC.CTG.GCT.CAG) and 16S-3 (TGT.AAA.ACG.ACG.GCC.AGT). Reactions were submitted to 35 amplification cycles (95 °C for 30 seg; 55 °C for 30 seg; 72 for one min) and checked using agarose gel electrophoresis and UV exposure. PCR products were submitted to direct sequencing using the BigDye terminator chemistry (Applied Biosystems) and the following primers: 16S-2 (TAT.TAC.CGC.RGC.TGC.TGG) and 1096-R (GTT.GCG.CTC.GTT.GCG.GG). The determined sequences consisted of about 1200 nucleotides, which were compared with other available sequences in the DDBJ (DNA Data Bank of Japan) using the Blast program. The strain showed 98% of homology with the C. striatum sequences available in the DDBJ database and was clearly distinct from C. amycolatum.

Minimum inhibitory concentrations (MICs) were determined by Etest (AB Biodisk Solna, Sweden) and were as follow: penicillin = 0.06 µg/mL; cefepime = 0.5 µg/mL; erythromycin = 0.12 µg/mL; tetracycline = 1 µg/mL; vancomycin = 0.25 µg/mL; clindamycin = 0.25 µg/mL and trimethoprim/sulfamethoxazole = 4/76 µg/mL.

The patient was treated with IV penicillin G crystalline three million IU each four hours during 14 days, when a significant decrease in purulent secretion as well as in the erythema of the borders of the lesion was noted. There was no more fever after 3-day therapy.

The lesion proved to be a T-cell lymphoma by histopathological and immunohistochemistry findings and the patient was further submitted to chemotherapy with complete resolution of the lesion.

DISCUSSION

This report showed an indolent infection of a neoplastic tissue by a usually human skin colonizer, C. striatum. This pathogen has been increasingly recognized as a human pathogen, particularly in patients with severe underlying diseases^5,8.

To our knowledge, this is the first case of a C. striatum infection of a malignant lesion. The tissue fragments collected by surgical procedure, the Gram staining with intracellular coryneform bacteria, and the heavy growth on culture were consistent with C. striatum as the etiologic agent of the infection.

Although C. striatum has been described as a cause of severe infections such as pneumonia and meningitis, mortality rates are usually low⁵. The infection from our report was not severe; however, even mild skin and soft tissue infections should be considered important, since it may be the source of more severe infections, such as bacteremia⁶.

C. striatum is usually susceptible to a wide range of antibiotics, particularly β-lactams⁷. Nevertheless, strains presenting resistance to multiple antibiotics have been described in nosocomial outbreaks⁹, limiting therapeutic options for treatment of infections by this organism. Our isolate, however, presented very low MIC values to all drugs tested, except for trimethoprim-sulfamethoxazole (MIC = 4/76 µg/mL).

It has been shown that the API system is an accurate and useful method to identify coryneform bacteria^2,4, although the API Coryne is not able to make the differentiation between C. striatum and C. amycolatum. Thus, molecular analysis is required to differentiation between these species.

In summary, our report reinforce the role of the C. striatum as an emerging opportunistic pathogen, which should no longer be considered just as a skin colonizer in immunocompromised patients with signs and symptoms of infection.

Received: 8 October 2008

Accepted: 3 February 2009

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Publication Dates

• Publication in this collection
  17 Apr 2009
• Date of issue
  Apr 2009

History

• Accepted
  03 Feb 2009
• Received
  08 Oct 2008