CONICET | Buscador de Institutos y Recursos Humanos

Case presentation: a 12-years-old girl from a northern Argentina region was seen by a physician due to ulcerative lesions in her arms and legs. The first clinical impressions were ulcers caused by group A beta-hemolytic streptococci or staphylococci and she received empirical antibiotic treatments, such as a topical rifampicin treatment concomitantly with penicillin G benzathine and ciprofloxacin, which were administered sequentially due to clinical worsening of the skin lesions. After 2 weeks, and judged by the evolution of the ulcers, the physicians suspected of a Leishmania infection and antibiotic treatment was interrupted. The patient was transferred to a regional children hospital for an accurate diagnosis. Diagnosis: on admission, biological samples were taken from 4 skin ulcers for diagnostic studies. Dermal scrapings revealed amastigotes inside macrophages and cultures of sterile biopsy specimens showed Leishmania promastigotes. By molecular tests, the amastigotes were identified as Leishmania (Viannia) braziliensis, which is the most common Leishmania species circulating in northern Argentina. Unexpectedly, bacteriological cultures of dermal scrapping revealed that all skin lesions were coinfected with antibiotic-susceptible strains of Streptococcus pneumoniae. By molecular tests, the species identification was confirmed and all strains showed the same clonal origin, suggesting a common source of infection. Treatment: once biological samples from lesions were obtained, the patient received empirical treatment with rifampicin/trimethoprim. When the Leishmania diagnosis was confirmed, an antiprotozoal treatment with meglumine antimoniate was also administered. After that, the patient was discharged. A month later, she came back to the hospital for a follow-up appointment, and ulcer lesions were completely healed.Discussion: leishmaniasis is a tropical disease caused by an infectious protozoan parasite of the genus Leishmania, which is transmitted by the bite of a sandfly and causes more than 30,000 deaths annually. This parasite presents four types of clinical diseases that are endemic to tropical and subtropical regions, such as in northern Argentina. Cutaneous leishmaniasis is the most common disease that is caused by all Leishmania species that are pathogenic to humans.It is known that Leishmania skin lesions predispose to coinfections with different bacterial pathogens (see Table). However, this is the first reported case of Leishmania coinfection with S. pneumoniae, a main human pathogen that causes infections in children and adults, such as otitis, pneumonia, bacteremia, meningitis, but it is unfrequently isolated from skin. Here, we cannot discard that this bacterial pathogen contributed to the infectious process of lesions caused by Leishmania. Considering the pathogenic potential of S. pneumoniae and a high carriage rate in children, it is expected to find more cases, however this kind of coinfection has never been reported before. We propose that S. pneumoniae infections are being underestimated in skin lesions of patients from Leishmania endemic areas, probably by a misidentification with other Gram-positive cocci that may coinfect these ulcers. Our purpose is to alert physicians and microbiologists about this kind of coinfection. We suggest the implementation of an accurate microbial diagnosis of skin ulcers to detect S. pneumoniae, which may cause complications in the antimicrobial treatment of skin infections.