Cutaneous Leishmania mexicana infections in the United States: defining strains through endemic human pediatric cases in northern Texas.

Over a 6-month span, three patients under 5 years old with cutaneous leishmaniasis presented to the Pediatric Infectious Diseases Clinic at the University of Texas Southwestern Medical Center/Children's Health Dallas. None had traveled outside of northern Texas/southern Oklahoma; all had Leishmania mexicana infections confirmed by PCR. We provide case descriptions and images to increase the awareness of this disease among United States (US) physicians and scientists. Two patients responded to fluconazole, but the youngest required topical paromomycin. Combining these cases with guidelines and our literature review, we suggest that (i) higher doses (10-12 mg/kg/day) of fluconazole should be considered in young children to maximize likelihood and rapidity of response and (ii) patients should transition to alternate agents if they do not respond to high-dose fluconazole within 6 weeks. Furthermore, and of particular interest to the broad microbiology community, we used samples from these cases as a proof of concept to propose a mechanism to strain-type US-endemic L. mexicana. For our analysis, we sequenced three housekeeping genes and the internal transcribed sequence 2 of the ribosomal RNA gene. We identified genetic changes that not only allow us to distinguish US-based L. mexicana strains from strains found in other areas of the Americas but also establish polymorphisms that differ between US isolates. These techniques will allow documentation of genetic changes in this parasite as its range expands. Hence, our cases of cutaneous leishmaniasis provide significant evolutionary, treatment, and public health implications as climate change increases exposure to formerly tropical diseases in previously non-endemic areas. IMPORTANCE: Leishmaniasis is a parasitic disease that typically affects tropical regions worldwide. However, the vector that carries Leishmania is spreading northward into the United States (US). Within a 6-month period, three young cutaneous leishmaniasis patients were seen at the Pediatric Infectious Diseases Clinic at the University of Texas Southwestern Medical Center/Children's Health Dallas. None had traveled outside of northern Texas and southern Oklahoma. We document their presentations, treatments, and outcomes and compare their management to clinical practice guidelines for leishmaniasis. We also analyzed the sequences of three critical genes in Leishmania mexicana isolated from these patients. We found changes that not only distinguish US-based strains from strains found elsewhere but also differ between US isolates. Monitoring these sequences will allow tracking of genetic changes in parasites over time. Our findings have significant US public health implications as people are increasingly likely to be exposed to what were once tropical diseases.

Cutaneous Leishmania mexicana Infections in the United States: Defining Strains Through Endemic Human Pediatric Cases in Northern Texas.

Over a six-month span, three patients under five years old with cutaneous leishmaniasis presented to the Pediatric Infectious Diseases Clinic at the University of Texas Southwestern Medical Center/Children's Health Dallas. None had traveled outside of the United States (US); all had confirmed L. mexicana infections by PCR. We provide case descriptions and images to increase the awareness of this disease among US physicians and scientists. Two patients responded to fluconazole, but one required topical paromomycin. Combining these cases with guidelines and our literature review, we suggest that: 1) higher doses (ten-twelve mg/kg/day) of fluconazole should be considered in young children to maximize likelihood and rapidity of response and 2) patients should transition to alternate agents if they do not respond to high-dose fluconazole within six weeks. Furthermore, and of particular interest to the broad microbiology community, we used samples from these cases as a proof-of-concept to propose a mechanism to strain-type US-endemic L. mexicana. For our analysis, we sequenced three housekeeping genes and the internal transcribed sequence 2 of the ribosomal RNA gene. We identified genetic changes that not only allow us to distinguish US-based L. mexicana strains from strains found in other areas of the Americas, but also establish polymorphisms that differ between US isolates. These techniques will allow documentation of genetic changes in this parasite as its range expands. Hence, our cases of cutaneous leishmaniasis provide significant evolutionary, treatment and public health implications as climate change increases exposure to formerly tropical diseases in previously non-endemic areas.

Lactococcus Species Central Line-Associated Bloodstream Infection in Pediatrics: A Case Series.

Lactococcus spp. is typically thought to be of low virulence and seldom considered pathogenic. Few cases of significant infections in children have been reported, all outside of the United States. There is also limited data on antimicrobial susceptibility testing for Lactococcus spp. We present three pediatric patients with central line bloodstream infections due to Lactococcus spp. between 2018 and 2020, along with a review of the pediatric literature.

Evaluation of the Treatment of Stenotrophomonas maltophilia in Tracheostomy-Dependent Pediatric Patients.

OBJECTIVE: Tracheostomy-dependent pediatric patients will often have respiratory cultures positive for Stenotrophomonas maltophilia (multidrug-resistant Gram-negative rod). There are limited data available to guide treatment in this population. The objective of this single-center, retrospective study was to evaluate if antibiotic treatment of S maltophilia improved clinical outcomes in tracheostomy-dependent pediatric patients. METHODS: We included tracheostomy-dependent pediatric patients who had a respiratory culture positive for S maltophilia. Patients were divided into 2 groups: 1) treatment and 2) no treatment. RESULTS: Forty patients with 55 encounters were included in this study. S maltophilia was treated with sulfamethoxazole-trimethoprim in 20 encounters (19 patients) and no antimicrobial treatment was given in 35 encounters (30 patients). The time to return to stable respiratory status was 5 days (0-10) (median [range]) in the treated group and 4 days (0-19) in the untreated group (p = 0.52). There was no statistically significant difference in time to baseline respiratory status between patients treated and those not treated for S maltophilia. There was no difference in hospital length of stay between patients who were or not treated. CONCLUSIONS: Based on these results, these data would suggest that there might not be a benefit to treating cultures positive for S maltophilia in tracheostomy-dependent pediatric patients.