Detection of pathogenic bacteria in skin lesions of patients with chiclero's ulcer. Reluctant response to antimonial treatment

Prokaryotic and eukaryotic skin microbiota modifications triggered by Leishmania infection in localized Cutaneous Leishmaniasis

Cutaneous Leishmaniasis (CL) is a tropical disease characterized by cutaneous ulcers, sometimes with satellite lesions and nodular lymphangitis. Leishmania parasites, transmitted by sandfly vectors, cause this widespread public health challenge affecting millions worldwide. CL's complexity stems from diverse Leishmania species and intricate host interactions. Therefore, this study aims to shed light on the spatial-temporal distribution of Leishmania species and exploring the influence of skin microbiota on disease progression. We analyzed 40 samples from CL patients at three military bases across Colombia. Using Oxford Nanopore's Heat Shock Protein 70 sequencing, we identified Leishmania species and profiled microbiota in CL lesions and corresponding healthy limbs. Illumina sequencing of 16S-rRNA and 18S-rRNA genes helped analyze prokaryotic and eukaryotic communities. Our research uncovered a spatial-temporal overlap between regions of high CL incidence and our sampling locations, indicating the coexistence of various Leishmania species. L. naiffi emerged as a noteworthy discovery. In addition, our study delved into the changes in skin microbiota associated with CL lesions sampled by scraping compared with healthy skin sampled by brushing of upper and lower limbs. We observed alterations in microbial diversity, both in prokaryotic and eukaryotic communities, within the lesioned areas, signifying the potential role of microbiota in CL pathogenesis. The significant increase in specific bacterial families, such as Staphylococcaceae and Streptococcaceae, within CL lesions indicates their contribution to local inflammation. In essence, our study contributes to the ongoing research into CL, highlighting the need for a multifaceted approach to decipher the intricate interactions between Leishmaniasis and the skin microbiota.

Possible clinical implications and future directions of managing bacterial biofilms in cutaneous leishmaniasis wounds

Cutaneous leishmaniasis (CL) lesions are chronic and result in disfiguring scars. The microbiological aspects of these wounds have not been systematically investigated. We have recently reported that 61.5% of CL wounds in a Sri Lankan cohort harboured bacterial biofilms, mainly composed of bacilli, Enterobacteriaceae, and Pseudomonas, which could delay wound healing. We have additionally reported that biofilms were significantly associated patients over 40 years of age, discharge, pain and/or itching of the wound, and high pus cell counts. Using this as background knowledge and other relevant literature, we highlight the importance of investigating the role of biofilms in CL wound healing, clinical indicators, cost-effective laboratory tests involving less invasive sampling techniques for diagnosing biofilms and potential therapeutic options for biofilm-containing CL wounds, such as adjunctive application of wound debridement and antimicrobial treatment along with anti-parasitic drugs.

Leishmania and its relationships with bacteria

Leishmaniasis is a zoonotic and neglected disease, which represents an important public health problem worldwide. Different species of Leishmania are associated with different manifestations, and a practical problem that can worsen the condition of hosts infected with Leishmania is the secondary infection caused by bacteria. This review aims to examine the importance and prevalence of bacteria co-infection during leishmaniasis and the nature of this ecological relationship. In the cases discussed in this review, the facilitation phenomenon, defined as any interaction where the action of one organism has a beneficial effect on an organism of another species, was considered in the Leishmania-bacteria interaction, as well as the effects on one another and their consequences for the host.

Coinfection with Leishmania major and Staphylococcus aureus enhances the pathologic responses to both microbes through a pathway involving IL-17A

Cutaneous leishmaniasis (CL) is a parasitic disease causing chronic, ulcerating skin lesions. Most humans infected with the causative Leishmania protozoa are asymptomatic. Leishmania spp. are usually introduced by sand flies into the dermis of mammalian hosts in the presence of bacteria from either the host skin, sand fly gut or both. We hypothesized that bacteria at the dermal inoculation site of Leishmania major will influence the severity of infection that ensues. A C57BL/6 mouse ear model of single or coinfection with Leishmania major, Staphylococcus aureus, or both showed that single pathogen infections caused localized lesions that peaked after 2–3 days for S. aureus and 3 weeks for L. major infection, but that coinfection produced lesions that were two-fold larger than single infection throughout 4 weeks after coinfection. Coinfection increased S. aureus burdens over 7 days, whereas L. major burdens (3, 7, 28 days) were the same in singly and coinfected ears. Inflammatory lesions throughout the first 4 weeks of coinfection had more neutrophils than did singly infected lesions, and the recruited neutrophils from early (day 1) lesions had similar phagocytic and NADPH oxidase capacities. However, most neutrophils were apoptotic, and transcription of immunomodulatory genes that promote efferocytosis was not upregulated, suggesting that the increased numbers of neutrophils may, in part, reflect defective clearance and resolution of the inflammatory response. In addition, the presence of more IL-17A-producing γδ and non-γδ T cells in early lesions (1–7 days), and L. major antigen-responsive Th17 cells after 28 days of coinfection, with a corresponding increase in IL-1β, may recruit more naïve neutrophils into the inflammatory site. Neutralization studies suggest that IL-17A contributed to an enhanced inflammatory response, whereas IL-1β has an important role in controlling bacterial replication. Taken together, these data suggest that coinfection of L. major infection with S. aureus exacerbates disease, both by promoting more inflammation and neutrophil recruitment and by increasing neutrophil apoptosis and delaying resolution of the inflammatory response. These data illustrate the profound impact that coinfecting microorganisms can exert on inflammatory lesion pathology and host adaptive immune responses.

Cutaneous leishmaniasis (CL) is a vector-borne ulcerating skin disease affecting several million people worldwide. The causative Leishmania spp. protozoa are transmitted by infected phlebotomine sand flies. During a sand fly bite, bacteria can be coincidentally inoculated into the dermis with the parasite. Staphylococcus aureus is the most common bacterium in CL skin lesions. Symptomatic CL is characterized by papulonodular skin lesions that ulcerate and resolve with scarring, although most cutaneous Leishmania infections are asymptomatic. We sought to explore factors that determine whether infection with a cutaneous Leishmania species would result in symptomatic CL rather than asymptomatic infection. We hypothesized that local bacteria promote the development of symptomatic CL lesions during infection with Leishmania major. We discovered that cutaneous lesions were significantly larger in mice inoculated simultaneously with S. aureus and L. major than in mice infected with either organism alone. Coinfection led to increased S. aureus growth in skin lesions, whereas L. major parasite numbers were unchanged by coinfection. The size of the exacerbated lesion correlated with early increased numbers of neutrophils and elevated levels of proinflammatory cytokines IL-1β and IL-17A during the first 7 days, and with sustained increases in IL-17A through 28 days of coinfection. Neutralizing antibody experiments suggested IL-17A was partially responsible for lesion exacerbation during coinfection, whereas IL-1β was important for both control of early lesion exacerbation and promotion of IL-17A production. These data suggest that treatment of symptomatic CL targeting the parasite, local commensal bacteria, and host proinflammatory IL-17A immune responses might improve the outcome of CL.

Decanethiol functionalized silver nanoparticles are new powerful leishmanicidals in vitro

We evaluated, for the first time, the leishmanicidal potential of decanethiol functionalized silver nanoparticles (AgNps-SCH) on promastigotes and amastigotes of different strains and species of Leishmania: L. mexicana and L. major isolated from different patients suffering from localized cutaneous leishmaniasis (CL) and L. mexicana isolated from a patient suffering from diffuse cutaneous leishmaniasis (DCL). We recorded the kinetics of promastigote growth by daily parasite counting for 5 days, promastigote mobility, parasite reproduction by CFSE staining's protocol and promastigote killing using the propidium iodide assay. We also recorded IC₅₀'s of promastigotes and amastigotes, therapeutic index, and cytotoxicity by co-culturing macrophages with AgNps-SCH or sodium stibogluconate (Sb) used as reference drug. We used Sb as a reference drug since it is used as the first line treatment for all different types of leishmaniasis. At concentrations 10,000 times lower than those used with Sb, AgNps-SCH had a remarkable leishmanicidal effect in all tested strains of parasites and there was no toxicity to J774A.1 macrophages since > 85% were viable at the concentrations used. Therapeutic index was about 20,000 fold greater than the corresponding one for Sb treated cells. AgNps-SCH inhibited > 80% promastigote proliferation in all tested parasites. These results demonstrate there is a high leishmanicidal potential of AgNps-SCH at concentrations of 0.04 µM. Although more studies are needed, including in vivo testing of AgNps-SCH against different types of leishmaniasis, they can be considered a potential new treatment alternative.

Leishmania mexicana cell death achieved by Cleoserrata serrata (Jacq.) Iltis: Learning from Maya healers

ETHNOPHARMACOLOGICAL RELEVANCE

Aerial parts of Cleoserrata serrata (Jacq.) Iltis are widely used in South-Central Mexico to treat wounds and bacterial skin infections and in Panama by Kuna, Ngöbe-Buglé, and Teribe Indians for tropical warm baths and by Kunas in the form of "Ina kuamakalet" for snakebites.

AIMS OF THE STUDY

To evaluate the effect of Cleoserrata serrata extract on growth and viability of L. mexicana amastigotes and promastigotes in vitro, as well as on bacteria that usually co-infect skin ulcers.

MATERIALS AND METHODS

Cleoserrata serrata was collected in La Chontalpa, Tabasco, Mexico. The antiproliferative effect of the extract was tested on growth of Leishmania mexicana amastigotes and promastigotes in vitro, as well as on bacteria that usually co-infect skin ulcers.

RESULTS

Our data show that Cleoserrata serrata significantly inhibits parasite growth (which was more important in infective amastigotes) and additionally inhibits growth of the co-infective bacteria Staphylococcus aureus and Pseudomonas aeruginosa. Confocal microscopy showed a leishmanicidal effect.

CONCLUSION

We conclude that Cleoserrata serrata extract is potentially an optimal treatment alternative for patients with cutaneous leishmaniasis infected with Leishmania mexicana, since it controls both the parasite as well as bacterial co-infections. Furthermore, it can be applied topically. The precise metabolites responsible for the anti-Leishmania and anti-bacterial effects remain to be established.

Cutaneous Leishmaniasis Induces a Transmissible Dysbiotic Skin Microbiota that Promotes Skin Inflammation

Skin microbiota can impact allergic and autoimmune responses, wound healing, and anti-microbial defense. We investigated the role of skin microbiota in cutaneous leishmaniasis and found that human patients infected with Leishmania braziliensis develop dysbiotic skin microbiota, characterized by increases in the abundance of Staphylococcus and/or Streptococcus. Mice infected with L. major exhibit similar changes depending upon disease severity. Importantly, this dysbiosis is not limited to the lesion site, but is transmissible to normal skin distant from the infection site and to skin from co-housed naive mice. This observation allowed us to test whether a pre-existing dysbiotic skin microbiota influences disease, and we found that challenging dysbiotic naive mice with L. major or testing for contact hypersensitivity results in exacerbated skin inflammatory responses. These findings demonstrate that a dysbiotic skin microbiota is not only a consequence of tissue stress, but also enhances inflammation, which has implications for many inflammatory cutaneous diseases.

The microbiological signature of human cutaneous leishmaniasis lesions exhibits restricted bacterial diversity compared to healthy skin

Localised cutaneous leishmaniasis (LCL) is the most common form of cutaneous leishmaniasis characterised by single or multiple painless chronic ulcers, which commonly presents with secondary bacterial infection. Previous culture-based studies have found staphylococci, streptococci, and opportunistic pathogenic bacteria in LCL lesions, but there have been no comparisons to normal skin. In addition, this approach has strong bias for determining bacterial composition. The present study tested the hypothesis that bacterial communities in LCL lesions differ from those found on healthy skin (HS). Using a high throughput amplicon sequencing approach, which allows for better populational evaluation due to greater depth coverage and the Quantitative Insights Into Microbial Ecology pipeline, we compared the microbiological signature of LCL lesions with that of contralateral HS from the same individuals.Streptococcus, Staphylococcus,Fusobacterium and other strict or facultative anaerobic bacteria composed the LCL microbiome. Aerobic and facultative anaerobic bacteria found in HS, including environmental bacteria, were significantly decreased in LCL lesions (p < 0.01). This paper presents the first comprehensive microbiome identification from LCL lesions with next generation sequence methodology and shows a marked reduction of bacterial diversity in the lesions.

Bacterial contamination in cutaneous leishmaniasis: its effect on the lesions' healing course

Background:

The colonization of aerobic and anaerobic microbial agents on cutaneous leishmaniasis (CL) lesions, especially acute erosive ulcerative ones, has been mentioned in previous studies showing controversial results on the healing course of lesions with the use of antibiotics.

Aims:

The purpose of this study was to evaluate the prevalence of secondary bacterial infections in CL lesions and the effect of its elimination on the lesions’ improvement rate.

Materials and Methods:

This cross-sectional clinical trial was performed on 84 acute CL patients. The required skin samples were taken. Cultivation for bacteria was conducted. Patients with positive culture results were divided into two groups. Both groups received standard anti-leishmania treatment, whereas only one group was treated with cephalexin 40-50 mg/kg/day for 10 days. The improvement rate was evaluated in the following visits based on changes in the lesions’ induration size.

Results:

Among the 84 studied patients, 22.6% had a negative culture result whereas the result was positive in 77.4%. The most common pathogenic germs were Staphylococcus aureus (52.3%) and Staphylococcus epidermidis (9.5%); 34/5% of the positive lesions received antibiotic treatment. Finally, among the lesions with a 75-100% improvement rate, no significant difference was observed between the antibiotic-treated and -untreated groups (36.1% vs. 63.9%, respectively, P = 0.403).

Conclusions:

The most common pathogen was S. aureus and, as a primary outcome, the simultaneous treatment for microbial agents did not have any considerable effect on the improvement rate of CL lesions.

The efficacy of 2-nitrovinylfuran derivatives against Leishmania in vitro and in vivo

Despite recent advances in the treatment of some forms of leishmaniasis, the available drugs are still far from ideal due to inefficacy, parasite resistance, toxicity and cost. The wide-spectrum antimicrobial activity of 2-nitrovinylfuran compounds has been described, as has their activity against Trichomonas vaginalis and other protozoa. Thus, the aim of this study was to test the antileishmanial activities of six 2-nitrovinylfurans in vitro and in a murine model of leishmaniasis. Minimum parasiticide concentration (MPC) and 50% inhibitory concentration (IC₅₀) values for these compounds against the promastigotes of Leishmania amazonensis, Leishmania infantum and Leishmania braziliensis were determined, as were the efficacies of two selected compounds in an experimental model of cutaneous leishmaniasis (CL) caused by L. amazonensis in BALB/c mice. All of the compounds were active against the promastigotes of the three Leishmania species tested. IC₅₀ and MPC values were in the ranges of 0.8-4.7 µM and 1.7-32 µM, respectively. The compounds 2-bromo-5-(2-bromo-2-nitrovinyl)-furan (furvina) and 2-bromo-5-(2-methyl-2-nitrovinyl)-furan (UC245) also reduced lesion growth in vivo at a magnitude comparable to or higher than that achieved by amphotericin B treatment. The results demonstrate the potential of this class of compounds as antileishmanial agents and support the clinical testing of Dermofural^(r) (a furvina-containing antifungal ointment) for the treatment of CL.

Antileishmanial activity of a mixture of Tridax procumbens and Allium sativum in mice

We tested a mixture of Tridax procumbens, known for its direct action against Leishmania mexicana, and Allium sativum, known for its immunomodulatory effect, as an alternative to treat cutaneous leishmaniasis. Acute oral toxicity was tested with the Up-and-Down Procedure (UDP) using a group of healthy mice administered with either T. procumbens or A. sativum extracts and compared with a control group. Liver injury and other parameters of toxicity were determined in mice at day 14. The in vivo assay was performed with mice infected with L. mexicana promastigotes and treated with either a mixture of T. procumbens and A. sativum or each extract separately. The thickness of the mice’s footpads was measured weekly. After the 12-week period of infection, blood samples were obtained by cardiac puncture to determine the total IgG, IgG1 and IgG2a immunoglobulins by a noncommercial indirect ELISA. We showed that the mixture of T. procumbens and A. sativum extracts was better at controlling L. mexicana infection while not being toxic when tested in the acute oral toxicity assay in mice. An increase in the ratio of IgG2a/IgG1 indicated a tendency to raise a Th1-type immune response in mice treated with the mixture. The mixture of T. procumbens and A. sativum extracts is a promising natural treatment for cutaneous leishmaniasis and its healing effects make it a good candidate for a possible new phytomedicine.

Decreased effect of glucantime in cutaneous leishmaniasis complicated with secondary bacterial infection

Background:

Glucantime is regarded as the first-line treatment of cutaneous leishmaniasis (CL); however, failure to treatment is a problem in many cases.

Aim:

The aim was to evaluate the therapeutic effect of glucantime in CL complicated with secondary bacterial infection compared to uncomplicated lesions.

Methods:

This experimental study was performed in Skin Diseases and Leishmaniasis Research Center, Isfahan, Iran. A total of 161 patients enrolled in the study had CL confirmed by positive smear of lesions. All the patients were treated with systemic glucantime for 3 weeks and followed for 2 months. Response to treatment was defined as loss of infiltration, reepithelization, and negative smear. Depending on the results of bacterial cultures, the lesions were divided into two groups and the efficacy of glucantime was compared.

Results:

A total of 123 patients (76.4%) were negative, and 38 patients (23.6%) were positive for secondary bacterial infection. In groups with negative bacterial culture response to treatment was 65% (80 patients) and in the other positive group, it was 31.6% (12 patients), with a difference (χ² = 13.77, P < 0.01).

Conclusion:

Therapeutic effect of glucantime showed a decrease in CL lesions with secondary bacterial infection. Therefore, in the cases of unresponsiveness to treatment, the lesions should be evaluated for bacterial infection, before repeating the treatment.

Isolation of bacteria causing secondary bacterial infection in the lesions of Cutaneous Leishmaniasis

Background:

Cutaneous Leishmaniasis (CL) is a parasitic disease characterized by single or multiple ulcerations. Secondary bacterial infection is one of the complications of the disease that can increase the tissue destruction and the resulting scar.

Objective:

To effectively determine the incidence of real secondary bacteria infection in cutaneous leishmaniasis, we designed the current study.

Methods and Materials:

This was a cross-sectional study performed in Skin Diseases and Leishmaniasis Research Centre, Isfahan, Iran. In this study, 854 patients with confirmed CL were enrolled. Samples were taken from all the patients. Sterile swaps were achieved for the ulcer exudates and scraping was used for nonulcerated lesions. All the samples were transferred to tryptic soy broth medium. After 24 h of incubation in 37°C, they were transferred to eosin methylene blue agar (EBM) and blood agar. Laboratory tests were used to determine the species of bacteria. All of the collected data were analyzed by SPSS software and chi-square.

Results:

Among 854 patients with confirmed cutaneous leishmaniasis, 177 patients (20.7%) had positive cultures for secondary bacterial infection. Bacteria isolated from the lesions were as follows: Staphylococcus aureus - 123 cases (69.4%), coagulase negative Staphylococcus - 41 cases (23.1%), E. coil - 7 cases (3.9%), Proteus - 3 cases (1.7%) and Klebsiella - 3 cases (1.7%).

Conclusions:

The incidence of secondary bacterial infection in lesions of CL was 20.7%. The most common isolated pathogen was Staphylococcus aureus. The incidence of secondary bacterial infection was significantly more in the ulcerated lesions as compared with nonulcerated lesions (P = 0.00001).

Leishmanicidal activity of racemic ± 8-[(4-Amino-1-methylbutyl)amino]-6-methoxy-4-methyl-5-[3,4-dichlorophenoxy]quinoline

In this work we studied the in vitro toxicity of ± 8-[(4-Amino-1-Methylbutyl)Amino]-6-Methoxy-4-Methyl-5-[3,4-dichlorophenoxy]quinoline (DN3-27-1) against stationary phase promastigotes Leishmania (L.) mexicana. Our results indicate that this drug induces an important reduction in parasite growth and killing compared to the reference drug N-methyl meglumine (Glucantime™). DN3-27-1 was not toxic to Hela cells cultured in vitro. This is the first report describing the promising potential of DN3-27-1 in treatment of L. ( L.) m exicana infections.

Distribution frequency of pathogenic bacteria isolated from cutaneus leishmaniasis lesions

Cutaneous leishmaniasis (CL) is a parasitic disease characterized by single or multiple ulcerations. Secondary bacterial infections are one of the complications that can increase the tissue destruction and the resulting scar. To better determine the incidence of real secondary bacterial infections in CL, we designed the current study. This was a cross-sectional study performed in Skin Diseases and Leishmaniasis Research Centre, Isfahan, Iran. A total of 1,255 patients with confirmed CL enrolled in the study. Sterile swaps were achieved for ulcer exudates and scraping was used for non-ulcerated lesions. All samples were transferred to tryptic soy broth medium. After 24 hr of incubation at 37 degrees C they were transferred to eosin methylene blue agar (EMB) and blood agar. Laboratory tests were used to determine the species of bacteria. Among 1,255 confirmed CL patients, 274 (21.8%) had positive cultures for secondary bacterial infections. The bacteria isolated from the lesions were Staphylococcus aureus in 190 cases (69.3%), coagulase negative Staphylococcus in 63 cases (23.0%), E. coli in 10 cases (3.6%), Proteus sp. in 6 cases (2.2%), and Klebsiella sp. in 5 cases (1.9%). The results show that the overall incidence of secondary bacterial infections in the lesions of CL was 21.8%, considerably high. The incidence of secondary bacterial infections was significantly higher in ulcerated lesions compared with non-ulcerated lesions.

Study of bacterial infections among the patients with suspected cutaneous leishmaniasis

The main objective of this study was to evaluate the prevalence of secondary bacterial infections in the patients with cutaneous lesions. The patients admitted to leishmaniasis laboratory of faculty of health, Tehran university of medical sciences from October 2004 to June 2005 were subjected in this study. Clinical samples were analyzed using standard bacteriological and parasitological methods. One hundred seventy three patients were subjected to this study and leishmania was found in 84 (48.5%) cases. According to bacteriological experiments, 47 cases (55.9%) had been also infected by bacterial infections. The most prevalent bacterial isolates included group D Streptococcus (19.1%), Enterococcus spp. (19.1%) and Staphylococcus aureus (12.7%). The findings of current study indicated that the bacterial infections are still an important problem in the patients with cutaneous leishmaniasis and should be considered in treating these patients.

Leishmanicidal Activity of Artemisinin, Deoxoartemisinin, Artemether and Arteether

In this work we studied the in vitro toxicity of artemisinin and its chemical derivatives deoxoartemisinin, artemether and arteether against stationary phase promastigotes of Leishmania (L) mexicana. Results presented in this work include dramatic changes in parasite morphology when they were cultured in the presence of these chemicals. These changes were accompanied by the parasite's lost of mobility and eventual death after four days of culturing. We also observed that parasite growth was much more effectively reduced in cultures carried out in the presence of either artemisinin or its semi-synthetic derivatives than the reference drug N-methyl meglumine (Glucantime™, Rhone Poulenc, France). The compounds tested in this work were not toxic to Hela cells cultured in vitro. This is the first report describing the promising potential use of Qinghaosu (artemisinin) and related chemical analogues to treat L (L) mexicana infections.