Characterization of bacteria expectorated during forced salivation of the Phlebotomus papatasi: A neglected component of sand fly infectious inoculums

The infectious inoculum of a sand fly, apart from its metacyclic promastigotes, is composed of factors derived from both the parasite and the vector. Vector-derived factors, including salivary proteins and the gut microbiota, are essential for the establishment and enhancement of infection. However, the type and the number of bacteria egested during salivation is unclear. In the present study, sand flies of Phlebotomus papatasi were gathered from three locations in hyperendemic focus of zoonotic cutaneous leishmaniasis (ZCL) in Isfahan Province, Iran. By using the forced salivation assay and targeting the 16S rRNA barcode gene, egested bacteria were characterized in 99 (44%) out of 224 sand flies. Culture-dependent and culture-independent methods identified the members of Enterobacter cloacae and Spiroplasma species as dominant taxa, respectively. Ten top genera of Spiroplasma, Ralstonia, Acinetobacter, Reyranella, Undibacterium, Bryobacter, Corynebacterium, Cutibacterium, Psychrobacter, and Wolbachia constituted >80% of the saliva microbiome. Phylogenetic analysis displayed the presence of only one bacterial species for the Spiroplasma, Ralstonia, Reyranella, Bryobacter and Wolbachia, two distinct species for Cutibacterium, three for Undibacterium and Psychrobacter, 16 for Acinetobacter, and 27 for Corynebacterium, in the saliva. The abundance of microbes in P. papatasi saliva was determined by incorporating the data on the read counts and the copy number of 16S rRNA gene, about 9,000 bacterial cells, per sand fly. Both microbiological and metagenomic data indicate that bacteria are constant companions of Leishmania, from the intestine of the vector to the vertebrate host. This is the first forced salivation experiment in a sand fly, addressing key questions on infectious bite and competent vectors.

Microbiota instruct IL-17A-producing innate lymphoid cells to promote skin inflammation in cutaneous leishmaniasis

Innate lymphoid cells (ILCs) comprise a heterogeneous population of immune cells that maintain barrier function and can initiate a protective or pathological immune response upon infection. Here we show the involvement of IL-17A-producing ILCs in microbiota-driven immunopathology in cutaneous leishmaniasis. IL-17A-producing ILCs were RORγt+ and were enriched in Leishmania major infected skin, and topical colonization with Staphylococcus epidermidis before L. major infection exacerbated the skin inflammatory responses and IL-17A-producing RORγt+ ILC accumulation without impacting type 1 immune responses. IL-17A responses in ILCs were directed by Batf3 dependent CD103+ dendritic cells and IL-23. Moreover, experiments using Rag1-/- mice established that IL-17A+ ILCs were sufficient in driving the inflammatory responses as depletion of ILCs or neutralization of IL-17A diminished the microbiota mediated immunopathology. Taken together, this study indicates that the skin microbiota promotes RORγt+ IL-17A-producing ILCs, which augment the skin inflammation in cutaneous leishmaniasis.

Resistance Against Leishmania major Infection Depends on Microbiota-Guided Macrophage Activation

Innate immune cells present a dual role during leishmaniasis: they constitute the first line of host defense but are also the main host cells for the parasite. Response against the infection that results in the control of parasite growth and lesion healing depends on activation of macrophages into a classical activated phenotype. We report an essential role for the microbiota in driving macrophage and monocyte-derived macrophage activation towards a resistance phenotype against Leishmania major infection in mice. Both germ-free and dysbiotic mice showed a higher number of myeloid innate cells in lesions and increased number of infected cells, mainly dermal resident and inflammatory macrophages. Despite developing a Th1 immune response characterized by the same levels of IFN-γ production as the conventional mice, germ-free mice presented reduced numbers of iNOS+ macrophages at the peak of infection. Absence or disturbance of host microbiota impaired the capacity of bone marrow-derived macrophage to be activated for Leishmania killing in vitro, even when stimulated by Th1 cytokines. These cells presented reduced expression of inos mRNA, and diminished production of microbicidal molecules, such as ROS, while presenting a permissive activation status, characterized by increased expression of arginase I and il-10 mRNA and higher arginase activity. Colonization of germ-free mice with complete microbiota from conventional mice rescued their ability to control the infection. This study demonstrates the essential role of host microbiota on innate immune response against L. major infection, driving host macrophages to a resistance phenotype.

Associated-risk determinants for anthroponotic cutaneous leishmaniasis treated with meglumine antimoniate: A cohort study in Iran

Background

The control of cutaneous leishmaniasis (CL) is facilitated by knowledge of factors associated with the treatment failures in endemic countries. The aim of this evaluation was to identify the potential risk determinants which might affect the significance of demographic and clinical characteristics for the patients with anthroponotic CL (ACL) and the outcome of meglumine antimoniate (MA) (Glucantime) treatment.

Methodology/Principal findings

This current was executed as a cohort spanning over a period of 5 years which centered in southeastern part of Iran. Altogether, 2,422 participants were evaluated and 1,391 eligible volunteer patients with ACL caused by Leishmania tropica were included. Overall, 1,116 (80.2%) patients received MA intraleisionally (IL), once a week for 12 weeks along with biweekly cryotherapy, while 275 (19.8%) patients received MA alone (20 mg/kg/day for 3 weeks) (intramuscular, IM). The treatment failure rate in ACL patients was 11% using IL combined with cryotherapy plus IM alone, whilst 9% and 18.5% by IL along with cryotherapy or IM alone, respectively. Multivariate logistic regression model predicted 5 major associated-risk determinants including male (odds ratio (OR) = 1.54, confidence interval (CI) = 1.079–2.22, p = 0.018), lesion on face (OR = 1.574, CI = 1.075–2.303, p = 0.02), multiple lesions (OR = 1.446, CI = 1.008–2.075, p = 0.045), poor treatment adherence (OR = 2.041, CI = 1.204–3.46, p = 0.008) and disease duration > 4 months (OR = 2.739, CI = 1.906–3.936, p≤0.001).

Conclusions/Significance

The present study is the original and largest cohort of ACL patients who treated with MA. A comprehensive intervention and coordinated action by the health authorities and policy-makers are crucial to make sure that patients strictly follow medical instructions. Early detection and effective therapy < 4 months following the onset of the lesion is critical for successful treatment of the patients. Since a significant number of patients are still refractory to MA, reducing man-vector exposure and development of new effective alternative drugs are essential measures against ACL due to L. tropica.

Cutaneous leishmaniasis (CL) is a serious neglected tropical disease with social stigma and associated disfiguring with health burden, especially in poor endemic regions of the world. Iran is among the seven high burden CL-infected countries. Limited data are available in regarding to CL treatment and related risk determinants. Parasitologically confirmed ACL patients caused by Leishmania tropica were treated over a 5-year period (2012–2016), with IL meglumine antimoniate (MA) (Glucantime), combined with cryotherapy or with IM MA alone. The objective of this study was to identify the potential risk factors that are associated with response to treatment. The ensuing results with both therapeutic routes identified 5 major risk determinants namely male patients, lesion on face, multiple lesions, poor treatment regimen and disease duration >4 months. The extent to which medical instructions related to patients, therapy and the healthcare system should be seriously monitored. This requires multidisciplinary actions to address specific barriers which directly threaten the treatment outcome. Furthermore, early detection and prompt treatment <4 months following the disease duration together with implementations of public health education and prophylactic measures should receive priority in high risk areas.

First Report and In Silico Analysis of Leishmania virus (LRV2) identified in an autochthonous Leishmania major isolate in Turkey

Leishmania virus (LRV) has previously been identified in different Leishmania species. Host-LRV interaction is associated with exacerbated clinical manifestations of cutaneous leishmaniasis (CL) and may cause poor therapeutic response. CL cases due to L. major with large skin lesions resistant to routine therapy were recently identified in Turkey. Here, we report the first autochthonous case of cutaneous leishmaniasis caused by LRV-positive Leishmania major, using conventional PCR targeting the viral capsid protein of LRV. The lesion of the case was 6 months old, relatively large (4 cm), and did not recover despite three consecutive intralesional applications of glucantime. Assessment of LRV's influence on prognosis and clinical outcomes of leishmaniasis, based on additional studies, is required.

Spatial distribution, Leishmania species and clinical traits of Cutaneous Leishmaniasis cases in the Colombian army

In Colombia, the cutaneous leishmaniasis (CL) is the most common manifestation across the army personnel. Hence, it is mandatory to determine the species associated with the disease as well as the association with the clinical traits. A total of 273 samples of male patients with CL were included in the study and clinical data of the patients was studied. PCR and sequencing analyses (Cytb and HSP70 genes) were performed to identify the species and the intra-specific genetic variability. A georeferenced database was constructed to identify the spatial distribution of Leishmania species isolated. The identification of five species of Leishmania that circulate in the areas where army personnel are deployed is described. Predominant infecting Leishmania species corresponds to L. braziliensis (61.1%), followed by Leishmania panamensis (33.5%), with a high distribution of both species at geographical and municipal level. The species L. guyanensis, L. mexicana and L. lainsoni were also detected at lower frequency. We also showed the identification of different genotypes within L. braziliensis and L. panamensis. In conclusion, we identified the Leishmania species circulating in the areas where Colombian army personnel are deployed, as well as the high intra-specific genetic variability of L. braziliensis and L. panamensis and how these genotypes are distributed at the geographic level.

Colombia is one of the countries with the highest incidence of Cutaneous Leishmaniasis in the world and the army population is the most vulnerable population. Herein, we identified the infecting Leishmania species (L. braziliensis, L. panamensis, L. guyanensis, L. mexicana and L. lainsoni). We also showed the high intra-specific genetic variability of L. braziliensis and L. panamensis and how these genotypes are distributed at the geographic level.

In Vitro and In Vivo Control of Secondary Bacterial Infection Caused by Leishmania major

Bacterial infections of cutaneous leishmaniasis cause skin ulcers on mice, resulting in increased tissue deterioration, and these infections can be controlled with liquid allicin. To isolate and identify the incidences of real secondary bacterial infections in mice, we performed the current study by injecting mice (n = 50) with Leishmania major. L. major infections were initiated by an intramuscular injection of 0.1 mL Roswell Park Memorial Institute (RPMI 1640 media/mouse (10⁷ promastigote/mL)). Scarring appeared 2–6 weeks after injection, and the bacteria were isolated from the skin ulcer tissues. Allicin (50 µL/mL) and ciprofloxacin (5 μg; Cip 5) were used for controlling L. major and bacteria. One hundred samples from skin ulcers of mice were examined, and 200 bacterial colonies were isolated. Forty-eight different genera and species were obtained and identified by Gram staining and physiological and biochemical characterization using identification kits. All samples were positive for secondary bacterial infections. Of the isolates, 79.16% were identified as Gram-negative bacteria, and 28.84% were identified as Gram-positive bacteria; only one yeast species was found. Interestingly, pure allicin liquid at a concentration 50 µL/mL exhibited antibacterial activity against a wide range of Gram-negative and some Gram-positive bacteria, in addition to yeast, and was 71.43% effective. Antimicrobial resistance patterns of all genera and species were determined using 15 different antibiotics. Allicin (50 µL/mL) and Cip 5 were the most effective against L. major and 92.30% of isolated bacteria. Stenotrophomonas maltophilia was the most resistant bacterium to the tested antibiotics with a survival rate of 73.33%, and it exhibited resistance to allicin.

Evaluation of the efficacy of systemic miltefosine associated with photodynamic therapy with liposomal chloroaluminium phthalocyanine in the treatment of cutaneous leishmaniasis caused by Leishmania (L.) amazonensis in C57BL/6 mice

BACKGROUND

The shortage of drugs is a concern and has become the object of studies to discover effective alternatives for cutaneous leishmaniasis (CL) treatment. A topical formulation has been sought due to its low toxicity. Development of alternative therapies, such as multimodal ones, is important in confronting drug resistance. This study aims to compare the in vivo efficacy of topical photodynamic therapy (PDT) using liposomal chloroaluminium phthalocyanine (AlClPC) in the treatment of CL, isolated and associated with systemic therapy with miltefosine.

METHODS

Five groups were adopted, each one with six isogenic adult female mice C57BL/6: (1) Negative Control-non-infected and non-treated; (2) Positive Control (PBS)-infected and non-treated; (3) Miltefosine-infected and treated with oral miltefosine 200 mg/kg/day; (4) Infected and treated with PDT with topical AlClPC (500 μL) on alternate days; (5) Oral Miltefosine 200 mg/kg/day and PDT with topical AlClPC (500 μL) on alternate days. Therapeutic schemes lasted 20 days. Infection was confirmed by culture in Nove-McNeal-Nicolle medium (NNN) of lymph collected from the animal paw, and animals were evaluated by paw measurement and parasitological criteria.

RESULTS

Miltefosine associated with PDT with AlClPC promoted a significant reduction in parasite number and viability when compared to the other infected groups, also returning the paw diameter to a size similar to the negative control group after 20 days of treatment.

CONCLUSIONS

Association of miltefosine with PDT mediated by topical AlClPC represents hopes for CL treatment, an increasing dermatological disease in some countries.

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.

[Antimicrobial susceptibility of aerobic bacteria isolated from leishmaniotic ulcers in Corte de Pedra, BA]

A prospective study regarding aspects of antimicrobial susceptibility aspects was realized among patients with tegumentary leishmaniasis in Corte de Pedra, Bahia. Cases were composed mainly of adolescent and adult farmer patients with single lesions. Staphylococcus aureus predominated (83%) in the cultures with susceptibility to the majority of antibiotics. A mixed bacterial flora in ulcers was encountered in 37 (44.1%) patients. Among the gram-negative bacteria isolated, Enterobacter sp (13.1%), Proteus sp (8.3%), Pseudomonas aeruginosa (7.1%) and Klebsiella sp (7.1%) were mainly found with susceptibility to ciprofloxacin, aminoglycosides, third generation cephalosporin and carbapenems.

Comparison of skin smears and biopsy specimens for demonstration of Leishmania tropica bodies in cutaneous leishmaniasis

OBJECTIVE

To determine and compare the diagnostic value of skin biopsy, saline aspirate smears, skin slit smears and skin biopsy impression smears to demonstrate Leishmania tropica (LT) bodies in cutaneous leishmaniasis and to determine any association within the applied diagnostic tests.

DESIGN

An analytical study.

PLACE AND DURATION OF STUDY

Department of Dermatology, PNS Shifa, Karachi from January to December 2003.

PATIENTS AND METHODS

Seventyeight patients of cutaneous leishmaniasis were subjected to saline aspirate smears, skin slit smears, skin biopsy impression smears and skin biopsy and looked for LT bodies. The percentage positivity of all methods was calculated. McNemar test was applied to determine the association between percentage positivities of methods.

RESULTS

Skin biopsy showed LT bodies in 70 (89.74%) patients, saline aspirate smears in 24 (30.76%), skin slit smears in 25 (32.05%) and skin biopsy impression smears in 27 (34.61%) patients. Smears demonstrated LT bodies in 10.25% cases in which biopsy was negative. Skin biopsy impression smears showed concordant results with skin biopsy in 20.51%, skin slit smears in 16.66% and saline aspirate smears in 19.25% of cases. Saline aspirate smears were positive in 48.1% of cases in which biopsy impression smears were negative, slit smears were positive in 50.9 % of cases in which biopsy impression smears were negative and slit smears were positive in 37% of cases in which saline aspirate smears were negative.

CONCLUSION

Skin biopsy for histopathology is the most useful method in the demonstration of Leishmania parasite. Sensitivity of smears can be increased by a combination of various skin smears.

Identification and antimicrobial susceptibility of micro-organisms recovered from cutaneous lesions of human American tegumentary leishmaniasis in Minas Gerais, Brazil

An evaluation of the microbiota present in cutaneous ulcers from 31 patients with a clinical and parasitological diagnosis of American tegumentary leishmaniasis (ATL) was carried out by the standard filter paper disc technique, including antimicrobial susceptibility of the bacterial isolates. Microbial examination indicated that 21 patients (67.7%) were contaminated with one to four bacteria and some of them also with yeast. A total of 142 micro-organisms were isolated. Staphylococcus aureus was the most frequently recovered bacterium (95.2% of positive patients) and was found to produce type B (70% of the staphylococcal isolates) and type C (50%) enterotoxins as well as toxic shock syndrome toxin (60%). Proteus mirabilis (33.3% of the positive patients), Streptococcus pyogenes (19.0 %), H(2)S-negative Proteus species (19.0%), Klebsiella oxytoca (14.3%), Enterobacter species (9.5%), Peptostreptococcus species (9.5%), Pseudomonas species (4.8%), Prevotella bivia (4.8%), Escherichia coli (4.8%), Streptococcus agalactiae (4.8%), Bacteroides fragilis (4.8%), Candida albicans (9.5%) and Candida tropicalis (4.8%) were also isolated. Surprisingly, Staph. aureus isolates were susceptible to almost all tested drugs, although some of them were resistant to penicillin (69%) and ampicillin + sulbactam (68%). Concerning obligate anaerobes, all the Gram-negative isolates (25% of the total) were resistant to metronidazole. The results of the present study show that microbial secondary contaminants, particularly Staph. aureus, should be considered in the diagnosis and treatment of ATL lesions.

Rodent control operations against zoonotic cutaneous leishmaniasis in rural Iran

BACKGROUND

Zoonotic cutaneous leishmaniasis (ZCL) is a serious and increasing public health problem in many rural areas of Iran. Previous studies showed that rodent control operations are effective in destroying rodents and reducing the incidence of ZCL on a small scale and in special circumstances. The objective of this study was to determine suitable timing for rodent control operations in reducing the incidence of ZCL in an endemic area in Badrood, Iran.

METHODS

We conducted rodent control operations by baiting rodent holes using zinc phosphide once a month in May, June, July and September in 1997 within a 500-meter circle of houses in the intervention area. From 1999 to 2002, the numbers of active rodent holes were counted in May and October in the intervention and control areas. When the numbers of rodent holes increased to 30% or more of the number before the first baiting in May 1997, holes in the intervention area were baited again with zinc phosphide in the intervention area; no baiting was done in the control village. Case findings were done by house-to-house visits once every season during 2000 to 2002.

RESULTS

Changes in the number of rodent holes over time in the intervention and control villages were statistically significant (P<0.000001). There were also significant differences in the incidence of ZCL between the intervention and control villages (P<0.005) during 2000 to 2002. The incidence of ZCLwas unchanged in the years 2000 and 2001, but increased in one village in 2002 after an increase in the number of rodent holes.

CONCLUSION

We suggest that rodent control operations using zinc phosphide be done within a 500-meter circle of houses once every two years before the beginning of the active season of sandflies, which begins in late April.

Germ-free mice produce high levels of interferon-gamma in response to infection with Leishmania major but fail to heal lesions

In order to investigate the importance of the host microbiota on differentiation of T cell subsets in response to infection, Swiss/NIH germ-free mice and conventional (microbiota-bearing) mice were infected with Leishmania major, and lesion development, parasite loads, and cytokine production were assessed. Germ-free mice failed to heal lesions and presented a higher number of parasites at the site of infection than their conventional counterparts. In addition, histopathological analysis indicated a higher density of parasitized macrophages in lesions from germ-free mice than in conventional mice. The initial production of interleukin (IL)-12 and interferon-gamma (IFN-gamma) in germ-free mice was comparable to the conventional controls. Also, germ-free mice produced elevated levels of IFN-gamma and lower levels of IL-4 throughout the course of infection, suggesting the development of a Th1 response. Macrophages from germ-free mice exposed to IFN-gamma and infected with amastigotes in vitro were not as efficient at killing parasites as macrophages from conventional animals. These observations indicate that the microbiota is not essential for the development of Th1 immune responses, but seems to be important for macrophage activation.

Positive Montenegro skin test among patients with sporotrichosis in Rio De Janeiro

We studied 52 patients with sporotrichosis confirmed by isolation of Sporothrix schenckii and reactivity to the Montenegro skin test (MST) during an ongoing outbreak of this mycosis in Rio de Janeiro. The objective was to emphasize the importance of parasitological confirmation and the possibility of incorrect diagnosis based on the lesion's appearance, epidemiological information, and immunological tests. The antigen used for the MST was conserved in either thimerosal 1:10,000 (group 1) or 0.4% phenol (group 2). Nineteen patients (39%) in group 1 and seven (12%) in group 2 presented an induration>or=10 mm (p<0.001). Sera from three patients (6.7%) reacted to indirect immunofluorescence (IIF) for leishmaniasis, while sera from 10 patients (22.2%) reacted to enzyme-linked immunosorbent assay (ELISA). Fifteen patients (28.8%) presented up to two lesions, with a predominance of ulcers. Forty-four patients (84.6%) were treated with itraconazole. In the differential diagnosis between sporotrichosis and cutaneous leishmaniasis, the possibility of co-infection, allergy to the reagent diluent, and cross-reactions should be further investigated, especially in regions with limited laboratory facilities.

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

We investigated the bacterial flora present in skin lesions of patients with chiclero's ulcer from the Yucatan peninsula of Mexico using conventional culture methods (11 patients), and an immunocolorimetric detection of pathogenic Streptococcus pyogenes (15 patients). Prevalence of bacteria isolated by culture methods was 90.9% (10/11). We cultured, from chiclero's ulcers (60%), pathogenic bacterial such as Staphylococcus aureus (20%), S. pyogenes (1.6%), Pseudomonas aeruginosa (1.6%), Morganella morganii (1.6%), and opportunist pathogenic bacteria such as Klebsiella spp. (20.0%), Enterobacter spp. (20%), and Enterococcus spp. (20%). We also cultured coagulase-negative staphylococci in 40% (4/10) of the remaining patients. Micrococcus spp. and coagulase-negative staphylococci constituted the bacterial genuses more frequently isolated in the normal skin of patients with chiclero's ulcer and healthy individuals used as controls. We also undertook another study to find out the presence of S. pyogenes by an immunocolorimetric assay. This study indicated that 60% (9/15) of the ulcerated lesions, but not normal controls, were contaminated with S. pyogenes. Importantly, individuals with purulent secretion and holding concomitant infections with S. pyogenes, S. aureus, P. aeruginosa, M. morganii, and E. durans took longer to heal Leishmania (L.) mexicana infections treated with antimonial drugs. Our results suggest the need to eliminate bacterial purulent infections, by antibiotic treatment, before starting antimonial administration to patients with chiclero's ulcer.

Fine-needle aspiration cytology in the diagnosis of cutaneous leishmaniasis

BACKGROUND

In areas of endemicity without sufficient laboratory infrastructure, cutaneous leishmaniasis (CL) is often diagnosed on the basis of clinical characteristics, but parasitologic confirmation is essential to exclude erroneous diagnoses. We compared fine-needle aspiration cytology (FNAC) with the conventional method of excisional biopsy to assess the efficacy, utility and accuracy of FNAC for the diagnosis of CL.

MATERIALS AND METHODS

In a consecutive series of 100 patients referred for a suspected CL lesion during June 2001 to May 2002, FNAC and 'excisional biopsy followed by histopathology' were done using hematoxylin and eosin (H&E) stain for both procedures.

RESULTS

The study group included 40 males and 60 females, ranging in age from 1 to 70 with a mean age of 28.4 years. In more than 60% of cases, the lesions were on the face. By histopathological examination, 86 of 100 patients were positive for CL; while FNAC showed 77 cases as positive for CL. Taking histopathology as a standard diagnostic procedure, FNAC showed a remarkably high sensitivity (89%) and specificity (100%). The positive and negative predictive values were 100% and 60%, respectively.

CONCLUSION

FNAC is easier, less painful and more cost effective than the conventional 'scraping method/biopsy followed by histopathology'. The high sensitivity and specificity eliminate the need for other time consuming and invasive procedures. Limitations include poor sampling and poor yield.

Cutaneous leishmaniasis of the Old World

Cutaneous Leishmaniasis is a vector-borne protozoal infection of the skin. Several species of Leishmania cause this disease in the Old World. It is manifested as chronic nodular to ulcerative lesions of the skin, which last for many months and may be disfiguring. They eventually heal leaving a scar. Local care of the lesion and treatment of secondary bacterial infection are essential for healing. Antileishmania therapy is indicated in immunocompromised hosts, patients with progressive, multiple, or critically located lesions. Pentavalent antimony compounds remain the main therapeutic option for all species. They are given intravenously (i.v.), intramuscularly (i.m.), or intralesionally. Cryotherapy, and some systemic antifungal agents have been used successfully. Oral azoles are promising new treatments for lesions caused by L. Major. Several other alternatives and their evidence are also presented.

Differentiation of old and new world leishmania species at complex and species levels by PCR

The variable and conserved sequence boxes of kinetoplast DNA (kDNA) of 11 standard strains of 6 complexes of New and Old World Leishmania were amplified using PCR. Four strains from 2 complexes of Old World Leishmania - L. major (MRHO/IR/64/Nadim-1), with 2 bands at 850 and 620 bp, L. major (MHOM/SU/73/5-ASKH), with a band at 620 bp, L. donovani, with a band at 800 bp and L. infantum, with a band at 650 bp - could be differentiated from each other and from the New World strains, with the exception of L. infantum. Seven Leishmania strains from 4 complexes of New World Leishmania - L. mexicana and L. pifanoi, with a band at 730 bp, L. guyanensis, with 2 bands at 730 and 650 bp, L. peruviana, with a band at 710 bp and L. amazonensis, L. garnhami and L. braziliensis, each with a band at 650 bp - were identified. Of these strains, L. guyanensis and L. peruviana could be differentiated from each other and from the Old World strains. These results show that using PCR amplification of kDNA we could differentiate between New and Old World Leishmania at both complex and strain levels. The amplified kDNA PCR products, together with other techniques, could be useful as a diagnostic tool for the identification of Leishmania species.

[Cutaneous leishmaniotic ulcers with Corynebacterium diphtheriae]

In a prospective study to evaluate the influence of secondary bacterial infection on the evaluation of cutaneous leishmaniasis, in Corte de Pedra (Bahia), we isolated Corynebacterium diphtheriae in 7 (8.3%) out of 84 patients with ulcers studied. Due to the small number of patients with the presence of the bacteria in the ulcer, we could not conclude whether Corynebacterium diphtheriae behaves only as a colonizer nor its influence on the healing of the leishmaniotic ulcer.

Bloodmeal digestion and Leishmania major infections in Phlebotomus duboscqi: effect of carbohydrates inhibiting midgut lectin activity

The carbohydrates galactosamine and heparin, previously shown to inhibit phlebotomine lectin activity in vitro, were fed to the sandfly Phlebotomus duboscqi Neveu-Lemaire (Diptera: Psychodidae) with blood, and the effects on mortality, fecundity, protease activity and susceptibility to Leishmania major Yakimoff & Schokhor (Kinetoplastida: Trypanosomatidae) were studied. Previous study revealed that galactosamine considerably enhanced the establishment of L. major infection in P. duboscqi and significantly increased parasite loads in late infections. This work demonstrates a similar but less pronounced effect of heparin. Heparin increased infection rates and parasite loads 3 and 9 days post-feeding but did not affect the location of Leishmania promastigotes and their anterior migration. Galactosamine supplement caused pronounced changes in bloodmeal digestion. It abolished the activity of alkaline proteases and trypsin, caused premature defecation of bloodmeal, increased mortality of female sandflies in days 1-4 post-feeding and decreased their fecundity. Heparin had a less pronounced effect on sandfly physiology. It lowered trypsin activity 12 and 72 h post-bloodmeal but did not alter defecation, mortality and oviposition. The data suggest that the enhancing effect of these carbohydrates on Leishmania infections in sandfly midgut could be explained by their interference with midgut proteases. The study supports the hypothesis that proteolytic activities of midgut proteases strongly influence the vector competence of sandflies.

[Evaluation of secondary bacterial infection's influence on the course of cutaneous leishmaniasis in Corte de Pedra, Bahia]

In order to study the prevalence of secondary bacterial infection in ulcerated lesions and its relationship to the healing process, 84 leishmaniotic patients were evaluated. Diagnosis of the secondary infection was made by bacterial aerobic culture of peripheral tissue specimen of the ulcer. All patients received antimonial therapy during 20 days and washed their ulcers with common soap. Cases were composed mainly of adolescent and adult farmer patients with single lesions. The evaluated ulcers were encountered on legs and feet in 47.6%. Secondary bacterial infection was found in 45/83 (54.2%), and was more frequent in lesions located below the knee. Staphylococcus aureus predominated (89%). The ulcers' healing process, evaluated in 79 patients one month after finishing treatment, was not influenced by the secondary bacterial infection.

Priming by microbial antigens from the intestinal flora determines the ability of CD4+ T cells to rapidly secrete IL-4 in BALB/c mice infected with Leishmania major

Infection of BALB/c mice with Leishmania major results in the rapid accumulation of IL-4 transcripts within CD4(+) T cells that react to the parasite Leishmania homologue of mammalian RACK1 (LACK) Ag. Because memory/effector cells secrete IL-4 more rapidly than naive cells, we sought to analyze the phenotype of these lymphocytes before infection. Indeed, a fraction of LACK-specific CD4(+) T cells expressed a typical CD62 ligand(low)CD44(high)CD45RB(low) phenotype in uninfected mice. LACK-specific T cells were primed in gut-associated lymphoid tissues by cross-reactive microbial Ags as demonstrated by their reactivity with bacterial extracts and by the ability of APCs from the mesenteric LN of BALB/c mice to induce their proliferation. Also, mice in which the digestive tract has been decontaminated exhibited a reduced proportion of LACK-specific T cells expressing a memory/effector phenotype and did not exhibit the early accumulation of IL-4 transcripts induced by L. major. Thus, LACK-specific T cells represent a subset of CD4(+) T cells which have acquired the ability to rapidly secrete IL-4 as the result of their priming by cross-reactive microbial Ags. Tracking the fate of these cells may provide information about the regulation of cell-mediated immune responses to gut Ags in physiological and pathological situations.

Influence of microbiota in experimental cutaneous leishmaniasis in Swiss mice

Infection of Swiss/NIH mice with Leishmania major was compared with infection in isogenic resistant C57BL/6 and susceptible BALB/c mice. Swiss/NIH mice showed self-controlled lesions in the injected foot pad. The production of high levels of interferon-gamma (IFN-gamma) and low levels of interleukin-4 (IL-4) by cells from these animals suggests that they mount a Th1-type immune response. The importance of the indigenous microbiota on the development of murine leishmaniasis was investigated by infecting germfree Swiss/NIH in the hind footpad with L. major and conventionalizing after 3 weeks of infection. Lesions from conventionalized Swiss/NIH mice were significantly larger than conventional mice. Histopathological analysis of lesions from conventionalized animals showed abscesses of variable shapes and sizes and high numbers of parasitized macrophages. In the lesions from conventional mice, besides the absence of abscess formation, parasites were rarely observed. On the other hand, cells from conventional and conventionalized mice produced similar Th1-type response characterized by high levels of IFN-gamma and low levels of IL-4. In this study, we demonstrated that Swiss/NIH mice are resistant to L. major infection and that the absence of the normal microbiota at the beginning of infection significantly influenced the lesion size and the inflammatory response at the site of infection.

Leishmania promastigotes evade interleukin 12 (IL-12) induction by macrophages and stimulate a broad range of cytokines from CD4+ T cells during initiation of infection

Leishmania major are intramacrophage parasites whose eradication requires the induction of T helper 1 (Th1) effector cells capable of activating macrophages to a microbicidal state. Interleukin 12 (IL-12) has been recently identified as a macrophage-derived cytokine capable of mediating Th1 effector cell development, and of markedly enhancing interferon gamma (IFN-gamma) production by T cells and natural killer cells. Infection of macrophages in vitro by promastigotes of L. major caused no induction of IL-12 p40 transcripts, whereas stimulation using heat-killed Listeria or bacterial lipopolysaccharide induced readily detectable IL-12 mRNA. Using a competitor construct to quantitate a number of transcripts, a kinetic analysis of cytokine induction during the first few days of infection by L. major was performed. All strains of mice examined, including susceptible BALB/c and resistant C57BL/6, B10.D2, and C3H/HeN, had the appearance of a CD4+ population in the draining lymph nodes that contained transcripts for IL-2, IL-4, and IFN-gamma (and in some cases, IL-10) that peaked 4 d after infection. In resistant mice, the transcripts for IL-2, IL-4, and IL-10 were subsequently downregulated, whereas in susceptible BALB/c mice, these transcripts were only slightly decreased, and IL-4 continued to be reexpressed at high levels. IL-12 transcripts were first detected in vivo by 7 d after infection, consistent with induction by intracellular amastigotes. Challenge of macrophages in vitro confirmed that amastigotes, in contrast to promastigotes, induced IL-12 p40 mRNA. Reexamination of the cytokine mRNA at 4 d revealed expression of IL-13 in all strains analyzed, suggesting that IL-2 and IL-13 may mediate the IL-12-independent production of IFN-gamma during the first days after infection. Leishmania have evolved to avoid inducing IL-12 from host macrophages during transmission from the insect vector, and cause a striking induction of mRNAs for IL-2, IL-4, IL-10, and IL-13 in CD4+ T cells. Each of these activities may favor survival of the organism.

Topical treatment of cutaneous leishmaniasis in Belize: in vitro and in vivo studies with Leishmania mexicana

Strains of Leishmania mexicana isolated from Belizian patients were found to be highly susceptible to paromomycin sulphate (PR) treatment. This drug at 100 micrograms ml-1 destroyed 85-99.5% of in vitro cultivated Leishmania promastigotes within 4 days of exposure to the drug. Leishmania promastigotes inoculated into the base of the tail of Balb/c mice caused the development of local lesions several weeks after infection. These lesions were totally cleared of parasites after 20 days of topical treatment with PR ointment, comprised of 15% paromomycin sulphate and 12% methylbenzethonium chloride in soft white paraffin. Similar results were also obtained with L. braziliensis infections. Isoenzyme analysis was found to be the method of choice for parasite strain identification. Excreted factor serotyping was only partially effective and promastigote agglutination gave negative results.