Comparative transcriptome expression analysis in susceptible and resistant potato (Solanum tuberosum) cultivars to common scab (Streptomyces scabies) revealed immune priming responses in the incompatible interaction.

Common scab disease in potato has become a widespread issue in major potato production areas, leading to increasing economic losses. Varietal resistance is seen as a viable and long-term scab management strategy. However, the genes and mechanisms of varietal resistance are unknown. In the current study, a comparative RNA transcriptome sequencing and differential gene signaling and priming sensitization studies were conducted in two potato cultivars that differ by their response to common scab (Streptomyces scabies), for unraveling the genes and pathways potentially involved in resistance within this pathosystem. We report on a consistent and contrasted gene expression pattern from 1,064 annotated genes differentiating a resistant (Hindenburg) and a susceptible (Green Mountain) cultivars, and identified a set of 273 co-regulated differentially expressed genes in 34 pathways that more likely reflect the genetic differences of the cultivars and metabolic mechanisms involved in the scab pathogenesis and resistance. The data suggest that comparative transcriptomic phenotyping can be used to predict scab lesion phenotype in breeding lines using mature potato tuber. The study also showed that the resistant cultivar, Hindenburg, has developed and maintained a capacity to sense and prime itself for persistent response to scab disease over time, and suggests an immune priming reaction as a mechanism for induced-resistance in scab resistant potato cultivars. The set of genes identified, described, and discussed in the study paves the foundation for detailed characterizations towards tailoring and designing procedures for targeted gene knockout through gene editing and phenotypic evaluation.

High burden and seasonal variation of paediatric scabies and pyoderma prevalence in The Gambia: A cross-sectional study.

BACKGROUND: Scabies is a WHO neglected tropical disease common in children in low- and middle-income countries. Excoriation of scabies lesions can lead to secondary pyoderma infection, most commonly by Staphyloccocus aureus and Streptococcus pyogenes (group A streptococcus, GAS), with the latter linked to acute post-streptococcal glomerulonephritis (APSGN) and potentially rheumatic heart disease (RHD). There is a paucity of data on the prevalence of these skin infections and their bacterial aetiology from Africa. METHODOLOGY/PRINCIPAL FINDINGS: A cross-sectional study, conducted over a four-month period that included the dry and rainy season, was conducted to determine the prevalence of common skin infections in Sukuta, a peri-urban settlement in western Gambia, in children <5 years. Swabs from pyoderma lesions were cultured for S. aureus and GAS. Of 1441 children examined, 15.9% had scabies (95% CI 12.2-20.4), 17.4% had pyoderma (95% CI 10.4-27.7) and 9.7% had fungal infections (95% CI 6.6-14.0). Scabies was significantly associated with pyoderma (aOR 2.74, 95% CI 1.61-4.67). Of 250 pyoderma swabs, 80.8% were culture-positive for S. aureus, and 50.8% for GAS. Participants examined after the first rains were significantly more likely to have pyoderma than those examined before (aRR 2.42, 95% CI 1.38-4.23), whereas no difference in scabies prevalence was seen (aRR 1.08, 95% CI 0.70-1.67). Swab positivity was not affected by the season. CONCLUSIONS/SIGNIFICANCE: High prevalence of scabies and pyoderma were observed. Pyoderma increased significantly during the rainy season. Given the high prevalence of GAS pyoderma among children, further research on the association with RHD in West Africa is warranted.

Scabies mites alter the skin microbiome and promote growth of opportunistic pathogens in a porcine model.

BACKGROUND: The resident skin microbiota plays an important role in restricting pathogenic bacteria, thereby protecting the host. Scabies mites (Sarcoptes scabiei) are thought to promote bacterial infections by breaching the skin barrier and excreting molecules that inhibit host innate immune responses. Epidemiological studies in humans confirm increased incidence of impetigo, generally caused by Staphylococcus aureus and Streptococcus pyogenes, secondary to the epidermal infestation with the parasitic mite. It is therefore possible that mite infestation could alter the healthy skin microbiota making way for the opportunistic pathogens. A longitudinal study to test this hypothesis in humans is near impossible due to ethical reasons. In a porcine model we generated scabies infestations closely resembling the disease manifestation in humans and investigated the scabies associated changes in the skin microbiota over the course of a mite infestation. METHODOLOGY/PRINCIPAL FINDINGS: In a 21 week trial, skin scrapings were collected from pigs infected with S. scabies var. suis and scabies-free control animals. A total of 96 skin scrapings were collected before, during infection and after acaricide treatment, and analyzed by bacterial 16S rDNA tag-encoded FLX-titanium amplicon pyrosequencing. We found significant changes in the epidermal microbiota, in particular a dramatic increase in Staphylococcus correlating with the onset of mite infestation in animals challenged with scabies mites. This increase persisted beyond treatment from mite infection and healing of skin. Furthermore, the staphylococci population shifted from the commensal S. hominis on the healthy skin prior to scabies mite challenge to S. chromogenes, which is increasingly recognized as being pathogenic, coinciding with scabies infection in pigs. In contrast, all animals in the scabies-free cohort remained relatively free of Staphylococcus throughout the trial. CONCLUSIONS/SIGNIFICANCE: This is the first experimental in vivo evidence supporting previous assumptions that establishment of pathogens follow scabies infection. Our findings provide an explanation for a biologically important aspect of the disease pathogenesis. The methods developed from this pig trial will serve as a guide to analyze human clinical samples. Studies building on this will offer implications for development of novel intervention strategies against the mites and the secondary infections.

The microbiology of impetigo in indigenous children: associations between Streptococcus pyogenes, Staphylococcus aureus, scabies, and nasal carriage.

BACKGROUND: Impetigo is caused by both Streptococcus pyogenes and Staphylococcus aureus; the relative contributions of each have been reported to fluctuate with time and region. While S. aureus is reportedly on the increase in most industrialised settings, S. pyogenes is still thought to drive impetigo in endemic, tropical regions. However, few studies have utilised high quality microbiological culture methods to confirm this assumption. We report the prevalence and antimicrobial resistance of impetigo pathogens recovered in a randomised, controlled trial of impetigo treatment conducted in remote Indigenous communities of northern Australia. METHODS: Each child had one or two sores, and the anterior nares, swabbed. All swabs were transported in skim milk tryptone glucose glycogen broth and frozen at -70°C, until plated on horse blood agar. S. aureus and S. pyogenes were confirmed with latex agglutination. RESULTS: From 508 children, we collected 872 swabs of sores and 504 swabs from the anterior nares prior to commencement of antibiotic therapy. S. pyogenes and S. aureus were identified together in 503/872 (58%) of sores; with an additional 207/872 (24%) sores having S. pyogenes and 81/872 (9%) S. aureus, in isolation. Skin sore swabs taken during episodes with a concurrent diagnosis of scabies were more likely to culture S. pyogenes (OR 2.2, 95% CI 1.1 - 4.4, p = 0.03). Eighteen percent of children had nasal carriage of skin pathogens. There was no association between the presence of S. aureus in the nose and skin. Methicillin-resistance was detected in 15% of children who cultured S. aureus from either a sore or their nose. There was no association found between the severity of impetigo and the detection of a skin pathogen. CONCLUSIONS: S. pyogenes remains the principal pathogen in tropical impetigo; the relatively high contribution of S. aureus as a co-pathogen has also been confirmed. Children with scabies were more likely to have S. pyogenes detected. While clearance of S. pyogenes is the key determinant of treatment efficacy, co-infection with S. aureus warrants consideration of treatment options that are effective against both pathogens where impetigo is severe and prevalent. TRIAL REGISTRATION: This trial is registered; ACTRN12609000858291 .

Skin disorders, including pyoderma, scabies, and tinea infections.

Pyoderma, scabies, and tinea are common childhood skin disorders too often considered to be merely of nuisance value. More than 111 million children are believed to have pyoderma, with many also co-infected with scabies, tinea, or both. These skin disorders cannot be differentiated by ethnicity or socioeconomic status but, in high-prevalence areas, poverty and overcrowded living conditions are important underlying social determinants. Each is transmitted primarily through direct skin-to-skin contact. For many Indigenous children, these skin conditions are part of everyday life. Although rarely directly resulting in hospitalization or death, there is a high and largely unmet demand for effective management at the primary health-care level, particularly for pyoderma and scabies. Despite particularly high prevalence in some settings, treatment is not sought for many children, and when sought, the clinical benefit from such consultations is variable. The lack of standard, evidence-based recommendations is of much concern. The current evidence base for clinical diagnosis and treatment of these common childhood skin disorders is highlighted.

Incidencia de enfermedades zoonóticas en niños menores de cinco (5) años de edad del Ambulatorio de la Concordia Municipio San Cristóbal Estado Táchira año 2005 / Incidence of zoonotics diseases on the smaller infantile population of five years during year 2005 in the Ambulatory of the Concordia, San Cristobal Municipality Táchira State

Las enfermedades Zoonóticas representan un riesgo de salud potencial para las comunidades humanas. El gran número de estas patologías animales repercuten directamente sobre los sistemas de salud pública que en la mayoría de los casos no alcanzan a cubrir las necesidades básicas concernientes al respecto. A continuación se presenta un estudio descriptivo realizado en el ambulatorio Urbano tipo II de la Concordia, Municipio San Cristóbal, referente a la incidencia de algunas de estas enfermedades sobre la población infantil menor de 5 años durante el año 2005.

Secondary bacterial infections complicating skin lesions.

Secondary bacterial infection in skin lesions is a common problem. This review summarises a series of studies of the microbiology of several of these infections: scabies, psoriasis, poison ivy, atopic dermatitis, eczema herpeticum and kerion. Staphylococcus aureus and group A beta-haemolytic streptococci were the most prevalent aerobes and were isolated from all body sites. In contrast, organisms that reside in the mucous membranes close to the lesions predominated in infections next to these membranes. In this fashion, enteric gram-negative bacilli and Bacteroides spp. were found most often in buttock and leg lesions. The probable sources of these organisms are the rectum and vagina, where they normally reside. Group A beta-haemolytic streptococci, pigmented Prevotella and Porphyromonas spp. and Fusobacterium spp. were most commonly found in lesions of the head, face, neck and fingers. These organisms probably reached these sites from the oral cavity, where they are part of the normal flora. This review highlights the polymicrobial aerobic-anaerobic microbiology of secondarily infected skin lesions.

Crusted scabies in systematic lupus erythematosus: a case report.

Crusted scabies (Norwegian scabies) is uncommon in clinical practice and may present as papulosquamous dermatosis. A case of crusted scabies in systemic lupus erythematosus (SLE) is described. The skin lesions simulated those of subacute cutaneous lupus erythematosus of the papulosquamous type, and became the source of epidemic scabies in the hospital. The colonization with Staphylococcus aureus within crusted lesions may have contributed to the patient's sepsis. This case illustrates the pitfalls in recognition of crusted scabies and the importance of rapid diagnosis.

Cutaneous infections in Trinidad.

Skin infection is common in patients with any skin diseases where pruritus is a prominent feature. A retrospective analysis was performed on the results of skin swab cultures from patients with eczema and a variety of other conditions. This paper presents the findings of bacteriologic culture and sensitivity testing of 131 swabs from 122 patients over a period of 22 months and examines the results in terms of the reported relationship between scabies and acute poststreptococcal glomerulonephritis. Staphylococcus aureus was most often isolated, and this appears to indicate that antistaphylococcal antibiotics should be the first line of treatment in the absence of the results of cultures.

Cutaneous infections in Trinidad

Skin infection is common in patients with any skin diseases where pruritus is a prominent feature. A retrospective analysis was performed on the results of skin swab cultures from patients with eczema and a variety of other conditions. This paper presents the findings of bacteriologic culture and sensitivity testing of 131 swabs from 122 patients over a period of 22 months and examines the results in terms of the reported relationship between scabies and acute poststreptococcal glomerulonephritis. Staphylococcus aureus was most often isolated, and this appears to indicate that antistaphylococcal antibiotics should be the first line of treatment in the absence of the results of cultures. (AU)

The aerobic bacteriology of infected skin lesions in children of the Eastern Highlands Province.

Of 480 children studied, the relative frequency of skin infections divided into three categories were: score 266 (55%), infected scabies 164 (34%) and tropical ulcers 50 (10%). Infected scabies was more prevalent in the less than 2 year age group and tropical ulcers were commonest in the 9-12 year age group and these differences were significant. The majority of lesions occurred on the lower extremities with the trunk the least commonly affected area. No significant differences were found in different age groups between males and females. Beta haemolytic streptococci (95%), Staphylococcus aureus (83%), Corynebacterium diphtheriae (72%) and Corynebacterium haemolyticum (35%) were the major bacteria isolated. Beta haemolytic streptococci were the most prevalent in infected scabies and least in tropical ulcers and these differences were significant. Three major Lancefield groups were isolated: group A (61%), group C (19%) and group G (19%). The distribution of these groups were unequal with group A most common in infected scabies but rarely seen in tropical ulcers. Groups C and G were found more commonly in tropical ulcers than the other two groups of lesions and these differences were significant. Multiple populations of beta haemolytic streptococci in a single lesion were seen in 19% of children. Less than one third of Streptococcus pyogenes were M typable and of these 18% were known nephritogenic serotypes. Staphylococcus aureus was significantly more common in infected scabies and least common in tropical ulcers. The prevalence of Vincent's organisms in tropical ulcers (74%) was significantly higher than scores (9%) and infected scabies (1%). The isolation rate of Corynebacterium diphtheriae was significantly higher in infected scabies than the other two groups. The most common biotype isolated was var mitis (72%). Only 2% of isolates were toxigenic. Corynebacterium haemolyticum was isolated significantly more frequently in tropical ulcers than the other lesions. All major bacteria, excluding betalactamase-producing Straphylococcus aureus, were uniformly sensitive to penicillin. Methicillin resistance was found in 1% of Staphylococcus aureus isolates and is reported here for the first time in this country. These isolates were also multiply resistant to erythromycin, chloramphenicol and tetracycline.

The bacteriology of skin sores in Goroka children.

The bacteriology of infected skin lesions was studied in paediatric outpatients. Thirty-nine untreated lesions were studied: 37 (95%) grew beta haemolytic streptococci (46% group A, 3% group B, 23% group C, 26% group G), 21 (54%) grew Staphylococcus aureus and 13 (33%) grew Corynebacterium haemolyticum. No attempt was made to selectively isolate Corynebacterium diphtheriae in this study. Vincent's organisms were seen in 13 (37%) of 35 gram stains from untreated lesions, including eight (73%) of 11 tropical ulcers. Twenty-three (92%) of the 25 strains of S. aureus isolated from untreated sores were resistant to penicillin.

Association of Malassezia (Pityrosporum) pachydermatis with sarcoptic mange in New York State.

Malassezia (Pityrosporum) pachydermatis consistently accompanied sarcoptic mange in all red foxes (Vulpes fulva), porcupines (Erethizon dorsatum), and coyotes (Canis latrans) examined. This yeastlike microorganism has not heretofore been reported on any of these hosts. Its presence on the exoskeleton of Sarcoptes scabiei taken from these animals suggests a carrier role for the mite. The yeast may be saprophytic or a secondary pathogen.

Bacterial skin infections in preschool and school children in coastal Tanzania.

In coastal Tanzania, 1,855 preschool and school children were studied for pyoderma (superficial bacterial infections of the skin exclusive of secondarily infected scabies) and for scabies. The predisposing personal, socleoeconomic, and hygienic variables for both conditions were studied also. Pyoderma lesions and some secondarily infected scabies were cultured aerobically for bacterial isolates and the predisposing factors were determined by interviews, home visits, and physical examinations. Pyoderma was present in 6.9% and scabies in 16.6% of the children; both combined totalled 23.5% of the children. Both conditions were more common in rural than in urban environments, but scabies was most common in populations with poor socioeconomic and hygienic conditions. The predisposing factors included trauma, insect bites, hot and damp coastal weather, and poor socioeconomic and hygienic conditions.

Scabies and other skin diseases in pre-school children in Ujamaa villages in Tanzania.

A survey of skin diseases was carried out in pre-school children in five Ujamaa villages in Rufiji district and 532 children (5.3% of the total population) were screened. The results showed that scabies was the commonest skin problem affecting 31% of the children. Primary pyoderma and fungal infections were relatively less common and accounted for 7.0 and 2.4% respectively. Staphylococcus aureus, Group A beta haemolytic streptococci and Corynebacterium diphteriae were the commonest pathogeneic bacteria isolated from both infected scabies and primary pyoderma. Tinea capitis was similarly the commonest fungal infection and Microsporium audouinii was the main pathogen. The high prevalence of scabies was attributed to poor hygiene, overcrowding with intimate personal contact. The low prevalence of pyoderma was due to the fact that we did not include secondarily infected scabies and eczema amongst the cases of pyoderma.