Etiological agents of diarrhea in patients infected by the human immunodeficiency virus-1: a review

Despite the importance of understanding the epidemiology of agents responsible for infectious diarrhea in human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS) population, the number of articles about this subject is relatively few. The current article summarizes published data on bacterial, fungal, viral and parasitic enteropathogens in the HIV/AIDS seropositive subjects in different countries, regions and localities. In general, there is a great difference in the frequencies of etiological agents due to factors which include immune status, geographical location, climate and socioeconomic conditions. It is important to stress that a great prevalence of infection by emergent agents has been reported in the more advanced stages of AIDS. Therefore, to establish specific treatment depends directly on knowledge of these agents and risk factors associated to their distribution. Moreover, the colonization by potential pathogenic agents verified in these individuals is high thus implicating that they act as carriers. Finally, public health measures of control and prevention must take into consideration the regional previously identified enteropathogens, especially in areas where HIV prevalence is high.

Pathogenicity of different rabies virus isolates and protection test in vaccinated mice

This study was aimed to evaluate and compare the pathogenicity of rabies virus isolated from bats and dogs, and to verify the efficacy of a commercial rabies vaccine against these isolates. For evaluation of pathogenicity, mice were inoculated by the intramuscular route (IM) with 500MICLD50/0.03mL of the viruses. The cross-protection test was performed by vaccinating groups of mice by the subcutaneous route and challenged through the intracerebral (IC) route. Isolates were fully pathogenic when inoculated by the IC route. When inoculated intramuscularly, the pathogenicity observed showed different death rates: 60.0% for the Desmodus rotundus isolate; 50.0% for dog and Nyctinomops laticaudatus isolates; 40.0% for Artibeus lituratus isolate; 9.5% Molossus molossus isolate; and 5.2% for the Eptesicus furinalis isolate. Mice receiving two doses of the vaccine and challenged by the IC route with the isolates were fully protected. Mice receiving only one dose of vaccine were partially protected against the dog isolate. The isolates from bats were pathogenic by the IC route in mice. However, when inoculated through the intramuscular route, the same isolates were found with different degrees of pathogenicity. The results of this work suggest that a commercial vaccine protects mice from infection with bat rabies virus isolates, in addition to a canine rabies virus isolate.

Cryptococcus neoformans isolation from swallow (Hirundo rustica) excreta in Iran

Cryptococcus neoformans is an encapsulated yeast that can cause cryptococcosis, a life-threatening infection that mainly occurs in immunocompromised patients. The major environmental sources of C. neoformans have been shown to be soil contaminated with avian droppings. In the present study, we evaluated the isolation of C. neoformans from swallow (Hirundo rustica) excreta in two northern cities of Iran. Ninety-seven swallow droppings were evaluated and 498 yeast-like colonies were isolated and identified as Rhodotorula spp. (62.8%), Candida spp. (28.5%)and C. neoformans (8.7%). Cryptococcus neoformans was isolated from 5/97 (5.2%) of collected samples. Min-Max colony forming units (CFU) per one gram for the positive samples were 3-10 C. neoformans colonies. The total mean CFU per one gram for the positive samples was 4.8. The results of this study demonstrate that excreta of swallow may harbor different species of potentially pathogenic yeasts, mainly C. neoformans, and may be capable of disseminating these fungi in the environment.

Oral colonization by yeasts in HIV-positive patients in Brazil

INTRODUCTION: In HIV-infected patients, colonization of the oral cavity by potential pathogenic yeast may lead to development of systemic fungemia. We evaluated the prevalence of yeast in the oral cavity of Brazilian HIV-positive patients and verified whether or not the species characterized were enzymatically active. Furthermore, the species identified were tested for their susceptibility to antifungal treatment. METHODS: Patient saliva and oropharyngeal candidiasis samples were collected from 60 seropositive HIV patients and identified by the API20C system. Enzymatic activity was evaluated by the production of proteinase and phospholipase. Susceptibility to antifungal treatments were determined using the broth microdilution method. RESULTS: the most commonly isolated species were C. albicans (51.56%) followed by non-albicans Candida species (43.73%), Trichosporon mucoides (3.12%) and Kodamaea ohmeri (1.56%). Oral colonization by association of different species was observed in 42% of the patients. Enzymatic activity was verified in most of species isolated, except for C. glabrata, C. lusitaniae and C. guilliermondii. Resistance to Fluconazole and Amphotericin B was observed in isolates of C. albicans, C. glabrata, C. parapsilosis, C. krusei, and K. ohmeri. CONCLUSION: HIV-positive patients are orally colonized by single or multiple species of yeast that are occasionally resistant to Fluconazole or Amphotericin B.

Ectopic dirofilariosis in two dogs from Rio de Janeiro state, Brazil

Report of two canine dirofilariosis cases of ectopic location in the state of Rio de Janeiro. This is the first report of erratic migration for this parasitosis in dogs in the state, calling attention to the short period of time between the two cases. The fact that the area is endemic for this parasite, its zoonotic potential and the report of human cases in the state, demonstrates that authorities should be alerted to the control programs of dirofilariosis along with the pathogenic profile of the infections.

Molecular characterization of Aeromonas spp. and Vibrio cholerae O1 isolated during a diarrhea outbreak

This work aimed to assess pathogenic potential and clonal relatedness of Aeromonas sp. and Vibrio cholerae isolates recovered during a diarrhea outbreak in Brazil. Clinical and environmental isolates were investigated for the presence of known pathogenic genes and clonal relatedness was assessed by intergenic spacer region (ISR) 16S-23S amplification. Four Aeromonas genes (lip, exu, gcat, flaA/B) were found at high overall frequency in both clinical and environmental isolates although the lip gene was specifically absent from selected species. A fifth gene, aerA, was rarely found in A. caviae, the most abundant species. The ISR profile revealed high heterogeneity among the Aeromonas isolates and no correlation with species identification. In contrast, in all the V. cholerae isolates the four genes investigated (ctxA, tcpA, zot and ace) were amplified and revealed homogeneous ISR and RAPD profiles. Although Aeromonas isolates were the major enteric pathogen recovered, their ISR profiles are not compatible with a unique cause for the diarrhea events, while the clonal relationship clearly implicates V. cholerae in those cases from which it was isolated. These results reinforce the need for a better definition of the role of aeromonads in diarrhea and whether they benefit from co-infection with V. cholerae.

PREVALENCE OF INTESTINAL PARASITISM AND ASSOCIATED SYMPTOMATOLOGY AMONG HEMODIALYSIS PATIENTS

Intestinal parasites are an important cause of morbidity and mortality. Immunocompromised individuals may develop more severe forms of these infections. Taking into account the immunity impairment in patients suffering from chronic renal failure (CRF), we will determine the prevalence and associated symptoms of intestinal parasites in these patients. Controls without CRF were used for comparison. Stool samples were collected and processed for microscopic identification of parasites using the Formalin-ether concentration method. For Cryptosporidium diagnosis, the ELISA technique was used. One hundred and ten fecal samples from hemodialysis patients were analyzed, as well as 86 from a community group used as control group. A result of 51.6% of intestinal parasites was observed in hemodialysis patients and 61.6% in the control group. Cryptosporidium and Blastocystis were the most common infections in patients with CRF (26.4% and 24.5%, respectively). Blastocystis was the most common infection in the control group (41.9%), however no individual was found positive for Cryptosporidium. Among the CRF patients, 73.6% were symptomatic, 54.3% of these tested positive for at least one parasite, in contrast to 44.8% in asymptomatic patients (p = 0.38). The most common symptoms in this group were flatulence (36.4%), asthenia (30.0%) and weight loss (30.0%). In the control group, 91.9% were symptomatic, 60.8% of these tested positive for at least one parasite, in contrast to 71.4% in asymptomatic patients (p = 0.703). A significant difference between the two groups was observed with regard to symptoms, with bloating, postprandial fullness, and abdominal pain being more frequent in the control group than in the hemodialysis group (all p < 0.05). Comparing symptomatic with asymptomatic, there was no association in either group between symptoms or the prevalence of parasitic infection, nor with the type of parasite or with multiple parasitic infections. Patients with chronic renal failure are frequent targets for renal transplantation, which as well as the inherent immunological impairment of the disease itself, results in immunosuppression by medication. For this reason, carriers of intestinal parasites with pathogenic potential can develop serious clinical complications influencing the success of transplantation. This fact, coupled with the high prevalence of intestinal parasites and the dissociation between symptoms and infection in CRF patients, suggests that the stool test should be incorporated in routine propedeutics. Furthermore, preventive measures for the acquisition of parasites through the fecal-oral contamination route should be introduced.

APPLICATION OF 6-NITROCOUMARIN AS A SUBSTRATE FOR THE FLUORESCENT DETECTION OF NITROREDUCTASE ACTIVITY IN Sporothrix schenckii

Introduction Sporothrix schenckii is a thermal dimorphic pathogenic fungus causing a subcutaneous mycosis, sporotrichosis. Nitrocoumarin represents a fluorogenic substrate class where the microbial nitroreductase activity produces several derivatives, already used in several other enzyme assays. The objective of this study was the analysis of 6-nitrocoumarin (6-NC) as a substrate to study the nitroreductase activity in Sporothrix schenckii. Methods Thirty-five samples of S. schenckii were cultivated for seven, 14 and 21 days at 35 °C in a microculture containing 6-nitrocoumarin or 6-aminocoumarin (6-AC) dissolved in dimethyl sulfoxide or dimethyl sulfoxide as a negative control, for posterior examination under an epifluorescence microscope. The organic layer of the seven, 14 and 21-day cultures was analyzed by means of direct illumination with 365 nm UV light and by means of elution on G silica gel plate with hexane:ethyl acetate 1:4 unveiled with UV light. Results All of the strains showed the presence of 6-AC (yellow fluorescence) and 6-hydroxylaminocoumarin (blue fluorescence) in thin layer chromatography, which explains the green fluorescence observed in the fungus structure. Conclusion The nitroreductase activity is widely distributed in the S. schenckii complex and 6-NC is a fluorogenic substrate of easy access and applicability for the nitroreductase activity detection.

PREVALENCE OF Entamoeba histolytica/Entamoeba dispar IN THE CITY OF CAMPINA GRANDE, IN NORTHEASTERN BRAZIL

There is a clear need to perform epidemiological studies to find the true prevalence of Entamoeba histolytica around the world. The evaluation of this prevalence has been hindered by the existence of two different species which are morphologically identical, but genetically different, namely E. histolytica, which causes amebiasis, and E. dispar, which is non-pathogenic. In Brazil, the E. dispar has been detected in communities in the Southeastern (SE) and Northeastern (NE) regions with poor sanitation. However, individuals infected with E. histolytica have been identified in other regions. There is an absence of reports on the prevalence of these parasites in the state of Paraíba, which also has areas with poor sanitary conditions where a high prevalence of the E. histolytica/E. dispar complex has been detected in children from urban slums. The present study evaluated the prevalence of E. histolytica and E. dispar in 1,195 asymptomatic children between two and 10 years of age, living in a sprawling urban slum in Campina Grande, in the state of Paraíba, in Northeastern Brazil. These children were examined and their feces samples were analyzed microscopically. A total of 553 children tested positive for the E. histolytica/E. dispar complex, and 456 of the positive samples were tested with the E. histolytica II® ELISA kit. All 456 samples were negative for the presence of the adhesin E. histolytica specific antigen. The evidence suggests that in this community E. histolytica is absent and E. dispar is the dominant species.

PREVALENCE OF DRUG RESISTANCE AND VIRULENCE FEATURES IN Salmonella spp. ISOLATED FROM FOODS ASSOCIATED OR NOT WITH SALMONELLOSIS IN BRAZIL

Salmonella is the most common etiological agent of cases and outbreaks of foodborne diarrheal illnesses. The emergence and spread of Salmonella spp., which has become multi-drug resistant and potentially more pathogenic, have increased the concern with this pathogen. In this study, 237 Salmonella spp., associated or not with foodborne salmonellosis in Brazil, belonging mainly to serotype Enteritidis, were tested for antimicrobial susceptibility and the presence of the virulence genes spvC, invA, sefA and pefA. Of the isolates, 46.8% were sensitive to all antimicrobials and 51.9% were resistant to at least one antimicrobial agent. Resistance to more than one antimicrobial agent was observed in 10.5% of the strains. The highest rates of resistance were observed for streptomycin (35.9%) and nalidixic acid (16.9%). No strain was resistant to cefoxitin, cephalothin, cefotaxime, amikacin, ciprofloxacin and imipenem. The invA gene was detected in all strains. Genes spvC and pefA were found in 48.1% and 44.3% of strains, respectively. The gene sefA was detected in 31.6% of the strains and only among S. Enteritidis. Resistance and virulence determinants were detected in Salmonella strains belonging to several serotypes. The high rates of antibiotic-resistance in strains isolated from poultry products demonstrate the potential risk associated with the consumption of these products and the need to ensure good food hygiene practices from farm to table to reduce the spread of pathogens relevant to public health.

FUNGI ISOLATED FROM THE EXCRETA OF WILD BIRDS IN SCREENING CENTERS IN PELOTAS, RS, BRAZIL

The identification of the fungal species belonging to the healthy microflora in animals is a precondition for the recognition of pathological processes causing them. The aim of this study was to investigate the presence of potentially pathogenic fungi in the feces of wild birds collected in Screening Centers. Samples were collected from the feces of 50 cages with different species of birds. The samples were processed according to the modified method STAIB and the plates incubated at 32 °C for up to ten days with daily observation for detection of fungal growth. The isolation of the following species was observed: Malassezia pachydermatis, Candida albicans, C. famata, C. guilliermondii, C. sphaerica, C. globosa, C. catenulata, C. ciferri, C. intermedia, Cryptococcus laurentii, Trichosporon asahii, Geotrichum klebahnii, Aspergillus spp., A. niger and Penicillium spp. Knowing the character of some opportunistic fungi is important in identifying them, facilitating the adoption of preventive measures, such as proper cleaning of cages, since the accumulation of excreta may indicate a risk for both health professionals and centers for screening public health.

Enterobacteriaceae ISOLATES FROM THE ORAL CAVITY OF WORKERS IN A BRAZILIAN ONCOLOGY HOSPITAL

The evaluation of workers as potential reservoirs and disseminators of pathogenic bacteria has been described as a strategy for the prevention and control of healthcare-associated infections (HAIs). The aim of this study was to evaluate the presence of Enterobacteriaceae in the oral cavity of workers at an oncology hospital in the Midwest region of Brazil, as well as to characterize the phenotypic profile of the isolates. Saliva samples of 294 workers from the hospital’s healthcare and support teams were collected. Microbiological procedures were performed according to standard techniques. Among the participants, 55 (18.7%) were colonized by Enterobacteriaceae in the oral cavity. A total of 64 bacteria were isolated, including potentially pathogenic species. The most prevalent species was Enterobacter gergoviae (17.2%). The highest rates of resistance were observed for β-lactams, and 48.4% of the isolates were considered multiresistant. Regarding the enterobacteria isolated, the production of ESBL and KPC was negative. Nevertheless, among the 43 isolates of the CESP group, 51.2% were considered AmpC β-lactamase producers by induction, and 48.8% were hyper-producing mutants. The significant prevalence of carriers of Enterobacteriaceae and the phenotypic profile of the isolates represents a concern, especially due to the multiresistance and production of AmpC β-lactamases.

PREVALENCE OF INTESTINAL PARASITES AMONG FOOD HANDLERS OF SARI, NORTHERN IRAN

Parasitic infection is highly prevalent throughout the developing countries of the world. Food handlers are a potential source of infection for many intestinal parasites and other enteropathogenic infections as well. The aim of this study was to determine the prevalence of intestinal parasite carriers among food handlers attending the public health center laboratory in Sari, Northern Iran for annual check-up. The study was performed from August 2011 through February 2012. Stool samples were collected from 1041 male and female food handlers of different jobs aged between 18 to 63 years and were examined following standard procedures. Sociodemographic, environmental and behavioral data analysis of the food handlers were recorded in a separate questionnaire. Intestinal parasites were found in 161 (15.5%) of the studied samples. Seven species of protozoan or helminth infections were detected. Most of the participants were infected with Giardia lamblia (53.9%) followed by Blastocystis hominis (18%), Entamoeba coli (15.5%), Entamoeba histolytica/dispar (5.5%), Cryptosporidium sp. (3.1%), Iodamoeba butschlii (3.1%) and Hymenolepis nana (1.9%) as the only helminth infection. The findings emphasized that food handlers with different pathogenic organisms may predispose consumers to significant health risks. Routine screening and treatment of food handlers is a proper tool in preventing food-borne infections.

CHEMICAL CHARACTERIZATION AND EVALUATION OF ANTIBACTERIAL, ANTIFUNGAL, ANTIMYCOBACTERIAL, AND CYTOTOXIC ACTIVITIES OF Talinum paniculatum

SUMMARY In this study, the bioactivity of Talinum paniculatum was evaluated, a plant widely used in folk medicine. The extract from the T. paniculatum leaves (LE) was obtained by percolation with ethanol-water and then subjecting it to liquid-liquid partitions, yielding hexane (HX), ethyl acetate (EtOAc), butanol (BuOH), and aqueous (Aq) fractions. Screening for antimicrobial activity of the LE and its fractions was evaluated in vitro through broth microdilution method, against thirteen pathogenic and non-pathogenic microorganisms, and the antimycobacterial activity was performed through agar diffusion assay. The cytotoxic concentrations (CC90) for LE, HX, and EtOAc were obtained on BHK-21 cells by using MTT reduction assay. The LE showed activity against Serratia marcescens and Staphylococcus aureus, with Minimum Inhibitory Concentration (MIC) values of 250 and 500 µg/mL, respectively. Furthermore, HX demonstrated outstanding activity against Micrococcus luteus and Candida albicans with a MIC of 31.2 µg/mL in both cases. The MIC for EtOAc also was 31.2 µg/mL against Escherichia coli. Conversely, BuOH and Aq were inactive against all tested microorganisms and LE proved inactive against Mycobacterium tuberculosisand Mycobacterium bovisas well. Campesterol, stigmasterol, and sitosterol were the proposed structures as main compounds present in the EF and HX/EtOAc fractions, evidenced by mass spectrometry. Therefore, LE, HX, and EtOAc from T. paniculatumshowed potential as possible sources of antimicrobial compounds, mainly HX, for presenting low toxicity on BHK-21 cells with excellent Selectivity Index (SI = CC90/MIC) of 17.72 against C. albicans.

PATHOGENICITY OF Blastocystis sp. TO THE GASTROINTESTINAL TRACT OF MICE: RELATIONSHIP BETWEEN INOCULUM SIZE AND PERIOD OF INFECTION

The pathogenic potential of Blastocystis sp. in experimental models requires further investigation. In this work, the pathogenicity of this parasite in the gastrointestinal tract of male Swiss mice was evaluated according to the inoculum size and period of infection. Animals were infected intragastrically, with 100, 500, 1,000, 5,000 and 10,000 Blastocystis sp. vacuolar forms obtained from a mixture of eight human isolates cultured axenically in Jones' medium. After seven, 14, 21, 28 and 60 days of infection, the animals were sacrificed and fragments of the small intestine (duodenum), large intestine, and cecum were subjected to histopathological analysis. Blastocystis sp. triggered an inflammatory response in the different tissues analyzed, with a predominance of mononuclear cells. The parasite was found in the muscular layer of the cecum, showing its invasive character. Larger inocula triggered inflammatory processes earlier (seven days) than smaller ones (from 21 days). We conclude that, in the proposed model, the pathogenicity of Blastocystis sp. isolates that were studied is related to inoculum size and period of infection.