Ordinary and opportunistic enteropathogens associated with diarrhea in Senegalese adults in relation to human immunodeficiency virus serostatus

Commensal Intestinal Protozoa-Underestimated Members of the Gut Microbial Community

The human gastrointestinal microbiota contains a diverse consortium of microbes, including bacteria, protozoa, viruses, and fungi. Through millennia of co-evolution, the host-microbiota interactions have shaped the immune system to both tolerate and maintain the symbiotic relationship with commensal microbiota, while exerting protective responses against invading pathogens. Microbiome research is dominated by studies describing the impact of prokaryotic bacteria on gut immunity with a limited understanding of their relationship with other integral microbiota constituents. However, converging evidence shows that eukaryotic organisms, such as commensal protozoa, can play an important role in modulating intestinal immune responses as well as influencing the overall health of the host. The presence of several protozoa species has recently been shown to be a common occurrence in healthy populations worldwide, suggesting that many of these are commensals rather than invading pathogens. This review aims to discuss the most recent, conflicting findings regarding the role of intestinal protozoa in gut homeostasis, interactions between intestinal protozoa and the bacterial microbiota, as well as potential immunological consequences of protozoa colonization.

Occurrence of the Seven Most Common Serotypes of Shiga Toxin-Producing Escherichia coli in Beef Cuts Produced in Meat Processing Plants in the State of São Paulo, Brazil

ABSTRACT

Healthy cattle are considered the main reservoir of Shiga toxin-producing Escherichia coli (STEC) strains, so in some places in the world, products derived from beef are the most common source for disease outbreaks caused by these bacteria. Therefore, to guarantee that the beef produced by our slaughterhouses is safe, there is a need for continuous monitoring of these bacteria. In this study, 215 beef cuts were evaluated, including chilled vacuum-packed striploins (151 samples), rib eyes (30 samples), and knuckles (34 samples), from March to June 2018. These meat samples were collected from the slaughter of unconfined cattle, being arbitrarily collected from eight meat processing companies in São Paulo state, Brazil. Each sample was examined for the presence of STEC toxin type (stx1 and/or stx2 genes) and also the attaching and effacing E. coli (eae) gene, determined by a multiplex PCR assay. We show that the major seven STEC strains (O serogroups O26, O45, O103, O111, O121, O145, and O157) are not detected in any of the analyzed beef cut samples; however, three of them presented the virulence eae gene. Therefore, the absence of STEC strains in the beef samples may be an indication of the low prevalence of this pathogen in the cattle herd on the farm, associated with good hygiene and handling practices adopted by the meat industry.

HIGHLIGHTS

Association between Blastocystis sp. infection and immunocompromised patients: a systematic review and meta-analysis

The significance of opportunistic infections in immunocompromised patients and the enigmatic pathogenicity of Blastocystis directed us to conduct the first global systematic review and meta-analysis on Blastocystis prevalence, odds ratios (ORs), and subtypes distribution in various immunocompromised patients (HIV/AIDS, cancer and hemodialysis patients, as well as transplant recipients). The systematic searching procedure was done in Web of Science, PubMed, Scopus, and Google Scholar databases for relevant published literature until November 11, 2020. Random-effects model was utilized to calculate the weighted estimates and 95% confidence intervals (95% CIs). The computed pooled prevalence of Blastocystis inferred from 118 papers (128 datasets) on immunocompromised patients was 10.3% (95% CI: 8.7-12.2%), with 16.1% (95% CI: 11.3-22.2%), 12.5% (95% CI: 8.5-18%), 8.4% (95 % CI: 6.6-10.6%), and 6% (95% CI: 2.6-13.3%) for hemodialysis patients, cancer patients, HIV/AIDS patients, and transplant recipients, respectively. Based on 50 case-control studies (54 datasets), the highest ORs were associated with cancer [2.81 (95% CI: 1.24-6.38, P = 0.013)] and hemodialysis patients [2.78 (95% CI: 1.19-6.48, P = 0.018)]. The most frequent subtype being found in immunocompromised patients was ST3 [41.7% (95% CI: 31.4-52.7%)], followed by ST1 [31.7% (95% CI: 23.2-41.8%)] and ST2 [23.1% (95% CI: 14.8-34.1%)]. Also, the weighted frequency of Blastocystis in various subgroups (publication year, WHO regions, geographical distribution, continents, and country income) was analyzed separately. In total, the results of the present meta-analysis highlighted that one's immunodeficiency status is probably associated with an increased Blastocystis infection, underpinning strict preventive measures to be taken.

Global prevalence and associated risk factors of diarrheagenic Giardia duodenalis in HIV/AIDS patients: A systematic review and meta-analysis

Giardia duodenalis is one of the leading causes of diarrhea, mostly in underdeveloped nations of Africa and Asia. The present review provides insights into the prevalence, odds ratios (ORs) and associated risk factors of giardiasis in HIV/AIDS patients. Four major English databases (Web of Science, PubMed, Scopus, and Google Scholar) were excavated for relevant literature without time limitation until 20 November 2020. Next, meta-analysis was performed using a random-effects model and 95% confidence intervals (CIs). As well, heterogeneity among studies was evaluated using Cochran's Q and the I²-statistic. Totally, 19,218 HIV/AIDS patients in 130 studies were examined, showing a 5% (95% CI: 4.2%-6%) pooled prevalence. Also, the weighted random-effects OR of G. duodenalis infection among HIV/AIDS patients in comparison with their controls in 48 case-control studies was estimated as 1.71% (95% CI: 1.1%-2.66%, p = 0.016). Based on sensitivity analysis, there was no remarkable variation in the pooled OR upon omitting individual studies. Diarrhea was a potent risk factor, since HIV/AIDS patients with diarrhea were 3.8-times (95% CI: 1.6-8.9, p = 0.002) more prone to G. duodenalis infection than those without diarrhea. Moreover, the prevalence of the parasitic infection was 1.2-times higher in patients without antiretroviral therapy (ART) than those with ART (p = 0.312). Meta-regression was employed to evaluate the possible association between G. duodenalis frequency in HIV/AIDS patients and some variables such as sample size, publication year, and HDI. Additionally, the pooled prevalence of G. duodenalis infection was estimated based on several subgroups, including publication years, WHO regions, countries, continents, country incomes, and CD4⁺ T-cell levels. Altogether, the epidemiology of giardiasis in HIV/AIDS patients and its association with various risk factors is still open to question and requires more detailed and comprehensive investigations.

Comparison of Two Real-Time PCR Assays Targeting Ribosomal Sequences for the Identification of Cystoisospora belli in Human Stool Samples

Cystoisospora (C.) belli is a coccidian parasite associated with acute or chronic gastroenteritis in immunocompromised patients. Dissatisfactory sensitivity of microscopy as the diagnostic standard approach has been described. Here, we comparatively evaluated two real-time PCRs targeting ribosomal RNA gene sequences of C. belli in stool in a test comparison without a reference standard applying latent class analysis. Therefore, 1000 stool samples from Ghanaian HIV (human immunodeficiency virus) patients (n = 905) as well as military returnees from the tropics (n = 95) were assessed by both assays in parallel. After the exclusion of 33 samples showing PCR inhibition, 29 and 33 positive results were recorded with the 5.8S rRNA gene/ITS-2 sequence PCR and the ITS-2 sequence PCR, respectively, resulting in an accuracy-adjusted prevalence of 3.2%. Nearly perfect agreement between both assays was indicated by Fleiss’ kappa of 0.933 with sensitivity and specificity of 92.8% and 100% as well as 100% and 99.8% for the 5.8S rRNA gene/ITS-2 sequence PCR and the ITS-2 sequence PCR, respectively. Both assays proved to be suitable for the diagnosis of C. belli in human stool samples with slightly better sensitivity of the ITS-2 sequence assay, while the 5.8S rRNA gene/ITS-2 sequence PCR may be considered for confirmatory testing.

A systematic review and meta-analysis reveal that Campylobacter spp. and antibiotic resistance are widespread in humans in sub-Saharan Africa

INTRODUCTION

Campylobacter spp. are zoonotic bacteria that cause gastroenteritis in humans worldwide, whose main symptom is diarrhea. In certain cases, extra intestinal manifestations may occur, such as Guillain Barré syndrome. The bacteria cause severe diarrhea mostly in children and in immunocompromised individuals. This review aims to address the prevalence of Campylobacter spp. in humans in sub-Saharan Africa. It also aims to understand the impact of HIV in the prevalence, as well as to report data on antibiotic resistance and propose research priorities.

METHODS

We followed PRISMA guidelines to find studies on the occurrence of Campylobacter spp. in humans in all countries from sub-Saharan Africa. Studies published between 2000 and 2020 were searched in PubMed, Cochrane Library, CINAHL, African Index Medicus, African Journals Online, Google Scholar and Science Direct. We have conducted a random-effect meta-analysis and calculated the proportion of resistant isolates to different antibiotics.

RESULTS AND DISCUSSION

We found 77 studies that described such occurrence in humans in 20 out of 53 sub-Saharan African countries. Campylobacter jejuni was the most prevalent species. Pooled prevalence was 9.9% (CI: 8.4%-11.6%). No major variations within the different sub-regions were found. Most studies reported Campylobacter spp. as the cause of diarrhea, mainly in children. Some studies reported the bacteria as a possible etiologic agent of acute flaccid paralysis and urinary tract infection. Campylobacter spp. presented a higher pooled prevalence in HIV infected patients, although not statistically significant. High proportions of resistant strains were reported for many antibiotics, including erythromycin and tetracycline.

CONCLUSION

Campylobacter spp. occur in sub-Saharan Africa, although information is scarce or inexistent for many countries. Research priorities should include investigation of the understudied species; extra intestinal manifestations; the impact of HIV infection and associated risk factors. Control strategies should be reinforced to contain the spread of this pathogen and drug resistance.

Worldwide prevalence of emerging parasite Blastocystis in immunocompromised patients: A systematic review and meta-analysis

BACKGROUND

Blastocystis is one of the most common pathogens of the human intestine, caused by an emerging parasite, which can lead to severe symptoms and even death in immunocompromised patients. We aimed to determine the global prevalence of Blastocystosis infection in people with immunodeficiency. A systematic literature search was conducted on Web of Science, Scopus, Google scholar, Science Direct and MEDLINE databases to select all observational studies reporting the prevalence of Blastocystosis infection in Worldwide, based on different diagnostic methods in immunocompromised patients of any age and published from inception to February 2019. Pooled estimates and 95% confidence intervals (95% CIs) were calculated using random effects models and in addition, the I² statistic was calculated. The geographic distribution of studies was evaluated and the diagnosis of Blastocystis was compared by various techniques. Electronic databases were reviewed for Blastocystosis infection in HIV/AIDS, cancer and other immunocompromised patients, and meta-analyses were conducted to calculate the overall estimated prevalence. Total68 eligible studies were included. The estimated pooled prevalence rate of Blastocystosis infection in immunocompromised patients was overall 10% (95% CI, 7-13%; I² 96.04%) (P < 0.001), of whom 21% [18-25] were in Australia, 12% [4-24] in America, 11% [6-17] in Europe and 10% [5-15], 7% [3-13] in Asia and Africa, respectively. It was calculated that the estimated pooled prevalence rate of Blastocystosis infection in immunocompromised patients was overall 10% and the prevalence estimates ranged from 0.44 to 72.39. Also, overall the prevalence of parasites co-infection in immunocompromised patients was detected as 0.024%. Our finding showed that immunocompromised people show a high prevalence of Blastocystosis infection compared to the control population. Adequate information on the prevalence rate is still missing from many countries. However, current information underscore that Blastocystis should not be neglected.

Cryptosporidiosis in HIV-positive patients and related risk factors: A systematic review and meta-analysis

Cryptosporidium is one of the major causes of diarrhea in HIV-positive patients. The aim of this study is to systematically review and meta-analyze the prevalence of Cryptosporidium in these patients. PubMed, Science Direct, Google Scholar, Web of Science, Cochrane and Ovid databases were searched for relevant studies dating from the period of 1 January 2000 to 31 December 2017. Data extraction for the included studies was performed independently by two authors. The overall pooled prevalence was calculated and subgroup analysis was performed on diagnostic methods, geographical distribution and study population. Meta-regression was performed on the year of publication, proportion of patients with diarrhea, and proportion of patients with CD4 < 200 cells/mL. One hundred and sixty-one studies and 51,123 HIV-positive participants were included. The overall pooled prevalence of Cryptosporidium infection in HIV-positive patients was 11.2% (CI95%: 9.4%–13.0%). The pooled prevalence was estimated to be 10.0% (CI95%: 8.4%–11.8%) using staining methods, 13.5% (CI95%: 8.9%–19.8%) using molecular methods, and 26.3% (CI95%: 15.0%–42.0%) using antigen detection methods. The prevalence of Cryptosporidium in HIV patients was significantly associated with the country of study. Also, there were statistical differences between the diarrhea, CD4 < 200 cells/mL, and antiretroviral therapy risk factors with Cryptosporidiosis. Thus, Cryptosporidium is a common infection in HIV-positive patients, and safe water and hand-hygiene should be implemented to prevent cryptosporidiosis occurrence in these patients.

Cystoisospora belli infections in humans: the past 100 years

Cystoisospora belli is a coccidian parasite of humans, with a direct fecal-oral transmission cycle. It is globally distributed, but mainly found in tropical and subtropical areas. Many cases of C. belli infections have been reported in patients with HIV, and in patients undergoing immunosuppressive therapy for organ transplants or those treated for tumours worldwide. Unsporulated or partially sporulated oocysts of C. belli are excreted in feces. When sporulated oocysts in contaminated water or food are ingested, asexual and sexual stages of C. belli are confined to the epithelium of intestines, bile ducts and gallbladder. Monozoic tissue cysts are present in extra-intestinal organs (lamina propria of the small and large intestine, lymph nodes, spleen, and liver) of immunosuppressed humans. However, a paratenic host has not been demonstrated. Cystoisospora belli infections can be persistent, lasting for months, and relapses are common; the mechanism of relapse is unknown. Recently, the endogenous stages of C. belli were re-examined and attention was drawn to cases of misidentification of non-protozoal structures in the gallbladder of patients as C. belli. Here, we review all aspects of the biology of C. belli, including morphology, endogenous stages, prevalence, epidemiology, symptoms, diagnosis and control.

Lower prevalence of Blastocystis sp. infections in HIV positive compared to HIV negative adults in Ghana

Background

Sub-Saharan Africa is endemic for intestinal parasites and distinguished for the largest burden of HIV cases. Blastocystis sp. is one of the most common protists infecting humans but its role in human disease is still controversial. Aim of this study was to investigate the prevalence of Blastocystis sp. in HIV positive and negative adults in Ghana and its association with immune status and other risk factors.

Methods

122 HIV positive outpatients and 70 HIV negative blood donors from the Komfo Anokye Teaching Hospital in Kumasi, Ghana, were included in the present study. Demographic, clinical and laboratory data were collected and HIV positive patients distinguished for CD4+ T cell count <200 cells/μl (n = 54) and >200 cells/μl (n = 68). A Blastocystis’s phylogenetic analysis was performed to determine sample subtype (ST).

Results

The prevalence of Blastocystis sp. in adult HIV positive individuals was lower than in HIV negative persons (6.6% vs. 20.0%, p = 0.008) and Blastocystis sp. ST1 was the most prevalent strain. Within HIV positive participants, the prevalence of Blastocystis sp. was lower in those individuals with CD4+ T cell count <200 cells/μl than in patients with higher CD4+ T cell count (1.9% vs. 10.3%, p = 0.076). Multiple regression analysis revealed that Blastocystis sp. was inversely associated with an obese Body Mass Index (BMI) in HIV negative persons (p = 0.040). Presence of Blastocystis sp. was correlated with higher CD4+ T cell count in HIV positive participants (p = 0.049).

Conclusion

It is largely reported that people living with HIV (PLHIV) in Africa are affected from parasite infections and that co-infections may adversely impact on their immune status, accelerating progress to AIDS and worsening gastrointestinal manifestations. Differently, in this study Blastocystis sp. was associated with a better immune status jointly with a healthy body weight while it seems to be reduced with the progression of HIV infection. This data agree with recent suggestions that Blastocystis sp. can represent a component of the healthy gut microbiota.

The common enteric bacterial pathogens and their antimicrobial susceptibility pattern among HIV-infected individuals attending the antiretroviral therapy clinic of Hawassa university hospital, southern Ethiopia

Background

The frequent occurrence of bacterial gastroenteritis among HIV-infected individuals together with increased antimicrobial drug resistance pose a significant public health challenge in developing countries. This study aimed to determine the prevalence of enteric bacterial pathogens and their antimicrobial susceptibility pattern among HIV-infected patients in a tertiary hospital in southern Ethiopia.

Methods

A hospital-based cross-sectional study was conducted at Hawassa University Comprehensive Specialized Hospital from February to May, 2016. A consecutive 215 HIV-infected patients, with complaints of gastrointestinal tract disease, were enrolled. Data on socio-demography and related factors was collected using a structured questionnaire. A stool sample was collected from each study participant and cultured to isolate enteric bacterial pathogens; isolates were characterized using biochemical tests. Antimicrobial susceptibility was determined using the Kirby- Bauer disk diffusion technique.

Results

Out of 215 patients, 27(12.6%) were culture positive for various bacterial pathogens. Campylobacter species was the most common bacterial isolate (6.04%), followed by Salmonella species (5.1%). The majority of isolates was sensitive to norfloxacin, nalidixic acid, gentamicin, ceftriaxone and ciprofloxacin and showed resistance to trimethoprim sulfamethoxazole (SXT) and chloramphenicol. Consumption of raw food was the only risk factor found to be significantly associated with enteric bacterial infection (crude odds ratio 3.41 95% CI 1.13–10.3).

Conclusions

The observed rate of enteric bacterial pathogens and their antimicrobial resistance pattern to the commonly prescribed antibiotics highlights the need to strengthen intervention efforts and promote rational use of antimicrobials. In this regard, the need to strengthen antimicrobial stewardship efforts should be emphasized to slow grown antimicrobial resistance among this population group.

Tropical Parasitic Infections in Individuals Infected with HIV

PURPOSE OF REVIEW

Neglected tropical diseases share both geographic and socio-behavioral epidemiological risk factors with HIV infection. In this literature review, we describe interactions between parasitic diseases and HIV infection, with a focus on the impact of parasitic infections on HIV infection risk and disease progression, and the impact of HIV infection on clinical characteristics of tropical parasitic infections. We limit our review to tropical parasitic infections of the greatest public health burden, and exclude discussion of classic HIV-associated opportunistic infections that have been well reviewed elsewhere.

RECENT FINDINGS

Tropical parasitic infections, HIV-infection, and treatment with antiretroviral therapy alter host immunity, which can impact susceptibility, transmissibility, diagnosis, and severity of both HIV and parasitic infections. These relationships have a broad range of consequences, from putatively increasing susceptibility to HIV acquisition, as in the case of schistosomiasis, to decreasing risk of protozoal infections through pharmacokinetic interactions between antiretroviral therapy and antiparasitic agents, as in the case of malaria. However, despite this intimate interplay in pathophysiology and a broad overlap in epidemiology, there is a general paucity of data on the interactions between HIV and tropical parasitic infections, particularly in the era of widespread antiretroviral therapy availability.

SUMMARY

Additional data are needed to motivate clinical recommendations for detection and management of parasitic infections in HIV-infected individuals, and to consider the implications of and potential opportunity granted by HIV treatment programs on parasitic disease control.

Determining intestinal parasitic infections (IPIs) in inmates from Kajang Prison, Selangor, Malaysia for improved prison management

BACKGROUND

The prison management in Malaysia is proactively seeking to improve the health status of the prison inmates. Intestinal parasitic infections (IPIs) are widely distributed throughout the world and are still gaining great concern due to their significant morbidity and mortality among infected humans. In Malaysia, there is a paucity of information on IPIs among prison inmates. In order to further enhance the current health strategies employed, the present study aims to establish firm data on the prevalence and diversity of IPIs among HIV-infected and non-HIV-infected individuals in a prison, an area in which informed knowledge is still very limited.

METHODS

Samples were subjected to microscopy examination and serological test (only for Strongyloides). Speciation for parasites on microscopy-positive samples and seropositive samples for Strongyloides were further determined via polymerase chain reaction. SPSS was used for statistical analysis.

RESULTS

A total of 294 stool and blood samples each were successfully collected, involving 131 HIV positive and 163 HIV negative adult male inmates whose age ranged from 21 to 69-years-old. Overall prevalence showed 26.5% was positive for various IPIs. The IPIs detected included Blastocystis sp., Strongyloides stercoralis, Entamoeba spp., Cryptosporidium spp., Giardia spp., and Trichuris trichiura. Comparatively, the rate of IPIs was slightly higher among the HIV positive inmates (27.5%) than HIV negative inmates (25.8%). Interestingly, seropositivity for S. stercoralis was more predominant in HIV negative inmates (10.4%) compared to HIV-infected inmates (6.9%), however these findings were not statistically significant. Polymerase chain reaction (PCR) confirmed the presence of Blastocystis, Strongyloides, Entamoeba histolytica and E. dispar.

CONCLUSIONS

These data will enable the health care providers and prison management staff to understand the trend and epidemiological situations in HIV/parasitic co-infections in a prison. This information will further assist in providing evidence-based guidance to improve prevention, control and management strategies of IPIs co-infections among both HIV positive and HIV negative inmates in a prison environment.

Update on the pathogenic potential and treatment options for Blastocystis sp

Although Blastocystis is one of the most common enteric parasites, there is still much controversy surrounding the pathogenicity and potential treatment options for this parasite. In this review we look at the evidence supporting Blastocystis as an intestinal pathogen as shown by numerous case studies and several in vivo studies and the evidence against. We describe the chronic nature of some infections and show the role of Blastocystis in immunocompromised patients and the relationship between irritable bowel syndrome and Blastocystis infection. There have been several studies that have suggested that pathogenicity may be subtype related. Metronidazole is the most widely accepted treatment for Blastocystis but several cases of treatment failure and resistance have been described. Other treatment options which have been suggested include paromomycin and trimethroprim- sulfamethoxazole.

Cryptosporidiosis in HIV/AIDS patients in Kenya: clinical features, epidemiology, molecular characterization and antibody responses

We investigated the epidemiological and clinical features of cryptosporidiosis, the molecular characteristics of infecting species and serum antibody responses to three Cryptosporidium-specific antigens in human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS) patients in Kenya. Cryptosporidium was the most prevalent enteric pathogen and was identified in 56 of 164 (34%) of HIV/AIDS patients, including 25 of 70 (36%) with diarrhea and 31 of 94 (33%) without diarrhea. Diarrhea in patients exclusively infected with Cryptosporidium was significantly associated with the number of children per household, contact with animals, and water treatment. Cryptosporidium hominis was the most prevalent species and the most prevalent subtype family was Ib. Patients without diarrhea had significantly higher serum IgG levels to Chgp15, Chgp40 and Cp23, and higher fecal IgA levels to Chgp15 and Chgp40 than those with diarrhea suggesting that antibody responses to these antigens may be associated with protection from diarrhea and supporting further investigation of these antigens as vaccine candidates.

Distribution of indigenous bacterial pathogens and potential pathogens associated with roof-harvested rainwater

The harvesting of rainwater is gaining acceptance among many governmental authorities in countries such as Australia, Germany, and South Africa, among others. However, conflicting reports on the microbial quality of harvested rainwater have been published. To monitor the presence of potential pathogenic bacteria during high-rainfall periods, rainwater from 29 rainwater tanks was sampled on four occasions (during June and August 2012) in a sustainable housing project in Kleinmond, South Africa. This resulted in the collection of 116 harvested rainwater samples in total throughout the sampling period. The identities of the dominant, indigenous, presumptive pathogenic isolates obtained from the rainwater samples throughout the sampling period were confirmed through universal 16S rRNA PCR, and the results revealed that Pseudomonas (19% of samples) was the dominant genus isolated, followed by Aeromonas (16%), Klebsiella (11%), and Enterobacter (9%). PCR assays employing genus-specific primers also confirmed the presence of Aeromonas spp. (16%), Klebsiella spp. (47%), Legionella spp. (73%), Pseudomonas spp. (13%), Salmonella spp. (6%), Shigella spp. (27%), and Yersinia spp. (28%) in the harvested rainwater samples. In addition, on one sampling occasion, Giardia spp. were detected in 25% of the eight tank water samples analyzed. This study highlights the diverse array of pathogenic bacteria that persist in harvested rainwater during high-rainfall periods. The consumption of untreated harvested rainwater could thus pose a potential significant health threat to consumers, especially children and immunocompromised individuals, and it is recommended that harvested rainwater be treated for safe usage as an alternative water source.

Management of protozoa-related diarrhea in HIV infection

Protozoa infections are an important cause of chronic diarrhea in patients infected with HIV. The introduction of highly active antiretroviral treatment to the management of HIV in the mid 1990s has led to a dramatic reduction in the incidence of these opportunistic infections in Europe and America. In contrast, in the developing world where such treatments are not readily affordable, protozoa-related diarrhea remains a major cause of morbidity and mortality in HIV-infected individuals. In this review, the optimum investigations required to diagnose these pathogens in HIV-related diarrhea, as well as current treatment options, will be discussed.

Community-acquired diarrhea among children and adults in urban settings in Senegal: clinical, epidemiological and microbiological aspects

Background

Only limited data are available relating to the etiology of diarrhea in children and adults in Senegal. The aim of this prospective study was to describe the epidemiology and etiology of community-acquired diarrheal infections in children and adults living in urban settings.

Methods

A prospective study was carried out from March 2009 to December 2010, in the urban region of Dakar, Senegal. Patients with acute diarrhea were enrolled, interviewed to collect their clinical history, and their stools were tested for bacteria, virus and parasites.

Results

A total of 223 patients (including 112 children younger than five years old) with diarrhea were included. At least one enteropathogen was detected in 81% (180/223) of the patients: 29% (64/223) had bacterial infections (mainly diarrheagenic E. coli and Shigella spp), 21% (39/185) viral infections (mainly rotavirus) and 14% (31/223) parasitic infections. Co-infection was identified in 17.8% (32/180) of the patients. Viral infection was significantly more frequent in children under five years old during the dry season. Bacteria and parasites were equally frequent in all age groups. There was a seasonal variation of bacterial infections during the study period, with a higher proportion of infections being bacterial, and due to Salmonella spp. in particular, during the rainy season.

Conclusion

Our study suggests that in urban settings in Senegal, rotavirus is the principal cause of pediatric diarrhea during the dry season and that the proportion of bacterial infections seems to be higher during the rainy season. Further work is needed to document the burden of diarrheal diseases in sub-Saharan urban communities and to identify risk factors, including those linked to the rapid and unplanned urbanization in Africa.

Diagnosis and subtype analysis of Blastocystis sp. in 442 patients in a hospital setting in the Netherlands

Background

Blastocystis sp. are among the most commonly observed intestinal parasites in routine clinical parasitology. Blastocystis in humans consists of at least 9 genetic subtypes. Different subtypes of Blastocystis may be associated with differences in pathogenicity and symptomatology.

Methods

Advanced microscopy on two samples and sequence-confirmed PCR on a third sample from the same individual were used for Blastocystis diagnosis and subtype analyses on routine clinical samples in a university hospital.

Results

With a combined gold standard of sequence-confirmed PCR and positive advanced microscopy, 107 out of 442 (24.2%) patients were diagnosed with Blastocystis. infection, which is a high frequency of detection in comparison to previous reports from industrialized countries. The sensitivity of microscopy and sequence-confirmed PCR was 99.1% (106/107) and 96.3% (103/107), respectively.

Among 103 typable samples, subtype 3 was most abundant (n = 43, 42%), followed by subtypes 1 and 2 (both n = 23, 22%), subtype 4 (n = 12, 12%), and single samples with subtypes 6 (1%) and subtype 7 (1%). The prevalence of Blastocystis infection was 38% in patients from the Department of Tropical Medicine and 18% in patients from other departments.

Conclusions

A high prevalence of Blastocystis infection was found with both advanced microscopy and sequence-confirmed PCR in our patient population. Most cases were caused by subtypes ST1, ST2, ST3 and ST4. A significantly higher prevalence was found among patients with a history of recent travel to tropical countries.

A systematic review and meta-analysis of the association between Giardia lamblia and endemic pediatric diarrhea in developing countries

We performed a systematic literature review and meta-analysis examining the association between diarrhea in young children in nonindustrialized settings and Giardia lamblia infection. Eligible were case/control and longitudinal studies that defined the outcome as acute or persistent (>14 days) diarrhea, adjusted for confounders and lasting for at least 1 year. Data on G. lamblia detection (mainly in stools) from diarrhea patients and controls without diarrhea were abstracted. Random effects model meta-analysis obtained pooled odds ratios (ORs) and 95% confidence intervals (CIs). Twelve nonindustrialized-setting acute pediatric diarrhea studies met the meta-analysis inclusion criteria. Random-effects model meta-analysis of combined results (9774 acute diarrhea cases and 8766 controls) yielded a pooled OR of 0.60 (95% CI, .38-.94; P = .03), indicating that G. lamblia was not associated with acute diarrhea. However, limited data suggest that initial Giardia infections in early infancy may be positively associated with diarrhea. Meta-analysis of 5 persistent diarrhea studies showed a pooled OR of 3.18 (95% CI, 1.50-6.76; P < .001), positively linking Giardia with that syndrome. The well-powered Global Enteric Multicenter Study (GEMS) is prospectively addressing the association between G. lamblia infection and diarrhea in children in developing countries.

Enteroaggregative Escherichia coli pathotype: a genetically heterogeneous emerging foodborne enteropathogen

Until now, a common feature that defines the enteroaggregative Escherichia coli (EAEC) strains is the ability to produce a 'stacked-brick' appearance on epithelial cells, but it does not distinguish between pathogenic and nonpathogenic strains. Numerous adhesins, toxins, and proteins associated with virulence have been described, as well as multiple factors contributing to EAEC-induced inflammation. None of these factors are found in all EAEC isolates, and no single factor has ever been implicated in EAEC virulence. The European outbreak of Shiga-toxin-producing EAEC raises its pathogenic potential and interest on finding the true pathogenic factors that may define this pathotype. EAEC were first associated with persistent diarrhea in infants from developing countries, since then they have increasingly been linked as a cause of acute and persistent diarrhea in young infants and children in developing and industrialized countries, individuals infected with human immunodeficiency virus, as a cause of acute diarrhea in travelers from industrialized regions, and with foodborne outbreaks. A major effect of EAEC infection is on the malnourished children in developing countries. Here, we will discuss the EAEC public health relevance and their complexity because of the strain heterogeneity regarding their pathogenesis, identification, diagnosis, lineage, epidemiology, and clinical manifestations.

Prevalence of Cryptosporidium species among HIV positive asymptomatic and symptomatic immigrant population in Kashmir, India

BACKGROUND AND OBJECTIVES

Cryptosporidiosis has not been reported as an endemic disease in Kashmir, but high prevalence of Cryptosporidium sp. has been found among asymptomatic (non-diarrheic) HIV positive immigrants in present study. Due to increasing number of HIV positive immigrants in Kashmir, Cryptosporidium may become a public health problem in Kashmir.

MATERIALS AND METHODS

A total of 45 stool samples were obtained from symptomatic (diarrheic n = 9) and asymptomatic (non-diarrheic n = 36) patients infected with HIV. The stool samples were concentrated using formalin ethyl acetate concentration technique, stained with modified Kinyoun's cold stain and oocysts were identified by microscopy under 1000 x magnification. It was confirmed by detection of antigens in stool samples by ELISA.

RESULTS

It was established that all the patients studied were carriers of Cryptosporidium. In present study though 80% of patients were asymptomatic (non-diarrheic) and HIV positive which involved non-Kashmiri army personals and travelers (immigrants) but were carriers of Cryptosporidium and 20% of HIV positive patients were emigrants (local Kashmiri traders) who travelled different states of India were having diarrhea (symptomatic) as well as carrier of Cryptosporidium.

CONCLUSION

Though Cryptosporidium infection causes chronic diarrhea but in present study all HIV positive patients screened whether diarrheic or non-diarrheic were positive for Cryptosporidium. To prevent the transmission of Cryptosporidium oocyst in environment and endemic spread of cryptosporidiosis as non-diarrheic HIV positive population may be potential source of infection, obligatory laboratory testing for Cryptosporidium in HIV positive immigrant population like traders and travelers is highly recommended in order to have a better understanding of the cause of spread Cryptosporidium infection in Kashmir.

Co-infection of HIV and intestinal parasites in rural area of China

BACKGROUND

Intestinal parasite infections (IPIs) are among the most significant causes of illness and disease of socially and economically disadvantaged populations in developing countries, including rural areas of the People's Republic of China. With the spread of the human immunodeficiency virus (HIV) among rural Chinese populations, there is ample scope for co-infections and there have been increasing fears about their effects. However, hardly any relevant epidemiological studies have been carried out in the country. The aim of the present survey was to assess the IPI infection status among a representative sample of HIV-positive Chinese in rural Anhui province, and compare the findings with those from a cohort of non-infected individuals.

METHODS

A case control study was carried out in a rural village of Fuyang, Anhui province, China. Stool samples of all participants were examined for the presence of intestinal parasites. Blood examination was performed for the HIV infection detection and anemia test. A questionnaire was administered to all study participants.

RESULTS

A total of 302 HIV positive and 303 HIV negative individuals provided one stool sample for examination. The overall IPI prevalence of intestinal helminth infections among HIV positives was 4.3% (13/302) while it was 5.6% (17/303) among HIV negatives, a non-significant difference. The prevalence of protozoa infections among HIV positives was 23.2% while the rate was 25.8% among HIV negatives. The species-specific prevalences among HIV positives were as follows: 3.6% for hookworm, 0.7% for Trichuris trichiura, zero for Ascaris lumbricoides, 0.3% for Clonorchis sinensis, 1.3% for Giardia intestinalis, 16.2% for Blastocystis hominis, 1.7% for Entamoeba spp. and 8.3% for Cryptosporidium spp.. Cryptosporidium spp. infections were significantly more prevalent among HIV positives (8.3%) compared to the HIV negative group (3.0%; P < 0.05). Among people infected with HIV, Cryptosporidium spp. was significantly more prevalent among males (12.6%) than females (4.4%; P < 0.05). According to multivariate logistic regression, the factors significantly associated with parasite infections of the people who were HIV positive included sex (male: OR = 6.70, 95% CI: 2.030, 22.114), younger age (less than 42 years old: OR = 4.148, 95% CI: 1.348, 12.761), and poor personal hygiene habits (OR = 0.324, 95% CI: 0.105, 0.994).

CONCLUSIONS

HIV positive individuals are more susceptible to co-infections with Cryptosporidium spp. than HIV negative people, particularly younger males with poor personal hygiene habits, indicating a need for targeted hygiene promotion, IPI surveillance and treatment.

Native X-DING-CD4 protein secreted by HIV-1 resistant CD4+ T cells blocks activity of IL-8 promoter in human endothelial cells infected with enteric bacteria

Onsets of bacterial infections devastate the compromised immune system in AIDS patients. Damaged gut mucosa permits dissemination of bacterial toxins into deeper layers and hyper-activation of the immune system. We previously reported that the unfractionated supernatants of HIV-resistant CD4(+) T cells impeded the NF-κB/DNA binding in macrophages induced by either HIV-1 or LPS. The active component of this soluble material was identified as X-DING-CD4 (extracellular DING from CD4 T cells). We hypothesized that the anti-inflammatory effect of the X-DING-CD4 protein might extend to non-immune cells, for example endothelial cells, undergoing persistent endotoxin stimulation in the course of advanced HIV disease. To test this proposition, we evaluated the efficiency of NF-κB and Ap-1 binding to the IL-8 promoter in LPS-activated endothelial cells and control human macrophages exposed to native X-DING-CD4 protein. We found a deficiency of NF-κB- but not AP-1-DNA binding in the systems where cells were treated with native soluble X-DING-CD4 protein. The X-DING-CD4-mediated inhibition of the IL-8 promoter also resulted in a reduction of the soluble IL-8 protein in endothelial cells and human macrophages infected with a subset of enteric bacteria frequently causing diarrhea in progressive HIV disease. Bacterial endotoxin did not induce the endogenous X-DING-CD4 mRNA activity in human macrophages and transformed CD4(+)T cells, indicating that the reduction of LPS-mediated IL-8 promoter activation was not related to de novo X-DING-CD4 protein synthesis, but depended on function of the exogenous X-DING-CD4 protein. This study provides evidence that the X-DING-CD4 protein might be developed as a novel biotherapeutic to control LPS-mediated inflammation in advanced HIV disease.

Etiology of diarrhea in older children, adolescents and adults: a systematic review

Background

Diarrhea is an important cause of morbidity and mortality in all regions of the world and among all ages, yet little is known about the fraction of diarrhea episodes and deaths due to each pathogen.

Methodology/Principal Findings

We conducted a systematic literature review to identify all papers reporting the proportion of diarrhea episodes with positive laboratory tests for at least one pathogen in inpatient, outpatient and community settings that met our inclusion and exclusion criteria. We identified a total of 25,701 papers with possible etiology data and after final screening included 22 papers that met all inclusion and exclusion criteria. Enterotoxigenic Escherichia coli and V. cholerae O1/O139 were the leading causes of hospitalizations. In outpatient settings, Salmonella spp., Shigella spp., and E. histolytica were the most frequently isolated pathogens.

Conclusions/Significance

This is the first systematic review which has considered the relative importance of multiple diarrhea pathogens. The few studies identified suggest that there is a great need for additional prospective studies around the world in these age groups to better understand the burden of disease and the variation by region.

Diarrhea is an important cause of illness and death around the world and among people of all ages, but unfortunately we often do not know what specific bacterium or virus causes the illness. We conducted a review of the scientific literature with the goal of finding published studies that identified bacteria and viruses among patients with diarrhea in the community and in hospital settings. We initially found nearly 26,000 papers on this topic but narrowed the list to 22 studies that met all of our specific criteria for inclusion in our review. Among patients hospitalized for diarrhea, E coli and Vibrio cholerae were found in more than 49% of people living in middle income and poor countries. Among patients who sought care from their doctor on an outpatient basis, Salmonella spp., Shigella spp., and E. histolytica were most often found. In our review we focused on the differences in the distribution of pathogens between patients in inpatient vs. outpatient settings because these estimates may best approximate what we would expect to see if the distribution were applied to global estimates of diarrhea deaths vs. uncomplicated illnesses.

Prevalence and correlates of helminth co-infection in Kenyan HIV-1 infected adults

Background

Deworming HIV-1 infected individuals may delay HIV-1 disease progression. It is important to determine the prevalence and correlates of HIV-1/helminth co-infection in helminth-endemic areas.

Methods

HIV-1 infected individuals (CD4>250 cells/ul) were screened for helminth infection at ten sites in Kenya. Prevalence and correlates of helminth infection were determined. A subset of individuals with soil-transmitted helminth infection was re-evaluated 12 weeks following albendazole therapy.

Results

Of 1,541 HIV-1 seropositive individuals screened, 298 (19.3%) had detectable helminth infections. Among individuals with helminth infection, hookworm species were the most prevalent (56.3%), followed by Ascaris lumbricoides (17.1%), Trichuris trichiura (8.7%), Schistosoma mansoni (7.1%), and Stongyloides stercoralis (1.3%). Infection with multiple species occurred in 9.4% of infections. After CD4 count was controlled for, rural residence (RR 1.40, 95% CI: 1.08–1.81), having no education (RR 1.57, 95% CI: 1.07–2.30), and higher CD4 count (RR 1.36, 95% CI: 1.07–1.73) remained independently associated with risk of helminth infection. Twelve weeks following treatment with albendazole, 32% of helminth-infected individuals had detectable helminths on examination. Residence, education, and CD4 count were not associated with persistent helminth infection.

Conclusions

Among HIV-1 seropositive adults with CD4 counts above 250 cells/mm³ in Kenya, traditional risk factors for helminth infection, including rural residence and lack of education, were associated with co-infection, while lower CD4 counts were not.

Trial Registration

ClinicalTrials.gov NCT00130910

Over one-third of people worldwide are currently infected with parasitic worms. The majority of these infections occur in sub-Saharan Africa, where over half of the population may be infected with at least one type of parasitic worm. HIV infection is also common in many of these countries, and there is significant geographic overlap in the presence of HIV and worm infection. Several studies have suggested that treatment of worm infections in people with HIV may delay the progression of HIV disease. Treatment has been shown to both decrease levels of the HIV virus in the blood of people with HIV and to increase the number of immune cells (CD4 cells) targeted by HIV. It is important to determine which populations of HIV-infected individuals are at greatest risk of worm infection in order to develop potential interventions for the treatment and prevention of worm infection in HIV-infected individuals. We report findings from a large study examining the prevalence and associated co-factors for worm infection among individuals at ten sites in Kenya.

Clinical significance of enteric protozoa in the immunosuppressed human population

Globally, the number of immunosuppressed people increases each year, with the human immunodeficiency virus (HIV) pandemic continuing to spread unabated in many parts of the world. Immunosuppression may also occur in malnourished persons, patients undergoing chemotherapy for malignancy, and those receiving immunosuppressive therapy. Components of the immune system can be functionally or genetically abnormal as a result of acquired (e.g., caused by HIV infection, lymphoma, or high-dose steroids or other immunosuppressive medications) or congenital illnesses, with more than 120 congenital immunodeficiencies described to date that either affect humoral immunity or compromise T-cell function. All individuals affected by immunosuppression are at risk of infection by opportunistic parasites (such as the microsporidia) as well as those more commonly associated with gastrointestinal disease (such as Giardia). The outcome of infection by enteric protozoan parasites is dependent on absolute CD4(+) cell counts, with lower counts being associated with more severe disease, more atypical disease, and a greater risk of disseminated disease. This review summarizes our current state of knowledge on the significance of enteric parasitic protozoa as a cause of disease in immunosuppressed persons and also provides guidance on recent advances in diagnosis and therapy for the control of these important parasites.

Spatial distribution of diarrhoea and microbial quality of domestic water during an outbreak of diarrhoea in the Tshikuwi community in Venda, South Africa

Total microbial quality assessment and geographical information system were used for evaluating the quality of water and the spatial distribution of diarrhoea cases in Tshikuwi, a rural community in South Africa, during an outbreak of diarrhoea. The water-abstraction points included two groundwater storage tanks, namely Tank 1 and Tank 2 and the Khandanama river. Indicator microbial counts for total coliforms, faecal coliforms, enterococci, and heterotrophic bacteria exceeded the limit for no risk as stipulated by the South African water-quality guidelines for domestic use for Tank 1 and the Khandanama river. Vibrio, Salmonella, and Shigella species were prevalent in the Khandanama river. The spatial distribution of diarrhoea cases showed a hot-spot of diarrhoea cases close to Tank 1 and the Khandanama river. Results of chi-square analysis showed that the proportion of infection from each water source was different or that infection depends on the type of water source (alpha = 0.05). The demonstrated spatial clustering of diarrhoea cases might have been influenced by the poor microbial quality of water used from Tank 1 and the Khandanama river. The results further highlight the urgent need of water-treatment facilities and monitoring of water quality in rural communities of South Africa.

Massive lower gastrointestinal bleeding attributable to heavy whipworm infection and Salmonella typhi co-infection: a case report

Massive lower gastrointestinal bleeding due to trichuriasis and/or typhoid fever is rarely reported. We reported a case of a 29-year-old male presented with per rectal bleeding, diarrhea, generalized abdominal pain and fever for two weeks. After diagnosis suspicion, emergency exploratory laparotomy was performed, where resection of the ulcerated part of the caecum and terminal ileum was performed. Microscopically analysis, diagnosed heavy infestation with Trichuris trichiura. It was complicated with Salmonella typhi infection confirmed later from the blood culture result.

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.

[Immigration and HIV Infection. An approximation to parasitic and viral infections]

Highly-active antiretroviral therapy is effective in reducing opportunistic infections in industrialized countries. However, opportunistic parasitic infections remain the leading cause of HIV-related mortality in developing countries. These infections can also affect HIV-positive immigrants residing in Spain, as well as HIV-infected patients traveling to low-income countries. In addition, immigrants often have viral infections caused by herpesvirus, papillomavirus and polyomavirus, which are closely related to risk behaviors and commercial sex. The present article reviews the characteristics of parasitic and viral infections in patients with HIV infection with the aim of improving understanding of this vulnerable population group.

Antimotility agents for chronic diarrhoea in people with HIV/AIDS

BACKGROUND

AIDS-related diarrhoea is a common cause of morbidity and mortality in HIV positive individuals, especially in the sub-Saharan Africa where 70% of deaths from HIV occur. It often compromises quality of life both in those receiving antiretroviral therapy (ART) and the ART naive. Empirical antidiarrhoeal treatment may be required in about 50% of cases which are non-pathogenic or idiopathic and in cases resulting from antiretroviral therapy. Antimotility agents (Loperamide, Diphenoxylate, Codeine) and adsorbents (Bismuth Subsalicylate, Kaolin/Pectin, Attapulgite) are readily available, and have been found to be useful in this condition and so, are often used. Antimotilitics are opioids, decreasing stool output by reducing bowel activity thereby increasing fecal transit time in the gut, promoting fluid and electrolyte retention while adsorbents act by binding to fluids, toxins and other substances to improve stool consistency and eliminate the toxins. Due to its potential impact on the management of chronic diarrhoea in persons with HIV/AIDS, we reviewed the effectiveness of antimotility agents in controlling chronic diarrhoea in immunocompromised states caused by HIV/AIDS.

OBJECTIVES

To assess the effectiveness of antimotility agents in controlling chronic diarrhoea in people with HIV/AIDS.

SEARCH STRATEGY

We searched Medline, EMBASE, the Cochrane Controlled Trials Register, the Cochrane HIV/AIDS Register and AIDSearch databases in November 2006. We also contacted WHO, CDC, pharmaceutical companies and experts in the field for information on previous or on-going trials and checked reference list from retrieved studies, irrespective of language and publication status.

SELECTION CRITERIA

Randomised controlled trials comparing an antimotility agent or an adsorbent with another antimotility agent, placebo, an adsorbent or no treatment in children and adults diagnosed with HIV and presenting with diarrhoea of three or more weeks duration.

DATA COLLECTION AND ANALYSIS

Two authors independently undertook study selection and examined full articles of potentially eligible studies.

MAIN RESULTS

One trial was found assessing the use of an adsorbent (attapulgite) compared to a placebo for chronic diarrhoea in people with HIV/AIDS. It included 91 adults (Aged 18 to 60), diagnosed with AIDS and experiencing diarrhoea for at least 7 days. There was no evidence that attapulgite is superior to placebo in controlling diarrhoea by reducing stool frequency and normalising stool consistency on days 1 (0.34 (95% CI 0.01 - 8.15)), 3 (1.35 (95% CI 0.51 - 3.62)) and 5 (1.74 (95% CI 0.89 - 3.38)). This was a small trial and may not have had enough power to show evidence of effects. Five deaths were reported which was not classified according to the arms of the study.Studies assessing the use of antimotility agents were not found.

AUTHORS' CONCLUSIONS

This review highlights the absence of evidence for the use of antimotility agents and adsorbents in controlling diarrhoea in people with HIV/AIDS. While no trials assessing the use of Antimotilitics were found, the retrieved study showed that attapulgite was not better than placebo in controlling diarrhoea in HIV/AIDS patients . For optimum patient care, these agents can still be used, with greater emphasis placed on adjunct therapies like massive fluid replacement while evidence for practice is awaited from further studies and reviews.

New insights on classification, identification, and clinical relevance of Blastocystis spp

SUMMARY

Blastocystis is an unusual enteric protozoan parasite of humans and many animals. It has a worldwide distribution and is often the most commonly isolated organism in parasitological surveys. The parasite has been described since the early 1900s, but only in the last decade or so have there been significant advances in our understanding of Blastocystis biology. However, the pleomorphic nature of the parasite and the lack of standardization in techniques have led to confusion and, in some cases, misinterpretation of data. This has hindered laboratory diagnosis and efforts to understand its mode of reproduction, life cycle, prevalence, and pathogenesis. Accumulating epidemiological, in vivo, and in vitro data strongly suggest that Blastocystis is a pathogen. Many genotypes exist in nature, and recent observations indicate that humans are, in reality, hosts to numerous zoonotic genotypes. Such genetic diversity has led to a suggestion that previously conflicting observations on the pathogenesis of Blastocystis are due to pathogenic and nonpathogenic genotypes. Recent epidemiological, animal infection, and in vitro host-Blastocystis interaction studies suggest that this may indeed be the case. This review focuses on such recent advances and also provides updates on laboratory and clinical aspects of Blastocystis spp.

Growing problem of multidrug-resistant enteric pathogens in Africa

A disproportionate number of low-income persons are affected.

Control of fecal–orally transmitted pathogens is inadequate in many developing countries, in particular, in sub-Saharan Africa. Acquired resistance to antimicrobial drugs is becoming more prevalent among Vibrio cholerae, Salmonella enteritidis, diarrheagenic Escherichia coli, and other pathogens in this region. The poor, who experience most of the infections caused by these organisms, bear the brunt of extended illness and exacerbated proportion of deaths brought about by resistance. Improved antimicrobial drug stewardship is an often cited, but inadequately implemented, intervention for resistance control. Resistance containment also requires improvements in infectious disease control, access to and quality assurance of antimicrobial agents, as well as diagnostic facilities. Structural improvements along these lines will also enhance disease prevention and control as well as rational antimicrobial drug use. Additionally, more research is needed to identify low-cost, high-impact interventions for resistance control.

Bacterial, yeast, parasitic, and viral enteropathogens in HIV-infected children from São Paulo State, Southeastern Brazil

We present here the frequency of enteropathogens in an HIV-infected children group and investigate their correlation with clinical and sociodemographic characteristics by collecting 100 stool samples from 55 HIV-seropositive Brazilian children. All specimens were processed according to standard methods for bacterial and yeast detection. A commercially available enzyme-linked immunosorbent assay was used to detect protozoan, and to perform virus detection, molecular tests were applied. Consumption of raw vegetables and fruits and severe immunosuppression were significantly associated with diarrhea. Cryptosporidium parvum was the commonest enteropathogen, followed by Candida albicans, enteropathogenic Escherichia coli, and astrovirus. The number of potential pathogenic agents identified in fecal specimens in asymptomatic HIV-seropositive infants is high, which raises the need for additional investigation in this area as well as in other Brazilian regions.

Surveillance for Bacterial Diarrhea and Antimicrobial Resistance in Rural Western Kenya, 1997-2003

BACKGROUND

Diarrhea is a major cause of preventable illness in sub-Saharan Africa. Although most cases of bacterial gastroenteritis do not require antimicrobial treatment, antimicrobial use is widespread. We examined the bacterial causes of diarrhea and monitored antimicrobial susceptibilities of isolates through clinic-based surveillance in a rural Kenyan community.

METHODS

From May 1997 through April 2003, diarrheal stool samples from persons presenting to 4 sentinel health centers were cultured by standard techniques for routine bacterial enteric pathogens, for which antimicrobial susceptibilities were determined. A random subset of specimens was also evaluated for diarrheagenic Escherichia coli.

RESULTS

Among stool specimens from 3445 persons, 1092 (32%) yielded at least 1 bacterial pathogen. Shigella species was most commonly isolated (responsible for 16% of all illnesses; 54% of isolates were Shigella flexneri). Campylobacter species and diarrheagenic E. coli predominated among children aged <5 years and were progressively replaced by Shigella species with increasing age. With the exception of Campylobacter species, susceptibility to the antimicrobials used most widely in the community was low: <40% for all isolates tested and <25% for Shigella species. Most persons were treated with an antimicrobial to which their isolate was resistant. Susceptibility to specific antimicrobials was inversely proportional to the frequency with which they were prescribed.

CONCLUSIONS

The utility of available antimicrobials for treating bacterial diarrhea in rural western Kenya is substantially limited by reduced susceptibility. More judicious use of appropriate antimicrobials is warranted. Efforts to prevent illness through provision of clean water, improved hygiene, and vaccine development should be strengthened.

Diarrhea, CD4 counts and enteric infections in a hospital - based cohort of HIV-infected patients around Varanasi, India

BACKGROUND

As most of the studies in HIV patients with diarrhea were cross sectional, focusing on the etiological agents, we are reporting data on the rate of diarrhea, associations between diarrhea and CD4 counts and variation in frequency of identifying a pathogen with consistency of diarrhea and duration in a prospective hospital based study.

METHODS

Stool specimens were obtained between Jan 2001 and April 2003 from HIV infected adults with diarrhea presenting to Infectious Disease clinic, Banaras Hindu University, Varanasi. In all patients with diarrhea, specimens were examined by microscopy and cultures to identify pathogens.

RESULTS

During the study, 630 person years of observations with diarrhea were analyzed. 140 stool samples were collected representing 43% of episodes of reported diarrhea. Positivity of finding a pathogen from watery stools and formed stools were 40%&24% respectively (p < 0.01) probably due to associated inflammation is more in watery diarrhea. Patients having chronic diarrhea are 2.25 (95%CI 1.52-2.81) times at more risk of developing other opportunistic infections compared to those who don't have. However this is not true with the acute diarrhea where risk of harboring the opportunistic infections remain same.

CONCLUSION

Diarrhea was most strongly associated with low CD4 counts. Over two-thirds of diarrheal episodes were undiagnosed, suggesting that unidentified agents or primary HIV enteropathy are important causes of diarrhea in this population. There is a strong negative association between duration of diarrhea and CD4 levels.

Méningites au cours des bactériémies à Escherichia coli à la clinique des maladies infectieuses Ibrahima-Diop-Mar du Centre hospitalier national de Fann à Dakar (Sénégal)

OBJECTIVES

The aim of this study was to describe epidemiological, clinical, and bacteriological aspects of Escherichia coli bacteremia and meningitis in the Ibrahima-Diop-Mar infectious diseases clinic, Dakar Fann National Hospital Center (Senegal).

MATERIALS AND METHODS

Data was collected from the bacteriology laboratory and hospitalization files.

RESULTS

57 cases of E. coli bacteremia were reported. Among them, 10 were associated with meningitis. AIDS was diagnosed in 74% of the cases. The global lethality rate was 47% but this rate was higher in cases of associated meningitis (80 vs 37%) and in AIDS patients (50 vs 27%). Ceftriaxone, aztreonam, gentamicin, and ciprofloxacin were active on more than 95% of strains but cotrimoxazole was active on only 49% of the strains. Resistance to cotrimoxazole was higher among E. coli strains isolated from AIDS patients (62 vs 13%).

CONCLUSION

The low susceptibility to cotrimoxazole might increase the incidence of E. coli infections among patients with AIDS. It is therefore important to find an alternative to cotrimoxazole chemoprophylaxis.

The effects of extracts from anti-diarrheic Thai medicinal plants on the in vitro growth of the intestinal protozoa parasite: Blastocystis hominis

The activities of n-hexane, dichloromethane and methanol extracts from five anti-diarrheic Thai medicinal plants, Acacia catechu (Fabaceae) resin, Amaranthus spinosus (Amaranthaceae) whole plant, Brucea javanica (Simaroubaceae) seed, Piper longum (Piperaceae) fruit and Quercus infectoria (Fagaceae) nut gall were tested against the in vitro growth of fresh isolates of the intestinal protozoan parasite, Blastocystis hominis. The extracts at concentrations that ranged from 62.5 to 2000 microg/mL, were incubated with several isolates of Blastocystis hominis for 48 h. The activities were classified as killed, inhibited, moderately inhibited and not-inhibited. Dichloromethane and methanol extracts from the Brucea javanica seed and a methanol extract from Quercus infectoria nut gall showed the highest activity. At a concentration of 2000 microg/mL, the three extracts killed 82, 75 and 67% of the Blastocystis hominis samples tested and inhibited 94, 100 and 76% of them, respectively. Metronidazole, used as a reference antiprotozoan drug, at a concentration of 40 microg/mL, killed 97% of the Blastocystis hominis isolates and inhibited all samples tested at concentrations that ranged from 1.25 to 20 microg/mL.

Nitazoxanide for persistent diarrhoea in Zambian acquired immune deficiency syndrome patients: a randomized-controlled trial

BACKGROUND

Adults with acquired immune deficiency syndrome and persistent diarrhoea in Zambia have intestinal infection, predominantly protozoa.

AIM

To search for treatment which can be offered with minimal investigation, we carried out a double-blind, randomized-controlled trial of nitazoxanide (a drug with a range of activity against parasites and bacteria).

METHODS

Patients with diarrhoea of 1 month duration or longer were randomized to receive nitazoxanide (1000 mg twice daily) or placebo for 2 weeks. End-points were clinical response, parasitological clearance and mortality.

RESULTS

Two hundred and seven adults were randomized; 42 died during the study. The primary assessment of efficacy was made after 17 days. Clinical response was observed in 56 (75%) of 75 patients receiving nitazoxanide and 45 (58%) of 77 patients receiving placebo (P = 0.03). The rate of improvement was markedly higher in patients with CD4 counts under 50 cells/microL receiving nitazoxanide (P = 0.007). The benefit was largely restricted to the period when the drug was being administered. No difference was seen in parasitological clearance between the two groups. Mortality was 19% by 4 weeks of follow-up and did not differ with treatment allocation.

CONCLUSIONS

Nitazoxanide given orally for 14 days was associated with clinical improvement in Zambian acquired immune deficiency syndrome patients with diarrhoea, especially those with very low CD4 counts.

Blastocystis in humans and animals: new insights using modern methodologies

Among the waterborne protozoan parasites of medical and veterinary importance, Blastocystis is perhaps one of the less well-understood. However, in recent years, there has been a surge of interest in the organism, fueled in part by the possible association of Blastocystis infection with intestinal disorders, and its unusual taxonomic affiliations. Although there is information on the parasite's morphology, taxonomy and mode of transmission, its pathogenicity, life cycle, and function of certain organelles continue to baffle investigators. The clinical relevance of Blastocystis will be better answered once an animal model is found. Blastocystis infections have a worldwide distribution but prevalence is highest in areas with poor hygiene and deficient sanitation services and facilities. Application of modern molecular tools has advanced knowledge of the organism's genetic diversity, taxonomy and zoonotic potential.

Integron-associated antibiotic resistance in enteroaggregative and enteroinvasive Escherichia coli

Ten enteroinvasive (EIEC) and 25 enteroaggregative (EaggEC) E. coli strains isolated from Senegalese patients were analyzed for their integron content. All strains were resistant to at least two antibiotics. Four EIEC and 15 EaggEC were found to carry a class 1 integron. An identical integron carrying a single dfrA5 cassette, conferring resistance to trimethoprim, was identified in all four EIEC strains. Five EaggEC strains harbored an integron with a single cassette, dfrA7, while the remaining 10 strains carried two integrons, one with a single cassette, aadA1a conferring resistance to streptomycin and spectinomycin, and the second one bearing two cassettes, dfrA13 and oxa5, the later being a beta-lactam resistance cassette. The presence of these integrons is worrying, because trimethoprim is largely used for diarrheal disease therapy in Africa. Thus, the presence of integrons in diarrheagenic strains is of public health importance because a limited number of antibiotics are available in developing countries.

A biologically active lectin of enteroaggregative Escherichia coli

The pathogenesis of enteroaggregative Escherichia coli, a major contributor to paediatric diarrhoea, is still not clearly understood. A complex carbohydrate specific lectin was identified from the culture supernatant of an enteroaggregative E. coli strain. The lectin was purified to 660-fold by a combination of sequential saturated ammonium sulphate precipitation and gel filtration chromatography in the FPLC system. The homogeneity of the purified lectin was established by analytical isoelectrofocusing [pI 6.75]. Hemagglutination of rabbit erythrocytes by the purified lectin was best inhibited by fetuin. The N-terminal sequence of the 41.7 kDa subunit showed homology to the outermembrane porins and the 23.4 kDa subunit showed homology to a hypothetical protein of Yersinia pestis and secreted Hcp protein. This protein could induce extensive morphological changes in HEp-2 cells and significant amount of fluid accumulation in rabbit ileal loop. GM1 showed maximum binding to the lectin among all other gangliosides. This purified protein showed cross-reactivity to the binding subunit of cholera toxin in western immunoblot. The presence of this toxin in some of the clinical isolates of enteroaggregative E. coli was also observed. The structural and functional characteristics of the toxin revealed that it is a novel virulence determinant of aggregative E. coli.