Epidemiological and microbiological aspects of acute bacterial diarrhea in children from Salvador, Bahia, Brazil

Common Etiological Agents in Adult Patients with Gastroenteritis from Central Iran

Aims: This study represents the first analysis from Iran for both the frequency of the most common causes of infectious diarrhoea and their antibiotic resistance patterns in adult patients. Methods: Adult stool specimens (n = 211) were analyzed. Stool specimens were analyzed using standard microbiological, polymerase chain reaction, and reverse transcription polymerase chain reaction tests to identify bacterial, parasitic, and viral enteropathogens. Antibiotic resistance profiles were determined. Results: Enteropathogens were identified in 46.4% (98/211) of the surveyed samples. This included 33.1% (70/211) bacterial infections, including 9.9% (21/211) diarrheagenic Escherichia coli (DEC) and 8.5% (18/211) Shigella spp. We detected 7.1% (15/211) parasitic infections (mostly Giardia lamblia) and 6.1% (13/211) viral infections (mostly adenovirus). The DEC and Shigella spp. isolates included many multi-drug resistant (MDR) isolates (95.2% and 77.7%, respectively), and extended spectrum-β-lactamase (ESBL) genes were often present (57.1% and 61.1%, respectively). The most commonly identified ESBL genes in the DEC and Shigella spp. isolates were bla_TEM (100% in both species), bla_CTX-M15 (91.6% and 100%, respectively), AmpC bla_CIT (80% and 100%, respectively), and bla_DHA (80% and 100%, respectively). Conclusions: Bacterial infection was the primary cause of infectious diarrhea, affecting one-third of the adults. The frequency of DEC and Shigella spp. was higher than for other enteropathogens. The high prevalence of MDR, the elevated incidence of ESBL genes among Shigella spp. and DEC isolates, and the presence of quinolone resistance in the Salmonella spp. isolates represent a significant challenge for gastroenteritis diagnosis and treatment in this region.

Acute diarrhea with blood: diagnosis and drug treatment

OBJECTIVE

To restate the epidemiological importance of Shigella in acute diarrhea with blood, providing an overview of the treatment and stressing the need for the correct indication of antibiotic therapy.

SOURCES OF DATA

A search was carried out in the Medline and Scopus databases, in addition to the World Health Organization scientific documents and guidelines, identifying review articles and original articles considered relevant to substantiate the narrative review.

SYNTHESIS OF DATA

Different pathogens have been associated with acute diarrhea with blood; Shigella was the most frequently identified. The manifestations of shigellosis in healthy individuals are usually of moderate intensity and disappear within a few days. There may be progression to overt dysentery with blood and mucus, lower abdominal pain, and tenesmus. Conventional bacterial stool culture is the gold standard for the etiological diagnosis; however, new molecular tests have been developed to allow the physician to initiate targeted antibacterial treatment, addressing a major current concern caused by the increasing resistance of Shigella. Prevention strategies include breastfeeding, hygiene measures, health education, water treatment, and the potential use of vaccines.

CONCLUSIONS

Acute diarrhea is an important cause of mortality in children under 5 years and shigellosis is the leading cause of acute diarrhea with blood worldwide. The current concern is the increase in microbial resistance to the recommended antibiotics, which brings an additional difficulty to therapeutic management. Although no vaccine is yet available against Shigella, several candidates are undergoing clinical trials, and this may be the most cost-effective preventative measure in future.

Prevalence and antimicrobial susceptibility of Salmonella and Shigella species isolated from diarrheic children in Ambo town

Background

Diarrhea, particularly of enteric bacterial pathogen, remains a major cause of morbidity and mortality in Ethiopia. Despite the high prevalence of diarrheal disease among under-five children, antibiotic resistance of bacterial pathogens test is not part of routine childcare in the study area. This study aimed to investigate the prevalence and antimicrobial susceptibility status of Salmonella and Shigella species among diarrheic children attending public health institutions in Ambo town, west Showa, Ethiopia.

Methods

Institutional based, cross-sectional study was carried out from January to July 2014 among 239 diarrheic children below five years of age in Ambo town, Ethiopia. Information about patient demographics, signs, and symptoms was obtained from the parents/guardians of each child using a questionnaire. Stool samples from diarrheic children were collected and processed for isolation of Salmonella and Shigella using conventional microbiology procedures. Suspected Salmonella isolates were confirmed by genus-specific PCR and serotyped using a slide agglutination test. Susceptibility to 10 commonly used antimicrobials was assessed using the Kirby Bauer disc diffusion method.

Results

From the 239 children screened, only nine (3.8%) of them were positive for either Salmonella (n = 3) or Shigella (n = 6) and 19 (7.9%) positive for the intestinal parasite. Three species of Shigella were identified: Shigella flexinari (n = 3), Shigella boydii (n = 2), and Shigella sonnei (n = 1). The three Salmonella isolates were S. chicago, S. caracas, and S. saintpaul. Salmonella and Shigella isolates were resistant to ampicillin (88.9%), followed by tetracycline (66.7%), cotrimoxazole (55.6%), chloramphenicol (44.4%), amoxicillin (33.3%), nalidixic acid (11.1%) and cefotaxime (11.1%). All isolates were sensitive to amikacin, ciprofloxacin, and gentamycin.

Conclusion

In this study, either Salmonella or Shigella species were detected only in 3.8% of diarrheic children in Ambo town, suggesting the dominance of other causes of diarrhea in the study area. A further study targeting other causes of diarrhea should be conducted to establish the major causes of childhood diarrhea in the study area.

Inconsistency in Diarrhea Measurements when Assessing Intervention Impact in a Non-Blinded Cluster-Randomized Controlled Trial

To explore the consistency in impact evaluation based on reported diarrhea, we compared diarrhea data collected through two different surveys and with observed diarrhea-associated hospitalization for children aged ≤ 5 years from a non-blinded cluster-randomized trial conducted over 2 years in urban Dhaka. We have previously reported that the interventions did not reduce diarrhea-associated hospitalization for children aged ≤ 5 years in this trial. We randomly allocated 90 geographic clusters comprising > 60,000 low-income households into three groups: cholera vaccine only, vaccine plus behavior change (cholera vaccine and handwashing plus drinking water chlorination promotion), and control. We calculated reported diarrhea prevalence within the last 2 days using data collected from two different survey methods. The "census" data were collected from each household every 6 months for updating household demographic information. The "monthly survey" data were collected every month from a subset of randomly selected study households for monitoring the uptake of behavior change interventions. We used binomial regression with a logarithmic link accounting for clustering to compare diarrhea prevalence across intervention and control groups separately for both census and monthly survey data. No intervention impact was detected in the census (vaccine only versus control: 2.32% versus 2.53%; P = 0.49; vaccine plus behavior change versus control: 2.44% versus 2.53%; P = 0.78) or in the vaccine only versus control in the monthly survey (3.39% versus 3.80%; P = 0.69). However, diarrhea prevalence was lower in the vaccine-plus-behavior-change group than control in the monthly survey (2.08% versus 3.80%; P = 0.02). Although the reasons for different observed treatment effects in the census and monthly survey data in this study are unclear, these findings emphasize the importance of assessing objective outcomes along with reported outcomes from non-blinded trials.

Antibacterial activity of crude extracts of some South African medicinal plants against multidrug resistant etiological agents of diarrhoea

BACKGROUND

This study evaluated the antibacterial activity of some plants used in folklore medicine to treat diarrhoea in the Eastern Cape Province, South Africa.

METHODS

The acetone extracts of Acacia mearnsii De Wild., Aloe arborescens Mill., A. striata Haw., Cyathula uncinulata (Schrad.) Schinz, Eucomis autumnalis (Mill.) Chitt., E. comosa (Houtt.) Wehrh., Hermbstaedtia odorata (Burch. ex Moq.) T.Cooke, Hydnora africana Thunb, Hypoxis latifolia Wight, Pelargonium sidoides DC, Psidium guajava L and Schizocarphus nervosus (Burch.) van der Merwe were screened against Staphylococcus aureus, Escherichia coli, Enterococcus faecalis, multi-resistant Salmonella enterica serovar Isangi, S. typhi, S. enterica serovar Typhimurium, Shigella flexneri type 1b and Sh. sonnei phase II. A qualitative phytochemical screening of the plants extracts was by thin layer chromatography. Plants extracts were screened for antibacterial activity using serial dilution microplate technique and bioautography.

RESULTS

The TLC fingerprint indicated the presence of terpenoids and flavonoids in the herbs. Most of the tested organisms were sensitive to the crude acetone extracts with minimum inhibitory concentration (MIC) values ranging from 0.018-2.5 mg/mℓ. Extracts of A. striata, C. uncinulata, E. autumnalis and P. guajava were more active against enteropathogens. S. aureus and Sh. flexneri were the most sensitive isolates to the crude extracts but of significance is the antibacterial activity of A. arborescens and P. guajava against a confirmed extended spectrum betalactamase positive S. enterica serovar Typhimurium.

CONCLUSION

The presence of bioactive compounds and the antibacterial activity of some of the selected herbs against multidrug resistant enteric agents corroborate assertions by traditional healers on their efficacies.

Prevalence and antibiotic resistance of bacterial pathogens isolated from childhood diarrhea in Beijing, China (2010-2014)

BACKGROUND

Diarrhea is one of the main causes of morbidity and mortality among children less than 5 years of age worldwide, and its causes vary by region. This study aimed to determine the etiologic spectrum, prevalent characteristics and antimicrobial resistance patterns of common enteropathogenic bacteria from diarrheagenic children in Beijing, the capital of China.

METHODS

Stool samples were collected from 2524 outpatients who were aged 0-5 years in Beijing, China during 2010-2014. Microbiological methods, real-time PCR and antimicrobial susceptibility test were used to identify the bacterial causes and antimicrobial resistance patterns in the isolates.

RESULTS

Of the 2524 patients screened, we identified the causes of 269 cases (10.7 %) as follows: diarrheagenic Escherichia coli (4.6 %), Salmonella (4.3 %), Shigella (1.4 %) and Vibrio parahaemolyticus (0.4 %). Atypical EPEC, Salmonella enteritidis, Shigella sonnei and serotype O3:K6 were the most common serogroups or serotypes of the four etiological bacteria. The prevalence of pathogens was correlated with age, season and clinical symptoms. The highest proportion of all causative bacteria was found in children aged 3-5 years and in summer. The clinical symptoms associated with specific bacterial infection, such as fever; abdominal pain; vomiting; and watery, mucus, and bloody stool, were observed frequently in diarrheal patients. Salmonella showed moderate rates of resistance (40-60 %) to ampicillin, nalidixic acid, streptomycin and sulfisoxazole. Resistance to at least three antimicrobials was found in 50 % of isolates. Of the top three serotypes in Salmonella, high-level antimicrobial resistance to single and multiple antibiotics was more common among Salmonella typhimurium and Salmonella 1, 4, [5], 12:i:- than among S. enteritidis. More than 90 % of Shigella isolates showed more alarming resistance to most antibiotics, with a widened spectrum compared to Salmonella.

CONCLUSION

Constant antibiotic surveillance is warranted because the bacteria were highly resistant to various antimicrobials. Our study contributes to the strengthening of the existing surveillance system and provides aid for effective prevention and control strategies for childhood diarrhea.

Identifying etiological agents causing diarrhea in low income Ecuadorian communities

Continued success in decreasing diarrheal disease burden requires targeted interventions. To develop such interventions, it is crucial to understand which pathogens cause diarrhea. Using a case-control design we tested stool samples, collected in both rural and urban Ecuador, for 15 pathogenic microorganisms. Pathogens were present in 51% of case and 27% of control samples from the urban community, and 62% of case and 18% of control samples collected from the rural community. Rotavirus and Shigellae were associated with diarrhea in the urban community; co-infections were more pathogenic than single infection; Campylobacter and Entamoeba histolytica were found in large numbers in cases and controls; and non-typhi Salmonella and enteropathogenic Escherichia coli were not found in any samples. Consistent with the Global Enteric Multicenter Study, focused in south Asia and sub-Saharan Africa, we found that in Ecuador a small group of pathogens accounted for a significant amount of the diarrheal disease burden.

Clinical study of acute childhood diarrhoea caused by bacterial enteropathogens

OBJECTIVE

There are not a large number of studies in India which can enlighten us regarding acute childhood diarrhoea and far lesser in number when it comes to its bacterial enteropathogenesis. The present study is specially targeted to determine the prevalence of various bacterial enteropathogens causing acute childhood diarrhoea and to find out their respective pattern of clinical features.

METHOD

All children under 12 years of age enrolled between 1st June, 2012 and 31st July 2012, in the Outpatient department, Inpatient department of pediatrics section and casualty of hospital, who presented with acute diarrhoea. Data collected by mean of study questionnaire. Stool sample were processed for bacteriological analysis. In 280 samples bacteria were isolated with the help of microscopy, culture and biochemical reactions. The isolates obtained were tested for antimicrobial sensitivity over Mueller Hinton agar by Kirby Bauer-disk diffusion method.

RESULTS

Out of 280 children frequency of diarrhoeagenic bacteria isolated from the samples showed that Escherichia coli was recorded as the predominant bacteria with 44.2% of prevalence followed by Shigella, Salmonella, Klebsiella and Campylobacter with 28.2%, 13.6%, 7.8% and 6.1% respectively. Patients falling in the age group of 1-3 years. were the major sufferers of diarrhoea due to all etiologies except Klebsiella which mainly had impact on the patients below six months. Majority of isolated bacterial agents were resistant to Co-trimoxazole and Shigella being highly resistant enteropathogen isolated. Salmonella spp. were least resistant isolates. None of the isolates were resistant to Cefotaxime, Cefuroxime and Azetronam.

CONCLUSION

RESULTS of study reveal that Escherichia coli is a predominant bacterial enteropathogen causing diarrhoea and Salmonella is a major contributor to the diarrhoea causing severe dehydration and to the clinical features like fever, vomiting and more than 10 times of frequency of stools. Shigella is among highly resistant isolates while Salmonella isolates had least resistance to majority of antibiotics.

Shigella in Brazilian children with acute diarrhoea: prevalence, antimicrobial resistance and virulence genes

Diarrhoeal disease is still considered a major cause of morbidity and mortality among children. Among diarrhoeagenic agents, Shigella should be highlighted due to its prevalence and the severity of the associated disease. Here, we assessed Shigella prevalence, drug susceptibility and virulence factors. Faeces from 157 children with diarrhoea who sought treatment at the Children's Hospital João Paulo II, a reference children´s hospital in Belo Horizonte, state of Minas Gerais, Brazil, were cultured and drug susceptibility of the Shigella isolates was determined by the disk diffusion technique. Shigella virulence markers were identified by polymerase chain reaction. The bacterium was recovered from 10.8% of the children (88.2% Shigella sonnei). The ipaH, iuc, sen and ial genes were detected in strains isolated from all shigellosis patients; set1A was only detected in Shigella flexneri. Additionally, patients were infected by Shigella strains of different ial, sat, sen and set1A genotypes. Compared to previous studies, we observed a marked shift in the distribution of species from S. flexneri to S. sonnei and high rates of trimethoprim/sulfamethoxazole resistance.

Comparison of the prevalence and changing resistance to nalidixic acid and ciprofloxacin of Shigella between Europe-America and Asia-Africa from 1998 to 2009

Shigella is becoming an increasing public health problem due to development of multiple antimicrobial resistance, frequently resulting in treatment failure. A systematic review was conducted based on a literature search of computerised databases. Random or fixed-effects models were used, based on the P-value considering the possibility of heterogeneity between studies, for meta-analysis. Statistical analyses were performed using STATA 10.0. In the area of Asia-Africa, resistance rates to nalidixic acid and ciprofloxacin were 33.6% [95% confidence interval (CI) 21.8-46.6%] and 5.0% (95% CI 2.8-7.8%), respectively, 10.5 and 16.7 times those of Europe-America. Moreover, resistance to nalidixic acid and ciprofloxacin in Asia-Africa progressively increased each year, reaching 64.5% (95% CI 13.8-99.3%) and 29.1% (95% CI 0.9-74.8%), respectively, in 2007-2009, whilst isolates in Europe-America remained at low levels of resistance (<5.0% and <1.0%, respectively). All Shigella flexneri strains showed higher resistance than Shigella sonnei in Europe-America: overall, 3.5% (95% CI 1.4-6.4%) vs. 2.6% (95% CI 1.0-5.0%) resistant to nalidixic acid and 1.0% (95% CI 0.3-2.2%) vs. 0.1% (95% CI 0.0-0.3%) resistant to ciprofloxacin. In Asia-Africa, a similar trend was found for ciprofloxacin [3.0% (95% CI 1.4-5.3%) vs. 0.5% (95% CI 0.2-0.8%)], whereas the trend was reversed for nalidixic acid [32.6% (95% CI 14.5-53.9%) vs. 44.3% (95% CI 26.9-62.5%). In conclusion, quinolone resistance in Shigella has increased at an alarming speed, reinforcing the importance of continuous monitoring of antimicrobial resistance in Shigella.

Molecular epidemiology of Shigella spp strains isolated in two different metropolitam areas of southeast Brazil

Shigella spp., the human pathogen responsible for shigellosis, is highly infectious even at low levels. The incidence rate of shigellosis varies with geographical distribution, location human development index, and age groups, being higher among children aged under 5 years. In Brazil, a few works indicate that shigellosis cases are underestimated, with S. flexneri and S. sonnei strains being the major agents responsible for the shigellosis cases. The present study used pulsed field gel electrophoresis (PFGE) to investigate the molecular epidemiology of 119 strains of S. sonnei and S. flexneri isolated from shigellosis cases that occurred in the metropolitan areas of Ribeirão Preto and Campinas Cities, São Paulo Sate, southeast Brazil. The results indicated (i) the existence of just a few strain clusters for both species, but with genotype variability with either a high speed of genetic change or constant introduction of several genotypes, considering the intense migration to these two metropolitan areas, and (ii) the prevalence of specific genotypes in each geographical area, which suggests the successful adaptation of some genotypes to the local environmental conditions. Our results indicate the need of more efficacious sanitary barriers to prevent Shigella spp. outbreaks and epidemics.

Part II. Analysis of data gaps pertaining to Shigella infections in low and medium human development index countries, 1984-2005

The global incidence of Shigella infection has been estimated at 80-165 million episodes annually, with 99% of episodes occurring in the developing world. To identify contemporary gaps in the understanding of the global epidemiology of shigellosis, we conducted a review of the English-language scientific literature from 1984 to 2005, restricting the search to low and medium human development countries. Our review yielded 11 population-based studies of Shigella burden from seven countries. No population-based studies have been conducted in sub-Saharan Africa or in low human development countries. In studies done in all age groups, Shigella incidence varied from 0.6 to 107 episodes/1000 person-years. S. flexneri was the most commonly detected subgroup in the majority of studies. Case-fatality rates ranged from 0% to 2.6% in population-based studies and from 0% to 21% in facility-based studies. This review highlights the large gaps in data on the burden of Shigella infections for low human development index countries and, more specifically, for sub-Saharan Africa.

Dipstick for rapid diagnosis of Shigella flexneri 2a in stool

BACKGROUND

Shigellosis or bacillary dysentery, an acute bloody diarrhoea, is a major public health burden in developing countries. In the absence of prompt and appropriate treatment, the infection is often fatal, particularly in young malnourished children. Here, we describe a new diagnostic test for rapid detection, in stool, at the bedside of patients, of Shigella flexneri 2a, the most predominant agent of the endemic form of the disease.

METHODOLOGY/PRINCIPAL FINDINGS

The test is based on the detection of S.flexneri 2a lipopolysaccharide (LPS) using serotype 2a-specific monoclonal antibodies coupled to gold particles and displayed on one-step immunochromatographic dipstick. A concentration as low as 20 ng/ml of LPS is detected in distilled water and in reconstituted stools in under 15 minutes. The threshold of detection corresponds to a concentration of 5x10(7) CFU/ml of S. flexneri 2a, which provides an unequivocal positive reaction in three minutes in distilled water and reconstituted stools. The specificity is 100% when tested with a battery of Shigella and unrelated strains, in culture. When tested in Vietnam, on clinical samples, the specificity and sensitivity were 99.2 and 91.5%, respectively. A decrease of the sensitivity during the evaluation on stool samples was observed after five weeks at room temperature and was due to moistening of the dipsticks caused by the humidity of the air during the fifth week of the evaluation. This drawback is now overcome by improving the packaging and providing dipsticks individually wrapped in waterproof bags.

CONCLUSION

This simple dipstick-bases test represents a powerful tool for case management and epidemiological surveys.