Antimicrobial susceptibility trends among Escherichia coli and Shigella spp. isolated from rural Egyptian paediatric populations with diarrhoea between 1995 and 2000

Prevalence and Antimicrobial-Resistant Features of Shigella Species in East Africa from 2015-2022: A Systematic Review and Meta-Analysis

Background

Shigellosis is the most common cause of epidemic dysentery found worldwide, particularly in developing countries, where it causes infant diarrhea and mortality. The prevalence of Shigella species resistant to commonly used antimicrobial drugs has steadily increased. The purpose of this review is to describe the prevalence and antimicrobial resistance (AMR) characteristics of Shigella species in East Africa between 2015 and 2022.

Methods

Studies were identified using a computerized search of Medline/PubMed, Google Scholar, and Web of Science databases, with a detailed search strategy and cross-checking of reference lists for studies published between 2015 and 2022. Articles presenting data on prevalence and AMR, accessibility of the full-length article, and publication dates between 2015 and 2022 were the eligibility criteria for inclusion in the review. Original research reports written in English were considered. The heterogeneities of the studies were examined, and a meta-analysis was performed to estimate the pooled prevalence and AMR using a random effects model.

Results

The pooled prevalence of Shigella species in East Africa was 6.2% (95% CI -0.20-12.60), according to an analysis of 22 studies. Shigella species prevalence was 4.0% in Ethiopia, 14.6% in Kenya, 0.7% in Sudan, 5.2% in South Sudan, and 20.6% in Somalia. The association of Shigella infection significantly varied among the countries (p = 0.01). Among the antibiotics tested, most Shigella isolates were susceptible to ciprofloxacin, norfloxacin, nalidixic acid, and ceftriaxone. Despite the fact that the reports varied in study sites and time, Shigella species were resistant to tetracycline, ampicillin, amoxicillin, chloramphenicol, and co-trimoxazole.

Conclusion

The pooled estimate indicates high burden of Shigella infection in East Africa, as well as a high proportion of drug resistance pattern to tetracycline, ampicillin, chloramphenicol, and amoxicillin. Therefore, initiating and scale-up of performing drug susceptibility test for each shigellosis case need to be considered and strengthened.

Antimicrobial Susceptibility Patterns of Shigella Species among Children under Five Years of Age with Diarrhea in Selected Health Centers, Addis Ababa, Ethiopia

Background

Shigella and parasitic infections are common public health problems throughout the world. Shigellosis is an acute gastroenteritis infection and one of Ethiopia's most common causes of morbidity and mortality, especially in children under five. High resistance rates to commonly used antibiotic agents have been documented in different locations in Ethiopia.

Objective

This study aimed to characterize the antimicrobial features of the Shigella species isolated from children under five years of age with acute diarrhea in Addis Ababa, Ethiopia.

Methods

Using a cross-sectional study, freshly passed fecal specimens were collected for intestinal parasite and bacterial isolation. Fecal samples for bacterial identification were placed immediately in Cary-Blair media and transported to the Ethiopian Public Health Institution (EPHI) laboratory. Antimicrobial susceptibility testing (AMST) was conducted using the disk diffusion method. Data were described using descriptive statistical tools. The association of independent and dependent variables was evaluated with logistic regression. A P value ≤0.05 was considered statistically significant.

Results

The prevalence of intestinal parasites was 8.2% with seven different species. Among the 534 stool-cultured specimens, 47 (8.8%) were positive for Shigella species. Antimicrobial susceptibility testing (AMST) showed that 100%, 93.6%, 80.9%, 72.3%, and 57.5% were susceptible to norfloxacin, nalidixic acid, ciprofloxacin, gentamicin, and cefoxitin, respectively. However, 100% of the isolates were resistant to amoxicillin and erythromycin. More than 50% of the isolates were resistant to three and above antibiotics, while none of them were susceptible to all the antibiotics tested. All risk factors assessed did not show a statistically significant association with Shigella infection.

Conclusion

The high levels of antibiotic resistance observed among the commonly prescribed antibiotics are alarming. The emerging resistance to ciprofloxacin and nalidixic acid signals a severe public health threat in the management of shigellosis. Raising awareness about resistance and educating health professionals, policymakers, and the public can help improve the quality of patient care and rational antibiotic use.

Review and analysis of the overlapping threats of carbapenem and polymyxin resistant E. coli and Klebsiella in Africa

BACKGROUND

Carbapenem-resistant Enterobacterales are among the most serious antimicrobial resistance (AMR) threats. Emerging resistance to polymyxins raises the specter of untreatable infections. These resistant organisms have spread globally but, as indicated in WHO reports, the surveillance needed to identify and track them is insufficient, particularly in less resourced countries. This study employs comprehensive search strategies with data extraction, meta-analysis and mapping to help address gaps in the understanding of the risks of carbapenem and polymyxin resistance in the nations of Africa.

METHODS

Three comprehensive Boolean searches were constructed and utilized to query scientific and medical databases as well as grey literature sources through the end of 2019. Search results were screened to exclude irrelevant results and remaining studies were examined for relevant information regarding carbapenem and/or polymyxin(s) susceptibility and/or resistance amongst E. coli and Klebsiella isolates from humans. Such data and study characteristics were extracted and coded, and the resulting data was analyzed and geographically mapped.

RESULTS

Our analysis yielded 1341 reports documenting carbapenem resistance in 40 of 54 nations. Resistance among E. coli was estimated as high (> 5%) in 3, moderate (1-5%) in 8 and low (< 1%) in 14 nations with at least 100 representative isolates from 2010 to 2019, while present in 9 others with insufficient isolates to support estimates. Carbapenem resistance was generally higher among Klebsiella: high in 10 nations, moderate in 6, low in 6, and present in 11 with insufficient isolates for estimates. While much less information was available concerning polymyxins, we found 341 reports from 33 of 54 nations, documenting resistance in 23. Resistance among E. coli was high in 2 nations, moderate in 1 and low in 6, while present in 10 with insufficient isolates for estimates. Among Klebsiella, resistance was low in 8 nations and present in 8 with insufficient isolates for estimates. The most widespread associated genotypes were, for carbapenems, blaOXA-48, blaNDM-1 and blaOXA-181 and, for polymyxins, mcr-1, mgrB, and phoPQ/pmrAB. Overlapping carbapenem and polymyxin resistance was documented in 23 nations.

CONCLUSIONS

While numerous data gaps remain, these data show that significant carbapenem resistance is widespread in Africa and polymyxin resistance is also widely distributed, indicating the need to support robust AMR surveillance, antimicrobial stewardship and infection control in a manner that also addresses broader animal and environmental health dimensions.

Molecular Characterization and Antimicrobial Resistance of Pathogenic Escherichia coli Strains in Children from Wolaita Sodo, Southern Ethiopia

Introduction

Pathogenic Escherichia coli strains cause diarrheal infection in children due to their virulence factors. A nonanalytical observational study followed by a purposive sampling technique was conducted from October 2017 to June 2018, to determine the antimicrobial susceptibility patterns and molecularly detect pathogenic Escherichia coli strains in under-five children at Wolaita Sodo town using molecular and the Kirby-Bauer disc diffusion method.

Result

In the current investigation, out of 110 stool samples, Escherichia coli was isolated in 68 (61.8%) (95% CI: 52.1–70.9%). Out of 68 Escherichia coli isolates, 61.9% of Escherichia coli isolates were resistant, 9.4% were intermediately resistant, and 28.7% were susceptible. Among the antimicrobial agents, 91.2% of Escherichia coli isolates were highly sensitive to ciprofloxacin followed by norfloxacin (86.8%). Virulence genes were detected in 55.9% (38/68) (95% CI 52.1%–70.9%) of isolates. The following genes were detected: stx1 (6 (8.8%)), stx2 (4 (5.9%)), eaeA (5 (7.4%)), eaat (14 (20.5%)), and St (4 (5.9%)). Out of 68 Escherichia coli isolates, 43 (63.2%) isolates had shown multidrug resistance patterns. Furthermore, 11.8% of Escherichia coli isolates had shown resistance to eight different drugs. The multidrug resistance index value of Diarrheagenic Escherichia coli pathotypes was greater than or equal to 0.4, which indicates the high risk of resistance.

Conclusion

This study demonstrated important pathogenic Escherichia coli strains and multidrug resistance in isolates containing virulence genes. Wise use of antimicrobials and improving the hygienic practices amongst parents of children reduce its occurrence. Therefore, appropriate usage of antimicrobial agents should also be highly practiced in hospitals.

Prevalence of Salmonella enterica serovar Typhi infection, its associated factors and antimicrobial susceptibility patterns among febrile patients at Adare general hospital, Hawassa, southern Ethiopia

BACKGROUND

Salmonellas enterica serovar Typhi (S.typhi) causes typhoid fever and is a global health problem, especially in developing countries like Ethiopia. But there is a little information about prevalence and factors association with S.typhi and its antimicrobial susceptibility pattern in Ethiopia especially in the study area. The aim of this study was to determine the prevalence of S.typhi infection, its associated factors and antimicrobial susceptibility pattern among patient with a febrile illness at Adare General Hospital, Hawassa, Southern Ethiopia.

METHODS

Hospital based cross sectional study was conducted among 422 febrile patients from May 23, 2018 to October 20, 2018. A 5 ml venous blood was collected from each febrile patient. Culture and biochemical test were performed for each isolate. Antimicrobial susceptibility testing was performed for each isolate using modified Kirby-Bauer disk diffusion techniques.

RESULT

In this study, the prevalence of S.typhi among febrile illness patients at Adare General Hospital was 1.6% [95% confidence interval (CI): 0.5-2.9]. The age of the study subjects were ranged from 15 to 65 years (mean age 32 years). It was observed that participants who came from rural area had 8 times (AOR 8.27: 95% CI: 1.33, 51.55) more likely to had S. typhi infection when compared with urban dwellers. The microbial susceptibility testing revealed that all six of S.typhi isolates showed sensitive to Ceftriaxone and all 6 isolates showed resistant to nalidixic acid and Cefotaxime and 5(83.3%) susceptible to Chloramphenicol and Ciprofloxaciline. Multidrug resistance (resistance to three or more antibiotics) was observed among most of the isolates.

CONCLUSION

S. typhi bacteraemia is an uncommon but important cause of febrile illness in our study population. Ceftriaxone therapy is a suitable empirical antibiotic for those that are unwell and suspected of having this illness. Further surveillance is required to monitor possible hanging antibiotic resistant patterns in Ethiopia.

Pathotyping and Antibiotic Resistance Profiling of Escherichia coli Isolates from Children with Acute Diarrhea in Amatole District Municipality of Eastern Cape, South Africa

Background

Diarrhea has been reported as the leading cause of childhood mortality and morbidity globally but with disproportionate impacts in developing nations. Among bacterial etiologic agents of diarrhea, diarrheagenic Escherichia coli is the main cause of the disease among children under the age of 5 years. This study is aimed at determining the prevalence and antibiogram pattern of diarrheagenic Escherichia coli (DEC) pathotypes associated with diarrhea cases in the study area.

Methods

A total of 120 presumptive isolates of E. coli were obtained from diarrheal stool samples from male and female patients below 12 years of age using chromogenic agar. Confirmation of the isolates and screening for virulence genes were determined by polymerase chain reaction (PCR) while antimicrobial susceptibility testing was performed using the disk diffusion method. The presence of antibiotic resistance genes to chloramphenicol and tetracycline among the confirmed isolates was also profiled by PCR based on the observed phenotypic resistance pattern.

Results

Of the 120 presumptive isolates, 88.3% (106/120) were confirmed as E. coli through PCR. The molecular pathotyping of the confirmed isolates showed their distribution as 41% (43/106) of diffusely adhering E. coli (DAEC), 17% (18/106) of enterohemorrhagic E. coli (EHEC), 17% (18/106) of enteropathogenic E. coli (EPEC), and 10% (11/106) of enteroinvasive E. coli (EIEC), while enteroaggregative E. coli (EAEC) and enterotoxigenic E. coli (ETEC) were not detected, and the remaining 15% did not belong to any pathotype. Notably, high resistance of the isolates to commonly used antimicrobials was observed as follows: ampicillin (98%), chloramphenicol (94%), trimethoprim-sulfamethoxazole (96%), and tetracycline (90.6%), while a relatively low number of the confirmed isolates were resistant to ciprofloxacin (45%) and imipenem (36%). In addition, 94% of the isolates that exhibited phenotypic resistance against chloramphenicol harbored the catA1 resistance gene while 89% that showed resistance to tetracycline had tetA genes.

Conclusions

These findings showed that DEC could be considered as the leading etiologic bacterial agent responsible for diarrhea in the study community, and the observable high degree of resistance of the isolates to antimicrobial agents is of huge significance, calling for stakeholders to adopt and consolidate the existing antimicrobial stewardship scheme of the government, in order to ensure an uncompromised public health.

Antibiotic resistance and virulence patterns of pathogenic Escherichia coli strains associated with acute gastroenteritis among children in Qatar

Background

The treatment of Enterobacteriaceae family including diarrheagenic E. coli (DEC) has been increasingly complicated due to the emergence of resistant strains. Here we report on the phenotypic resistance profiles and ESBL genotype and virulence profiles of Enteroaggregative E. coli (EAEC) and Enteropathogenic E. coli (EPEC) isolated from children hospitalized with acute gastroenteritis in Qatar (AGE).

Results

E. coli were isolated and characterized from 76 diarrheagenic stool positive samples, collected from hospitalized children less than 10 years old. Isolates were tested for antibiotic susceptibility against eighteen clinically relevant antibiotics using E-test method. Conventional PCR was performed to detect genes encoding ESBL and virulence factors. Chi-square test was performed to compare the individual antibiotic resistance between EPEC and EAEC.

A significant percentage (73.7%) of isolates were resistant to at least one antibiotic. Overall, high resistance (70%) was reported to the first-line antibiotics such as ampicillin, tetracycline (46.4%), and sulfamethoxazole-trimethoprim (42.9%). Further, 39.5% of the isolates were multidrug resistant (MDR), with 22.4% being ESBL producers. On the other hand, all isolates were susceptible to carbapenem, fosfomycin, amikacin and colistin. The incidences of resistance to the 18 antibiotics between EPEC and EAEC were not significantly different by Pearson chi -square test (P > 0.05). Genetic analysis revealed that 88.23% of ESBL production was bla_CTX-M-G1 (bla_CTX-M-15, bla_CTX-M-3) - encoded. Several different combinations of virulence markers were observed, however, there was no specific trend among the isolates apart from absence of the bundle-forming pilus (bfpA) gene, which encodes the type IV fimbriae in EPEC adherence factor (EAF) plasmid (pEAF), among all EPEC (atypical). 15% of the EAEC strains were positive for a combination of astA, aap & capU, while 10% were positive for three different combinations. The aap, aatA, capU and aggR virulence genes showed the highest frequency of 65, 60, 55 and 55% respectively. Others genes, east, astA, and aai, showed frequencies of 35, 30 and 20% respectively.

Conclusions

Atypical EPEC and EAEC were the primary etiological agents of diarrhea in children among DEC pathotypes. Our results indicated high rate of antimicrobial resistance pattern of DEC strains, which necessities the development of regulatory programs and reporting systems of antimicrobial resistance in DEC and other AGE-associated bacteria to insure effective control of diarrheal diseases. Results from this study demand a further research on identifying the phenotypic and genotypic profiles of more DEC pathotypes in various clinical samples.

Diarrheagenic Escherichia coli Pathotypes From Children Younger Than 5 Years in Kano State, Nigeria

Diarrheagenic Escherichia coli (DEC) is one of the leading causes of gastrointestinal disorders worldwide and an important public health challenge. DEC infection is often underdiagnosed during routine microbiological analysis, especially in resource constrained settings; the use of molecular tests could however help to determine the distribution of DEC and its clinical significance. Here, a study to assess the prevalence of DEC in clinical samples from patients <5 years attending three hospitals in Kano state, Nigeria, was carried out. Samples from 400 patients and 50 controls were collected and screened for E. coli. Compatible colonies from 248 individuals (215 patients and 33 controls) were characterized using biochemical test, a set of real-time PCRs for detection of nine virulence factors (VF: eae, bfpA, elt, est, stx1, stx2, ehxA, aggR, and invA) associated with five DEC pathotypes (EPEC, ETEC, EHEC, EAEC, and EIEC) and antimicrobial susceptibility tests. One or more VFs typical of specific pathotypes were detected in 73.8% (183/248) of the isolates, with those associated with EAEC (36.3%), ETEC (17.3%), and EPEC (6.0%) being the most common, although proportion of specific pathotypes differed between hospitals. est was the only VF detected in a significantly higher proportion in cases compared to controls (P = 0.034). Up to 86.9% of DEC were resistant to at least one class of antibiotics, with trimethoprim-sulfamethoxazole being the least effective drug (77.6% resistance). Our results demonstrate the widespread circulation of different DEC pathotypes that were highly resistant to trimethoprim-sulfamethoxazole among children in Kano state, and highlight the need of characterizing the causative agents in cases of gastrointestinal disorders.

Characterization and immunogenicity of a Shigella flexneri 2a O-antigen bioconjugate vaccine candidate

Shigellosis remains a major cause of diarrheal disease in developing countries and causes substantial morbidity and mortality in children. Vaccination represents a promising preventive measure to fight the burden of the disease, but despite enormous efforts, an efficacious vaccine is not available to date. The use of an innovative biosynthetic Escherichia coli glycosylation system substantially simplifies the production of a multivalent conjugate vaccine to prevent shigellosis. This bioconjugation approach has been used to produce the Shigella dysenteriae type O1 conjugate that has been successfully tested in a phase I clinical study in humans. In this report, we describe a similar approach for the production of an additional serotype required for a broadly protective shigellosis vaccine candidate. The Shigella flexneri 2a O-polysaccharide is conjugated to introduced asparagine residues of the carrier protein exotoxin A (EPA) from Pseudomonas aeruginosa by co-expression with the PglB oligosaccharyltransferase. The bioconjugate was purified, characterized using physicochemical methods and subjected to preclinical evaluation in rats. The bioconjugate elicited functional antibodies as shown by a bactericidal assay for S. flexneri 2a. This study confirms the applicability of bioconjugation for the S. flexneri 2a O-antigen, which provides an intrinsic advantage over chemical conjugates due to the simplicity of a single production step and ease of characterization of the homogenous monomeric conjugate formed. In addition, it shows that bioconjugates are able to raise functional antibodies against the polysaccharide antigen.

Prevalence of Shigella species and its drug resistance pattern in Ethiopia: a systematic review and meta-analysis

BACKGROUND

Shigella species are a major cause of dysentery and may attribute for death worldwide. Currently antibiotic resistance became the critical challenges for management of infectious disease. The aim was to conduct a systematic review and meta-analysis of Shigella species and its drug resistance pattern in Ethiopia.

METHODS

A comprehensive literature search was conducted through internet searches using database of MEDLINE, PubMed, Google scholar, EMBASE, HINARI, Cochrane Library and reference lists of previous prevalence studies from January 1999 to November 2018. Results were presented in forest plot, tables and figures with 95% CI. The Cochrane Q test and I2 test statistic were used to test heterogeneity across studies. The Pooled estimate of Shigella species and its drug resistance pattern was computed by a random effects model.

RESULTS

The pooled prevalence of Shigella species in Ethiopia was 6.6% (95% CI 4.7-8.8). In the subgroup analysis, the highest prevalence was observed among patients in Health facility (8.5%, 95% CI 6.2-11.5) whereas the lowest prevalence was observed in Community based studies (1.6%, 95% CI 0.8-3.4). In addition, Shigella species were highly resistant to ampicillin, amoxicillin, erythromycin and multi-drug resistant (MDR) with the pooled resistance proportions of 83.1% (95% CI 75.7-88.6), 84.1% (95% CI 75.6-90.1), 86.5% (95% CI 70.9-94.4) and 83.2% (95% CI 77.1-87.9), respectively. On the other hand, comparably low resistance pattern was reported for ciprofloxacin 8.9% (95% CI 6.0-12.8), ceftriaxone 9.3% (95% CI 3.9-20.5), and norfloxacin 8.2% (95% CI 3.8-16.6) and gentamycin 17.3% (95% CI 11.2-25.9). Subgroup analyses indicated that study years were associated with a decreasing Shigella prevalence over time (p = 0.002).

CONCLUSION

The pooled estimate showed high burden of Shigella infection and its high proportion of drug resistance pattern to ampicillin, amoxicillin and erythromycin in Ethiopia. Therefore, initiating and scale up of performing drug susceptibility test for each shigellosis case, educate the community and health care providers on appropriate use of antibiotics need to be considered and strengthened.

Evaluation of Shigella Species Azithromycin CLSI Epidemiological Cutoff Values and Macrolide Resistance Genes

Azithromycin (AZM) has been recommended by the American Academy of Pediatrics for the treatment of shigellosis in children. In this study, 502 Shigella species isolated between 2004 and 2014 were tested for AZM epidemiological cutoff values (ECV) by disk diffusion. AZM MICs and the presence of the macrolide resistance genes [erm(A), erm(B), erm(C), ere(A), ere(B), mph(A), mph(B), mph(D), mef(A), and msr(A)] were determined for all 56 (11.1%) isolates with an AZM disk diffusion zone diameter of ≤15 mm. The distribution of AZM ECV MICs was also determined for 186 Shigella isolates with a disk zone diameter of ≥16 mm. Finally, pulsed-field gel electrophoresis (PFGE) was performed on 15 Shigella flexneri isolates with an AZM disk zone diameter of <16 mm from different years and geographic locations. Serotyping the 502 Shigella species isolates revealed that 373 (74%) were S. sonnei, 119 (24%) were S. flexneri, and 10 (2%) were S. boydii Of the 119 Shigella flexneri isolates, 48 (42%) isolates had an AZM disk diffusion zone diameter of ≤15 mm and a MIC of ≥16 µg/ml. With the exception of one isolate, all were positive for the macrolide resistance gene mph(A). S. flexneri PFGE showed four distinct patterns, with patterns I and II presenting with 92.3% genetic similarity. On the other hand, 2 (0.5%) of the 373 S. sonnei isolates had the AZM non-wild-type (NWT) ECV phenotype (those with acquired or mutational resistance), as the AZM MICs were ≥32 µg/ml and the isolates were positive for the mph(A) gene. Overall, our S. flexneri results are in concordance with the CLSI AZM ECV, but isolates with an AZM disk diffusion zone diameter between 14 and 15 mm should be carefully evaluated, as the S. flexneri AZM MIC for NWT isolates may need adjustment to 32 µg/ml. Our data on S. sonnei support that the AZM NWT ECV should be 11 mm for the disk diffusion zone diameter and ≥32 µg/ml for the MICs.

Fingerprints of resistant Escherichia coli O157:H7 from vegetables and environmental samples

BACKGROUND

Some routes of transmission of Escherichia coli O157:H7 to fresh produce include contaminated irrigation water and manure polluted soils. The aim of the present study was to determine the genetic relationships of E. coli O157:H7 isolated from some produce growing region in Nigeria using enterobacterial repetitive intergenic consensus (ERIC) DNA fingerprinting analysis. A total of 440 samples comprising leafy greens, irrigation water, manure and soil were obtained from vegetable producing regions in Kano and Plateau States, Nigeria. Genes coding for the quinolone resistance-determinant (gyrA) and plasmid (pCT) coding for multidrug resistance (MDR) were determined using polymerase chain reaction (PCR) in 16 isolates that showed MDR.

RESULTS

Cluster analysis of the ERIC-PCR profiles based on band sizes revealed six main clusters from the sixteen isolates analysed. The largest cluster (cluster 3) grouped isolates from vegetables and manure at a similarity coefficient of 0.72.

CONCLUSION

The present study provides data that support the potential transmission of resistant strains of E. coli O157:H7 from vegetables and environmental sources to humans with potential public health implications, especially in developing countries. © 2017 Society of Chemical Industry.

Diarrhoeagenic Escherichia coli in mother-child Pairs in Ile-Ife, South Western Nigeria

Background

Diarrhoeagenic Escherichia coli (DEC) pathotypes are among the most common bacterial causes of morbidity and mortality in young children. These pathogens are not sought routinely and capacity for their detection is limited in Africa. We investigated the distribution and dissemination of DEC in 126 children paired with their mothers in a Nigerian community.

Methods

A total of 861 E. coli were isolated from 126 children with diarrhoea and their mothers. Antimicrobial susceptibility of each isolate was determined by Kirby-Bauer disc diffusion technique. All the isolates were screened for DEC markers by multiplex PCR. Genetic relatedness of DEC strains was determined by flagellin typing and Insertion element 3 (IS3)-based PCR.

Results

DEC were identified from 35.7 % of individuals with the most common pathotype being shiga toxin-producing E. coli (42, 16.7 %). Identical pathotypes were found in 13 (10.3 %) of the mother-child pairs and in three of these strains from mothers and their children showed identical genetic signatures. Over 90 % of DEC isolates were resistant to ampicillin, sulphonamide, tetracycline, streptomycin or trimethoprim, but only 9 (7.2 %) were ciprofloxacin resistant

Conclusion

The data suggest that healthy mothers are asymptomatic reservoirs of multiply-resistant strains that are pathogenic in their children and there are instances in which identical strains are found in mother-child pairs.

Purification and characterization of a Shigella conjugate vaccine, produced by glycoengineering Escherichia coli

Shigellosis remains a major cause of diarrheal disease in developing countries and causes substantial morbidity and mortality in children. Glycoconjugate vaccines consisting of bacterial surface polysaccharides conjugated to carrier proteins are the most effective vaccines for controlling invasive bacterial infections. Nevertheless, the development of a multivalent conjugate vaccine to prevent Shigellosis has been hampered by the complex manufacturing process as the surface polysaccharide for each strain requires extraction, hydrolysis, chemical activation and conjugation to a carrier protein. The use of an innovative biosynthetic Escherichia coli glycosylation system substantially simplifies the production of glycoconjugates. Herein, the Shigella dysenteriae type 1 (Sd1) O-polysaccharide is expressed and its functional assembly on an E. coli glycosyl carrier lipid is demonstrated by HPLC analysis and mass spectrometry. The polysaccharide is enzymatically conjugated to specific asparagine residues of the carrier protein by co-expression of the PglB oligosaccharyltransferase and the carrier protein exotoxin A (EPA) from Pseudomonas aeruginosa. The extraction and purification of the Shigella glycoconjugate (Sd1-EPA) and its detailed characterization by the use of physicochemical methods including NMR and mass spectrometry is described. The report shows for the first time that bioconjugation provides a newly developed and improved approach to produce an Sd1 glycoconjugate that can be characterized using state-of-the-art techniques. In addition, this generic process together with the analytical methods is ideally suited for the production of additional Shigella serotypes, allowing the development of a multivalent Shigella vaccine.

The burden of different pathogens in acute diarrhoeal episodes among a cohort of Egyptian children less than five years old

Introduction

Diarrhoea continues to cause significant morbidity in Egypt.

Aim

To determine the frequency and distribution of different enteropathogens in acute diarrhoeal episodes, utilising an expanded testing regimen, and to correlate clinical signs and symptoms associated with the detected pathogens.

Material and methods

The case-control study enrolled 356 patients < 5 years old with acute diarrhoea and 356 age and sex-matched healthy controls. Both cases and controls underwent a full history and physical examination, and provided two rectal swab specimens and a stool sample. Laboratory analysis included stool culture, microscopy, and indirect methods.

Results

Rotavirus was detected in 11% of patients. Enterotoxigenic Escherichia coli (ETEC), Campylobacter, Shigella, and Salmonella were detected in 7%, 3.7%, 1.1%, and 1.4% of patients, respectively; and in 11.1%, 3.1%, 0.6%, and 0.6% of controls, respectively, with no significant statistical difference. Cryptosporidium was detected in 3.9% of cases. Mixed infection was detected in 5.9% of cases and 0.9% of controls, with a significant difference (p < 0.001). No pathogen was detected in 66.3% of cases and in 83.5% of controls. Rotavirus infection was associated with recurrent vomiting, dehydration, and hospitalisation. Bacterial diarrhoea was associated with vomiting (52%) in ETEC infections, fever (80%) in Salmonella infections, mucus (100%) and blood (50%) in stools of Shigella infections, and convulsions (15%) in Campylobacter infections.

Conclusions

Rotavirus is a prominent cause of diarrhoea among Egyptian children. Despite utilising an expanded testing regimen, more work is still needed for identification of other enteropathogens that constitute other causative agents of diarrhoea.

Characterization of Diarrheagenic Antimicrobial Resistant Escherichia coli Isolated From Pediatric Patients in Tehran, Iran

Background:

Acute infectious diarrhea is one of the most important causes of morbidity and mortality worldwide.

Objectives:

The objective of this study was to characterize antimicrobial resistant diarrheagenic Escherichia coli strains isolated from diarrheic children in Tehran, IR Iran.

Patients and Methods:

In total, 550 stool samples from diarrheic pediatric patients, aged less than 60 months, were collected and immediately transferred to the laboratory. Isolation and identification of E. coli strains was done using bacteriological methods. Antimicrobial susceptibility testing was performed using the disk diffusion technique. Multiplex PCR was used to detect aadA1, tetA, tetB, dfrA1, qnr, aac (3)-IV, sul1, blaSHV, CITM, cat1, and cmlA antibiotic resistance genes.

Results:

From the total of 550 fecal samples examined, 154 samples (28%) were positive for diarraheagenic E. coli. High rates of antibiotic resistance were seen against penicillin ﴾100%), ampicillin ﴾89.6%﴿ and tetracycline ﴾83.1%﴿. Resistance against ciprofloxacin was low ﴾28.6%﴿. The prevalence of different resistance genes in the studied strains varied from 96.10% for aadA1 gene to 40.25% for sul1 gene. The frequencies of aadA1, tetA, tetB, dfrA1, qnr, aac(3)-IV, sul1, blaSHV, CITM, cat1, and cmlA genes were 96.10%, 85.06%, 84.41%, 51.94%, 72.07%, 54.54%, 40.25%, 57.79%, 90.25%, 59.74% and 60.38%, respectively.

Conclusions:

Our results indicated that antibiotic resistance is increasing in diarraheagenic E. coli strains in Iran. It is imperative to develop strategies for prevention and control of resistant organisms. Changes in patterns of resistance against commonly used antibiotics in Iran indicate that an applied surveillance system and introduction of guidelines for appropriate antibiotic prescription are necessary.

Increased carriage of macrolide-resistant fecal E. coli following mass distribution of azithromycin for trachoma control

BACKGROUND

Mass drug treatment with azithromycin (MDA) is part of the WHO-endorsed 'SAFE' strategy for trachoma control in endemic communities. MDA has been associated with reduced trachoma prevalence and short-term reductions in other bacterial infections, but can also lead to increased circulation of macrolide-resistant bacteria.

METHODS

We prospectively monitored macrolide resistance in fecal E. coli collected from young children participating in the PRET+ Study in rural Tanzania. MDA was administered in four villages with >10% trachoma prevalence. Four nearby communities with lower trachoma prevalence served as controls. Rectal swabs were collected during cross-sectional surveys performed at baseline, 1, 3 and 6 months after MDA. Fecal E. coli isolates were screened for macrolide susceptibility using disc diffusion and minimum inhibitory concentration methods. Cross-sectional and longitudinal differences in resistance prevalence by MDA exposure were compared using t-tests and logistic regression.

RESULTS

There was no difference in the proportion of individuals carrying azithromycin-resistant E. coli at baseline (0.21 vs. 0.16, P > 0.05). Azithromycin resistance carriage prevalence remained stable over follow-up in non-MDA villages but increased sharply in MDA villages (0.61 at 1 month, 0.42 at 3 months and 0.31 at 6 months). MDA exposure was highly associated with azithromycin resistance carriage at 1 month post-MDA (OR 15.27, P < 0.001) and subsequent surveys. Younger age and recent diarrhoea were also associated with increased odds of resistance (P < 0.01).

CONCLUSIONS

MDA resulted in significantly increased prevalence of macrolide resistance in E. coli. Although MDA is effective for trachoma elimination, it has costs; it is essential to monitor antimicrobial resistance following MDA.

Changing trends in the prevalence of Shigella species: emergence of multi-drug resistant Shigella sonnei biotype g in Bangladesh

Shigellosis, caused by Shigella species, is a major public health problem in Bangladesh. To determine the prevalence and distribution of different Shigella species, we analyzed 10,827 Shigella isolates from patients between 2001 and 2011. S. flexneri was the predominant species isolated throughout the period. However, the prevalence of S. flexneri decreased from 65.7% in 2001 to 47% in 2011, whereas the prevalence of S. sonnei increased from 7.2% in 2001 to 25% in 2011. S. boydii and S. dysenteriae accounted for 17.3% and 7.7% of the isolates respectively throughout the period. Of 200 randomly selected S. sonnei isolates for extensive characterization, biotype g strains were predominant (95%) followed by biotype a (5%). Resistance to commonly used antibiotics including trimethoprim-sulfamethoxazole, nalidixic acid, ciprofloxacin, mecillinam and ampicillin was 89.5%, 86.5%, 17%, 10.5%, and 9.5%, respectively. All isolates were susceptible to ceftriaxone, cefotaxime, ceftazidime and imipenem. Ninety-eight percent of the strains had integrons belonging to class 1, 2 or both. The class 1 integron contained only dfrA5 gene, whereas among class 2 integron, 16% contained dhfrAI-sat1-aadA1-orfX gene cassettes and 84% harbored dhfrA1-sat2 gene cassettes. Plasmids of ∼5, ∼1.8 and ∼1.4 MDa in size were found in 92% of the strains, whereas only 33% of the strains carried the 120 MDa plasmid. PFGE analysis showed that strains having different integron patterns belonged to different clusters. These results show a changing trend in the prevalence of Shigella species with the emergence of multidrug resistant S. sonnei. Although S. flexneri continues to be the predominant species albeit with reduced prevalence, S. sonnei has emerged as the second most prevalent species replacing the earlier dominance by S. boydii and S. dysenteriae in Bangladesh.

Prevalence, seasonality and severity of disease caused by pathogenic Escherichia coli in children with diarrhoea in Bolivia

The prevalence of infection caused by different categories of diarrhoeagenic E. coli (DEC) strains, including enteroaggregative (EAEC), enteropathogenic (EPEC), enterotoxigenic (ETEC), enteroinvasive (EIEC) and enterohaemorrhagic (EHEC) E. coli, in children who suffered from diarrhoea (n = 3943) or did not have diarrhoea (n = 1026) were analysed in two areas in Bolivia over a period of 4 years. We also analysed the seasonality of DEC infections and severity of diarrhoea in children with DEC infection and compared antibiotic resistance in DEC strains isolated from children with and without diarrhoea. Stool samples were analysed for the presence of DEC by culturing followed by PCR. The most prevalent DEC categories in samples from the children were: EAEC (11.2 %); ETEC (6.6 %); EPEC (5.8 %); and EIEC and EHEC (<1 %). DEC strains were isolated significantly more often from diarrhoea cases (21.6 %) than from controls (17.6 %; P = 0.002). The number of children with diarrhoea associated with EAEC, EPEC and ETEC infections peaked in the Bolivian winter (April-September), although the proportion of DEC-positive stool samples was higher during the warm rainy season (October-March). High levels of antibiotic resistance were detected among the DEC strains. In particular, resistance to tetracycline and sulfamethoxazole-trimethoprim was significantly higher in strains isolated from individuals with diarrhoea than in samples from controls. The severity of disease in children infected with EAEC, EPEC and ETEC varied from mild to severe diarrhoea, although disease severity did not differ significantly between the different DEC categories. ETEC, EPEC and EAEC are commonly found in Bolivia and may cause severe disease in children.

Genetic characterization of antimicrobial resistance of Shigella flexneri 1c isolates from patients in Egypt and Pakistan

Background

Shigella flexneri serotype 1c emerged as a critical isolate from children in Egypt and Pakistan. The pattern of antimicrobial susceptibility (AMS) and resistance genes of this serotype have yet to be characterized.

Findings

Sixty nine S. flexneri 1c isolates isolates were identified from both Egypt (n-46) and Pakistan (n = 23) and tested for AMS by disk diffusion method and minimal inhibitory concentrations were also determined. Isolates were genotyped by pulsed field gel electrophoresis (PFGE) and five relevant resistance genes (bla_TEM, bla_SHV, bla_OXA, sulI and sulII) were detected by polymerase chain reaction (PCR) and confirmed by DNA sequencing. High resistance was observed in all isolates for ampicillin (AM >96%); trimethoprim-sulphamethoxazole and tetracycline (>88%). Most AM-resistant isolates from Egypt (70%) harbored bla_TEM resistance, while 52% of isolates from Pakistan expressed bla_OXA. All isolates were closely related by PFGE, irrespective of source or time of collection. The sulII gene was present in 100% of isolates from pediatric cases in Egypt, 65% of Pakistan isolates, and 53% of isolates from older Egyptian patients.

Conclusions

While different Shigella serotypes gathered in specific genotypic groups, 1c serotype isolates formed multiple clusters. Although AMS was considerably high to most commonly used drugs, genetic determinants were variable between countries over time. The data stress the need for a more careful selection of antibiotics in the treatment of shigellosis.

Prevalence and trends of aminoglycoside resistance in Shigella worldwide, 1999-2010

Shigellosis causes diarrheal disease in humans in both developed and developing countries, and multi-drug resistance in Shigella is an emerging problem. Understanding changing resistance patterns is important in determining appropriate antibiotic treatments. This meta-analysis systematically evaluated aminoglycoside resistance in Shigella. A systematic review was constructed based on MEDLINE and EMBASE databases. Random-effect models or fixed-effect models were used based on P value considering the possibility of heterogeneity between studies for meta-analysis. Data manipulation and statistical analyses were performed using software STATA 11.0. By means of meta-analysis, we found a lower resistance to three kinds of aminoglycosides in the Europe-America areas during the 12 year study period than that of the Asia-Africa areas. Kanamycin resistance was observed to be the most common drug resistance among Shigella isolates with a prevalence of 6.88% (95%CI: 6.36%-7.43%). Comparison of data from Europe-America and Asia-Africa areas revealed that Shigella flexneri resistance was greater than the resistance calculated for Shigella sonnei. Importantly, Shigella sonnei has played a significant role in aminoglycoside-resistance in recent years. Similarly, data showed that resistance to these drugs in children was higher than the corresponding data of adults. In conclusion, aminoglycoside-resistant Shigella is not an unusual phenomenon worldwide. Distribution in Shigella resistance differs sharply based on geographic areas, periods of time and subtypes. The results from the present study highlight the need for continuous surveillance of resistance and control of antibiotic usage.

Molecular analysis of typical and atypical enteropathogenic Escherichia coli (EPEC) isolated from children with diarrhoea

Diarrhoea continues to be one of the most common causes of morbidity and mortality among infants and children in developing countries. To investigate the incidence, antimicrobial resistance and genetic relationships of enteropathogenic Escherichia coli (EPEC) in children with diarrhoea, a total of 612 stool specimens were collected in Tehran, Iran, and cultured to isolate strains of EPEC. The disc diffusion method was used to determine the susceptibility of the isolates according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. The presence of eae, stx and bfp-A genes was determined by PCR. The genetic relationships between EPEC isolates were determined by pulsed-field gel electrophoresis (PFGE). Out of the 412 strains of E. coli obtained from 612 diarrhoeal stool specimens, 23 (5.6 %) were identified as EPEC, of which seven (30.4 %) were classified as typical strains of EPEC and 16 (69.6 %) were classified as atypical. Out of the 23 EPEC isolates, 69.5 % were resistant to ampicillin, 39.1 % were resistant to tetracycline and cotrimoxazole, 30.4 % were resistant to cefpodoxime, ceftazidime, ceftriaxone and aztreonam, and 26.1 % were resistant to imipenem. The isolates were classified into 21 pulsotypes by PFGE profiles. The present study shows that typical and atypical EPEC isolates displayed considerable heterogeneity in PFGE profiles and EPEC infections were only sporadic in Tehran. Overall 69 % of isolates were resistant to at least one of the antibiotics tested.

Comparative analysis of Shigella sonnei biotype g isolated from paediatric populations in Egypt, 1999-2005

Strain characteristics of 51 Shigella sonnei isolates obtained from children seeking medical care (MC) and 48 isolates recovered during a prospective diarrhoea birth cohort (BC) study were compared. Biochemical characterization and antibiotic susceptibility testing determined that all S. sonnei isolates were biotype g and multidrug-resistant. Plasmid profiling identified 15 closely related patterns and XbaI pulsed-field gel electrophoresis confirmed the high degree of genetic similarity between isolates. All S. sonnei isolates harboured ipaH and class II integrase genes and 84∙3 and 80% of the MC and BC isolates, respectively carried the sen gene. Neither the class I integrase nor the set gene was detected. Our results indicate that S. sonnei isolates associated with severe diarrhoea were indistinguishable from those associated with mild diarrhoea. Additional genetic tests with greater discrimination might offer an opportunity to determine genetic differences within the globally disseminating biotype g clone.

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.

Prevalence and antimicrobial resistance of diarrheagenic Escherichia coli and Shigella species associated with acute diarrhea in Tehran, Iran

A study was performed to determine the prevalence and antimicrobial resistance of Shigella species and diarrheagenic Escherichia coli isolates cultured from patients with acute diarrhea in Tehran, Iran. Between May 2003 and May 2005, 1120 diarrheal specimens were collected and assayed for bacterial enteropathogens by conventional and molecular methods. Etiological agents were isolated from 564 (50.3%) specimens, and included 305 (54%) E coli, 157 (27.8%) Shigella species, and 102 (18%) from other genera of bacteria. The predominant E coli was Shiga toxin-producing E coli (105 isolates [34.5%]) and the predominant Shigella serotype was Shigella sonnei (88 isolates [56.1%]). A high rate of antibiotic resistance was observed among E coli, with 40 of 53 (75.5%) Shiga toxin-producing E coli isolates resistant to amoxicillin and tetra-cycline, and eight (5.2%) E coli isolates resistant to more than six antibiotics. Most Shigella isolates were resistant to tetracycline (95%) and trimethoprim-sulfamethoxazole (91.7%), with greatest antibiotic resistance observed among S sonnei (53 of 88 [60.2%] isolates). Antibiotic resistance is widespread in diarrheagenic E coli and Shigella in children with acute diarrhea in Tehran, Iran; hence, updated strategies for appropriate use of antimicrobial agents in Iran are needed.

Genetic diversity and antibiotic resistance in Shigella dysenteriae and Shigella boydii strains isolated from children aged <5 years in Egypt

Diversity within Shigella dysenteriae (n=40) and Shigella boydii (n=30) isolates from children living in Egypt aged <5 years was investigated. Shigella-associated diarrhoea occurred mainly in summer months and in children aged <3 years, it commonly presented with vomiting and fever. Serotypes 7 (30%), 2 (28%), and 3 (23%) accounted for most of S. dysenteriae isolates; 50% of S. boydii isolates were serotype 2. S. dysenteriae and S. boydii isolates were often resistant to ampicillin, chloramphenicol and tetracycline (42%, 17%, respectively), although resistance varied among serotypes. Pulsed-field gel electrophoresis separated the isolates into distinct clusters correlating with species and serotype. Genetic differences in trimethoprim/sulfamethoxazole and β-lactam-encoding resistance genes were also evident. S. dysenteriae and S. boydii are genetically diverse pathogens in Egypt; the high level of multidrug resistance associated with both pathogens and resistance to the most available inexpensive antibiotics underlines the importance of continuing surveillance.

Discovery and phylogenetic analysis of novel members of class b enterotoxigenic Escherichia coli adhesive fimbriae

Enterotoxigenic Escherichia coli (ETEC) is recognized to be a common cause of acute watery diarrhea in children from developing countries. Colonization factors (CFAs) have been identified predominantly in ETEC isolates secreting heat-stable enterotoxin (ST) or cosecreting ST with a heat-labile toxin (LT). We hypothesized that LT-only-secreting ETEC produces unique colonization factors not previously described in ST and LTST-secreting ETEC. A set of degenerate primers based on nucleotide sequence similarities between the major structural genes of CS20 (csnA), CS18 (fotA), CS12 (cswA), and porcine antigen 987 (fasA) was developed and used to screen a collection of 266 LT-secreting ETEC isolates in which no known CFA was detected. PCR-amplified products of different molecular masses were obtained from 49 (18.4%) isolates. Nucleotide sequence analysis of the PCR amplicons followed by GenBank nucleotide BLASTn analysis revealed five novel DNA sequences; translated amino acid BLASTx analysis confirmed sequence similarity to class 1b major structural proteins encoded by csnA, fotA, and fasA. Strains expressing the novel CFAs were phylotyped and analyzed using multilocus sequence typing (MLST; Achtman scheme), and the types detected were compared to those of a collection of archived global E. coli strains. In conclusion, application of the degenerate primer sets to ETEC isolates from surveillance studies increased the total number of ETEC isolates with detectable CFAs by almost 20%. Additionally, MLST analysis suggests that for many CFAs, there may be a requirement for certain genetic backgrounds to acquire and maintain plasmids carrying genes encoding CFAs.

Diarrhoeagenic Escherichia coli are not a significant cause of diarrhoea in hospitalised children in Kuwait

Background

The importance of diarrhoeagenic Escherichia coli (DEC) infections in the Arabian Gulf including Kuwait is not known. The prevalence of DEC (enterotoxigenic [ETEC], enteropathogenic [EPEC], enteroinvasive [EIEC], enterohemorrhagic [EHEC] and enteroaggregative [EAEC]) was studied in 537 children ≤ 5 years old hospitalised with acute diarrhoea and 113 matched controls from two hospitals during 2005–07 by PCR assays using E. coli colony pools.

Results

The prevalence of DEC varied from 0.75% for EHEC to 8.4% for EPEC (mostly atypical variety) in diarrhoeal children with no significant differences compared to that in control children (P values 0.15 to 1.00). Twenty-seven EPEC isolates studied mostly belonged to non-traditional serotypes and possessed β and θ intimin subtypes. A total of 54 DEC isolates from diarrhoeal children and 4 from controls studied for antimicrobial susceptibility showed resistance for older antimicrobials, ampicillin (0 to 100%), tetracycline (33 to 100%) and trimethoprim (22.2 to 100%); 43.1% of the isolates were multidrug-resistant (resistant to 3 or more agents). Six (10.4%) DEC isolates produced extended spectrum β-lactamases and possessed genetic elements (bla_CTX-M, bla_TEM and ISEcp1) associated with them.

Conclusion

We speculate that the lack of significant association of DEC with diarrhoea in children in Kuwait compared to countries surrounding the Arabian Gulf Region may be attributable to high environmental and food hygiene due to high disposable income in Kuwait.

Risk factors for antibiotic-resistant E. coli in children in a rural area

We surveyed antimicrobial susceptibility in faecal Escherichia coli in primary schoolchildren in rural Tamil Nadu, India. Resistance profiles of E. coli samples from local water sources were also obtained. We investigated sociodemographic characteristics as risk factors for resistance and local paediatric prescription patterns. In 119 stool samples, carriage of resistance to 1 antibiotic was 63% and multiple drug resistance was 32%. Resistance outcomes were associated with school of attendance, having a sibling attend the same school, younger age, and less crowded households. Eight of nine water samples were resistant to > or =1 antibiotic. Recent history of medication use was not associated with resistance carriage. Resistance patterns may have been influenced by local paediatric prescription patterns and veterinary antibiotic use. Frequent, low-cost surveillance of commensal resistance can guide development of locally appropriate treatment guidelines. School-based hygiene programmes should be considered as means of limiting the spread of antibiotic resistance.

Emerging resistance to newer antimicrobial agents among Shigella isolated from Finnish foreign travellers

In Finland, most cases of shigellosis are related to travel abroad. Antimicrobial drug resistance of 1814 Shigella strains isolated from Finnish patients during 1990-2005 was studied using discs of 12 antimicrobial agents. Since 2000, the E-test has been performed to determine ciprofloxacin minimum inhibitory concentrations of nalidixic acid-resistant isolates. The proportion of multi-resistant strains (resistant to >or =4 antimicrobials) was highest among isolates from China and India, but is increasing significantly in other parts of Asia. Resistance to nalidixic acid has become common among the strains from the Far East, and the first isolates also resistant to ciprofloxacin were detected during 2004-2005. All the ciprofloxacin-resistant isolates belonged to the S. flexneri 2a serotype. All the nalidixic acid-resistant S. flexneri strains had reduced susceptibility to ciprofloxacin, whereas 23% of the nalidixic acid-resistant S. sonnei strains were still completely susceptible to ciprofloxacin.

Epidemiology and genetic characterization of Shigella flexneri strains isolated from three paediatric populations in Egypt (2000-2004)

Ninety-seven isolates of Shigella flexneri from children seeking medical care from three sites in Egypt were characterized. Overall, 46.4% of children (median age 17 months) were febrile or reported blood in their stools, 25.8% were dehydrated and 16.5% were admitted to hospital. Serotypes 2a (37.1%), 1b (18.6%), 1c (17.5%), and 6 (15.5%) comprised over 88.7% of the total isolates. We observed marked resistance to ampicillin (87.6%), tetracycline (84.5%) and trimethoprim-sulfamethoxazole (63.9%). Pulsed-field electrophoresis grouped the majority of isolates within a serotype together, separately from isolates of an alternative serotype. The set gene was present in all serogroup 2a isolates, however, the sen gene was detected in every isolate. Our results show S. flexneri 1c has emerged as a dominant S. flexneri serotype in Egypt. Development and application of a Shigella vaccine should consider the diversity of Shigella serotypes within a geographical region prior to administration.

Poorly Absorbed Antibiotics for the Treatment of Traveler' Diarrhea

This article describes the use of poorly absorbed antibiotics for the treatment of traveler's diarrhea. Poorly absorbed oral antibiotics can deliver high concentrations of drug to the site of enteric infection with minimal risk of systemic adverse effects, toxicity, and drug interactions. Compared with systemically absorbed oral antibiotics, poorly absorbed oral antibiotics may be less associated with the pressure that leads to the development of bacterial resistance, because they do not affect bacteria outside the gastrointestinal tract. In clinical studies, poorly absorbed oral antibiotics, including aztreonam, bicozamycin, and rifaximin, were more effective than and as well tolerated as placebo; in particular, rifaximin was as effective as oral ciprofloxacin in reducing the duration of illness in traveler's diarrhea. More research is warranted to delineate the effects of poorly absorbed antibiotics in invasive infection and to assess the potential for the development of bacterial resistance.

Drug-resistant diarrheogenic Escherichia coli, Mexico

Diarrheogenic Escherichia coli isolates from 45 (73%) of 62 hospitalized patients were resistant to common antimicrobial drugs. Sixty-two percent were multidrug resistant, and >70% were resistant to trimethoprim-sulfamethoxazole and ampicillin. Ciprofloxacin and cefotaxime were uniformly active. Effective and safe oral agents are needed to treat children with bacterial diarrhea.