Prevalence of Salmonella spp., Shigella spp., and intestinal parasites among food handlers working in University of Gondar student's cafeteria, Northwest Ethiopia.

Background: Food-borne infections continue to be a major public health problem at the international level. The issue becomes more serious in developing countries like Ethiopia. Objective: This study aimed to examine the prevalence of Salmonella and Shigella species and intestinal parasites, as well as antimicrobial resistance patterns and associated factors among food handlers at the University of Gondar cafeteria in northwest Ethiopia. Methods: An institutional-based cross-sectional study was conducted from February to June 2021 in the University of Gondar cafeterias. Data related to the socio-demographic characteristics and hygienic practices of study participants were collected using structured questionnaires. A total of 290 stool samples were collected from food handlers. Culture and conventional biochemical tests were used to isolate the Salmonella and the Shigella species. Wet mount, Formol-ether concentration, and Kato Katz techniques were applied to identify intestinal parasites. Additionally, drug susceptibility tests were performed using the disk diffusion method. Statistical analysis was done using SPSS version 26. Results: Of 290 food handlers' stool samples analyzed, Twenty-seven 27 (9.3%) were positive for both Salmonella and Shigella species. The prevalence of Salmonella and Shigella species was 16 (5.5%) and 11 (3.8%), respectively. Most of the isolated pathogens were resistant to tetracycline 19 (70.4%), and trimethoprim/sulphamethoxazole 19 (70.4%). The overall rate of multi-drug resistant Shigella and Salmonella isolate was 59.3%. Besides, Fifty-seven 57 (19.7%) of the participants were positive for one or more intestinal parasites. The most prevalent intestinal Parasitosis was E. histolytica/dispar 22 (7.6%), followed by G. lamblia 13 (4.5%), and Ascaris lumbricoides 11 (3.8) not washing hands after using the toilet (AOR: 4.42, 95% CI: 1.57, 10.56), and consuming unpasteurized milk (AOR: 3.14, 95% CI: 1.65, 3.96), were factors significantly associated with the prevalence of Salmonella, and Shigella infection. Similarly, not washing hands after using the toilet (AOR: 2.19, 95% CI: 1.0, 1.4), and consuming unpasteurized milk (AOR: 10.4, 95% CI: 3.8, 28.8), were factors significantly associated with the prevalence of intestinal parasites infection. Conclusion: The prevalence of intestinal parasites, Salmonella, and Shigella species was high. Therefore, it is imperative to implement a public health policy that includes ongoing microbiological surveillance.

Characterization of genotypes and antimicrobial resistance profiles of clinical isolates of Shigella from patients in the southern region of Iran.

BACKGROUND: Shigella spp., which are facultative anaerobic bacilli within the Enterobacteriaceae family, present a significant public health burden due to their role as prominent contributors to diarrheal diseases worldwide. A molecular analysis can facilitate the identification and assessment of outbreaks involving this bacterium. So, we aimed to investigate the antibiotic susceptibility pattern and clonal relatedness of clinical Shigella spp. isolates obtained from patients with diarrhea in Hormozgan province, South of Iran. METHODS: From 2019 to 2021, a cross-sectional investigation was conducted on 448 stool samples obtained from patients who were experiencing diarrhea, in the southern region of Iran. Shigella spp. isolates were identified based on biochemical and serological tests. All Shigella species were verified using species-specific polymerase chain reaction (PCR), followed by susceptibility testing to antimicrobial agents. Subsequently, genotyping of all Shigella species was conducted using ERIC-PCR. RESULTS: Out of a total of 448 stool samples, the presence of Shigella was detected in 62 cases, accounting for a prevalence rate of 13.84%. Among the identified isolates, the majority were attributed to S. flexneri, representing 53.23% of the cases. This was followed by S. sonnei at 24.19% and S. boydii at 22.58%. Notably, no instances of S. dysenteriae were found. The highest prevalence of Shigella isolates was observed in infants and children under the age of five. A significant proportion of the identified isolates demonstrated resistance to various antibiotics. Specifically, high resistance rates were noted for ampicillin (90.78%), piperacillin-tazobactam (87.1%), cefixime (83.87%), trimethoprim-sulfamethoxazole (83.87%), cefotaxime (82.26%), and ceftriaxone (80.65%). In addition, a substantial number (87.1%) of the isolates exhibited a multidrug-resistant (MDR) phenotype. Using the ERIC-PCR method, a total of 11 clusters and 6 distinct single types were identified among all the Shigella isolates. CONCLUSION: A notable occurrence of antibiotic-resistant Shigella species has been noted, with multi-drug resistant (MDR) strains presenting an increasing challenge for treating shigellosis worldwide, and this includes Iran. Techniques such as ERIC-PCR are useful for assessing the genetic variation and connections between Shigella strains, which indirectly contributes to understanding antimicrobial resistance patterns. Further research is needed to explore the specific correlation between resistance genes and ERIC genotyping patterns in Shigella strains.

Molecular Mechanisms of Shigella Pathogenesis; Recent Advances.

Shigella species are the main cause of bacillary diarrhoea or shigellosis in humans. These organisms are the inhabitants of the human intestinal tract; however, they are one of the main concerns in public health in both developed and developing countries. In this study, we reviewed and summarised the previous studies and recent advances in molecular mechanisms of pathogenesis of Shigella Dysenteriae and non-Dysenteriae species. Regarding the molecular mechanisms of pathogenesis and the presence of virulence factor encoding genes in Shigella strains, species of this bacteria are categorised into Dysenteriae and non-Dysenteriae clinical groups. Shigella species uses attachment, invasion, intracellular motility, toxin secretion and host cell interruption mechanisms, causing mild diarrhoea, haemorrhagic colitis and haemolytic uremic syndrome diseases in humans through the expression of effector delivery systems, protein effectors, toxins, host cell immune system evasion and iron uptake genes. The investigation of these genes and molecular mechanisms can help us to develop and design new methods to detect and differentiate these organisms in food and clinical samples and determine appropriate strategies to prevent and treat the intestinal and extraintestinal infections caused by these enteric pathogens.

The increasing antimicrobial resistance of Shigella species among Iranian pediatrics: a systematic review and meta-analysis.

BACKGROUND: Shigellosis remains one of the global causes of morbidity and mortality. However, the global emergence of antibiotic resistance has become the leading cause of treatment failure in shigellosis. This review aimed to provide an updated picture of the antimicrobial resistance rates in Shigella species in Iranian pediatrics. METHODS: A comprehensive systematic search was performed on PubMed, Scopus, Embase, and Web of Science until 28 July 2021. The meta-analysis was performed by computing the pooled using a random-effects model with Stata/SE software, v.17.1. The discrepancy within articles was surveyed by the forest plot in addition to the I2 statistic. All statistical interpretations were reported on a 95% confidence interval (CI) basis. RESULTS: Totally, of 28 eligible studies published between 2008 and 2021. The pooled prevalence rate of multidrug-resistant (MDR) was 63% (95% CI 50-76). Regarding suggested antimicrobial agents for Shigella species, the prevalence of resistance for ciprofloxacin, azithromycin, and ceftriaxone as first- and second-line treatments for shigellosis were 3%, 30%, and 28%, respectively. In contrast, resistance to cefotaxime, cefixime, and ceftazidime was 39%, 35%, and 20%. Importantly, subgroup analyses indicated that an increase in resistance rates during the periods (2008-2014, 2015-2021) was recognized for ciprofloxacin (0 % to 6%) and ceftriaxone (6% to 42%). CONCLUSION: Our findings revealed that ciprofloxacin is an effective drug for shigellosis in Iranian children. The substantially high prevalence estimation proposes that the first- and second-line treatments for shigellosis are the major threat to public health and active antibiotic treatment policies are essential.

Shigella iron-binding proteins: An insight into molecular physiology, pathogenesis, and potential target vaccine development.

Shigella is a well-known etiological agent responsible for intestinal infection among children, the elderly, and immunocompromised people ranging from mild to severe cases. Shigellosis remains endemic in Malaysia and yet there is no commercial vaccine available to eradicate the disease. Iron is an essential element for the survival of Shigella within the host. Hence, it is required for regulating metabolic mechanisms and virulence determinants. Alteration of iron status in the extracellular environment directly triggers the signal in enteropathogenic bacterial, providing information that they are in a hostile environment. To survive in an iron-limited environment, molecular regulation of iron-binding proteins plays a vital role in facilitating the transportation and utilization of sufficient iron sources. Given the importance of iron molecules for bacterial survival and pathogenicity, this review summarizes the physiological role of iron-binding proteins in bacterial survival and their potential use in vaccine and therapeutic developments.

Characterization of multi-resistant Shigella species isolated from raw cow milk and milk products.

This study was organized to investigate the prevalence, antibiotic and disinfectant resistance phenotypes and genotypes as well as plasmid profiles of Shigella species isolated from raw cow milk and milk products in Egypt. Genotypic analysis was performed to determine the presence of ß-lactamase encoding genes (blaTEM, blaCTX-M, blaOXA-1 and blaSHV), tet(A) and qacE∆. Forty-two (7%) Shigella isolates (S. dysenteriae, S. flexneri, and S. sonnei) were recovered, with S. dysenteriae as the predominant type. Antibiotic sensitivity tests showed that 71.4% of Shigella isolates were resistant to three or more antibiotic classes (multidrug-resistant). High resistance rates were observed against tetracyclines (100%), ampicillin, amoxicillin-clavulanate (90.5%, each) and cefaclor (66.7%), while no resistance was detected against imipenem, sulfamethoxazole/trimethoprim, and azithromycin. Disinfectant susceptibility test of Shigella isolates revealed resistance to phenolic compound (vanillic acid), while 85.7% of the Shigella isolates were resistant to benzalkonium chloride. Uniplex PCR analysis declared the existence of ß-lactamase encoding genes (blaTEM in all isolates and blaCTX-M in 28.6% of isolates) and, tet(A) in all isolates and 85.7% of the isolates were positive for qacE∆1, while all isolates were negative for blaOXA-1 and blaSHV. All Shigella extended spectrum ß-lactamases (ESBL) producers (12, 100%) were positive for the blaTEM, blaCTX-M, and qacE∆1 genes. Furthermore, plasmid profiling revealed seven distinct plasmid patterns (P1-P7), ranging from 1.26 to 33.61 kb, among all the Shigella strains; S. dysenteriae exhibited the greatest variance. The co-transfer of ß-lactamase genes (blaTEM and blaCTX-M) and qacE∆1 genes was observed by conjugation from all ESBL producers to a recipient strain. These findings indicate the emergence of Shigella species in Egypt that exhibited multi-resistance to either antibiotics (particularly ESBL producer strains) or disinfectants. Thus, the resistance of Shigella species should regularly be monitored and appropriate measures should be taken to manage this problem.

Genetic diversity and antibiotic resistance of Shigella spp. isolates from food products.

The emergence of multidrug-resistant Shigella is a significant threat to global public health. Limited studies have investigated the incidence, antimicrobial susceptibility, and genetic diversity of Shigella isolated from food products. Conventional culture-based, serologic, molecular, disk diffusion, PCR, and RAPD-PCR methods were used to determine the prevalence rate, phenotypic and genotypic antibiotic resistance profile, and genetic diversity of the Shigella isolates from food samples including vegetable salad, ground meat, and raw cow's milk (405 samples). The prevalence rate of Shigella in food samples was 4.44%. The incidence of S. sonnei (3.7%) was higher than that of S. flexneri (0.74%). S. dysenteriae and S. boydii were not detected in food samples examined. Also, no Shigella were recovered from raw cow's milk. This study showed that the Shigella isolates were resistant to sulfamethoxazole/trimethoprim (83.3%), amoxicillin (66.6%), streptomycin (66.6%), tetracycline (61.1%), ampicillin (50%), amoxicillin-clavulanic acid (50%), azithromycin (50%), and chloramphenicol (50%) and completely sensitive to cefoxitin, cefepime, amikacin, and gentamicin. All Shigella isolates were multidrug-resistant. We detected bla SHV resistance gene in all isolates; however, no isolate harbored bla TEM gene. RAPD-PCR categorized the Shigella isolates into five main clusters. The highest antibiotic resistance was observed in the isolates of cluster R4. The finding of this study also indicated an association between antimicrobial resistance profiles and genotyping properties of the isolates. Novel food monitoring systems, including surveillance of multidrug-resistant foodborne pathogens, especially in developing countries, are required to control the foodborne diseases.

Burden, Antibiotic Resistance, and Clonality of Shigella spp. Implicated in Community-Acquired Acute Diarrhoea in Lilongwe, Malawi.

Although numerous studies have investigated diarrhoea aetiology in many sub-Saharan African countries, recent data on Shigella species' involvement in community-acquired acute diarrhoea (CA-AD) in Malawi are scarce. This study investigated the incidence, antibiotic susceptibility profile, genotypic characteristics, and clonal relationships of Shigella flexneri among 243 patients presenting with acute diarrhoea at a District Hospital in Lilongwe, Malawi. Shigella spp. were isolated and identified using standard microbiological and serological methods and confirmed by identifying the ipaH gene using real-time polymerase chain reaction. The isolates' antibiotic susceptibility to 20 antibiotics was determined using the VITEK 2 system according to EUCAST guidelines. Genes conferring resistance to sulfamethoxazole (sul1, sul2 and sul3), trimethoprim (dfrA1, dfrA12 and dfrA17) and ampicillin (oxa-1 and oxa-2), and virulence genes (ipaBCD, sat, ial, virA, sen, set1A and set1B) were detected by real-time PCR. Clonal relatedness was assessed using ERIC-PCR. Thirty-four Shigella flexneri isolates were isolated (an overall incidence of 14.0%). All the isolates were fully resistant to sulfamethoxazole/trimethoprim (100%) and ampicillin (100%) but susceptible to the other antibiotics tested. The sul1 (79%), sul2 (79%), sul3 (47%), dfrA12 (71%) and dfrA17 (56%) sulfonamide and trimethoprim resistance genes were identified; Oxa-1, oxa-2 and dfrA1 were not detected. The virulence genes ipaBCD (85%), sat (85%), ial (82%), virA (76%), sen (71%), stx (71%), set1A (26%) and set1B (18%) were detected. ERIC-PCR profiling revealed that the Shigella isolates were genetically distinct and clonally unrelated, indicating the potential involvement of genetically distinct S. flexneri in CA-AD in Malawi. The high percentage resistance to ampicillin and sulfamethoxazole/trimethoprim and the presence of several virulence determinants in these isolates emphasises a need for continuous molecular surveillance studies to inform preventive measures and management of Shigella-associated diarrhoeal infections in Malawi.

Antibiotic susceptibility and genetic relatedness of Shigella species isolated from food and human stool samples in Qazvin, Iran.

OBJECTIVE: The aim of this study was to investigate the genetic relatedness and antimicrobial resistance among Shigella species isolated from food and stool samples. Using cross sectional study method, Shigella spp. were isolated from food and clinical samples using culture-based, biochemical and serological methods. Antimicrobial susceptibility and genetic relatedness among the isolates were evaluated using disk diffusion and RAPD-PCR methods respectively. RESULTS: The prevalence of Shigella spp. were 4.84 and 7.7% in food and stool samples respectively. All food isolates were Sh. sonnei. 91.42% of the Shigella stool isolates were Sh. sonnei. 62.5% of food isolates were resistant to tetracycline. 46.8, 50 and 65.8% of clinical isolates were resistant to imipenem, amikacin and azithromycin respectively. 50 and 85.7% of the food and clinical isolates respectively were MDR. Dendrogram generated by RAPD-PCR showed that the isolates from food and stool samples were categorized in a same group. Close genetic relatedness between MDR Shigella isolates from food and clinical samples indicate that foods can be considered as one of the main vehicles for transmission of MDR Shigella to human causing acute diseases. Survey of MDR Shigella among food and clinical samples is strongly suggested to be implemented.

Development of rapid gold nanoparticles based lateral flow assays for simultaneous detection of Shigella and Salmonella genera.

Salmonella and Shigella genera are common pathogens that contaminate foods and beverages. Lateral flow assays (LFA) are commonly used to detect these pathogens. However, most of the developed LFAs are for single detection. Simultaneous detection of pathogens is required to reduce cost and time. In this work, 40 nm gold nanoparticles (AuNPs) were synthesized using the seeding growth method as labeling agent. The AuNPs were characterized and conjugated with mouse anti-Gram negative endotoxin antibody. The nitrocellulose membrane HF135 was immobilized with anti-mouse IgG antibody as a control line and two separate test lines with either anti-Shigella or anti-Salmonella antibody, respectively. Color intensity of test lines was observed for positive samples. A milk sample was used as proof of concept to mimic actual contamination. The limit of detection of the LFA was 3.0 × 106 CFU/mL for multiplex detection of Shigella flexneri and Salmonella Typhi and for both single detections. The result was comparable with the enzyme-linked immunosorbent assay (ELISA) analysis. The produced LFA could differentiate between Shigella flexneri, Shigella boydii, Salmonella Enteritidis, and Salmonella Typhi. The developed LFA was able to identify Shigella flexneri and Salmonella Typhi with good sensitivity in milk samples, thus, beneficial to ensure the safety of food before entering the market.

The Prevalence of Shiga Toxin-1 in Non-Shigella Dysenteriae Isolates Collected from Diarrhea Samples in Patients, Ahvaz, Iran.

BACKGROUND: Acute diarrhea is a major public health problem, particularly in developing countries. Shigellosis is one of the substantial causative agents of microbial dysentery and still has a remarkable prevalence, particularly in areas with poor hygienic infrastructures. The probable existence of the deadly Shiga toxin (Stx) protein in some Shigella strains would manifest life-threatening clinical symptoms of the infection. METHODS: The aim of this study was to determine the presence of Shigella toxin 1 (Stx1) in isolated from patients with diarrhea. Totally, 227 Shigella species, including 60 S. flexneri, 157 S. sonnei, and 10 S. boydii were collected from diarrheal patients in the tropical infectious diseases research center of Ahvaz, Iran, during 2013-2015. The isolates were collected mostly from the intensive care unit, infectious disease, and surgery settings. The isolates were identified, and the polymerase chain reaction (PCR) was performed to detect the stx gene. RESULTS: The results indicated that none of them encode the stx1 gene. CONCLUSION: Isolates of this study were not capable of stx1 encoding. Future investigations should consider the relations between other Shigella species and Shigella toxin in Iran.

Emergence of multidrug-resistant Shigella species harboring extended-spectrum beta-lactamase genes in pediatric patients with diarrhea from southwest of Iran.

Owing to the scarce evidence about the multidrug-resistant (MDR) beta-lactamase-producing Shigella isolates in Iran, this study aimed to evaluate the occurrence of extended-spectrum beta-lactamases (ESBL) and AmpC ß-lactamases in Shigella species collected in the southwest of Iran. This study was conducted on Shigella species isolated from stool samples of pediatric patients aged less than 15 years suffering from diarrhea. These isolates were identified by bacteriology tests, serotyping, and polymerase chain reaction (PCR). The antibiotic resistance was determined by disc diffusion. The production of ESBLs and AmpC was investigated by phenotypic confirmatory tests and PCR. In total, 79 Shigella isolates, including 46.8% (n = 37) of S. flexneri and 53.2% (n = 42) of S. sonnei, were isolated, respectively. The most effective antibiotic was imipenem with 93.7% of susceptibility followed by ampicillin (29.1%), and cotrimoxazole (30.4%).The resistance rates of ceftriaxone, ceftazidime, and cefotaxime were 41.8%, 34.2%, and 41.8%, respectively. Also, a total of 57 (72.2%) isolates showed MDR profiles. The phenotypic tests showed that 43.0% (34/79) of isolates can produce ESBLs, and no one was positive for ApmC. The frequency of blaTEM and blaCTX-M were 30.4% and 32.9%, respectively, while the blaPER, blaSHV, and AmpC genes were not detected. The ESBL-producing isolates had a significant (p-value Ë‚ 0.05) resistance rate against ceftriaxone, ceftazidime, cefotaxime, cefepime, erythromycin, and amikacin. The significant prevalence of MDR Shigella isolates harboring ESBL genes highlights the need for effective surveillance measures to prevent the more spread of drug resistance among species.

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.

Precise, direct, and rapid detection of Shigella Spa gene by a novel unmodified AuNPs-based optical genosensing system.

Early detection of infectious bacteria is a necessity for combating infectious diseases. Due to low infectious dose of Shigella, rapid and sensitive detection is needed. Compared to the presented genes, Spa gene can be introduced as a novel sequence for all species of Shigella detection. Herein, the possibility of Spa genes for detection of four species of Shigella was investigated for the first time by AuNPs-based optical genosensing system. In this method, AuNP-DNA probes were hybridized with Spa gene sequence. When the complementary target is present, it prevents the aggregation of the complex under acid environment and the solution remains red whereas in the absence of the specific sequence, it turns to purple. Therefore, visual detection is possible with bare eye. The comparison of this Optical DNA biosensor and PCR-based method showed that the proposed method is simple, cost-effective, rapid operation, with high or comparable detection limit of (LOD and LOQ: 8.14 and 26.6 ng mLl-1, respectively), without need of any expensive techniques, and equipments compared to the conventional methods. In conclusion, the described method may develop into a platform that could be utilized for detection of various bacterial species with high accuracy and prompt screening of samples.

Prevalence and antimicrobial susceptibility pattern of Salmonella and Shigella species among asymptomatic food handlers working in Haramaya University cafeterias, Eastern Ethiopia.

OBJECTIVE: Salmonellosis and Shigellosis remain a major public health problem across the globe, particularly in developing countries like Ethiopia, where hand hygiene and food microbiology are still below the required standards. The growing problem of antimicrobial resistance species also continues to pose public health challenges. This study assessed the prevalence and antimicrobial susceptibility pattern of Salmonella and Shigella species among asymptomatic food handlers. A cross-sectional study was conducted among 417 randomly selected asymptomatic food handlers. Data were collected using a structured questionnaire. The stool specimens collected were examined for Salmonella and Shigella species using standard bacteriological methods. Descriptive statistics were used to describe the basic features of the data. RESULTS: The overall prevalence of Salmonella and Shigella species was 5.04%. Salmonella and Shigella species were 76.2% resistant to both co-trimoxazole and tetracycline, 71.4% to amoxicillin and 66.7% to chloramphenicol. Moreover, 85.7% of Salmonella and Shigella species were multidrug resistant. The findings highlighted the food handlers as potential sources of food borne infections, which demands the establishment of appropriate hygiene and sanitary control measures at the University cafeterias.

Patterns of Bacillary Dysentery in China, 2005-2010.

Although the incidence of bacillary dysentery in China has been declining progressively, a considerable disease burden still exists. Few studies have analyzed bacillary dysentery across China and knowledge gaps still exist in the aspects of geographic distribution and ecological drivers, seasonality and its association with meteorological factors, urban-rural disparity, prevalence and distribution of Shigella species. Here, we performed nationwide analyses to fill the above gaps. Geographically, we found that incidence increased along an east-west gradient which was inversely related to the economic conditions of China. Two large endemically high-risk regions in western China and their ecological drivers were identified for the first time. We characterized seasonality of bacillary dysentery incidence and assessed its association with meteorological factors, and saw that it exhibits north-south differences in peak duration, relative amplitude and key meteorological factors. Urban and rural incidences among China's cities were compared, and disparity associated with urbanization level was invariant in most cities. Balanced decrease of urban and rural incidence was observed for all provinces except Hunan. S. flexneri and S. sonnei were identified as major causative species. Increasing prevalence of S. sonnei and geographic distribution of Shigella species were associated with economic status. Findings and inferences from this study draw broader pictures of bacillary dysentery in mainland China and could provide useful information for better interventions and public health planning.

Molecular Evaluation of High Fluoroquinolone Resistant Genes in Endemic Cases of Shigellosis, Northeast Part of Karnataka, India.

OBJECTIVES: Shigellosis is an acute infection of the intestine caused by bacteria in the genus Shigella and also an important cause of diarrhea in developing countries. This study was carried out to find the extent and nature of the emerging resistance in north part of Karnataka, India, and surrounding region with huge population, and also focused on the molecular mechanism of development of resistance against different generations of fluoroquinolones and explored the diversity of restriction endonucleases; we also tried to establish the significance of reduced minimal inhibitory concentrations (MIC) values. METHODS: A total of 32 multidrug-resistant Shigella species (isolated from infants' stools) were subjected to MICs of fluoroquinolone-resistant isolates done by both broth dilution and E-test method. The genes implicated in resistance to fluoroquinolone generations ciprofloxacin, ofloxacin, and gatifloxacin (gyrA, gyrB, parC, and parE) were amplified using polymerase chain reaction (PCR) method and restriction digestion analysis of PCR product were performed using PvuI and HaeII enzymes. FINDINGS: Fluoroquinolone-resistant Shigella species (n = 32) comprising S dysenteriae, S flexneri, and S sonnei were selected for MIC; 90.6% (29/32), 93.75% (30/32), and 93.75% (30/32) of isolates were ciprofloxacin, ofloxacin, and gatifloxacin resistant and showed the MIC range from 4-128 µg/mL. The PCR amplification results were positive for all species and asserted the presence of gyrA, gyrB, parC, and pare and sizes of the amplified products. The restriction banding patterns of amplified resistant genes were employed to detect differences among the Shigella species. CONCLUSIONS: The present study found that the genetic basis and its characterization of fluoroquinolone resistance in Shigella isolates was considered for the common resistant genes, namely, gyrA, gyrB, parC, and pare, and had mutations at position 83 of gyrA and at position 80 of parC of the quinolone-resistant determining regions and associated molecular mechanism. Our study beneficial in identification of the causative agents of the infections, careful control and cautions use of antibiotics must be promoted, particularly to monitor the emergence of isolates that are fully resistant to fluoroquinolones.

Rapid and reliable discrimination between Shigella species and Escherichia coli using MALDI-TOF mass spectrometry.

E. coli-Shigella species are a cryptic group of bacteria in which the Shigella species are distributed within the phylogenetic tree of E. coli. The nomenclature is historically based and the discrimination of these genera developed as a result of the epidemiological need to identify the cause of shigellosis, a severe disease caused by Shigella species. For these reasons, this incorrect classification of shigellae persists to date, and the ability to rapidly characterize E. coli and Shigella species remains highly desirable. Until recently, existing matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) assays used to identify bacteria could not discriminate between E. coli and Shigella species. Here we present a rapid classification method for the E. coli-Shigella phylogroup based on MALDI-TOF MS which is supported by genetic analysis. E. coli and Shigella isolates were collected and genetically characterized by MLVA. A custom reference library for MALDI-TOF MS that represents the genetic diversity of E. coli and Shigella strains was developed. Characterization of E. coli and Shigella species is based on an approach with Biotyper software. Using this reference library it was possible to distinguish between Shigella species and E. coli. Of the 180 isolates tested, 94.4% were correctly classified as E. coli or shigellae. The results of four (2.2%) isolates could not be interpreted and six (3.3%) isolates were classified incorrectly. The custom library extends the existing MALDI-TOF MS method for species determination by enabling rapid and accurate discrimination between Shigella species and E. coli.

Options for treating resistant Shigella species infections in children.

Infection due to Shigella species remains an important public health problem, especially in developing countries where it remains the most common cause of bloody diarrhea. In the United States (US), 10,000 to 15,000 cases of shigellosis are reported each year in both children and adults. US surveillance data from 2004 has demonstrated increased resistance in Shigella species to first-line antibiotics such as ampicillin and trimethoprim-sulfamethoxazole, with approximately 37% of isolates demonstrating resistance to both ampicillin and trimethoprim-sulfamethoxazole. Since approximately 69% of Shigella infections occur in children younger than 5 years of age, it is important that alternative antibiotics other than typical first-line agents such as ampicillin and trimethoprim-sulfamethoxazole be available to treat Shigella infections in this population. The American Academy of Pediatrics (AAP) recommends cefixime, ceftriaxone, azithromycin, and fluoroquinolones as alternative antibiotics for the treatment of Shigella species infections in children. This paper will review the microbiology, susceptibility, efficacy and safety data of these alternative antibiotics with regard to the treatment of Shigella species infections in children, and will attempt to define the role of each of these agents in the pediatric population.