Childhood Dysentery Due to <i>Shigella sonnei</i> and the Challenges of Antibiotic Resistance: A Report from an Outbreak

Background: Shigellosis is a diarrheal disease caused by Shigella spp. The majority of cases and deaths occur among children less than 5 years old. In severe cases, antibiotic therapy is recommended to lessen the risk of serious complications and death. Prevalence of different Shigella species and their antibiotic resistance patterns are changing over the time. Objectives: The current study aimed at assessing the changes in the prevalence of Shigella species and their antibiotic susceptibility among 0- to 14-year-old children referred to Children’s Medical Center, Tehran, Iran, from 2009 to 2014. Methods: The results of stool cultures were retrospectively analyzed to determine the prevalence of different Shigella species, their antibiotic susceptibility patterns and their changes in the largest university affiliated pediatrics center in Tehran. Results: Among 40 700 stool cultures, 507 cases were positive for Shigella spp. Most cases occurred among children under 5 years old. Shigellosis was more prevalent among males. The most common species were Shigella sonnei and Shigella flexneri. In general, they were most sensitive to cefotaxime and most resistant to cotrimoxazole. Resistance to cefotaxime and nalidixic acid increased annually. Resistance to ampicillin had a descending trend. Resistance to cotrimoxazole remained almost constant. Conclusions: The most common species of Shigella changed from Shigella flexneri to Shigella sonnei over the years. In comparison with the previous studies, resistance to nalidixic acid increased and resistance to ampicillin decreased. The prevalence and antibiotic resistance patterns of Shigella species, at different times and regions are changing. To make appropriate decisions on treatment, it is necessary to monitor the changes.

Aim: This study aims to evaluate the effect of antibiotic therapy based on wound culture results on wound healing in patients with stage C6 -Chronic Venous Insufficiency (CVI) who have resistant stasis ulcers that do not respond to standard CVI treatments. Material and Methods: The study included 40 patients diagnosed with stage C6 -CVI at our clinic between 2020 and 2024. All stasis ulcers were located in the medial malleolus region. Swab cultures were obtained from all stasis ulcers, and antibiograms were performed on the cultures. Based on the antibiogram results, antibiotics to which the microorganisms were sensitive were administered concurrently with standard CVI treatment. Follow-up visits were scheduled at 30 and 45 days after treatment. Demographic data, history of Deep Vein Thrombosis (DVT), pre-treatment ulcer size, and wound healing times at follow-up were recorded. Results: The most frequently isolated microorganisms from the stasis ulcer cultures were Staphylococcus aureus (70%), Pseudomonas aeruginosa (20%), Escherichia coli (7.5%), and Klebsiella oxytoca (2.5%). The average wound healing time for patients who received antibiotics based on the culture antibiogram and standard CVI treatment was 34.5 days. In patients with stage C6-CVI, administering antibiotics according to culture and antibiogram results may shorten the wound healing time in stasis ulcers. Conclusion: In patients with stage C6-CVI, administering antibiotics according to culture and antibiogram results may shorten the wound healing time in stasis ulcers.

Introduction: Most cases of acute diarrhea are self-limited and due to viral or baterial infections. Stool cultures only test for the specific enteroinvasive bacteria, including Campylobacter jejuni, Salmonella species, Shigella species, Escherichia coli, which represent a small fraction of the infectious agents that can cause acute diarrhea. Previous studies have shown these organisms are positive in approximately 0.2 to 1.8% of cultures. We evaluated the effect of stool culture results on the management of inpatients with acute diarrhea. Methods: The database from the inpatient electronic medical records system at a university hospital was queried for stool bacterial cultures performed on inpatients from June 2010 through June 2014. Chart review was performed to assess the impact of stool culture results on clinical management and was limited to patients with an admitting diagnosis of acute diarrhea.Table 1: Stool Culture DistributionTable 2: Stool Culture DistributionFigure 1Figure 2Results: A total of 4576 stool cultures were evaluated within the study period. Of these stool cultures, 527 (11.5%) were positive, the most common organisms being: Candida sp. (n=282, 6.16%), Staphylococcus aureus (n=88, 1.92%), Campylobacter jejuni (n=25, 0.55%), Salmonella sp. (n=22, 0.48%), Shigella sp. (n=13, 0.28%). Escherchia coli 0157:H7 was not isolated in any cultures. Candida and S. aureus were considered contaminants and did not impact clinical management. This left 54 positive stool cultures for analysis, excluding duplicate cultures and those taken from patients without diarrhea. Seven cultures (15.5%) resulted in a change of the patient's management. Management changes included initiating antibiotics (n=4, 7.4%) and changing to narrower spectrum antibiotics (n=3, 5.6%). Results from 33 of the positive cultures (61%) were obtained after the patient was discharged with improved symptoms (with or without empiric antibiotic treatment). Results from the remaining 14 stool cultures (26%) were obtained during the patient's admission, but did not result in a change in management. Conclusion: In this large single center retrospective analysis, we demonstrate that bacterial stool cultures have a low rate of positivity, and positive culture results are of limited utility in guiding clinical management in patients admitted with acute diarrhea. Clinical judgment as to the benefits of culture results in guiding management should be considered prior to collecting them, and may enhance high value care and cost effectiveness.

Acute Bloody Diarrhea: A Medical Emergency for Patients of All Ages

Background and ObjectivesRecently, nosocomial infections have been discussed as a critical issue among intubated patients leading to significant morbidity and mortality. Hence, the pattern of microbiological colonization and antibiotic resistance are much valuable in this regard. We aimed to investigate the pattern of microorganism colonization and antibiotic resistance in patients with endotracheal tube or tracheostomy to propose a proper empirical antibiotic therapy in this setting.Materials and MethodsThis cross sectional study was conducted among 880 patients admitted in Imam Khomeini hospital between 2008 and 2011 who were subsequently intubated or underwent tracheostomy due to insufficient self ventilation. Samples for microbiological cultures were obtained after extubation and then sent to the central laboratory for further assessment. Antibiograms and microbiological cultures were obtained for each sample.ResultsOf 880 patients enrolled in this study, 531 (60.3%) were male and 349 (39.7%) were female. Nineteen different organisms were isolated including Acinetobacter (213, 24.2%), Pseudomonas aeruginosa (147, 16.7%), Staphylococcus aureus (106, 12%), Proteus mirabilis (90, 10.2%), and other organisms (324, 36.8%). Antibiotic resistance was mainly seen in Acinetobacter (ciprofloxacin, ceftazidim, cefepim, and penicillin), S. aureus (imipenem) and Klebsiella (pipracillintazobactam and ampicillin-sulbactam).ConclusionThis study represents the most common microorganisms colonizing tracheal tube of hospitalized patients and their pattern of antibiotic resistance. Acinetobacter was the most common microorganism isolated from endotracheal tube. Hence, it may be possible to initiate the empiric antibiotic treatment before the results of culture are become available. Ciprofloxacin was also the most prevalent antibiotic revealing resistant pattern. Moreover, most of the microorganisms were sensitive to imipenem and pipracillin-tazobactam.

Sir, Shigella dysenteriae type 1 is known to cause epidemics of bacillary dysentery worldwide. In 1984, an extensive outbreak of bacillary dysentery swept through several districts of West Bengal, including the state capital Kolkata, and subsequently, spread to other parts of India (1). Multidrug-resistant S. dysenteriae type 1 was identified as the sole aetiological agent in this outbreak. In the later period, the number of shigellosis cases gradually declined. During the last five years, the number of dysentery cases admitted to the Infectious Diseases Hospital, Kolkata (which serves as a referral centre for all types of diarrhoea cases in Kolkata and suburbs) was relatively low. The isolation rate of Shigella species varied from 1% to 1.3%, and S. flexneri was the commonest serotype identified (2). However, continuous surveillance of diarrhoeal cases at the Infectious Diseases Hospital, Kolkata, revealed a sudden increase in acute bloody diarrhoea cases since July 2002. During 1 July-15 September 2002, stool samples were collected from 100 patients (both children and adults) suffering from acute bloody diarrhoea and were screened for the entire gamut of enteric pathogens following standard microbiological techniques (3). Among these 100 patients, Shigella species was isolated as the sole pathogen from 39 patients. S. dysenteriae type 1 was the commonest serotype (34 strains), followed by S. flexneri (4 strains), and S. sonnei (1 strain). Besides bloody diarrhoea, the other clinical manifestations of 39 bacteriologically-positive cases included severe abdominal pain (85.7%), fever ranging from 37.2[degrees]C to 38.3[degrees]C (63.8%), tenesmus (20.4%), and moderate dehydration (87.8%); only four cases showed signs of severe dehydration requiring administration of intravenous fluid. The table shows the age distribution of 39 bacteriologically culture-positive cases of shigellosis. When enriched stool samples were subjected to polymerase chain reaction (PCR) for detection of ipaH (invasive plasmid antigen H) gene using published primers (4), 49 samples (49%) were positive by PCR test, which included all 39 bacteriologically-confirmed cases. No other enteropathogens, such as Vibrio parahaemolyticus, Campylobacter species, and enterohaemorrhagic Escherichia coli, could be detected from the cases. During this sporadic outbreak of dysentery, clinicians of the Infectious Diseases Hospital were using conventional anti-Shigella drugs--norfloxacin or ciprofloxacin (the fluoroquinolone derivatives)--for treatment of the patients. The clinical response was, however, very poor. Subsequently, in vitro antimicrobial susceptibility test revealed that the strains of S. dysenteriae type 1 were resistant to ampicillin (100%), tetracycline (100%), nalidixic acid (100%), norfloxacin (100%), and ciprofloxacin (100%) but were susceptible to ofloxacin (100%), ceftriaxone (100%), gentamicin (100%), amikacin (100%), cefotaxime (100%), cefuroxime (100%), cefoxitin (100%), and ceftazidime (100%). Surprisingly, strains of S. flexneri and S. sonnei were susceptible to norfloxacin, ciprofloxacin, ofloxacin, and other newer generations of antibiotics. This finding prompted the physicians to switch over to oral ofloxacin (another fluoroquinolone derivative) for treatment with a total dose of 7.5 mg/kg.day in two divided doses for five days. The majority of the Shigella-positive cases responded well to ofloxacin; abdominal colic and tenesmus subsided within an average of 72 hours; and return of normal stool character was observed within 96 hours. …

This Month in Gastroenterology

The Variable Presentations and Broadening Geographic Distribution of Hepatic Fascioliasis

Aim: This study aimed to determine the rate of aerobic bacterial infection in disc samples taken from the surgical field in patients with lumbar disc herniation (LDH) undergoing single-level lumbar microdiscectomy (LMD).Material and Methods: Disc tissue samples were collected from the surgical fields in patients with single-level LDH undergoing elective LMD between September 2019 and May 2020. Tissues were then cultivated in cultures to determine the rate of aerobic bacteria and the results obtained were noted. The effects of parameters such as age, gender, affected side, Modic changes (MCs), and accompanying systemic diseases on culture results were statistically investigated. The patients were examined retrospectively with their demographic values. Results: This study included 33 patients with single-level LDH and all of these patients underwent LMD. Two patients additionally underwent posterior lumbar instrumentation. The mean age was 50.87±12.20 years (25-71 years) and 17 (51.51%) of the patients were men and 16 (48.49%) were women. The mean follow-up duration was 3.03±1.64 months (1–8 months). Aerobic infection was observed in four patients (12.12%). Two of them (6.06%) were Enterobacteriaceae and the other two (6.06%) were coagulase-negative staphylococci (CNS). The antibiotic that patients were sensitive to was added to the postoperative medical treatment for two weeks according to the culture and antibiogram results. Age, gender, affected side, MC, and accompanying systemic diseases were found to have no statistically significant effect on culture results.Conclusion: The prevalence of subclinical aerobic bacterial infection has been found to be 12.12% in patients undergoing LMD. Although sterilization rules have been strictly followed, the possibility of contamination of disc cultures could have not been completely rejected. In conclusion, the present study has shown that culture results have no effect on postoperative outcomes.

Objective To investigate the source, transmission mode and infection range of the bacterial dysentery outbreak in two colleges in Nanjing. Methods Suspected cases were defined as students and staff members in these two colleges with the symptoms of diarrhea during the period from September 7 to October 8, 2015. Probable cases were defined as suspected cases with one of the three symptoms: fever(T≥37.4℃), tenesmus, or abdominal pain. Confirmed cases were defined as suspected or probable cases with PCR detection for Shigella DNA fragment positive in fecal or anal swab specimens or with isolated Shigella. The general situation of these 2 colleges was investigated. We conductedactive case searching by reporting from local medical institutions, college health center and counselors; conducted case study and describing general information, clinical manifestations, and distribution features; conducted matched case control study for suspicious meals and food; collected stools or rectal swab specimens of cases and food handlers, environmental samples and food retention samples to test Salmonella and Shigella by PCR; used PFGE for analysis of homology of the isolated strains; analyzing the distribution of cases by descriptive epidemiology method andthe difference of attack rates by Chi-square test, and calculate Odds ratios (OR) with 95 % confidence intervals (CI) of suspicious meals in case control study. Results A total of 436 and 36 cases were found out in collage A and B, leading to attack rates of 2.6% (436/15 385) and 0.23% (36/15 449) respectively and the epidemic curve indicated a point source exposure. In collage A, the attack rate of boarders was higher than that of day students (2.9%, 434/15 027 vs 0.78%, 2/258, χ2=4.09, P<0.05); the attack rate of the students lived in the south dormitory area was higher than that in the north area (4.6%, 351/7 666 vs 1.1%, 83/7 361), χ2=159.46, P<0.001). The case control study result showed that the suspicious exposure meal was dinner on September 20(OR=2.4, 95%CI: 1.2-4.7). Shigella sonnei strain I was isolated from anal swab specimens of cases and canteen employees in these two colleges, and the PFGE detection results showed a high degree of homology. Conclusions This is a bacterial dysentery outbreak caused by Shigella sonnei involving two colleges in Nanjing. We should continue to enhance the surveillance of foodborne disease and sanitary control and supervision of canteens in schools and other collective units. Key words: Bacillary dysentery; Outbreak; Shigella sonnei; Pulsed Field Gel Electrophoresis(PFGE)

Introduction: Shigellosis is a major health problem, especially in developing countries and in children under 5 years of age. The prevalence of Shigella species in a region can be considered as an indicator for hygiene level of that region. Due to the lack of an efficient vaccine, antibiotic therapy is the main strategy to combat the disease. In this study, the prevalence of the Shigella species and their antibiotic resistant pattern has been investigated. Materials and Methods: A total of 300 diarrheal stool samples were collected from 4 different hospitals in Tehran during a period of 6 months June to November 2016. Bacterial identification and species discrimination was performed using biochemical and serotyping tests. Antibiotic resistance patterns of isolates were obtained using Bauer-Kirby method. Results: 8.7% of all diarrheal cases were caused by Shigella species (5% by Shigella sonnei and 3.7% by Shigella flexneri). Antibiogram test revealed that the isolates were more sensitive or intermediate to ciprofloxacin (92.3%), while most of the isolates were resistant to tetracycline. Conclusions: The prevalence of Shigella species has changed in Tehran. Since antibiotics are the treatment of choice to combat these pathogens, also, because of the emergence of the antibiotic resistance Shigella strains, there is a need for regularly updated regional antibiotic sensitivity patterns of the pathogen to guide therapy.

Shigellosis is a form of bacterial diarrhea caused by gram-negative bacteria Shigella species. It is common in developing countries and results from contaminated food, poor sanitation conditions, or direct person to person contact. Shigella can cause infection in all age groups. High-risk group include very young, elderly, and immunocompromised person. Shigella species is relatively resistant to acid in the stomach, and few organisms are required to cause the disease. Once ingested, it multiplies in the small intestine and enters the colon. In the colon, it produces shigella enterotoxins and serotype toxin 1, resulting in watery or bloody diarrhea. Clinical presentation of shigellosis may vary over a wide spectrum from mild diarrhea to severe dysentery. We report the case of 7 years old previously healthy boy, who presented to our hospital with abdominal pain, vomiting, and constipation. On examination, we noticed abdominal tenderness with guarding at the right lower quadrant. With the diagnosis of acute appendicitis, open appendectomy was performed. Exploration of the abdominal cavity revealed perforated appendicitis and generalized peritonitis. Shigella sonnei was isolated from the peritoneal fluid culture. The patient completely recovered without any complications. Surgical complications, including appendicitis, could have developed during shigellosis. There are few reported cases of perforated appendicitis associated with Shigella. Prompt surgical intervention can be beneficial to prevent morbidity and mortality if it is performed early in the course of the disease.

BackgroundDue to financial issues and the rise in antimicrobial resistance, updating dry cow therapy (DCT) methods is still being researched by scientists worldwide. This investigation aimed to evaluate a new method of selective treatment by choosing an appropriate dry cow antimicrobial product for each cow based on the individual culture and antibiogram results and examining its effects on clinical and subclinical mastitis indices, cure rate, new infection rate, and milk yield during the first 30 days in milk (DIM).Materials and methodsA total of 291 Holstein dairy cows were selected from three herds. These cows had a somatic cell count (SCC) > 200,000 (cells/mL) just before drying off, had positive composite milk culture results, and were gradually dried over five days. The milk samples were taken before drying off and on the day after calving (1 DIM) for microbial culture evaluation, as well as 3 days before drying off and between 3 and 7 days postpartum to evaluate SCC. The cows were randomly divided into two groups of control (n = 151) and treatment (n = 140). The control group included cows that were treated with dry cow antimicrobial products regardless of the pathogens involved in mammary infection, and the treatment group contained cows that received dry cow antimicrobial products based on the type of pathogen isolated during culture and the antibiogram results before drying off.ResultsThe results revealed that the cure rate in the treatment group was significantly better than that in the control group (P = 0.0006). In addition, the rate of new intramammary infections (IMI, P = 0.0006) and the rate of clinical mastitis (P = 0.015) decreased in the first 30 DIM in the treatment group. Nevertheless, the SCC and milk yield at the onset of subsequent lactation did not differ significantly between the control and treatment groups (P > 0.05).ConclusionAccording to the findings of our study, based on individual milk culture and antibiogram results, selectively treating cows with appropriate dry cow antimicrobial products had significant benefits for increasing the cure rate of pathogens, lowering the incidence of new IMIs, and minimizing the risk of clinical mastitis in the first 30 DIM.

In August 2006 a physician from a rural village reported an outbreak of acute gastroenteritis. An investigation was undertaken in order to determine the magnitude of the outbreak, the source of infection and to prevent further disease. This is the first published outbreak of acute gastroenteritis caused by contaminated drinking water in Austria. For descriptive epidemiology, the investigators had to rely on voluntary cooperation from physicians and patients, data collected by a police officer and data on sick leave reported by physicians to the health insurance system. Microbiological testing of water samples indicated that this cluster was caused by fecal contamination of untreated drinking water. Age and sex distributions were available for 146 of 160 cases: ages ranged from 5 to 91 years (median 45) and 81 cases (55.5%) were female. Stool samples from 14 patients were sent for microbiological analysis: all tested negative for Salmonella, Campylobacter, Shigella and Yersinia enterocolitica. Specimens were not tested for viruses, parasites or enteropathogenic Escherichia coli. In this outbreak no identification was made of pathogenic microorganisms in stool samples from affected patients, despite the occurrence of fecal indicator organisms in samples of drinking water. In outbreaks of gastroenteritis, medical practitioners should encourage microbiological testing beyond the limited routine program. Public health officers must be made aware that the spectrum of routine laboratory tests on stool specimens does not cover the wide array of pathogens capable of causing waterborne outbreaks. The springs serving the affected village originate in a mountainous area of karst formations, and heavy falls of rain that occurred at the beginning of the outbreak may explain introduction of fecal bacteria. In view of the unsolved problem of possible future contamination of springs in karst areas, the water department of this district authority has issued an order requesting installation of a permanent ultraviolet water-treatment facility.

A comparison of disease caused by Shigella and Campylobacter species: 24 months community based surveillance in 4 slums of Karachi, Pakistan