Early treatment of Campylobacter jejuni enteritis

Minding the gap: The impact of B-cell tolerance on the microbial antibody repertoire

B lymphocytes must respond to vast numbers of foreign antigens, including those of microbial pathogens. To do so, developing B cells use combinatorial joining of V-, D-, and J-gene segments to generate an extraordinarily diverse repertoire of B-cell antigen receptors (BCRs). Unsurprisingly, a large fraction of this initial BCR repertoire reacts to self-antigens, and these "forbidden" B cells are culled by immunological tolerance from mature B-cell populations. While culling of autoreactive BCRs mitigates the risk of autoimmunity, it also opens gaps in the BCR repertoire, which are exploited by pathogens that mimic the forbidden self-epitopes. Consequently, immunological tolerance, necessary for averting autoimmune disease, also acts to limit effective microbial immunity. In this brief review, we recount the evidence for the linkage of tolerance and impaired microbial immunity, consider the implications of this linkage for vaccine development, and discuss modulating tolerance as a potential strategy for strengthening humoral immune responses.

A novel mouse model of Campylobacter jejuni enteropathy and diarrhea

Campylobacter infections are among the leading bacterial causes of diarrhea and of 'environmental enteropathy' (EE) and growth failure worldwide. However, the lack of an inexpensive small animal model of enteric disease with Campylobacter has been a major limitation for understanding its pathogenesis, interventions or vaccine development. We describe a robust standard mouse model that can exhibit reproducible bloody diarrhea or growth failure, depending on the zinc or protein deficient diet and on antibiotic alteration of normal microbiota prior to infection. Zinc deficiency and the use of antibiotics create a niche for Campylobacter infection to establish by narrowing the metabolic flexibility of these mice for pathogen clearance and by promoting intestinal and systemic inflammation. Several biomarkers and intestinal pathology in this model also mimic those seen in human disease. This model provides a novel tool to test specific hypotheses regarding disease pathogenesis as well as vaccine development that is currently in progress.

Role of antimicrobials in the treatment of adult patients presenting to the emergency department with acute gastroenteritis - A mini review

BACKGROUND & OBJECTIVE

Acute gastroenteritis is generally considered a self-limiting illness that does not require the use of antibiotics. However, many emergency departments in the country frequently prescribe antibiotics to patients presenting with diarrhoea. This review attempts to determine whether this practice is reasonable. Our objective was to determine the role of antimicrobials in the empiric management of acute gastroenteritis.

METHODS

The online data base "PubMed", as well as the World Wide Web, were searched for relevant articles (RCTs, Reviews, Prospective studies, etc.) with key words such as "gastroenteritis AND antibiotics", "Management AND gastroenteritis", "Treatment AND diarrhoea" etc. and covered the years 1960-2016. Fifty articles were studied, of which 43 were chosen on the basis of relevance for qualitative assessment.

RESULTS

The articles reviewed for this paper suggest that antimicrobial therapy is not appropriate for the majority of cases of (uncomplicated) gastroenteritis, as risks (antibiotic-associated diarrhoea, hypersensitivity reactions, etc.) outweigh benefits. However, there are instances where antibiotics are clearly indicated. Further, it is noted that there have not been any recent trials to clarify the role of antimicrobials in adult diarrhoeal illness.

CONCLUSIONS

The focus in management of patients presenting with diarrhoea in the Emergency Department should be on rehydration and that only certain patients, such as those with fever or dysentery, or those with an impaired immune response should receive empiric antimicrobial therapy. More studies are needed to determine in what instances antimicrobials are of greatest benefit, so that adverse effects of rampant antibiotic prescription can be curtailed.

Bacterial enteric infections in children: etiology, clinical manifestations and antimicrobial therapy

Bacterial enteric infections have a huge impact on human health, particularly among the pediatric population. Despite the explosion of knowledge of the pathogenesis of bacterial enteric infections experienced in the past decade, the number of diarrheal episodes and childhood deaths reported continues to increase in many areas of the world. Specific antimicrobial therapy is indicated for certain confirmed infections, notably shigellosis, enterotoxigenic and enteroinvasive Escherichia coli infections, typhoid fever and cholera. Antimicrobial therapy may have a role in severe and prolonged gastrointestinal illness caused by nontyphoid Salmonella and Campylobacter. However, the use of antimicrobial agents may increase the risk of hemolytic uremic syndrome in children with E. coli O157:H7 infection. Bacterial genome sequencing and better understanding of the pathogenic mechanisms involved in the onset of diarrhea are leading to new preventive interventions, such as enteric vaccines, which may have a significant impact on the magnitude of this human plague.

Antibiotic resistance in bacterial pathogens from retail raw meats and food-producing animals in Japan

To determine the prevalence and antimicrobial susceptibility profiles of Campylobacter, Salmonella, Staphylococcus aureus, methicillin-resistant S. aureus (MRSA), and vancomycin-resistant enterococci (VRE) in food-producing animals and retail raw meats in Japan, raw meat samples as well as food-producing animal feces, cutaneous swabs, and nasal swabs collected from 2004 to 2006 were analyzed. Isolation rates of Campylobacter jejuni and Campylobacter coli, Salmonella, and S. aureus were 34.6% (363 of 1,050), 2.7% (28 of 1,050), and 32.8% (238 of 725), respectively. MRSA was isolated from 3% (9 of 300) of meat samples. No VRE were isolated in this study. Antibiotic resistance in C. coli was higher than that in C. jejuni. Three C. jejuni isolates from a patient with diarrhea in a hospital of Shizuoka Prefecture and two chicken samples that exhibited resistance to ciprofloxacin had identical pulsed-field gel electrophoresis patterns, suggesting that ciprofloxacin-resistant C. jejuni could have been distributed in meat. S. aureus isolates showed the highest level of resistance to ampicillin and tetracycline. Resistance to tetracycline in S. aureus isolates from beef was lower than that seen in isolates from chicken and pork (P < 0.01). This study revealed that the prevalence of MRSA and VRE were low in food-producing animals and retail domestic meats in Japan, although Campylobacter isolates resistant to fluoroquinolone and erythromycin were detected. The occurrence of antimicrobial-resistant pathogens should be monitored continuously to improve the management of the risks associated with antimicrobial drug resistance transferred from food-producing animals to humans.

Antimicrobial resistance of Campylobacter isolates from retail meat in the United States between 2002 and 2007

The emergence of antimicrobial resistance in Campylobacter spp. has been a growing public health concern globally. The objectives of this study were to determine the prevalence, antimicrobial susceptibility, and genetic relatedness of Campylobacter spp. recovered by the National Antimicrobial Resistance Monitoring System (NARMS) retail meat program. Retail meat samples (n = 24,566) from 10 U.S. states collected between 2002 and 2007, consisting of 6,138 chicken breast, 6,109 ground turkey, 6,171 ground beef, and 6,148 pork chop samples, were analyzed. A total of 2,258 Campylobacter jejuni, 925 Campylobacter coli, and 7 Campylobacter lari isolates were identified. Chicken breast samples showed the highest contamination rate (49.9%), followed by ground turkey (1.6%), whereas both pork chops and ground beef had <0.5% contamination. The most common resistance was to doxycycline/tetracycline (46.6%), followed by nalidixic acid (18.5%), ciprofloxacin (17.4%), azithromycin and erythromycin (2.8%), telithromycin (2.4%), clindamycin (2.2%), and gentamicin (<0.1%). In a subset of isolates tested, no resistance to meropenem and florfenicol was seen. C. coli isolates showed higher resistance rates to antimicrobials, with the exception of doxycycline/tetracycline, than those seen for C. jejuni. Pulsed-field gel electrophoresis (PFGE) fingerprinting resulted in 1,226 PFGE profiles among the 2,318 isolates, with many clones being widely dispersed throughout the 6-year sampling period.

Pediatric campylobacteriosis in northern Taiwan from 2003 to 2005

Background

There has been a marked increase in the incidence of, and concern regarding, human Campylobacter jejuni and C. coli infections worldwide during the last decade. As the highest infectious disease control apparatus in Taiwan, we aimed to describe the character of Campylobacter isolates from infected children, as well as basic information about the patients, from December 2003 to February 2005.

Methods

A total of 894 fecal specimens were collected by several clinics and hospitals from children who had diarrhea, followed by plating onto selective media. Drug susceptibility test of the isolates from these specimens were conducted by disc diffusion method and their serotypes were also studied using commercial antisera made in Japan.

Results

The isolation rate of Campylobacter during these 15 months was 6.8% and was higher in winter (11.1%) than in other seasons. C. jejuni was the most prevalent (95.1%) species in northern Taiwan, comparable to other developed countries. Among the 61 Campylobacter isolates, most were resistant to tetracycline (93.4%), nalidixic acid (91.8%), ciprofloxacin (90.2%), and ampicillin (85.5%). Erythromycin-resistant isolates represented 3.3% of all isolates, suggesting that this drug may be the first choice for treatment. The serotypes of the 61 isolates were demonstrated and only 41.4% were typable.

Conclusion

In this study, the Taiwan CDC provided an epidemiological analysis of Campylobacter infection, including the isolation rate, age, seasonal distribution, antimicrobial drug susceptibility patterns, and serotypes of the isolates from pediatric patients in northern Taiwan from 2003 to 2005.

Host-pathogen interactions in Campylobacter infections: the host perspective

Campylobacter is a major cause of acute bacterial diarrhea in humans worldwide. This study was aimed at summarizing the current understanding of host mechanisms involved in the defense against Campylobacter by evaluating data available from three sources: (i) epidemiological observations, (ii) observations of patients, and (iii) experimental observations including observations of animal models and human volunteer studies. Analysis of available data clearly indicates that an effective immune system is crucial for the host defense against Campylobacter infection. Innate, cell-mediated, and humoral immune responses are induced during Campylobacter infection, but the relative importance of these mechanisms in conferring protective immunity against reinfection is unclear. Frequent exposure to Campylobacter does lead to the induction of short-term protection against disease but most probably not against colonization. Recent progress in the development of more suitable animal models for studying Campylobacter infection has opened up possibilities to study the importance of innate and adaptive immunity during infection and in protection against reinfection. In addition, advances in genomics and proteomics technologies will enable more detailed molecular studies. Such studies combined with better integration of host and pathogen research driven by epidemiological findings may truly advance our understanding of Campylobacter infection in humans.

High-level resistance to trimethoprim in clinical isolates of Campylobacter jejuni by acquisition of foreign genes (dfr1 and dfr9) expressing drug-insensitive dihydrofolate reductases

The pathogenic bacterium Campylobacter jejuni has been regarded as endogenously resistant to trimethoprim. The genetic basis of this resistance was characterized in two collections of clinical isolates of C. jejuni obtained from two different parts of Sweden. The majority of these isolates were found to carry foreign dfr genes coding for resistant variants of the dihydrofolate reductase enzyme, the target of trimethoprim. The resistance genes, found on the chromosome, were dfr1 and dfr9. In about 10% of the strains, the dfr1 and dfr9 genes occurred simultaneously. About 10% of the examined isolates were found to be negative for these dfr genes and showed a markedly lower trimethoprim resistance level than the other isolates. The dfr9 and dfr1 genes were located in the context of remnants of a transposon and an integron, respectively. Two different surroundings for the dfr9 gene were characterized. One was identical to the right-hand end of the transposon Tn5393, and in the other, the dfr9 gene was flanked by only a few nucleotides of a Tn5393 sequence. The insertion of the dfr9 gene into the C. jejuni chromosome could have been mediated by Tn5393. The frequent occurrence of high-level trimethoprim resistance in clinical isolates of C. jejuni could be related to the heavy exposure of food animals to antibacterial drugs, which could lead to the acquisition of foreign resistance genes in naturally transformable strains of C. jejuni.

Antimicrobial susceptibilities of Campylobacter jejuni and coli by using E-test in Taiwan

To report the in vitro antibiotic susceptibility of Campylobacter species, we determined the MICs of 6 antibiotics by E-test for 93 human clinical strains and 35 chicken strains. The 6 antimicrobial agents tested were gentamicin, erythromycin, clindamycin, tetracycline, ciprofloxacin, and nalidixic acid. Isolates from humans were significantly more susceptible than chicken strains to erythromycin, clindamycin and ciprofloxacin. Nearly all of the human and chicken strains were susceptible to gentamicin. Among human isolates of C. jejuni, cross-resistance between nalidixic acid and ciprofloxacin was found in 66% of the strains, but none of the nalidixic acid-susceptible strains was resistant to ciprofloxacin. The higher prevalence of ciprofloxacin resistance in this area may be attributable to the large amount use of quinolones in poultry. Because of the high resistance rates of chicken isolates to the commonly used antimicrobial agents, it is necessary to create innovative methods to limit the inappropriate use of antibiotics in poultry in order to prevent the spread of the drug-resistant strains to humans.

Infectious Diarrhea

Infectious diarrhea constitutes a major source of morbidity and mortality for all age groups. The focus of this article is to identify high risk host and pathogenic risk determinants of enteric infections, discuss pathophysiologic mechanisms for diarrhea, review conventional and upcoming therapeutic managements of bacterial, protozoal or viral-type diarrhea, and describe the integral role of the pharmacist in the overall care of patients having this illness.

Susceptibilities of fluoroquinolone-resistant strains of Campylobacter jejuni to 11 oral antimicrobial agents

The resistance of Campylobacter jejuni strains to the fluoroquinolones is increasingly frequent, and in our area it reaches nearly 50%. We studied the susceptibilities of 60 of these strains to 11 oral antibiotics. All strains except one were susceptible to the macrolides tested, with azithromycin being the most active agent tested. Of the rest of the antibiotics studied, amoxicillin-clavulanic acid, clindamycin, and fosfomycin displayed good in vitro activities. Knowledge of the susceptibilities of these microorganisms to a varied group of oral agents is necessary in view of the appearance of multiresistant strains, such as those included in our series.

Control of infections in child care

The control of infections in child-care centres involves vaccination of children and staff, attention to hygiene (particularly to handwashing), exclusion of children (and employees) while infectious and/or grouping of infectious children, separation of toilet-trained children from those in nappies, and judicious use of antimicrobial agents and vaccination during outbreaks. By reporting cases of infectious diseases in patients with child-care contact to public health authorities, doctors can assist in controlling such diseases in child care.

Acute infectious diarrhea

Diarrhea continues to be a major cause of mortality and morbidity in third world countries as well as a major symptomatic complaint in the primary care setting in the United States. The etiologic pathogen depends on an exposure history to include recent travel to foreign countries, consuming fecally contaminated water or food, prior use of antibiotics, or homosexual behavior. A careful history from patients directed at attempting to identify particular risk factors may help in making a diagnosis. Not all patients require a diagnostic workup. A large number of patients may only require oral rehydration, careful observation over time with or without use of antimotility agents. In toxic appearing patients or patients with fever, however, bloody stools, abdominal pain or tenesmus, a selective diagnostic workup is indicated. Antimicrobial treatments are not always required, some pathogens clearly call for treatment while some have less clear indications and other pathogens are not responsive to antimicrobial agents at all. Finally, one needs to remember that the differential diagnosis of acute diarrhea includes many noninfectious origins.

Antimicrobial susceptibilities of Campylobacter jejuni and Campylobacter coli isolated in Sweden: a 10-year follow-up report

Resistance to erythromycin and doxycycline and more recently to fluoroquinolones has been reported to occur in Campylobacter spp. both in vitro and in patients treated with these antibiotics. The frequency of resistance to 14 antimicrobial agents in Campylobacter jejuni and Campylobacter coli isolated from patients infected in Sweden or abroad is described. For some agents, a comparison of susceptibility in strains of Campylobacter spp. isolated in 1978 with those isolated in 1988 is made. No general increase in in vitro resistance to antibiotics commonly used for the treatment of human gastroenteritis caused by C. jejuni or C. coli has occurred during the last 10 years in Sweden, which might be a consequence of strict antibiotic control. The numbers of strains from 1988 to 1989 resistant to ciprofloxacin and to norfloxacin included in this study (0.7 and 1.4%, respectively) are still fewer than those that were resistant to erythromycin (7.3%) or doxycycline (12.4%). There is, however, since 1989 to 1990 an indication of increasing resistance to these antibiotics.

Infectious Gastroenteritis

Infectious gastroenteritis currently constitutes the greatest source of morbidity and mortality among various age groups. Issues of focus for this article include establishing epidemiological determinants of risk for enteric infection, describing host factors that favor survival of the infecting enteric pathogen, defining pathophysiological mechanisms of diarrhea, and reviewing the therapeutic management of bacterial, protozoal, and viral infectious diarrhea.

Therapy for acute infectious diarrhea in children

This article reviews current recommendations of therapy with antidiarrheal compounds and antimicrobial agents for acute infectious diarrhea in children. In most infants and children with acute infectious diarrhea, treatment with antidiarrheal compounds is not indicated. Many of these compounds interfere with identification of enteropathogens in stool specimens, and the antimotility class has an overdose potential. Antimicrobial therapy is given to reduce symptoms and to prevent the spread of infection by decreasing fecal shedding of organisms. Although effective therapy is not available for patients with enteric viruses, Cryptosporidium, and Microsporidium, therapy is useful for children with amebiasis, antimicrobial-associated colitis, cholera, giardiasis, various forms of Escherichia coli diarrhea and Salmonella disease, isosporiasis, shigellosis, and strongyloidiasis. For several other conditions, antimicrobial therapy is of questionable benefit (infection with Campylobacter jejuni or Yersinia enterocolitica, intestinal salmonellosis and enterohemorrhagic E. coli infection). Compounds such as the fluoroquinolones, which are effective in the treatment of acute infectious diarrhea in adults, are not approved for use in children because of potential side effects. Many bacterial, viral, and parasitic organisms cause acute infectious diarrhea; appropriate antimicrobial therapy requires the accurate, rapid identification of the offending enteropathogen. In children with an underlying illness such as acquired immunodeficiency syndrome, manifestations may be prolonged, severe, and recurrent despite appropriate therapy.