Microbiology and management of intra‐abdominal infections in children

Brook, Itzhak

doi:10.1046/j.1442-200x.2003.01701.x

Cited by 34 publications

(16 citation statements)

References 51 publications

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“…As in adults, Bacteroides isolates are most predominant in infections that have an intra-abdominal origin; normally present in the GI tract, these organisms may enter the peritoneal cavity due to a disturbance such as perforation, obstruction, or direct trauma. A few studies evaluating the microbiology of the peritoneal cavity and postoperative wounds in children following perforated appendix in pediatric patients found that Bacteroides species were recovered from 93% of peritoneal fluids, along with enteric gram-negative bacteria and enterococci (38). Complications following peritonitis may include subphrenic, hepatic, splenic, and retroperitoneal abscesses (39) (which may occur secondary to appendicitis), necrotizing enterocolitis, pelvic inflammatory disease, tubo-ovarian infection, surgery, or trauma (39).…”

Section: Anaerobes In Pediatric Infectionsmentioning

confidence: 99%

Bacteroides: the Good, the Bad, and the Nitty-Gritty

2007

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SUMMARY Summary: Bacteroides species are significant clinical pathogens and are found in most anaerobic infections, with an associated mortality of more than 19%. The bacteria maintain a complex and generally beneficial relationship with the host when retained in the gut, but when they escape this environment they can cause significant pathology, including bacteremia and abscess formation in multiple body sites. Genomic and proteomic analyses have vastly added to our understanding of the manner in which Bacteroides species adapt to, and thrive in, the human gut. A few examples are (i) complex systems to sense and adapt to nutrient availability, (ii) multiple pump systems to expel toxic substances, and (iii) the ability to influence the host immune system so that it controls other (competing) pathogens. B. fragilis, which accounts for only 0.5% of the human colonic flora, is the most commonly isolated anaerobic pathogen due, in part, to its potent virulence factors. Species of the genus Bacteroides have the most antibiotic resistance mechanisms and the highest resistance rates of all anaerobic pathogens. Clinically, Bacteroides species have exhibited increasing resistance to many antibiotics, including cefoxitin, clindamycin, metronidazole, carbapenems, and fluoroquinolones (e.g., gatifloxacin, levofloxacin, and moxifloxacin).

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Section: Anaerobes In Pediatric Infectionsmentioning

confidence: 99%

Bacteroides: the Good, the Bad, and the Nitty-Gritty

2007

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“…For example, Haemophilus influenza and Neisseria meningitidis are commensal bacteria of the upper respiratory tract that can cause life-threatening diseases once they invade their host (11)(12)(13)(14)(15)(16). Upon host entry, H. influenza and N. meningitidis replicate in the blood stream, resulting in a steadily increasing bacteremia within hours after infection (12,(17)(18)(19).…”

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confidence: 99%

Protozoan predation, diversifying selection, and the evolution of antigenic diversity in Salmonella

Wildschutte

Wolfe

Tamewitz

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

147

142

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Extensive population-level genetic variability at the Salmonella rfb locus, which encodes enzymes responsible for synthesis of the O-antigen polysaccharide, is thought to have arisen through frequency-dependent selection (FDS) by means of exposure of this pathogen to host immune systems. The FDS hypothesis works well for pathogens such as Haemophilus influenzae and Neisseria meningitis, which alter the composition of their O-antigens during the course of bloodborne infections. In contrast, Salmonella remains resident in epithelial cells or macrophages during infection and does not have phase variability in its O-antigen. More importantly, Salmonella shows host-serovar specificity, whereby strains bearing certain O-antigens cause disease primarily in specific hosts; this behavior is inconsistent with FDS providing selection for the origin or maintenance of extensive polymorphism at the rfb locus. Alternatively, selective pressure may originate from the host intestinal environment itself, wherein diversifying selection mediated by protozoan predation allows for the continued existence of Salmonella able to avoid consumption by host-specific protozoa. This selective pressure would result in high population-level diversity at the Salmonella rfb locus without phase variation. We show here that intestinal protozoa recognize antigenically diverse Salmonella with different efficiencies and demonstrate that differences solely in the O-antigen are sufficient to allow for prey discrimination. Combined with observations of the differential distributions of both serotypes of bacterial species and their protozoan predators among environments, our data provides a framework for the evolution of high genetic diversity at the rfb locus and host-specific pathogenicity in Salmonella.T he enteric pathogen Salmonella enterica presents at least 70 different O-antigens [the outermost structure of the Gramnegative lipopolysaccharide (LPS)] to mammalian immune systems (1); this polysaccharide decorates the outer surface of the cell. Historically, extensive genetic diversity at the rfb locus, which encodes enzymes directing O-antigen synthesis (2-6), has been attributed to frequency-dependent selection (FDS) (7,8) imposed by the host immune system (5, 9, 10). Novel rfb loci would have an advantage because their cognate O-antigens would be unrecognized by immune systems (Fig. 1A); strains carrying rare loci would have higher fitness and would avoid rapid stochastic loss, rising to higher frequency. Yet selective advantages decrease with abundance; as a result, strains with common rfb loci cannot dominate the population or elicit a selective sweep (7) because their fitnesses become lower as they become more abundant. In concert, FDS prevents the loss of rare alleles or the dominance of common alleles, thus maintaining diversity (8).According to the FDS model, expression of different LPS molecules through gene regulation allows invading bacteria to escape host immunity, survive, and proceed throughout its life cycle; this hypothesis explains...

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“…Similar Þ ndings were corroborated by previous studies. [15,16] Although the reports of ileal perforations are many, studies showing aetiological diagnosis conÞ rmed by culture of blood sample or lymph node aspirate or ulcer edge or peritoneal ß uid are scarce. [15] The APACHE II score is of value in predicting outcome and in stratiÞ cation of patients with intra-abdominal infection as it is independently associated with the rate of mortality.…”

Section: Discussionmentioning

confidence: 99%

Role of enteric fever in ileal perforations: An overstated problem in tropics?

Capoor¹,

Nair²,

Chintamani³

et al. 2008

Indian J Med Microbiol

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Purpose: To determine the role of enteric fever in ileal perforations. Methods: A prospective cohort of 47 patients of ileal perforation was subjected to clinical examination and investigations for APACHE II scoring. Blood, ulcer edge biopsy, mesenteric lymph node and peritoneal aspirate were subjected to culture to determine the predominant aerobic bacterial isolate and its antibiogram. Results: Seven patients (14.9%) required intensive care and seven (14.9%) developed septicaemia. Mortality was 17%. Highest isolation rate was seen in ulcer edge (70.2%) followed by lymph node (66%) culture. The bacterial spectrum was Escherichia coli (23.4%), Enterococcus faecalis (21.3%), Salmonella enterica serovar Typhi (6.3%), Salmonella enterica serovar Paratyphi A (4.2%), etc. Conclusions: Enteric fever organisms are not the predominant causative agents of ileal perforations. Culture of ulcer edge biopsy, lymph node is crucial for aetiological diagnosis. The use of APACHE II triaging and prescription of antimicrobials based on the local pattern of susceptibility proÞ le of the aetiological agent is recommended.

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Microbiology and management of intra‐abdominal infections in children

Cited by 34 publications

References 51 publications

Bacteroides: the Good, the Bad, and the Nitty-Gritty

Bacteroides: the Good, the Bad, and the Nitty-Gritty

Protozoan predation, diversifying selection, and the evolution of antigenic diversity in Salmonella

Role of enteric fever in ileal perforations: An overstated problem in tropics?

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