Defining causality in emerging agents of acute bacterial diarrheas: a step beyond the Koch’s postulates

Repertoire of human breast and milk microbiota: a systematic review

Breastfeeding is a major determinant of human health. Breast milk is not sterile and ecological large-scale sequencing methods have revealed an unsuspected microbial diversity that plays an important role. However, microbiological analysis at the species level has been neglected while it is a prerequisite before understanding which microbe is associated with symbiosis or dysbiosis, and health or disease. We review the currently known bacterial repertoire from the human breast and milk microbiota using a semiautomated strategy. Total 242 articles from 38 countries, 11,124 women and 15,489 samples were included. Total 820 species were identified mainly composed of Proteobacteria and Firmicutes. We report variations according to the analytical method (culture or molecular method), the anatomical site (breast, colostrum or milk) and the infectious status (healthy control, mastitis, breast abscess, neonatal infection). In addition, we compared it with the other human repertoires. Finally, we discuss its putative origin and role in health and disease.

A systematic review for pursuing the presence of antibiotic associated enterocolitis caused by methicillin resistant Staphylococcus aureus

BACKGROUND

Although it has received a degree of notoriety as a cause for antibiotic-associated enterocolitis (AAE), the role of methicillin resistant Staphylococcus aureus (MRSA) in the pathogenesis of this disease remains enigmatic despite a multitude of efforts, and previous studies have failed to conclude whether MRSA can cause AAE. Numerous cases of AAE caused by MRSA have been reported from Japan; however, due to the fact that these reports were written in the Japanese language and a good portion lacked scientific rigor, many of these reports went unnoticed.

METHODS

We conducted a systematic review of pertinent literatures to verify the existence of AAE caused by MRSA. We modified and applied methods in common use today and used a total of 9 criteria to prove the existence of AAE caused by Klebsiella oxytoca. MEDLINE/Pubmed, Excerpta Medica Database (EMBASE), the Cochrane Database of Systematic Reviews, and the Japan Medical Abstract Society database were searched for studies published prior to March 2013.

RESULTS

A total of 1,999 articles were retrieved for evaluation. Forty-five case reports/series and 9 basic studies were reviewed in detail. We successfully identified articles reporting AAE with pathological and microscopic findings supporting MRSA as the etiological agent. We also found comparative studies involving the use of healthy subjects, and studies detecting probable toxins. In addition, we found animal models in which enteritis was induced by introducing MRSA from patients. Although we were unable to identify a single study that encompasses all of the defined criteria, we were able to fulfill all 9 elements of the criteria by collectively analyzing multiple studies.

CONCLUSIONS

AAE caused by MRSA-although likely to be rarer than previous Japanese literatures have suggested-most likely does exist.

Asymptomatic viral gastrointestinal infection: the missing link?

We present the case of an 8-month-old boy who presented with apparent life-threatening events later characterized as seizures in clusters. A total of 14 apneic episodes were observed within 24 hours before loading the patient with phenobarbital at which point the seizures stopped. There was no obvious explanation for his seizures. EEG revealed midline interictal discharges; MRI-head was normal; and all other investigations were normal. The patient's stool was sent for virology with the clinical suspicion of benign infantile seizures associated with mild gastroenteritis (BISMG) despite lack of gastrointestinal symptoms. A small round virus was found. His clinical course followed the same progression as typical BISMG. This begs the question whether it is possible for virus in the stool to cause an asymptomatic gastrointestinal infection with its only clinical manifestation as seizures. We conclude that it may be possible for BISMG to present without gastrointestinal symptoms. As well, BISMG may be an unrecognized cause of apparent life-threatening events and should be considered in the differential diagnosis.

The cystic fibrosis airway microbiome

PURPOSE OF REVIEW

Culture and molecular approaches have established that lower airway infections are polymicrobial. We consider how this new perspective in cystic fibrosis (CF) may affect treatment choices.

RECENT FINDINGS

Standard clinical microbiology of CF infection exacerbations often fails to provide indications of microbial causes that may drive the onset of exacerbation and the anticipated bacteriologic responses to the usual parenteral antibiotics prescribed as treatment. Antimicrobial responses by nonclassical members of the CF airway microbiome may explain why most patients clinically improve. These other organisms contribute to disease either directly as pathogens missed by conventional microbiology or through synergy with conventional pathogens. With these considerations, therapy may best be guided by directed antibiotic therapy to numerically significant isolates. An example is the Streptococcus milleri group, which we now believe to represent new pathogens that profile the exacerbations of infection in the CF lung and that necessitate specific antibiotic therapy to prevent loss of lung function and reduce frequency of exacerbations.

SUMMARY

A comprehensive understanding of airway infections offers the potential for improved disease management in CF patients. Accurate quantitative microbiology will be a prerequisite for routine intervention based on the polymicrobial perspective of CF infection exacerbations.

Intelligibility in microbial complex systems: Wittgenstein and the score of life

Knowledge in microbiology is reaching an extreme level of diversification and complexity, which paradoxically results in a strong reduction in the intelligibility of microbial life. In our days, the "score of life" metaphor is more accurate to express the complexity of living systems than the classic "book of life." Music and life can be represented at lower hierarchical levels by music scores and genomic sequences, and such representations have a generational influence in the reproduction of music and life. If music can be considered as a representation of life, such representation remains as unthinkable as life itself. The analysis of scores and genomic sequences might provide mechanistic, phylogenetic, and evolutionary insights into music and life, but not about their real dynamics and nature, which is still maintained unthinkable, as was proposed by Wittgenstein. As complex systems, life or music is composed by thinkable and only showable parts, and a strategy of half-thinking, half-seeing is needed to expand knowledge. Complex models for complex systems, based on experiences on trans-hierarchical integrations, should be developed in order to provide a mixture of legibility and imageability of biological processes, which should lead to higher levels of intelligibility of microbial life.

Gianotti-Crosti syndrome, pityriasis rosea, asymmetrical periflexural exanthem, unilateral mediothoracic exanthem, eruptive pseudoangiomatosis, and papular-purpuric gloves and socks syndrome: a brief review and arguments for diagnostic criteria

Several exanthems including Gianotti-Crosti syndrome, pityriasis rosea, asymmetrical periflexural exanthem, eruptive pseudoangiomatosis, and papular-purpuric gloves and socks syndrome are suspected to be caused by viruses. These viruses are potentially dangerous. Gianotti-Crosti syndrome is related to hepatitis B virus infection which is the commonest cause of hepatocellular carcinoma, and Epstein-Barr virus infection which is related to nasopharyngeal carcinoma. Pityriasis rosea has been suspected to be related to human herpesvirus 7 and 8 infections, with the significance of the former still largely unknown, and the latter being a known cause of Kaposi's sarcoma. Papular-purpuric gloves and socks syndrome is significantly associated with human B19 erythrovirus infection which can lead to aplastic anemia in individuals with congenital hemoglobinopathies, and when transmitted to pregnant women, can cause spontaneous abortions and congenital anomalies. With viral DNA sequence detection technologies, false positive results are common. We can no longer apply Koch's postulates to establish cause-effect relationships. Biological properties of some viruses including lifelong latent infection, asymptomatic shedding, and endogenous reactivation render virological results on various body tissues difficult to interpret. We might not be able to confirm or refute viral causes for these rashes in the near future. Owing to the relatively small number of patients, virological and epidemiology studies, and treatment trials usually recruit few study and control subjects. This leads to low statistical powers and thus results have little clinical significance. Moreover, studies with few patients are less likely to be accepted by mainstream dermatology journals, leading to publication bias. Aggregation of data by meta-analyses on many studies each with a small number of patients can theoretically elevate the power of the results. Techniques are also in place to compensate for publication bias. However, these are not currently feasible owing to different inclusion and exclusion criteria in clinical studies and treatment trials. The diagnoses of these rashes are based on clinical assessment. Investigations only serve to exclude important differential diagnoses. A wide spectrum of clinical features is seen, and clinical features can vary across different populations. The terminologies used to define these rashes are confusing, and even more so are the atypical forms and variants. Previously reported virological and epidemiological results for these rashes are conflicting in many aspects. The cause of such incongruence is unknown, but low homogeneity during diagnosis and subject recruitment might be one of the factors leading to these incongruent results. The establishment and proper validation of diagnostic criteria will facilitate clinical diagnosis, hasten recruitment into clinical studies, and allow results of different studies to be directly compared with each another. Meta-analyses and systematic reviews would be more valid. Diagnostic criteria also streamline clinical audits and surveillance of these diseases from community perspectives. However, over-dependence on diagnostic criteria in the face of conflicting clinical features is a potential pitfall. Clinical acumen and the experience of the clinicians cannot be replaced by diagnostic criteria. Diagnostic criteria should be validated and re-validated in response to the ever-changing manifestations of these intriguing rashes. We advocate the establishment and validation of diagnostic criteria of these rashes. We also encourage the ongoing conduction of studies with a small number of patients. However, for a wider purpose, these studies should recruit homogenous patient groups with a view towards future data aggregation.