Geoffrey A Preidis

Baylor College of Medicine | BCM · Department of Pediatrics

Background Many disorders of gut-brain interaction (DGBIs) are more prevalent in women than men and feature alterations in gastrointestinal motility and bile acid homeostasis. Mechanisms by which bile acids regulate gastrointestinal motility are poorly characterized. We recently validated an adapted tissue bath technique using everted mouse ileum,...

Background: In very low birth weight (VLBW) infants, human milk cream added to standard human milk fortification is used to improve growth. This study aimed to evaluate the impact of cream supplement on the intestinal microbiome of VLBW infants. Methods: Whole genome shotgun sequencing was performed on stool (n = 57) collected from a cohort of 2...

Importance Systematic reviews and meta-analyses often report conflicting results when assessing evidence for probiotic efficacy, partially because of the lack of understanding of the unique features of probiotic trials. As a consequence, clinical decisions on the use of probiotics have been confusing. Objective To provide recommendations to improv...

Background Early‐life events impact maturation of the gut microbiome, enteric nervous system, and gastrointestinal motility. We examined three regions of gastric tissue to determine how maternal separation and gut microbes influence the structure and motor function of specific regions of the neonatal mouse stomach. Methods Germ‐free and convention...

This Viewpoint outlines a framework for optimizing probiotic product stringency and use in the neonatal intensive care unit.

Growth failure is among the most prevalent and devastating consequences of prematurity. Up to half of all extremely preterm neonates struggle to grow despite modern nutrition practices. Although elegant preclinical models suggest causal roles for the gut microbiome, these insights have not yet translated into biomarkers that identify at-risk neonat...

Plain Language Summary What is the context? Probiotics, available to healthy consumers as both dietary supplements and foods, are also used by some patient populations. The goal of this paper is to determine if any new factors have emerged that would impact current views about probiotic safety for both these populations. What is new? The authors co...

Cholestasis refers to impaired bile flow from the liver to the intestine. In neonates, cholestasis causes poor growth and may progress to liver failure and death. Normal bile flow requires an intact liver-gut-microbiome axis, whereby liver-derived primary bile acids are transformed into secondary bile acids. Microbial bile salt hydrolase (BSH) enzy...

Objectives: Preterm infants are born functionally pancreatic insufficient with decreased pancreatic production of lipase and proteases. Developmental pancreatic insufficiency (PI) may contribute to reduced nutrient absorption and growth failure. We sought to determine longitudinal fecal elastase (ELA1) levels in a cohort of preterm infants and whe...

The human gastrointestinal (GI) tract harbors a rich and diverse community of organisms referred to as the microbiota. The microbiota contain an even more complex sum of genetic material. This microbiome (trillions of gut microbes and their gene repertoires) contributes to a wide variety of functions critical for intestinal and host health includin...

Acute malnutrition, or wasting, is implicated in over half of all deaths in children under five and increases risk of infectious disease. Studies in humans and preclinical models have demonstrated that malnutrition is linked to an immature intestinal microbiota characterized by increased prevalence of Enterobacteriaceae. Observational studies in ch...

The nutrient sensing nuclear receptor peroxisome proliferator-activated receptor-α (PPARα) regulates the host response to short-term fasting by inducing hepatic transcriptional programming of ketogenesis, fatty acid oxidation and transport, and autophagy. This adaptation is ineffective in chronically undernourished individuals, among whom dyslipide...

Individuals who are minoritized as a result of race, sexual identity, gender, or socioeconomic status experience a higher prevalence of many diseases. Understanding the biological processes that cause and maintain these socially driven health inequities is essential for addressing them. The gut microbiome is strongly shaped by host environments and...

To gain insights into mechanisms underlying coagulopathy in malnutrition, we fed mice a low-protein, low-fat diet and assessed hepatic gene expression and plasma coagulation indices. Malnourished males were affected more profoundly than females, and exhibited coagulopathy, decreased expression of fibrinogen-alpha and factor 11, decreased FXR activa...

The early stages of the metagenomics era produced countless observational studies linking various human diseases to alterations in the gut microbiota. Only recently have we begun to decipher the causal roles that gut microbes play in many of these conditions. Despite an incomplete understanding of how gut microbes influence pathophysiology, clinica...

In this commentary, we summarize the current evidence from randomized controlled trials on enteral lactoferrin supplementation in preterm neonates. Our recently completed systematic review includes 12 randomized controlled trials performed all over the world. Our meta-analysis suggests clinical benefit in decreasing late-onset sepsis, late-onset fu...

Background Slow gastrointestinal (GI) transit occurs in moderate‐to‐severe malnutrition. Mechanisms underlying malnutrition‐associated dysmotility remain unknown, partially due to lack of animal models. This study sought to characterize GI dysmotility in mouse models of malnutrition. Methods Neonatal mice were malnourished by timed maternal separa...

Background and aims We aimed to compare the effectiveness of single- vs multiple-strain probiotics in a network meta-analysis of randomized trials. Methods We searched MEDLINE, EMBASE, Science Citation Index Expanded, CINAHL, Scopus, Cochrane CENTRAL, BIOSIS Previews, and Google Scholar through January 1, 2019 for studies of single-strain and mult...

Background An important limitation of gastrointestinal motility testing is high variability. Conditions that could contribute to variability, including the duration of pretest fasting and time of day, are rarely reported and have not been examined systematically. This study aimed to explore whether these conditions, as well as age, sex, and strain...

Background Mother's own milk (MOM) is protective against gut microbiota alterations associated with necrotizing enterocolitis (NEC) and feeding intolerance among preterm infants. It is unclear whether this benefit is preserved with donor milk (DM) feeding. Objective We aimed to compare microbiota development, growth, and feeding tolerance in very-...

The volume of research into pathogenesis and treatment of malnutrition has increased markedly over the past ten years, providing mechanistic insights that can be leveraged into more effective treatment options. These discoveries have been driven by several landmark studies employing metabolomics, metagenomics, and new preclinical models. This revie...

Background Folate and choline are essential methyl donor nutrients throughout the life span; however, the adverse effects of combined deficiency on early growth, intestinal epithelial morphology, and the gut microbiome remain only partially understood. Objectives We investigated the effects of dietary folate and choline deficiency on early growth,...

The volume of research into the pathogenesis and treatment of malnutrition has increased markedly over the past ten years, providing mechanistic insights that can be leveraged into more effective treatment options. These discoveries have been driven by several landmark studies employing metabolomics, metagenomics, and new preclinical models. This r...

The importance of gut microbiota in gastrointestinal (GI) physiology was well described, but our ability to study gut microbial ecosystems in their entirety was limited by culture-based methods prior to the sequencing revolution. The advent of high-throughput sequencing opened new avenues, allowing us to study gut microbial communities as an aggreg...

The nuclear receptors PPARα (encoded by NR1C1) and farnesoid X receptor (FXR, encoded by NR1H4) are activated in the liver in the fasted and fed state, respectively. PPARα activation induces fatty acid oxidation, while FXR controls bile acid homeostasis, but both nuclear receptors also regulate numerous other metabolic pathways relevant to liver en...

Undernutrition remains one of the most pressing global health challenges today, contributing to nearly half of all deaths in children under five years of age. Although insufficient dietary intake and environmental enteric dysfunction are often inciting factors, evidence now suggests that unhealthy gut microbial populations perpetuate the vicious cy...

Gut microbes are essential to the normal development and function of the enteric nervous system and gastrointestinal tract. The simple microbiome of infancy gradually matures into a rich and diverse adult intestinal microbial ecosystem that supports the development of normal sensorimotor function. Microbial factors that modulate intestinal motility...

Background: Protein-energy undernutrition during early development confers a lifelong increased risk of obesity-related metabolic disease. Mechanisms by which metabolic abnormalities persist despite catch-up growth are poorly understood. Objective: We sought to determine whether abnormal metabolomic and intestinal microbiota profiles from undern...

Undernutrition remains one of the key global health challenges facing children today. Distinct microbial profiles have been associated with obesity and undernutrition, although mechanisms behind these associations are unknown. We sought to understand how protein-energy undernutrition alters the microbiome and to propose mechanisms by which these al...

The international Human Microbiome Project trumpeted the coming of age of the field of metagenomics, the study of entire communities of microbes and their contributions to health and disease. In parallel, the field of metabolomics emerged as the systematic, nonbiased analysis of all low-molecular-weight small molecules, or metabolites, produced by...

Background Early identification and entry into care is critical to reducing morbidity and mortality in children with HIV. The objective of this report is to describe the impact of the Tingathe programme, which utilizes community health workers (CHWs) to improve identification and enrolment into care of HIV‐exposed and ‐infected infants and children...

Strategies to effectively identify and refer children with severe acute malnutrition (SAM) to Nutritional Rehabilitation units (NRU) can reduce morbidity and mortality. From December 2011 to May 2012, we conducted a prospective study task-shifting inpatient malnutrition screening of Malawian children 6-60 months to lay-screeners and evaluated World...

Background: Pulmonary tuberculosis contributes to increased morbidity and mortality in severely malnourished children in endemic settings. Despite high clinical suspicion, few tuberculosis prevalence estimates exist in malnourished African children. Diagnostics such as Xpert MTB/RIF may help to determine pulmonary tuberculosis prevalence, however...

Objective: The objective of this study is to evaluate the impact of the HIV Infant Tracking System (HITSystem) for quality improvement of early infant diagnosis (EID) of HIV services. Design and Setting: This observational pilot study compared 12 months of historical preintervention EID outcomes at one urban and one peri-urban government hospital i...

An analysis of 570 HIV-infected women in Swaziland using the Jadelle implant showed that age, condom use, which provider placed the implant, and CD4 cell count had no effect on unintentional pregnancy rates. However, antiretroviral regimen at the time of pregnancy correlated with pregnancy outcomes (P <0.001). None of the women on nevirapine or lop...

Undernutrition contributes to half of all childhood deaths under the age of 5 y, and confers upon survivors a life-long predisposition to obesity, type 2 diabetes, and cardiovascular disease. Mechanisms underlying the link between early nutrient deprivation and noncommunicable diseases are unknown. Using outbred CD1 neonatal mice, we measured metab...

Many African infants fail to receive their diagnostic HIV molecular test results and subsequently, antiretroviral therapy (ART). To determine whether a point-of-care molecular HIV test increases ART access for hospitalized Malawian infants, we simulated a point-of-care test using rapid HIV RNA polymerase chain reaction (Rapid PCR) and compared pati...

BACKGROUND: Although pneumonia is the leading cause of child mortality worldwide, little is known about the quality of routine pneumonia care in high burden settings like Malawi that utilize World Health Organization's Integrated Management of Childhood Illnesses (IMCI) guidelines. Due to severe human resource constraints, the majority of clinical...

To develop a new paediatric illness severity score, called inpatient triage, assessment and treatment (ITAT), for resource-limited settings to identify hospitalised patients at highest risk of death and facilitate urgent clinical re-evaluation. We performed a nested case-control study at a Malawian referral hospital. The ITAT score was derived from...

The Tingathe program utilizes community health workers to improve prevention of mother-to-child transmission (PMTCT) service delivery. We evaluated the impact of antiretroviral (ARV) regimen and maternal CD4+ count on HIV transmission within the Tingathe program in Lilongwe, Malawi. We reviewed clinical records of 1088 mother-infant pairs enrolled...

Although hypoxemic children have high mortality, little is known about hypoxemia prevalence and oxygen administration in African hospitals. We aimed to determine the hypoxemia prevalence and quality of oxygen treatment by local clinicians for hospitalized Malawian children. The study was conducted in five Malawian hospitals during January-April 201...

Objective: We aimed to improve paediatric inpatient surveillance at a busy referral hospital in Malawi with two new programmes: (i) the provision of vital sign equipment and implementation of an inpatient triage programme (ITAT) that includes a simplified paediatric severity-of-illness score, and (ii) task shifting ITAT to a new cadre of healthcar...

Objective: To determine how routine inpatient provider-initiated HIV testing differs from traditional community-based client-initiated testing with respect to clinical characteristics of children identified and outcomes of outpatient HIV care. Design: Prospective observational cohort. Methods: Routine clinical data were collected from children...

Purpose: Malnutrition is a leading cause of mortality among children in sub-Saharan Africa. In Malawi, 3% of children under five are severely malnourished. At Kamuzu Central Hospital (KCH) in Lilongwe, Malawi, malnutrition screening is not routinely performed on the pediatric wards. Patients suspected of malnutrition at admission are referred direc...

Objectives: Beneficial microbes and probiotics are promising agents for the prevention and treatment of enteric and diarrheal diseases in children; however, little is known about their in vivo mechanisms of action. We used a neonatal mouse model of rotavirus diarrhea to gain insight into how probiotics ameliorate acute gastroenteritis. Methods: Rot...

Loss to follow-up is a major challenge in the prevention of mother to child transmission of HIV (PMTCT) programme in Malawi with reported loss to follow-up of greater than 70%. Tingathe-PMTCT is a pilot intervention that utilizes dedicated community health workers (CHWs) to create a complete continuum of care within the PMTCT cascade, improving ser...

Beneficial microbes and probiotics show promise for the treatment of pediatric gastrointestinal diseases. However, basic mechanisms of probiosis are not well understood, and most investigations have been performed in germ-free or microbiome-depleted animals. We sought to functionally characterize probiotichost interactions in the context of normal...

Beneficial microbes and probiotics are promising agents for the prevention and treatment of enteric and diarrheal diseases in children; however, little is known about their in vivo mechanisms of action. We used a neonatal mouse model of rotavirus diarrhea to gain insight into how probiotics ameliorate acute gastroenteritis. Rotavirus-infected mice...

Beneficial microbes and probiotics show promise for the treatment of pediatric gastrointestinal diseases. However, basic mechanisms of probiosis are not well understood, and most investigations have been performed in germ-free or microbiome-depleted animals. We sought to functionally characterize probiotic-host interactions in the context of normal...

To identify clinical characteristics predicting death among inpatients who are infected with or exposed to human immunodeficiency virus (HIV) during a period of pediatric antiretroviral therapy scale-up in sub-Saharan Africa. Retrospective review of medical records from every child with HIV infection (n = 834) or exposure (n = 351) identified by ro...

Routine Human Immunodeficiency Virus (HIV) testing, called provider-initiated opt-out HIV testing and counseling (PITC), is recommended in African countries with high HIV prevalence. However, it is unknown whether PITC increases access to pediatric HIV care. In 2008, the Baylor International Pediatric AIDS Initiative implemented PITC (BIPAI-PITC) a...

This review explores the abilities of beneficial microbes including probiotics to stimulate mucosal and systemic immunity, so that global vaccination strategies may be enhanced. Beneficial microbes secrete microbial factors and express cell surface features that stimulate different types of immune cells to alter their gene expression programs and p...

The HIV/AIDS pandemic disproportionately afflicts regions of the world that have minimal access to formal schooling and low literacy rates. Health educational interventions are difficult to evaluate efficiently in these settings because standard approaches such as written questionnaires cannot easily be employed. Here, we describe a novel method of...

Inpatient Pediatric PITC Program - Orientation. Pediatric department and inpatient pediatric PITC staff orientation presentation. Baylor International Pediatric AIDS Initiative PowerPoint slides 1–7. (9.77 MB TIF)

Diagnosis of Pediatric HIV Infection Training. Presentation to train the inpatient pediatric PITC program staff in pediatric HIV diagnosis. Baylor International Pediatric AIDS Initiative PowerPoint slides 1–6. (7.67 MB TIF)

Diagnosis of Pediatric HIV Infection Training. Presentation to train the inpatient pediatric PITC program staff in pediatric HIV diagnosis. Baylor International Pediatric AIDS Initiative PowerPoint slides 25–29. (6.51 MB TIF)

Diagnosis of Pediatric HIV Infection Training - Diagnosis Workshop Session. A small group session to train the inpatient pediatric PITC program staff in pediatric HIV diagnosis. Includes Baylor International Pediatric AIDS Initiative facilitator and participant materials for workshop session. (0.85 MB TIF)

Inpatient Pediatric PITC Program - Patient Escort Training. Presentation to train patient escorts in their roles and responsibilities within the inpatient pediatric PITC program. Baylor International Pediatric AIDS Initiative PowerPoint slides 1–4. (7.55 MB TIF)

Inpatient Pediatric PITC Program - Patient Escort Training. Presentation to train patient escorts in their roles and responsibilities within the inpatient pediatric PITC program. Baylor International Pediatric AIDS Initiative PowerPoint slides 5-8. (4.96 MB TIF)

Diagnosis of Pediatric HIV Infection Training. Presentation to train the inpatient pediatric PITC program staff in pediatric HIV diagnosis. Baylor International Pediatric AIDS Initiative PowerPoint slides 7–12. (6.95 MB TIF)

Diagnosis of Pediatric HIV Infection Training. Presentation to train the inpatient pediatric PITC program staff in pediatric HIV diagnosis. Baylor International Pediatric AIDS Initiative PowerPoint slides 13–18. (7.75 MB TIF)

Diagnosis of Pediatric HIV Infection Training. Presentation to train the inpatient pediatric PITC program staff in pediatric HIV diagnosis. Baylor International Pediatric AIDS Initiative PowerPoint slides 19–24. (7.81 MB TIF)

Inpatient Pediatric PITC Program - Manual of Procedures. A detailed description of inpatient pediatric PITC program procedures, recommended staffing levels, suggested budget, and program materials. (8.80 MB TIF)

Inpatient Pediatric PITC Program - Register. A confidential inpatient pediatric PITC program register for routine program monitoring and linkage of HIV-infected and HIV-exposed patients to inpatient clinical care. (1.66 MB TIF)

Inpatient Pediatric PITC Program - Overview. A one page overview outlining the eight steps that comprise the Baylor International Pediatric AIDS Initiative inpatient pediatric PITC system. (0.26 MB TIF)

Inpatient Pediatric PITC Program - Orientation. Pediatric department and inpatient pediatric PITC staff orientation presentation. Baylor International Pediatric AIDS Initiative PowerPoint slides 14–20. (8.73 MB TIF)

Inpatient Pediatric PITC Program - Orientation. Pediatric department and inpatient pediatric PITC staff orientation presentation. Baylor International Pediatric AIDS Initiative PowerPoint slides 8–13. (9.57 MB TIF)

This study evaluated two models of routine HIV testing of hospitalized children in a high HIV-prevalence resource-constrained African setting. Both models incorporated "task shifting," or the allocation of tasks to the least-costly, capable health worker.Two models were piloted for three months each within the pediatric department of a referral hos...

Studies of metagenomics and the human microbiome will tremendously expand our knowledge of the composition of microbial communities in the human body. As our understanding of microbial variation and corresponding genetic parameters is refined, this information can be applied to rational remodeling or "tailoring" of human-associated microbial commun...

Traditional approaches to preventative education are often unfeasible in high-risk, low-literacy populations, not only because many interventions rely on the printed word, but also because of the difficulty in efficiently evaluating programs without written questionnaires or resource-intensive interviews. A community-based HIV/AIDS drama-in-educati...

Water-borne illness is a leading cause of mortality among children throughout the developing world, and accounts for significant morbidity among all age groups, especially those living with HIV. The transmission of enteric pathogens is directly related to water access, water quality, and hygiene. In Haiti, the nation ranked last in the Water Povert...

Cryptosporidiosis is an important cause of diarrhea worldwide. In normal hosts, infection is self-limited and associated with seroconversion and partial immunity to reinfection. Immunity is associated with interferon gamma (IFNgamma) production. Cryptosporidium surface proteins gp15 and gp40 are among the immunodominant proteins in terms of antibod...

Historically, CD4 and CD8 antigens have been used to designate functionally distinct T-lymphocyte subsets. However, these antigens also have been described on macrophages in the normal and pathologic central nervous system (CNS). Signaling through CD4 or CD8 may impart unique functions in macrophage subsets that express these antigens. In the curre...