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Neonatal Infections: A Global Perspective

Acknowledgment The authors are grateful to Dr. Danyal Thaver for excellent assistance with article references and editing of this chapter. Among the greatest challenges in global public health are to eliminate the gaps between high- and low-income countries in health care resources, provide access to preventive and curative services, and improve health outcomes. Although child and infant mortality burden has declined substantially in recent decades, neonatal…

Current Concepts of Infections of the Fetus and Newborn Infant

Overview Current concepts of pathogenesis, microbiology, diagnosis, and management of infections of the fetus and newborn are reviewed in this chapter with the goal of providing a brief synthesis and overview. Information within this chapter regarding specific infections or syndromes is illustrative only. Detailed discussions are provided in the subsequent sections, to which the reader should refer to gain the more comprehensive knowledge needed to properly…

Bacteremia

What Is Bacteremia? Human blood is supposed to be a sterile environment. Bacteremia is defined as the presence and detection of bacteria in blood. The body has several defense mechanisms against this, mainly barrier and immunologic defenses. There are several ways in which bacteria can enter the bloodstream. Bacteria can compromise the internal mucosal barrier of the body when the integrity of the gastrointestinal tract is…

HIV Infection

Introduction Human immunodeficiency virus (HIV) infection in the United States has evolved over the past three decades from an untreatable illness that predictably led to death to a chronic disease that can be medically managed, with life expectancy for many patients similar to that for the general population. Most patients who take combination antiretroviral therapy (ART) experience immune reconstitution and resume normal lives. Natural History of…

Sexually Transmitted Infections

Introduction Sexually transmitted infections (STIs) contribute to the majority of reportable communicable diseases worldwide. More than a million STIs are acquired every day worldwide, with an estimated 357 million new infections annually with gonorrhea, chlamydia, syphilis, or trichomoniasis. Furthermore, there are emerging STIs such as Mycoplasma genitalium and viral STIs such as genital herpes that are highly prevalent on a global scale. The growing threat of…

Sepsis

Introduction Sepsis is among the oldest medical conditions described, yet remains a leading cause of death. The Centers for Disease Control and Prevention estimate that 1.5 million people in the United States are affected each year, with a resulting 250,000 American deaths annually. For many, if not most, hospitals, sepsis is the main cause of mortality, and in a 2016 report contributed to $24 billion in…

Vector-Borne Infections

Introduction Vector-borne infections include diseases caused by diverse pathogens (bacteria, viruses, parasites) that are transmitted to humans by a variety of vectors such as ticks, mosquitoes, lice, tsetse flies, sandflies, triatome bugs, blackflies, mites, and snails. Vectors are typically blood-sucking insects that ingest the pathogen from an infected host reservoir (human, animal, bird) and then transmit them to a susceptible human during their next bloody meal.…

Diagnostic Approach to a Patient with Suspected Central Nervous System Infection

A diagnostic hypothesis for a suspected central nervous system (CNS) infection has two components: an anatomic and a microbiologic or etiologic diagnosis. The anatomic diagnosis localizes the inflammation to a specific part of the CNS. The microbiologic or etiologic diagnosis identifies the pathogen or etiology that is causing the CNS inflammation. An accurate anatomic and microbiologic hypothesis requires a detailed history (including symptoms, duration, exposure, and…

Bone and Joint Infections

Infectious Arthritis Infectious arthritis is defined as infection of one or more joints. It can be caused by bacteria, fungi, viruses, and parasites. Acute Bacterial Arthritis Introduction Native joint septic arthritis is an uncommon illness, with a reported incidence in the United States of 2 to 10 cases per 100,000 persons per year. However, the incidence appears to be rising, in part due to an increasing…

Skin and Soft Tissue Infections

Introduction Skin and soft tissue infections (SSTIs) are among the most commonly occurring bacterial infections, and their frequency approaches 10% of hospital admissions for infections in the United States. Many factors contribute to the increase in awareness of SSTIs: the aging of the general population, the growing number of critically ill or immunocompromised patients, and the emergence of multidrug-resistant (MDR) pathogens are commonly considered the main…

Urinary Tract Infections

Introduction Urinary tract infection (UTI) is one of the most common infectious diseases, both in ambulatory and hospital settings, and is a major cause of antimicrobial use. This is especially relevant in the era of increasing antimicrobial resistance, and in particular, resistance developing in the Gram-negative organisms, which cause most UTI episodes. In many locations, it is increasingly difficult to select an empiric agent for UTI…

Select Gastrointestinal and Hepatobiliary Infections

Esophagitis Esophagitis is an inflammatory mucosal injury disorder that may be caused by infectious agents and local irritants. The inflammation may present with substernal pain, odynophagia, and occasionally dysphagia. The risk factors for esophageal inflammatory disorders may be iatrogenic (i.e., pill esophagitis, chemical injuries) or disease related. Infectious esophagitis often presents with odynophagia in the setting of immunosuppression, recent antibiotics, corticosteroids, or neutropenia. Most infectious esophagitis…

Lower Respiratory Tract Infections

Lower respiratory tract infections (LRTIs) are among the most frequently encountered and difficult to diagnose infectious syndromes. Symptoms of most LRTIs overlap with other clinical conditions, such as congestive heart failure and obstructive lung disease, such asthma and chronic obstructive pulmonary disease (COPD). Diagnostic tests are not specific to LRTIs, and even invasive studies have a low yield in terms of confirming the diagnosis. This means…

Ear, Nose, Throat, and Neck Infections

Infections of the ear, nose, and throat (ENT) run the gamut from annoying but relatively harmless otitis externa to life-threatening infections of the airway. Despite the broad array of syndromes, most of these share a common set of pathogens and similar principles of evaluation and treatment. This chapter will discuss these pathogens and diagnostic tests before discussing anatomically distinct syndromes and specific treatments. Pathogens The anatomic…

Fever and Rash

Overview Generalized rashes with fever are among the most frequent conditions seen by primary care physicians, and are a common reason for patient visits to the emergency department and dermatologists. The majority of cases do not represent an immediate danger, but some patients may have a life-threatening diagnosis, and a prompt and accurate approach is warranted. Diagnosing fever and rash is frequently challenging, because there is…

Fever of Unknown Origin

Introduction Fever is a common complaint encountered by primary caregivers, internists, and surgeons. We all experience fever throughout our lives, and although frequently the cause of fever is never explained, few of us experience a true “classic” fever of unknown origin (FUO). The term FUO should be reserved for patients who experience all of the following: Fever >3 weeks Oral temperature ≥101° F (38.3° C) on…

A Primer on Antimicrobials

Introduction The serendipitous discovery of penicillin by Sir Alexander Fleming in 1928 was one of the greatest medical advances of the 20th century and marks the beginning of the antibiotic era. The term antibiotic originated with Selman Waksman in 1941, who defined it as any small molecule made by a microbe that antagonizes the growth of another microbe. With the widespread clinical use of antibiotics in…

General Principles of Antimicrobial Therapy

Introduction Antimicrobials differ intrinsically from other drugs. Antimicrobials do not aim to affect biologic processes in the patient, but instead inhibit or kill invading pathogens and commensal microorganisms. The properties of these microorganisms are crucial when choosing an antimicrobial regimen, as are the patient and drug characteristics. The pyramid of infectious diseases is a useful learning tool and illustrates the multiple interactions between the host, pathogen(s),…

A Primer on Microbiology

Introduction to Microorganisms That Interact with Humans In this section, we will introduce the main categories of organisms that interact with humans both as part of the human microbiome and those that are able to cause disease. Some organisms are primarily colonizers of humans and exist in a symbiotic relationship, others are primarily pathogens that cause disease, and some are able to do both. The predominant…

Interacting with the Clinical Microbiology Laboratory

Introduction The clinical microbiology laboratory offers an increasingly diverse menu of diagnostic assays, including maintenance of traditional methods first developed in the early 1900s, to implementing increasingly complex molecular assays and, most recently, implementing whole-genome and next-generation sequencing assays for pathogen detection, typing, and assessment of antimicrobial susceptibility. The laboratory is also becoming increasingly automated, from the adoption of automated enzyme immunoassay (EIA) processors, to nucleic…