Only a small proportion of microbes cause infection and disease.
Infections remain a significant cause of hospital admissions and death, especially in the aging population.
Emergence of new infectious agents necessitates a renewed focus on prevention and treatment.
Infectious diseases spread more rapidly due to environmental disruption and human mobility.
Antibiotic-resistant microorganisms are a major public health concern.
Signs and Symptoms of Infectious Diseases
Systemic symptoms include fever, chills, sweating, malaise, nausea, and vomiting.
Changes in blood composition, such as altered leukocyte counts, may occur.
Older adults may exhibit changes in mentation.
Fever
Fever is a sustained temperature above normal, caused by various factors, including infections.
Pyrogens elevate the hypothalamic thermostat, raising body temperature.
Fever patterns vary depending on the infectious disease.
Temperature elevations above 104°F(40°C) may cause delirium and seizures; extremely high fever may cause irreversible cell damage.
Common Signs and Symptoms
Fever, chills, and malaise are common early symptoms.
Other signs include enlarged lymph nodes, purulent drainage, skin rashes, bleeding, tachycardia, and altered mental status.
Older adults may have subtle and atypical symptoms such as change in mental status, subnormal body temperature, fatigue, and decreased appetite.
Aging and Infectious Diseases
Older adults are more susceptible to infectious diseases due to changes in immune function and comorbidities.
Modest changes in T-cell function and slower response of memory T cells occur with aging.
Extrinsic factors like atrophic skin, decreased cough and gag reflexes, and reduced mobility increase infection risk.
Early recognition of infection in older adults is difficult due to underreported and atypical symptoms.
Infectious Diseases: Definition and Overview
Infection is a parasitic relationship where an organism invades and multiplies in a host, producing an immune response, signs, and symptoms.
Colonization occurs when microorganisms are present without causing symptomatic disease.
Infection development depends on the pathogen, conducive environment, and host susceptibility.
Possible outcomes include contamination, subclinical infection, and clinically apparent infection (infectious disease).
The incubation period is the time between pathogen entry and symptom appearance.
A latent infection occurs when a microorganism remains dormant in the host.
The period of communicability is when an organism can be shed.
A communicable disease is one where the causative agent can be transmitted directly or indirectly.
Types of Organisms
Various microorganisms cause infectious diseases, including viruses, mycoplasmas, bacteria, rickettsiae, chlamydiae, protozoa, fungi, helminths, mycobacteria, and prions.
Viruses consist of RNA or DNA and are dependent on host cells for replication; antiviral medications can mitigate viral illnesses.
Mycoplasmas are self-replicating bacteria without cell walls, sensitive to some antibiotics.
Bacteria are single-celled microorganisms with cell walls, classified by shape, staining, motility, capsulation, and spore formation; can be aerobic or anaerobic.
Rickettsiae are animal pathogens transmitted by insect vectors; require a host for replication.
Chlamydiae depend on host cells for replication; contain both DNA and RNA and are susceptible to antibiotics.
Protozoa are single-celled organisms with cell membranes; larger parasites include roundworms and flatworms.
Fungi are unicellular to filamentous organisms occurring as yeasts or molds; fungal diseases are called mycoses.
Prions are proteinaceous infectious particles without nucleic acids, causing a rapidly progressive deteriorating state.
The Chain of Transmission
Infection transmission depends on a pathogenic agent, reservoir, portal of exit, mode of transmission, portal of entry, and susceptible host.
Healthcare-Associated Infections (HAIs)
HAIs develop in hospitalized persons; prevention is critical. In the US, about 1 in every 31 people who are hospitalized will contract an HAI.
Standard precautions treat all clients as potentially carrying a transmissible disease; handwashing is essential.
HAIs prolong hospital stays, increase costs, and cause morbidity and mortality.
Key Components in Chain of Transmission
Pathogens: Microorganisms that cause disease; pathogenicity depends on reproduction speed, tissue damage, and toxin strength; virulence measures disease severity.
Reservoir: Environment where an organism lives and multiplies.
Portal of Exit: Place where the parasite leaves the reservoir.
Mode of Transmission: Routes include contact, airborne, droplet, vehicle, and vector-borne.
Portal of Entry: Methods include ingestion, inhalation, bites, or contact with mucous membranes.
Host Susceptibility: Influenced by characteristics, health, and behaviors.
Lines of Defense
First-line defenses: External, such as skin, mucous membranes, cilia, and reflexes; inhibit invasion.
Second-line defense: Inflammatory process; a local reaction to cell injury.
Third-line defense: Immune response; responds specifically to individual pathogens.
Control of Transmission
Methods include barriers and isolation, immunizations, drug prophylaxis, improved conditions, and environmental correction.
Standard precautions are the foundation for preventing transmission, including hand hygiene and personal protective equipment.
Transmission-based precautions are used for specific infections and include contact, airborne, and droplet precautions.
Special Implications for the PTA
Infections decrease endurance and delay recovery.
Adherence to CDC guidelines and hospital transmission-based precautions is essential.
Promote handwashing and maintain adequate immunization status.
Prevent HAIs by following strict infection-control procedures and observing clients for signs of infection.
Hydrotherapy and Therapeutic Pool Protocol
Good disinfection and cleaning procedures manage infection spread; private rooms and proper PPE for wound care.
Home Health Care
Preventing infection spread to family and community is crucial; collaborate with home health nurse.
Emphasize handwashing and proper handling of soiled linens and trash.
Specific Infectious Diseases
Bacterial Infections
Clostridioides Difficile Infection (CDAD)
Associated with antibiotic use; transmission via fecal-oral route; risk factors include age and healthcare facility residence.
Symptoms include persistent diarrhea, abdominal cramping, and tenderness; severe disease may lead to fever and sepsis.
Prevention includes hand hygiene, environmental disinfection, and contact precautions.
Staphylococcal Infections
Common bacterial pathogens on the skin; S. aureus is a leading cause of HAIs.
Risk factors include direct contact, colonization, damaged skin, and immunosuppression.
Infection produces abscess formation; symptoms vary with the affected area.
Streptococcal Infections
Group A Streptococci (GAS) cause diverse diseases; transmission via respiratory droplets.
Streptococcal pharyngitis (strep throat) requires antibiotic treatment; impetigo occurs commonly in children; Erysipelas can lead to an acute infection of the skin accompanied by fever and chills.
Group B Streptococci cause neonatal pneumonia, meningitis, and sepsis.
Streptococcus pneumoniae causes pneumonia, meningitis, and otitis media.
Pseudomonas
Opportunistic pathogen causing pneumonia, wound infections, and sepsis.
Risk factors include burns, urinary catheterization, cystic fibrosis, and diabetes.
Causes vascular thrombosis and hemorrhagic necrosis; treat with proper cleaning of equipment.
Viral Infections
Blood-Borne Viral Pathogens
Hepatitis B Virus (HBV), Hepatitis C Virus (HCV), and HIV; minimize exposure through standard precautions
Preexposure HBV vaccination is strongly recommended.
Herpesviruses
Herpes Simplex Viruses Types 1 and 2 can affect the oral, genital areas, or visceral organs; transmission via contact with lesions.
Prevent with good handwashing and barriers.
Varicella-Zoster Virus (VZV) causes chickenpox and shingles; prevent with vaccination; treat with pharmacological intervention.
Shingles can lead to postherpetic neuralgia, causing severe nerve pain.
Infectious Mononucleosis (Epstein–Barr virus) causes fever, sore throat, and lymphadenopathy; care should be taken to avoid trauma.
Cytomegalovirus (CMV, herpesvirus type 5) is transmitted by human contact with infected secretions. May be transmitted from mother to child during pregnancy.. Treat through practice based on organ systems involved and clinical presentation.
Viral Respiratory Infections
Influenza viruses cause illness and death. Vaccination is recommended.
Respiratory Syncytial Virus (RSV) can cause low-grade fever, tachypnea, and wheezing. Treat with hydration, humidification, and ventilator support.
Miscellaneous Infectious Diseases
Prostheses and Implant Infections
Infections can arise from any synthetic device implanted into the body.
Lyme Disease
Caused by Borrelia burgdorferi and transmitted by tick bites.
Prevent with Lyme disease prevention strategies.
Monitor nervous system abnormalities; caution against fatigue after acute episodes.
Sexually Transmitted Infections
Spread through sexual contact; prevention includes abstinence and safe sex practices.
If the clinical manifestations may be correlated to an STD, the client must be further evaluated by a physician.
Infections in Drug Users
Increased risk due to drug routes, administration sites, and preparation methods.
Maintain awareness about signs of substance abuse and associated infection patterns.
Take precautions against HBV from needle EMG and blood-borne practices.