Week 1: Bacterial Pathophysiology

Gram Staining Classification

• based on cell wall structure

• NOT disease severity

Gram-Positive Bacteria

• thick peptidoglycan layer

• no outer membrane

• retains crystal violet

  • stains purple

Gram-Negative Bacteria

• thin peptidoglycan layer

• outer membrane with lipopolysaccharide (LPS)

• loses crystal violet

• strains pink with safranin (counterstain)

Gram-Negative Triggers…

• stronger inflammatory responses

  • endotoxins

• harder to treat and leads to serious infections

• sepsis and shock

Sepsis

• harmful response to an infection

• causes inflammation that can damage organs

Shock

• inflammation from sepsis causes blood vessels to leak and widen

Early Gram Staining

• help guide empiric antibiotic therapy while awaiting cultures

• cannot use once antibiotics are given

  • bacteria may not show up

Empiric Antibiotics

• broad spectrum antibiotic

• given before culture comes back

Culture Time Frame

• takes 24-72 hours

• possibly longer

Sensitivity Testing Purpose

• determines which antibiotics:

  • kill the organisms (susceptible)

  • are ineffective (resistant)

• initial treatment

Culture Purpose

• identifies the specific organisms

• used for specific antibiotic treatment

Nurse’s Role in Cultures and Sensitivities

• ensuring proper specimen collection technique

• monitoring for clinical improvement or worsening

• understanding C&S helps nurses explain why antibiotics change mid-hospitalization

How Resistance Occurs With Bacteria

• mutation

  • changes during DNA replication

• gene transfer

  • bacteria swap genetic material, allowing resistant genes to spread

  • can spread across species

How Bacteria Adhere to Host Tissues

• pili/fimbriae attach to mucosal surfaces

  • (ex. E. coli in the urinary tract)

• first step in infection

• mechanical flushing helps prevent infection

Mechanical Flushing Examples

• urination

• coughing

• sneezing

• diarrhea

• vomiting

Where Bacteria Adhere to Host Tissue

• mucous membranes

• urinary tract cells

• intestinal walls

• tissue surfaces.

Exotoxins Defintion

• secreted proteins that directly damage host cells

• both Gram-negative and Gram-positive bacteria produce

Endotoxins

• part of Gram-negative LPS

• released upon bacterial death

• causes fever, hypotension, DIC, septic shock

Toxin Production Nursing Relevance

• patient’s fever, hypotension, or altered mental status in infection = systemic toxin effects, not just local inflammation

  • altered vital signs = problem

Biofilm Definition

• formation protects bacteria from antibiotics

• (device infections often require device removal)

Where Biofilm Occurs + Why

• medical devices

  • urinary catheters

  • IV lines

  • pacemakers

• teeth (dental plaque)

• mucosal surfaces (gastrointestinal and respiratory tracts)

• likes moist environments and synthetic surfaces

Opportunistic Infection

• normal flora takes advantage of weakened immunity or disrupted barriers

• high-risk: elderly, immunocompromised, post-surgical

Local vs Systemic Bacterial Infection Presentation

• Local: change at a specific site

  • edema, erythema, warmth

  • cellulitis, wound infection

• Systemic: affects the body

  • vital sign alteration

  • sepsis, shock

How to Know Patient is Responding to Antibiotics

• symptom resolution

• monitor temperature

• WBC

• cultures

C. Diff Organism

• Gram-positive, spore forming, anaerobic bacillus

C. Diff Pathophysiology

• disrupts normal gut flora

  • (most often by broad-spectrum antibiotics)

• spores germinate in the colon

• activates toxin A (enterotoxin) and toxin B (cytotoxin)

C. Diff Spreading

• spreads by pores

• contact isolation

• alcohol hand sanitizer is ineffective

• soap and water is required (mechanical)

C. Diff Symptoms

• watery diarrhea

  • dehydration

  • electrolyte imbalance

• abdominal pain

• fever

• can progress to toxic megacolon

Toxic Megacolon

• life-threatening

• colon is inflamed/paralyzed

  • colitis: colon inflammation, nothing is moving

  • rupture

  • shock

Toxic Megacolon Signs

• abdominal distention

• absent bowel sounds

• rebound tenderness

  • (pain after palpation)

Treatment of C. Diff

• oral vancomycin

• fidaxomicin

  • NOT anti-diarrheal medications

Pneumonia Pathophysiology

• causes alveolar inflammation and fluid

• leads to impaired has exchange

• hypoxia

Pneumonia Symptoms

• fever

• productive cough

• dyspnea

• crackles

• consolidation on chest x-ray

• (exudate - RBCs, WBCs, bacteria)

Antibiotics for Pneumonia

• start empirically

• narrowed after cultures

Pneumonia Nursing Relevance

• early mobility (mucus)

• incentive spirometry to aid clearance

• monitor O2

• monitor sputum color

• vaccination education

Streptococcus Organism

• Gram-positive cocci in chains

Streptococcus Causes

• throat, skin, and lung infections

  • pharyngitis (strep throat)

  • scarlet fever (rash)

Post Streptococcal Complications

• can trigger immune-mediated complications after the infection resolves

Post-Streptococcal Glomerulonephritis

• caused by a type III hypersensitivity reaction

  • not active infection

• kidney disease

  • hematuria, edema, hypertension

Staphylococcus Organism

• Gram-positive cocci in clusters

Staphylococcus Causes

• skin infections

• abscesses

  • build up of pus

• sepsis

MRSA

• reistant to beta-lactam antibiotics

• requires alternative therapy

Food-Borne E. Coli Symptoms

• severe abdominal cramping

• bloody diarrhea

E. Coli Warning

• can lead to:

  • hemolytic uremic syndrome (HUS)

  • acute kidney injury

E. Coli Nursing Relevance

• AVOID antibiotics

  • can worsen toxin release

  • give supportive care

• monitor urine output

• notify provider if bloody stool

C. Botulism Toxin MOA

• blocks acetylcholine release

  • causing descending paralysis

  • and respiratory failure

C. Botulism Symptoms

• neurologic symptoms

  • diplopia (double vision)

  • dysphagia (difficulty swallowing)

• little or no fever

Staphylococcal Food Poisoning Caused By

• pre-formed toxin

• leading to rapid, onset vomiting

Gonorrhea + Chlamydia Defintion

• STI

• transmitted through unprotected vaginal, anal, or oral sex

• may be asymptomatic

Untreated Chlamydia + Gonorrhea

• at risk for:

• pelvic inflammatory disease (PID)

  • infection of the female reproductive organs

• infertility

• ectopic pregnancy

  • fetus develops outside the uterus

Chlamydia and Gonorrhea Screenings

• based on sites of sexual contact

• not assumed anatomy

Syphilis Stages

1. Primary: painless chancre (ulcerated skin lesion)

2. Secondary: immune → rash on palms/soles

3. Latent: organism dormant (no visible symptoms)

4. Tertiary: chronic inflammation

• organ damage

Syphilis Screening

• blood screening test (PRP or VDRL)

• “reactive” titer may need titer result to look for active infection

• history of syphilis → always has reactive RPR

Nursing Key Role in Infection Control

• medication timing

• patient education

• prevention of resistance

Sepsis

• life threatening response to an infection

  • occurs when the immune response becomes systemic and dysregulated

• not the infection itself

Sepsis Inflammation Causes

• widespread vasodilation

• capillary leak

Sepsis Vasodilation Leads to

• hypotension

• poor tissue perfusion

  • a critical reduction in blood flow, oxygen, and nutrients to body tissues

  • lactic acidosis

    • leads to shock, organ failure, or death.

Sepsis Capillary Leak Causes

• third spacing

• edema

Early Signs of Sepsis

• hypothermia

• tachycardia

• tachypnea

• labs:

  • elevated lactate

  • abnormal WBC

Late Sign of Sepsis

• hypotension (dangerous)

Septic Shock

• sepsis can rapidly progress to septic shock

• defined by persistent hypotension despite fluids

  • vasopressor needed (constricts blood vessels)

Sepsis First-Line Treatment

• IV resuscitation

  • rapidly administering fluids

  • restore lost volume, improve blood pressure, and ensure vital organs get oxygen

• antibiotic therapy

Bacteriostatic

• interfere with the cell’s ability to reproduce

Bactericidal

• actively kill bacteria