MDRO Infectious Disorders: Routes of Transmission

Coordinating Care for Patients with Multidrug Resistant Organism Infectious Disorders

• Chapter 21, written by Autumn Eastman on March 26, 2025

Routes of Transmission

• Contact: Occurs when a person or object comes into contact with a pathogen such as touching a doorknob, pressing an elevator button, or shaking hands.
• Airborne: Occurs when pathogens are carried through the air, for example, sneezing, coughing, Influenza, and TB.
• Vehicle: An indirect mode of transmission that occurs when a disease-carrying agent touches a person’s body or is ingested such as water contamination, food, medications, and Hepatitis B+C
• Vector: An indirect mode of transmission that occurs when a vector infects a person such as birds, insects, Lyme Disease, Malaria, and West Nile Virus.

Multidrug-Resistant Organisms (MDROs) Defined

• Microorganisms, predominantly bacteria, are resistant to one or more classes of antimicrobial agents.
• MDRO infections have clinical manifestations similar to infections caused by susceptible pathogens.
• Options for treating patients with MDRO infections are often limited.
• MDROs are associated with increased lengths of stay, costs, and mortality.

Methicillin-Resistant Staphylococcus Aureus (MRSA)

• It is the most common multi-drug-resistant pathogen.
• MRSA is the result of decades of unnecessary antibiotic use.
• MRSA is currently resistant to all beta-lactam antibiotics, including Penicillin's, cephalosporins, and carbapenems.

Risk Factors for MRSA

• Hospitalization in the last 12 months
• Soft tissue infection
• Hospitalization in intensive care
• Residing in a long-term care facility
• Weakened or immature immune system (young children, older adults, HIV/AIDS, cancer, chronic conditions)
• Consider invasive procedures such as catheters, IV lines, and long-term antibiotic use.

MRSA Continued

• Pathophysiology involves contact with a pathogen.
• MRSA lives on surfaces and humans for days to weeks.
• When colonized with MRSA, the pathogen is easily transferred to the skin and other body areas.
• If MRSA colonizes in the nose, wiping the nose and touching open skin can transfer MRSA to the wound.

MRSA Clinical Manifestations

• Serious infections
• Pneumonia
• Skin and soft tissue infections
• Surgical site infections
• Bloodstream infections
• Cardinal signs of inflammation

MRSA Complications

• Increased morbidity and mortality
• Longer lengths of stay and higher hospital costs
• High risk of death
• Osteomyelitis
• Toxic shock syndrome
• Multisystem organ failure

Vancomycin-Resistant Enterococci (VRE)

• Enterococci are bacteria that normally live in the gastrointestinal tract, the female genital tract, and are found in soil, water, and food.
• VRE are bacteria that have evolved and become resistant to vancomycin.
• There is a higher incidence of VRE in larger teaching hospitals.
• Hand hygiene compliance affects the prevalence of VRE.
• Antibiotic stewardship is associated with lower rates of VRE.
• Reducing the use of vancomycin and cephalosporins has decreased VRE prevalence in the US.

VRE Risk Factors

• Prolonged hospital stays
• Immunosuppression (patients in ICUs, transplant recipients, cancer patients)
• Prolonged exposure to antibiotics
• Invasive procedures and devices
• Similar to MRSA

VRE Pathophysiology

• Direct contact from skin or patient equipment, hands, and unclean equipment.
• VRE can remain on surfaces for up to 2 months.
• There is a large emphasis on prevention because it is difficult to control due to antibiotic use increasing the microbial load of VRE.
• Treatment options are limited and a polypharmacological approach is often necessary.

VRE Clinical Manifestations

• Urinary tract infections result in back pain, dysuria, urinary urgency, and fever.
• Bacteremia leads to tachycardia, hypotension, fever, and sepsis.
• Wound infections present red, warm to the touch, and have purulent drainage.
• Peritonitis (intra-abdominal and pelvic wound infections) has signs and symptoms depending on location and severity.

VRE Complications

• Vancomycin-resistant S. aureus
• Prolonged hospital stay
• Prolonged antibiotic therapy
• Higher mortality
• Increased cost of hospitalization
• Osteomyelitis, pneumonia, sepsis, and endocarditis

Clostridioides Difficile (C. diff)

• The most common cause of antibiotic-associated diarrhea.
• Approximately 12% of all hospital-acquired infections.
• 4-15% of healthy individuals are colonized with C. diff, with 3-21% of patients admitted to hospitals colonized without showing symptoms.

C. diff Risk Factors

• Use of antimicrobials, clindamycin, cephalosporins, aminoglycosides, penicillins, and fluoroquinolones to suppress normal bowel flora.
• Duration of hospitalization
• GI surgery
• Immunosuppression
• Nasogastric tubes due to prolonged periods of no oral intake and impaired bowel motility.
• Use of acid-suppressing medications (H2 blockers and proton pump inhibitors)

C. diff Pathophysiology

• Spore-forming bacteria is resistant to many types of disinfectants, heat, and dryness
• C. diff. lives on surfaces for months, and in skin folds, as well as on the hands of healthcare workers.
• Almost exclusively found in healthcare settings, the hands of healthcare workers are the primary source.
• Transmitted via oral-fecal route, a patient with C. diff must be placed on contact-isolation precautions

C. diff Major Complications

• Volume depletion
• Renal insufficiency
• Electrolyte imbalance
• Hyperalbuminemia
• Peritonitis
• Paralytic ileus
• Toxic megacolon
• Perforation of the colon
• Sepsis
• Death

C. diff and Skin Breakdown

• Excessive moisture, alkaline pH, colonization with microorganisms, and friction contribute to C. diff and skin breakdown.
• Proper perineal cleansing is imperative.
• Barrier creams/ointments and fecal management systems are necessary.

Acinetobacter Baumannii

• Resistant to more than three classes of antibiotics.
• The emergence of MDR Acinetobacter is due to the use of broad-spectrum antimicrobials and transmission of strains among patients.
• There is a 35% increase in Carbapenem-resistant Acinetobacter, with a hospital-onset rate of 78%.
• The organism survives for weeks to months on dry and moist surfaces
• Acinetobacter is typically colonized in the skin, throat, rectum, and urinary tract.
• There is an increase in morbidity and mortality as well as an increased length of stay.
• The incidence of Acinetobacter infections is highest in ICUs with complex patients.

Acinetobacter Risk Factors

• Recent surgery
• Central venous catheters, tracheostomy, and mechanical ventilation.
• Exposure to antimicrobial agents, especially fluoroquinolone and carbapenems
• Prior colonization with MRSA
• Hemodialysis
• Malignancy
• Poor glucocorticoid therapy
• Vascular catheters and the respiratory tract are the most frequent sources.

Acinetobacter Clinical Manifestations

• Dependent on colonization/Infection Site: respiratory tract, GI tract, blood, pleural fluid, peritoneum, urinary tract, surgical wounds, CNS, skin, and eyes.
• Most common are ventilator-associated pneumonia and bloodstream infections.

Carbapenem-Resistant Enterobacteriaceae (CRE)

• In 2018, the CDC reported 9,300 CRE healthcare-associated infections in the US.
• 50% of patients who develop bloodstream infections from CRE die from them.
• The CDC has labeled CRE as an urgent concern and can cause infections in both hospital and community settings but healthy people are typically not at risk.
• Carbapenem antibiotics are typically used as a last resort for treating severe infections, so CRE organisms are especially dangerous, leading to high mortality.

CRE Risk Factors

• Older adults
• Hospitalization
• Resident of long-term care facilities
• Diabetes
• Heart disease
• Renal disease
• Indwelling devices (catheters, central venous lines, feeding tubes)

CRE Pathophysiology

• Direct contact with infected or colonized people, wounds, or stool
• Enterobacteriaceae include Klebsiella and E. coli.
• These organisms are usually found in the intestines and are harmless.
• Outside of the intestines, it can cause serious infections such as UTIs, bloodstream infections, wound infections, and pneumonia.

CRE Clinical Manifestations

• Fever, chills, and signs of sepsis, vary depending on the location of infection

Management of Multidrug-Resistant Organisms

• Diagnosis: Surveillance in some facilities will perform screening on any patient admitted, bacterial cultures, and risk assessment tools.
• Treatment: Hand hygiene is the best treatment with alcohol-based hand rubs (not effective for C. diff), isolation and contact isolation precautions, medications

Nursing Assessment

• Vital signs, pain assessment, skin turgor, urine output, wound or surgical site, WBC count, lab work, bowel movement frequency/consistency, and skin integrity

Nursing Actions and Priorities

• Hand hygiene, isolation precautions, administering antibiotics, fever reducer, and pain medications, as well as IV fluids, supplemental oxygen, chest physiotherapy, and encouraging early mobilization

Antibiotics Used for MRSA

• Vancomycin: Serum levels and trough levels must be monitored to avoid toxic doses and maintain therapeutic levels because it can cause nephrotoxicity and ototoxicity, and weekly BUN and serum creatinine levels are necessary
• Other antibiotic options include Linezolid (Zyvox), Daptomycin (Cubicin), Tigecycline (Tygacil), Clindamycin (Cleocin), and Sulfamethoxazole-trimethoprim (Bactrim).

Antibiotics Used for VRE

• Difficult to treat and often require multiple antibiotics due to resistance to penicillin and ampicillin.
• Susceptibility testing is recommended.
• Quinupristin-dalfopristin (Synercid) can be caustic to veins; PICC placement is recommended if long-term use is required.
• Other options include Linezolid, Daptomycin and Chloramphenicol effectively treated VRE for many years but should not be a first-line agent due to the high incidence of toxicity

Medications Used for C. diff

• Before treatment can begin, the suspected causative antibiotic must be stopped, and the use of peristaltic agents should be avoided; there must be a suspected causation as to why.
• Oral vancomycin is a first-line agent for the initial episode of severe C. diff and can be administered IV or orally.
• Other medications include Fidaxomicin (Dificid), Monoclonal antibody Bezlotoxumab, Probiotics, and Fecal Microbiota transplantation.

Medications Used for Acinetobacter

• Mild to severe cases treated with Sulbactams combined with ampicillin-sulbactam (Unasyn).
• Other options include Tetracyclines (Minocycline, Doxycycline) and Carbapenems (Imipenem, meropenem).
• It is getting increasingly more challenging to treat and dose due to increased carbapenem resistance.

Medications Used for CRE

• Treatment is based on susceptibility.
• Limited options but include third-generation cephalosporins, meropenems, polymyxib, and plazomicin.

Patient Teaching

• Contact precautions require teaching the patient and visitors the importance of wearing gowns and gloves when entering the room and removing them when exiting the patient's room; also, teach them the importance of performing hand hygiene after removing the gown and gloves.
• Patient takes medications as prescribed by finishing the course of antibiotics to reduce risk.
• Clinical manifestations of infection need to be taught to the patient.
• Sun protection is crucial because tetracycline antibiotics can cause sun sensitivities, so it is important to avoid prolonged sun exposure, wear sunscreen, and appropriate clothing.

Nursing Considerations

• Risk for deficient fluid volume, ineffective airway clearance, and alteration in comfort
• Risk for skin breakdown, impaired tissue integrity, impaired urinary elimination, and acute pain.

Antibiotic Stewardship

• An effort to measure and improve how antibiotics are prescribed by clinicians and used by patients
• Improving antibiotic prescribing and use is critical to treating infections effectively, protecting patients from harm caused by unnecessary antibiotic use, and combating antibiotic resistance.