Nosocomial Infections: Hospital Acquired Infections

Nosocomial Infections

• Definition: Infections developed in a hospital environment, including fungal and bacterial infections
• Examples: Ventilator-associated pneumonia, Staphylococcus aureus, Methicillin-resistant Staphylococcus aureus, Clostridium difficile, Tuberculosis, Urinary tract infection, Hospital-acquired pneumonia, Gastroenteritis
• Risk factors: People in hospitals with poor health, invasive devices such as intubation tubes, catheters, surgical drains, and tracheostomy tubes
• Prevention methods: Sterilization, isolation, handwashing, gloving, surface sanitation, and wearing aprons during patient care

Lassa Fever

• Definition: An acute viral hemorrhagic fever caused by the Lassa virus, first described in 1969 in Nigeria
• Distribution: Outbreaks have been observed in Nigeria, Liberia, Sierra Leone, Guinea, and the Central African Republic
• Primary animal hosts: The multimammate rat (Mastomys natalensis), an animal indigenous to most of sub-Saharan Africa
• Transmission: Through contact with the feces or urine of animals accessing grain stores in residences
• Pathogenesis: The virus infects almost every tissue in the body, starting with the mucosa, intestine, lungs, and urinary system, and then progressing to the vascular system
• Symptoms: Incubation period of 6-21 days, with symptoms including headache, nausea, vomiting, diarrhea, muscle fatigue, conjunctivitis, and mucosal bleeding
• Prevention: Control of the rodent population, keeping rodents out of homes and food supplies, maintaining effective personal hygiene

Rabies

• Definition: An acute, highly fatal viral disease of the central nervous system
• Epidemiology: Endemic in most parts of the world, except for Great Britain, Australia, New Zealand, Scandinavia, and some Pacific Islands
• Reservoir: Rabies is a zoonotic infection of mammals, especially wild carnivores such as dogs, cats, jackals, wolves, and vampire bats
• Clinical features: In mammals, restlessness, excitability, unusual aggressiveness or friendliness; paralysis of the lower jaw; and finally, coma and paralysis
• In humans: prodromal symptoms like headache, nausea, sore throat, and slight fever, followed by widespread excitement and stimulation of all parts of the central nervous system
• Transmission: Through the bite of an infected animal, the virus being present in the saliva
• Diagnosis: Brain tissue examination, saliva, spinal fluid, and urine
• Control: Control of dogs, vaccination of pets, and isolation of patients in a quiet room protected from external stimuli

Plague

• Definition: A rapidly fatal disease caused by Yersinia pestis, which can manifest itself in bubonic, pneumonic, and septicemic forms
• Occurrence: South East Asia, South America, Middle East, Africa
• Organism: Yersinia pestis, a gram-negative bacillus
• Reservoir: Rats and non-domestic rats
• Transmission: Flea bite (bubonic), droplet (pneumonic)
• Clinical features: Sudden fever, chills, headache, prostration, and painful lymphadenitis
• Control: Bubonic plague: isolation, antibiotics, strict hygiene; Pneumonic plague: strict isolation, antibiotics, respiratory and cardiac support

Brucellosis

• Definition: One of the most important zoonosis that can affect humans
• Clinical features: Fever, heavy night sweats, splenomegaly, and weakness
• Incubation period: 6 days to 3 months
• Organism: Brucella abortus, Br. suis, and Br. melitensis from cattle, swine, and goats, respectively
• Occurrence: Worldwide, mostly prevalent in countries around the Mediterranean Sea and the Near East
• Reservoir: Cattle, swine, goats, and sheep
• Transmission: Ingestion, contact, inhalation, and inoculation
• Laboratory diagnosis: Culture from blood, bone marrow, synovial fluid, and lymph nodes
• Control: Pasteurization of milk, environmental sanitation of farms, personal hygiene, antibiotics, and vaccination

Anthrax

• Definition: An acute disease caused by Bacillus anthracis, a gram-positive spore-bearing rod
• Epidemiology: Commonly a disease of hoofed animals, but humans can also be infected
• Reservoir: Horses, sheep, goats, and pigs
• Transmission: Contact with infected material, ingestion, inhalation, and inoculation
• Pathogenesis: Macrophages ingest spores at the site of skin wounds or mucosa, germinate to the replicative form, and then spread rapidly through the lymphatic system and bloodstream
• Clinical features: Cutaneous anthrax: blister or ulcer with black scab; Inhalation anthrax: fever, malaise, headache, cough, shortness of breath, and chest pain; Gastrointestinal anthrax: nausea, vomiting, diarrhea, and abdominal pain
• Diagnosis: Culture of skin sore, Chest X-ray, Sputum culture, Gram stain of a sample of tissue
• Treatment: Antibiotics, such as penicillin, deoxycycline, and ciprofloxacin

Severe Acute Respiratory Syndrome (SARS)

• Definition: A serious form of pneumonia caused by a member of the coronavirus family of viruses
• Epidemiology: First identified in 2003, affecting people worldwide
• Transmission: Through droplets in the air when someone with SARS coughs or sneezes
• Symptoms: Cough, difficulty in breathing, fever, chills, headache, muscle ache, and other breathing symptoms
• Complications: Respiratory failure, liver failure, and heart failure
• Prevention: Reduce contact with people with SARS, avoid travel to places with uncontrolled outbreaks, hand hygiene, and wearing masks and goggles