NURS 218 MICROBIOLOGY IN NURSING Microbial Infections of the Nervous System and Cardiovascular and lymphatic system

Learning Objectives At the end of this lecture the students will be able to: Recognize common microbial infections involving the nervous system the cardiovascular system Identify specific pathogens that are responsible for the development of the disease in the specific system Outline the various signs and symptoms Describe the treatments involved.

OUTLINE Microbial Infections of the cardiovascular system Microbial Infections of the Nervous System MENINGITIS PURULENT MENINGITIS CHRONIC MENINGITIS TETANUS (CLOSTRIDIUM TETANI) BOTULISM (CLOSTRIDIUM BOTULINUM) POLIOMYELITIS RABIES ARBORAL ENCEPHALITIS Common Pathogens of the CNS General Treatment Microbial Infections of the cardiovascular system Intravascular Infections Infectious Endocarditis Sepsis and Septic Shock Gas Gangrene Bacterial Infections:Plague Brucellosis Lyme Disease Viral Infection Epstein-Barr Virus Infection Parasitic Infection Malaria Chag’s Disease Filiariasis Schistosomiasis

Microbial Infections of the Nervous System

COMMON PATHOGENS AND ROUTES FOR CNS INFECTIONS CNS consists of the brain and the spinal cord & infections can be caused by: Normal bacterial flora Pathogens acquired through ingestion Pathogens acquired during the birthing process Contamination of shunts Microbial infections of the CNS are infrequent have often have serious consequences. In preantibiotic times, there were almost fatal

MENINGITIS Initial symptoms are a triad of fever, headache and a stiff neck Often followed by nausea and vomiting eventually progress to convulsions and coma many who survived an attack suffer some degree of neurological damage. It can be caused by different types of pathogen: viruses, bacteria, fungi and protozoa

PURULENT MENINGITIS Infection of the meninges ( the system of membranes which envelopes the central nervous system). Usually caused by a bacterial infection Characterized by fever, irritability, and various degrees of neurological dysfunction

CHRONIC MENINGITIS Usually caused by Mycobacterium tuberculosis, fungi, or protozoan parasites. Characterized by fever, headache, stiff neck and back, nausea, and vomiting

TETANUS (CLOSTRIDIUM TETANI) Tetanus is caused by Clostridium tetani. Gram-positive Anaerobic Rod shaped Produces a terminal spore Toxin produced by C. tetani is neurogenic

BOTULISM (CLOSTRIDIUM BOTULINUM) Etiologic agent is Clostridium botulinum. Gram-positive Anaerobic Spore-forming Rod-shaped Found naturally in soil and sediments of ponds and lakes.

POLIOMYELITIS POLIOMYELITIS: Infection which destroys cells associated with the anterior the spinal cord, and brain stem. Causes weakness or paralysis of muscle groups & Can cause respiratory difficulties Characterized by asymmetrical paralysis ACUTE POLIOMYELITIS : Inflammatory infection of the peripheral nervous system (consists of the nerves and ganglia outside of the brain and the spinal cord) Characterized by symmetrical paralysis Can be caused by diphtheria toxin, enteric pathogens, cytomegalovirus, and Epstein-Barr virus

RABIES Rabies is an acute and fatal viral CNS infection. Can affect all mammals Transmitted by infected secretions (usually through a bite). Prevention is the best cure. Treatment consists of a course of injections. Only beneficial if administered before the onset of symptoms Mortality for rabies is 90%.

ARBORAL ENCEPHALITIS Encephalitis – caused by mosquito-borne viruses ( arboviruses) causes subclinical to severe symptoms including rapid death Active cases – characterized by chills, headache, and fever. As disease progress – mental confusion and coma Survivors suffer from permanent neurological problems

COMMON PATHOGENS OF THE CNS Acute meningitis usually caused by: H. influenzae Neiserria meningitidis streptococcus pneumoniae A vaccine is available to protect against H. influenzae. Group B streptococci and E. coli often involved in meningitis in newborns Acquired through the birthing process

Most common viral causes of acute CNS infections: Enterovirus Herpes simplex virus HIV Epstein-Barr virus Also several arthropod-borne viruses Deep fungal mycoses Cryptococcus neoformans and Coccidioides immitis

GENERAL TREATMENT OF CNS INFECTIONS Bacterial and fungal infections require prompt and aggressive treatment. Treatment periods vary depending on the type of infection. 10 days to 12 months for uncomplicated cases Longer if the infection is caused by M. tuberculosis Treatment of fungal infections can last for years. Treatment of viral infections is mostly supportive.

INFECTIONS OF BLOOD AND CARDIOVASCULAR SYSTEM

Infections in the blood easily become systemic and systemic infections can have devastating effects on the patient. Types: Bacteremia Viremia Fungemia Parasitemia Pathogenic organisms growing in the blood can lead to major clinical conditions: Sepsis & Septic shock

Why is this Important? Infections in the blood easily become systemic and systemic infections can have devastating effects on the patient.

OVERVIEW Systemic nature of blood infections requires aggressive treatment. Blood has access to the entire body: Can carry pathogens from one location to another. Presence of circulating pathogens is a natural progression of an infection: These are quickly removed from the blood by host defenses. In some cases pathogens in the blood reflect a serious, uncontrollable infection.

Depending on type of organism blood infections are classified as: Bacteremia Viremia Fungemia Parasitemia Pathogenic organisms growing in the blood can lead to major clinical conditions: Sepsis Septic shock Bacteremia and fungemia can also be caused by pathogens growing inside or outside of intravenous devices.

INTRAVASCULAR INFECTIONS INTRAVASCULAR INFECTIONS-arise when pathogens enter the blood and damage the structures of cardiovascular system Endocarditis – infection of the heart Thrombophlebitis – infection in the veins Endoarteritis – infection of the arteries Most commonly caused by bacteria Fungi are sometimes involved. Infections of the cardiovascular are very dangerous & Can be fatal Commonly produce shedding of organisms into the blood.

INFECTIOUS ENDOCARDITIS Once referred to as bacterial endocarditis Now known that organisms other than bacteria can cause it Infection affects the heart valves Can also develop on the septa of the heart and cardiac shunts. Infectious endocarditis classified in two ways: Acute – high fever and toxicity Can result in death within few days or weeks Subacute – low fever, weight loss, and night sweats Death can take weeks to months

INFECTIOUS ENDOCARDITIS

Complications from infectious endocarditis: Risk of congestive heart failure Rupture of the chordae tendineae (group of tough, tendinous strands in the heart ) Perforation of the valves Kidney damage Blood is found in urine.

SEPSIS AND SEPTIC SHOCK SEPSIS AND SEPTIC SHOCK- both result from the progression of bacteremia Gram-positive and Gram-negative bacteria can be responsible Fungi, protozoa, and viruses can also be the cause Sepsis – an infection which causes a host response including: sepsis causing altered blood flow to organs causing reduced urine ; changes in mental status; Development of hypotension Multiorgan failure and death.

GAS GANGRENE Gangrene caused by Clostridium perfringens. Tissue necrosis resulting from an obstructed blood supply. Bacteria responsible for the infection release gases. Usually associated with deep tissue wounds. Movement of the affected area causes snap, crackle, and popping sounds , a foul smell Infection is accompanied by high fever, massive tissue destruction, shock, and blackened skin. If not treated, gas gangrene is lethal.

BACTERIAL INFECTIONS OF THE BLOOD: PLAGUE Vector-transmitted to humans. Most explosively virulent bacterial infection ever known. Spreads from lymph nodes to blood From there can spread to the lungs Referred to as pneumonic plague Bacteria multiply very rapidly in lymph nodes Produces a bubo From bubo, bacteria spread rapidly into the blood.

PLAGUE: Pathogenesis

BRUCELLOSIS Brucella enters the host through cuts in the skin, contact with mucous membranes, inhalation; Ingestion Zoonotic infection which involves infection of the reproductive tract. Transmission to humans is by: Occupational contact Ingesting contaminated animal products Chronic illness in humans Can last for weeks or months Causes fever, night sweats, and weight loss Cyclic pattern of symptoms – undulant fever

LYME DISEASE Transmitted to humans by Ixodes tick. Caused by the spirochete Borrelia burgdorferi Gram-negative Requires specialized medium for growth Involves ticks, mice, and deer Humans are incidentally involved Acute Lyme disease characterized by: Fever Migratory bull’s-eye rash Muscular and joint pain Often meningeal irritation Deer are host for the final stages

LYME DISEASE: Pathogenesis

VIRAL INFECTIONS OF THE BLOOD Viruses can be found in the blood – viremia. Some viruses use blood cells as their hosts. CYTOMEGALOVIRUS- is a herpes viral genus of the Herpesviruses group ARBOVIRUSES- a group of viruses that are transmitted by arthropod vectors & infections in blood are classified as fever infections. Dengue fever & Yellow fever: arbovirus attacks the liver and vector for both are mosquitoes.

EPSTEIN-BARR VIRUS INFECTION EPSTEIN-BARR VIRUS- human herpesvirus, a cancer-causing virus of the herpes family, which includes herpes simplex virus1 and 2, and is one of the most common viruses in humans.

PARASITIC INFECTIONS OF THE BLOOD There are several important and dangerous parasitic infections of the blood: Malaria Trypanosomiasis Filariasis Toxoplasmosis Schistosomiasis

Malaria

CHAGAS’ DISEASE/ Trypanosomiasis American form of trypanosomiasis. Caused by the flagellate protozoan Trypanosoma cruzi.

FILARIASIS Caused by thread-like filarial nematodes (roundworms) family known as "filariae Tissue changes seen in elephantiasis are often irreversible. Enlarging of the extremities may be ameliorated through the use of pressure bandages. Control of the vector helps prevent infection.

Schistosomiasis Schistosomiasis also known as bilharzia, bilharziosis or snail fever) is a parasitic disease caused by several species of tremotodes ("flukes") a parasitic worm of the genus Schistosoma