A primary infection develops as a direct result of a particular bacterial invasion; an example of a primary infection is “Strep” throat; in contrast a secondary infection is a result of another infection and AIDS provides an example of a secondary infection.
Secondary infections develop for a variety of reasons; in particular the primary infection itself may over attacks the normal defense mechanisms and weaken their ability to attack additional infections; additionally treatment measures for the primary infection may disrupt the normal defense mechanisms; if a secondary infection results due to antibiotic therapy for a primary infection it is termed a super infection; a super infection is a dangerous type of secondary infections; oral antibiotic treatment results in some alteration in the populations of normal flora particularly in the gastrointestinal and urogenital tracts and the upper respiratory system.
Sometimes the antibiotic can kill or reduce the normal often helpful bacteria in the body; this allows more harmful bacteria to grow and multiply with little or no competition; for example a patient being treated for infection of the urinary tract by the E. coli can develop a super infection of the blood and heart by a bacterium resistant to a broad range of antibiotics Enterococcus faecalis which can eventually kill the patient.
Opportunistic infections are caused by bacteria often normal flora that is usually not virulent enough to cause disease but become pathogenic when conditions within the host or surrounding environment change in favorable ways; such changes include loss of competition from other microorganisms, weakened host defenses and re-location of the bacteria to a more favorable environment; an example of opportunistic bacteria in the category of loss of competition from other microorganism is Clostridium difficile a species that is usually non-pathogenic but it causes severe diarrhea when the normal flora that inhabit the lower gastrointestinal tract are eliminated by course of antibiotic therapy; examples of opportunistic bacteria that fall in the weakened host defenses category include pathogens that cause disease in AIDS patients; Cryptococcus neoformans causes meningitis and pulmonary infections and Mycobacterium avium causes lung infections that becomes systemic.
Finally a common an example of opportunistic bacteria from the re-location to a more favorable environments category is that which occurs when E. coli which normal inhabit the large intestine as mutualistic bacteria gain access to the urinary tract when they become pathogenic causing urinary tract infections.
Nosocomial infections of those acquired in hospitals
Hospitals are full of pathogens that have developed resistance to disinfectants, antiseptics and sterilization techniques as well as to antibiotics; Enterobacter cocci, Pseudomonas aeruginosa and Methicillin-Resistant Staphylococcus Aureus (MRSA) are examples of bacteria that common the cause nosocomial infections; community acquired infections are those affect populations or individuals and transmitted from one individual to another; they may occurs sporadically or in large numbers of people simultaneously in which case that called epidemics.
Epidemics can arise from a common source as will many people eat contaminated food and develop food poisoning or they spread from person to person as with pneumonia.
Lower Respiratory Tract Infections (LRTIs)
The four major infectious diseases of the lower respiratory tract are
The four major infectious diseases of the lower respiratory tract are
· Tracheitis
· Bronchitis
· Pneumonia
· Lung abscess
Tracheitis is an inflammation of the trachea and is usually caused by Staphylococcus aureus.
Bronchitis is an inflammation of the bronchial mucous membranes and it is associated with Mycoplasma pneumoniae and Mycoplasma catarrhalis, Streptococcus pneumoniae and Haemophilus influenzae.
Pneumonia is characterized by inflammation of the lung tissue and it is caused by numerous species of bacteria and viruses; some common pneumonia causing bacteria are Streptococcus pneumoniae, Haemophilus influenzae, Klebsiella pneumoniae, Mycoplasma pneumoniae, Pseudomonas aeruginosa and Staphylococcus aureus.
Finally Lung abscess a pus filled pockets surrounded by dying and inflamed tissue; possible causes of lung abscess include anaerobic bacteria such as Bacteroides and Fusobacterium species.
Intra-Abdominal infections
The most common Intra-Abdominal infections are related to food poisoning or diarrhea and include diseases such as gastritis inflammation of the stomach lining; enteritis inflammation of the intestinal lining and gastroenteritis inflammation of both the stomach and intestinal linings; intra abdominal infections can occurs in the abdominal organs themselves or in the recessive sacs between them; resulting in peritonitis inflammation of the peritoneum.
Obstetrics And Gynecologic Infections
Obstetrics related to pregnancy and child birth and gynecologic related to the female reproductive organs diseases are by definition restricted to women; bacteria can infect any of the female reproductive oranges or genitalia; bacterial infection of the internal organs the uterus, ovaries, and fallopian tubes is referred to by the collective term Pelvic Inflammatory Disease (PID); the most serious type of PID is salpingitis inflammation of the fallopian tubes; there are two types of salpingitis; Gonococcal salpingitis caused by Neisseria gonorrhoeae and non- Gonococcal salpingitis which can result from the numerous other bacterial species including Chlamydia trachomatis; besides PID another common obstetric gynecological disease is Endometritis an inflammation of the endometrium the lining of the uterus; bacterial endometritis usually results from pregnancy and gynecologic surgery; the bacteria most commonly involved in endometritis are normal flora of the vagina and lower GI tract including E. coli, Klebsiella, group B Streptococcus, Peptostreptococcus, Bacteroides fragilis, Prevotella disiens and Prevotella bivia.
Urinary Tract Infections
Urinary tract infections (UTIs) are among the most common health problems accounting for more than six million physician visits each year; since the uritis, urinary bladder and urethra are lined with a continuous mucous membranes; bacterial infections can easily spread up towards the kidneys from the of opening though which the urine leaves the body; the most common causes of bacterial infections of the urinary tract are the migration of intestinal bacteria from the anus particularly in women because of the proximity of the anus and the end of the urethra and transmission of bacteria by the contact of sexual intercourse; the most common UTIs are inflammation of the urethra urethritis and bladder cystitis; either of these infections can lead to the more serious pyelonephritis inflammation of the kidneys; in man prostatitis inflammation of the prostate gland is also common; UTIs are usually caused by gram negative E. coli, Proteus, Klebsiella and Enterobacter; the gram positive bacteria most often associated with the UTIs Staphylococcus saprophyticus, Staphylococcus aureus and Enterococcus faecalis.
Wounds And Skin Infections
Wounds, burns and skin disorders such as eczema destroy the integrity of the normally intact skin providing an opportunity for pathogens to establish infections; the skin is composed of two primary layers the thin outer epidermis and the thick endodermis beneath these two layers of the skin are soft tissues subcutaneous; the major uncomplicated bacterial skin infection is Cellulitis; cellulitis is an acute inflammation of the skin and soft tissues due to infections by Streptococcus particularly Streptococcus pyogenes and Clostridium such as Clostridium perfringens; in contrast major complicated bacterial skin infections include decubitus ulcers or bed sores and diabetic foot; bed sores are produced when hospitalized patients lies too long in one position there by breaking this skin down and destroying the tissue; bed sores are often infected by Bacteroides fragilis and Clostridium perfringens; diabetic patients are at risk of numerous infections because diabetes compromises the normal blood supply that maintain the health of tissues; diabetic foot is a serious skin infections that can occur after of diabetic patients experienced any minor trauma to the foot; these minor wounds easily infected usually with several bacterial species including Staphylococcus aureus, Peptostreptococcus, Bacteroides fragilis, Enterococcus and Enteric microorganisms.
Bone And Joints Infections
The two major infectious diseases that affect bone and joint tissues are osteomyelitis and septic arthritis; osteomyelitis is an infection of the bone usually of the medullary cavity; osteomyelitis usually occurs as a result of the introduction of bacteria into the bone by trauma, surgery including surgery to insert processes into bones or the spread of bacteria into the bone from adjacent tissue infections; osteomyelitis can also be caused by an organism spreading from a distant sites to the bone via bloodstream; examples of bacteria that can cause osteomyelitis are Staphylococcus aureus, Staphylococcus epidermidis, E. coli, Bacteroides, Clostridium and Actinomyces.
Septic arthritis is an inflammation of the joints due to bacterial infections it is often categorized as Gonococcal caused by gram negative aerobic Neisseria gonorrhoeae responsible for gonorrhea and non-Gonococcal; non-Gonococcal septic arthritis can be caused by a number of common pathogens such as Staphylococcus as aureus, Staphylococcus epidermidis, Haemophilus influenzae, E. Coli, Salmonella, Pseudomonas, Mycobacterium and Fusobacterium.
Pia Mater And Arachnoid Infections
Meningitis is an inflammation of the meninges the membranes covering the brain and spinal cord; meninges form a protective sheath around the spinal cord of and extend into the skull to cover the brain; the three separate membranes of the meninges are arranged in layers; dura mater the strong outer layer, arachnoid mater the meddle layer and pia mater the innermost membrane; bacterial meningitis is an inflammation resulting from bacterial infection of the pia mater and arachnoid; many bacteria can cause meningitis the three species account for eighty percent of all cases Haemophilus influenzae the most common pathogen in children, Neisseria meningitides also known as meningococcas which cause meningitis epidemics, Streptococcus pneumoniae the most common pathogen in individuals over age forty.
