Term
| GRAM-NEGATIVE RODS THAT CAUSE ENTERIC DISEASE BUT ARE NOT MEMBERS OF THE FAMILY ENTEROBACTERIACEAE |
|
Definition
| oxidase postitive, gram negative rods; Pseudomonas, Vibrionaceae, Campylobacter, Helicobacter |
|
|
Term
|
Definition
| aeruginosa. motile(polar flagella), capable of growing on simple media, oxidase-positive, obligate aerobes, moist environment, capable of growing by anaerobic respiration if nitrate is available, Some strains are mucoid because of abundant production of a polysaccharide capsule and some produce water-soluble pigments |
|
|
Term
|
Definition
| produces two water-soluble pigments: Pyocyanin, a bluish-green pigment, and fluorescin, a fluorescent greenish-yellow pigment, grape-like aroma, opportunistic in immunocompromised-septicemia, endocarditis, pulmonary infections, ear infections, burn wound infections, urinary tract infections, gastroenteritis, eye infections, and musculoskeletal infections, often resistent to antibiotics, largest genome sequenced, Pili, Polysaccharide capsule,Exotoxin A (ribosylation of EF2),Exoenzyme S (ribosylation via type III of gprotein ras; cytoskeleton collapse), Cytotoxin (pore forming protein),Extracellular proteases (elastase; necrosis of vasculature and alkaline protease; complement, IgG, IgM), Phospholipase (Phospholipase C breaks down membranes- lecithin), Endotoxin (fever, shock, etc.) |
|
|
Term
|
Definition
| facultative Gram-negative curved rods, motile (single polar flagellum), oxidase-positive, grow well in alkaline media (pH 9 to 9.6), and have simple nutritional requirements Vibrio cholerae and Vibrio parahaemolyticus, although V. vulnificus, V. alginolyticus, and other species also cause some wound infections |
|
|
Term
|
Definition
| many different serotypes,Cholera is often spread by contaminated water or food, and it is believed that Vibrio cholerae is capable of existing as a free-living organism in brackish water in bays and estuaries, possibly infecting shellfish there, dose required to produce infection is very high, about 10 to the 9 cells.Cholera is characterized by a profuse, watery diarrhea containing flecks of mucus (called "rice-water" stool), but no blood or inflammatory cells, nonivasive,colonizes the surface of the brush-border cells of the small intestine, but remains in the lumen of the intestine,Cholera toxin is composed of an A subunit and 5 B subunits. The B subunit is responsible for the binding of the toxin to its receptor on the surface of the epithelial cells, and for the delivery of the A subunit into the cytoplasm of the intoxicated cell. Once the A subunit is inside the cytoplasm, it becomes an active enzyme, capable of causing the ADP ribosylation of a cellular G protein which regulates the activity of the cellular enzyme adenylate cyclase |
|
|
Term
|
Definition
| halophilic marine vibrio that requires salt for growth,Gastroenteritis caused by these organisms typically follows ingestion of raw or improperly cooked seafood, such as oysters,the disease will begin after a 5-hour to 92-hour incubation period with an explosive watery diarrhea,self-limiting and recovery is generally uneventful,Pathogenic strains produce Kanagawa hemolysin |
|
|
Term
|
Definition
| particularly virulent species of Vibrio which causes rapidly progressive wound infections after exposure to contaminated seawater, as well as septicemia following ingestion of raw oysters,septicemia may produce mortality of 50% if antibiotic treatment is not begun soon enough, |
|
|
Term
|
Definition
| slender, Gram-negative, oxidase-positive, highly motile, curved rod. Gram stained cells may be S-shaped, gull-winged, or comma-shaped, microaerophilic.Special selective culture medium containing antibiotics to inhibit the growth of enteric normal flora is used to culture Campylobacter, and the plates are incubated microaerophilically and at high temperature. Campylobacter is widely distributed among animals,Large outbreaks of human infection have been traced to the consumption of contaminated milk, food, and watera bloody, muco-purulent diarrhea affecting both the small and large intestine with fever and abdominal cramps. Most infections are self-limited with symptoms subsiding in about 7 days. C. jejuni (major cause of diarrheal disease in the United States) and C. fetus (bacteremic infections in compromised hosts) |
|
|
Term
|
Definition
| H. pylori. gastritis, duodenitis, and peptic and duodenal ulcers,Gram-negative, highly motile, oxidase-positive, strongly curved bacterium, microaerophilic, produces urease (survival and growth in acidic environment),found within the mucus layer overlying the gastric epithelium or adherent to its surface, does not appear to invade the mucosa,produces an exotoxin called vacuolating cytotoxin, because of its cytopathic effect on cell cultures, as well as a protein of unknown function called CagA,contain a 40kb pathogenicity island that encodes a Type IV secretion system which injects effector proteins into gastric epithelial cells which induces the production of the proinflammatory cytokine IL-8. The use of multiple antibiotic therapy to treat ulcers and gastritis is currently under investigation, with some success |
|
|
Term
|
Definition
| large group of heterogeneous bacteria with unusual morphology (spiral-shaped, long, very slender, flexible) and motility (wiggling, corkscrew-like).Cell wall and cell membrane are similar to those of Gram-negative bacteria, except that the cell wall of spirochetes is flexible, not rigid. Spiral-shaped bacteria with rigid cell walls are called spirilla, not spirochetes. All are motile (axial fibrils = periplasmic flagella). They are difficult to stain(darkfield, silver stain, fluorescent antibody), and many do not grow in vitro. Treponema pertenue,carateum,pallidum AND Borrelia Borrelia is thicker and longer, with coarse irregular coils and many axial fibrils. Treponema and Leptospira are about the same size as each other. The coils of Treponema are tight and regular, while those of Leptospira are very tight. Leptospira cells are hooked at one or both ends. Treponema has 6 to 10 axial fibrils, while Leptospira has only 2 recurrentis,burgdorferi,vincentii AND Leptospira |
|
|
Term
| T. pertenue - yaws in tropics and T. carateum - pinta in South America |
|
Definition
| Tropical diseases - chronic skin lesions Non-venereal Associated with poor personal hygiene and insect vectors.Give false-positive serological reactions for syphilis.Respond well to penicillin. |
|
|
Term
|
Definition
Syphilis, sexually transmitted. Primary stage: Syphilis is a systemic disease from the onset, initial infection is through host mucocutaneous tissues,organism travels through the lymphatics to reach the systemic circulation and then infects other distant tissues. Primary- first sign of infection is a papule, which then turns into an painless, ulcerated hard chancre. Secondary- become ill with fever, sore throat, headache, generalized lymphadenopathy, and prominent mucocutaneous lesions over much of the body. There is a macular rash over the trunk and limbs (including the palms of the hands and the soles of the feet). Around moist areas of the skin the lesions occur as coalesced masses called condylomata lata. On mucous membranes the lesions may appear as white patches. Latent stage: Absence of signs and symptoms of disease, but positive serology. Not infectious. Late (tertiary) stage: Not infectious. Three to 30 years after the initial infection, some patients (about 30%) again show signs of illness,. The least serious of these are gummas, which are localized, relatively quiescent granulomatous lesions of the dermal elements or supporting structures of the body. Moreserious manifestations of late syphilis include neurosyphilis and cardiovascular syphilis, which can result in death.Congenital syphilis: If a pregnant woman has active syphilis, the fetus can be transplacentally infected during the pregnancy, infected women can transmit at any stage.
Cannot be grown in culture.
1)Direct microscopic visualization of organisms only in primary and secondary(Darkfield microscopy, Fluorescent antibody technique, Special stain (silver nitrate))
2)Serological methods- Non-treponemal antigen (cardiolipin) (Rapid Plasma Reagin (RPR) and VDRL (Venereal Disease Research Lab), AND Treponemal antigen (FTA (Fluorescent Treponemal Antibody)
- indirect FA test using anti-human Ig labeled with fluorescein andFTA-ABS (FTA-Absorbed)
- like FTA, except the patient's serum is first absorbed with nonpathogenic treponeme to remove nonspecific treponemal antibodies.
Test remains positive for years, even after successful treatment)
Treatment: Penicillin. Since T. pallidum is a very slow-growing organism, the antibiotic therapy must continue over a long period of time. This requires repeated treatment, or a single injection of a long-acting formulation of penicillin |
|
|
Term
| Borrelia recurrentis (louse-borne) and B. hermsii (tick-borne) |
|
Definition
| louse-borne relapsing fever- transmitted directly from person to person by the louse. tick-borne- zoonotic sudden onset of chills, fever, headache, muscle pain, vomiting, and diarrhea followed by recovery, which in turn is followed by another bout of illnessPeriods of illness correspond to bacteremia, and recovery corresponds to production of type-specific antibody. Relapse corresponds to emergence of a new antigenic type due to a special genetic mechanism,The large Borrelia spirochetes are readily seen in Wright, Giemsa, or Gram stains of blood from people with an active episode of relapsing fever. There is no serological test for relapsing fever. |
|
|
Term
|
Definition
| Lyme Disease. erythema chronicum migrans-skin lesion begins to develop at the site of the tick bite. Over a period of weeks it can become quite large, with a red flat border and central clearing, "flu-like" symptoms also occur in early disease, then neurologic and cardiac symptoms, and, even later, arthralgias and arthritis (late pathogenesis potentially crossrxn), Serologic testing provides confirmation of a clinical diagnosis of Lyme disease. |
|
|
Term
|
Definition
| Acute Necrotizing Ulcerative Gingivitis (ANUG),". An abundant mixture of Borrelia spirochetes and fusiform Gram-negative anaerobic bacteria is seen in the infected tissue, and is termed the "fusospirochetal complex" detected by gramstain and tx antibiotic therapy |
|
|
Term
|
Definition
| infectious jaundice, Weil's disease, canicola fever, Unlike other spirochetes, most species can be cultured on ordinary lab media containing animal serum at 25°C. Leptospires are obligate aerobes. |
|
|
Term
|
Definition
which has more than 100 serotypes. Three of these serotypes are pathogenic to humans: pomona (pig), canicola (dog), and icterohaemorrhagiae (rat).Indirect contact with urine from a wide range of infected animals, including rodents, dogs, cats, pigs, horses, etc. The contact may be through contaminated water. Portal of entry can be through abraded skin or exposed mucous membranes (conjunctiva, nasal, or oral).
(1) Organs involved are brain (meninges), lungs, liver, and kidney (where spirochetes finally colonize).
(2) Signs and symptoms include chills and fever, headache, photophobia (conjunctival infection), gastrointestinal disturbances, muscle pain. The occurrence of hemorrhage, jaundice (icterus), and azotemia indicate a poor prognosis.
Lab Dx
Direct examination of specimen (darkfield microscopy) AND Culture (Fletcher's medium, aerobic incubation, 25°C)...Blood and CSF - first week Urine - after first week AND Microscopic agglutination test to detect presence of antibody in patient serum
Tx Antibiotic treatment is effective in early stages of disease. If disease progresses to jaundice, mortality is10 to 40% |
|
|
Term
|
Definition
| anaerobic Gram-negative rods, resistant to the aminoglycoside antibiotics, such as gentamicin and kanamycin, B. fragilis, B. thetaiotaomicron, and B. melaninogenicus. |
|
|
Term
|
Definition
| It is an obligately anaerobic, non-sporeforming, non-motile, Gram-negative, small pleomorphic rod, sometimes coccobacillus, is resistant to many common antibiotics, including penicillin. Clindamycin and metronidazole are two antibiotics that are often effective against anaerobes, including B. fragilis, has a polysaccharide capsule which serves as an important virulence factor. It is antiphagocytic and promotes abscess formation, LPS has a very weak endotoxic activity,Among the most aerotolerant anaerobes; produces both superoxide dismutase and catalase, Produces neuraminidase, lipase, and proteases,Associated with intra-abdominal, lung, brain, and pelvic abscesses; also peritonitis, and septicemia, Also endocarditis (uncommon |
|
|
Term
| PORPHYROMONAS AND PREVOTELLA |
|
Definition
| They produce a black iron-containing pigment when grown on medium with blood in it. Iron storage, Commonly isolated from oral cavity (both) or vagina (Prevotella), Cause infections of the head, neck, and respiratory tract, as well as chronic periodontitis. Also pelvic or abdominal infections. anaerobes previously associated with the bacteroides |
|
|
Term
|
Definition
| anaerobes. Fusobacteria are normal flora in the oral cavity. Fusobacterium nucleatum is the most frequent member of this group isolated from human infections. F. necrophorum also seen. Fusobacteria are long slender cells which taper to a point at both ends. Unlike the Bacteroides they have a normal, fully toxic endotoxin, and thus can produce septic shock and vascular collapse. Causes similar infections to those caused by Bacteroides |
|
|
Term
| Peptococcus and Peptostreptococcus |
|
Definition
| Anaerobic Gram-positive cocci ) are members of the normal flora and frequently found in mixed anaerobic infections. |
|
|
Term
|
Definition
|
|
Term
|
Definition
| oral anaerobic Gram-negative coccus whose pathogenic role is uncertain. |
|
|
Term
|
Definition
| Gram positive anaerobic rod which is a common component of skin flora and which is associated with the inflammatory process in acne lesions |
|
|
Term
| Eubacterium and Bifidobacterium |
|
Definition
| Gram positive anaerobic rods found in the fecal flora which may occasionally cause infections. |
|
|
Term
| CHARACTERISTICS OF ENDOGENOUS ANAEROBIC INFECTIONS |
|
Definition
1. Proximity to colonized mucosal surfaces.
2. Abscesses frequently seen.
3. Foul-smelling discharge
4. Presence of gas in tissues
5. Necrotic tissue.
6. Frequently are mixed infections containing both obligate anaerobes and facultative bacteria (several species).
7. Not responsive to aminoglycosides; often responsive to clindamycin or metronidazole |
|
|
Term
|
Definition
| large, anaerobic, Gram-positive, endospore-forming rods, ubiquitous in soil and endogenous flora,pathogenesis of clostridia is based primarily upon their production of protein exotoxins, including cytolytic and histolytic enzymes which degrade tissue. Clostridium are C. tetani (tetanus), C. perfringens (gas gangrene), C. botulinum (botulism), and C. difficile (pseudomembranous colitis). |
|
|
Term
| Clostridium tetani (Tetanus) |
|
Definition
Round terminal spores in long, narrow, pleomorphic rods, Motile (peritrichous flagella) colonies with "ground-glass" appearance, hemolytic, thin, spreading growth.
Spores enter wound, germinate, organisms multiply, produce toxin
-Intracellular protein released from bacterial cell by autolysis, not by secretion, Toxin gene is located on a plasmid, Toxin is split into two fragments of increased toxicity, Initially binds to peripheral nerve endings, and is then internalized and transported up the axon to the cell body of the neuron, in the spinal cord, Then transported to inhibitory interneurons where it binds to gangliosides in synaptic membranes and inhibits the release of an inhibitory neurotransmitter- Result is convulsive contraction of voluntary muscles
Tx-Antitoxin - must be used before toxin becomes fixed to nervous system tissue, Surgical debridement of wound site, Antibiotics, "Booster" injection of tetanus toxoid (formalin-inactivated toxin). |
|
|
Term
| Clostridium botulinum (Botulism) |
|
Definition
Oval, subterminal spores, Large, grayish colonies, hemolysis usually present. Inhibits the release of acetylcholine at neuromuscular synapses. Toxin genes are located on genome of lysogenic bacteriophage.
The classical form (Flaccid paralysis and respiratory failure); wound botulism; and infant botulism (infects and colonizes the gastrointestinal tract of newborn infants and produces toxin)
Tx-Trivalent antitoxin (against A,B,E toxin variants), Maintain ventilation via mechanical respirator, if necessary. No antibiotics needed for foodborne botulism; may be used in the other two forms of botulism |
|
|
Term
|
Definition
Very large rods, encapsulated within tissue, nonmotile, Spores are rare (oval, subterminal, not bulging), Rapid growth, double zone of hemolysis on anaerobic blood agar plate, Organisms ferment carbohydrate in muscles with gas production, Many varied toxins (cytolytic, histolytic enzymes) are produced (up to 12 reported).
Wound infection, Uterine infection-Septic abortion, Septicemia, Food poisoning- Enterotoxin-producing strains, preformed toxin in food. Mild and common form of food poisoning. Third most common after S. aureus and Salmonella. Enteritis necroticans. Rare. Acute infection of small intestine. Necrosis and perforation. Mortality is 50%.
Tx-Surgical debridement, Massive antibiotic therapy, Hyperbaric oxygen treatment. |
|
|
Term
| Clostridium difficile (Pseudomembranous colitis) |
|
Definition
iatrogenic infection; that is, an infection which is caused by medical treatment The classic example is treatment with clindamycin.produces a potent cytotoxin, and which is present as endogenous flora at very low levels in some people. It is kept at low levels by competition with the rest of the normal flora, result is formation of necrotic pseudomembranous plaques on the bowel mucosa. This can lead to bowel perforation, peritonitis and death.
Tx-stop giving the antibiotic which caused the problem, start fluid replacement therapy, and start giving (orally) a different antibiotic which is effective against C. difficile |
|
|
Term
|
Definition
15 immunotypes (A-L). genital tract infections, eye and respiratory infections. A, B, and C cause trachoma (transmitted from finger to eye or fomite to eye contact), D-K cause genital tract infections which are occasionally transmitted to eyes and respiratory tract In men, it is a common cause for nongonococcal urethritis (NGU) which may progress to epididymitis and prostatitis. • In women, cervicitis develops and progress to salpingitis and pelvic inflammatory disease (PID)sexually transmitted disease, high incidence of Reiter’s syndrome (autoimmune disease caused by antibodies against C. trachoma that cross reacts with antigens present in cells of eyes, joints and urethra),• C. trachomatis L1-L3 immunotypes cause lymphogranuloma venerium, a sexually transmitted disease characterized by lesions on genitalia and infection and inflammation in lymph nodes
Tx- azithromycin because there is usually co-infection of C. trachomatis and gonococci
-neonatal conjunctivitis is erythromycin
-L1-3 DOG tetracyclines such as doxycycline |
|
|
Term
|
Definition
obligate intracellular pathogen, They have a rigid cell wall but do not have peptidoglycan layer, infects epithelial cells of the mucous membranes, replicative cycle that is different from other bacteria. The replicative cycle begins when a metabolically inert, extracellular spore-like, elementary body enters the epithelial cell,inert elementary bodies get transformed into a metabolically active reticuloid body, reticuloid body undergoes division by binary fission to form daughter cells, At the site of replication there appear an inclusion (glycogen) body which can stained (iodine)(Dx) and observed under the microscope, share a group specific lipopolysacharide antigen that can be detected by complement fixation and a species specific and immunotype specific antigens that can be detected by immunofluorescence, The cells wall resembles that of Gram negative bacteria but lacks muramic acid
Dx
• Fluorescent antibody staining of the samples
• DNA hybridization
• ELISA can done to detect chlamydial antigens in urine samples
• Serological test can be used detect antibodies against Chlamydia
• Serological tests are often useful to detect C. psittaci and C. pneumoniae infection. However, serological tests are not useful to diagnose C. trachomatis infection because the frequency of infections is so high that many people (carriers, patients and contacts will have antibodies
Tx• All chlamydia are susceptible to tetracyclines such as doxyclines, and macrolides such as erythromycin and azithromycin
-Erythromycin should be given to the newborns of infected mothers to prevent inclusion conjunctivitis and pneumonitis |
|
|
Term
|
Definition
primarily infects lungs. The infection may be asymptomatic may cause fever and pneumonia, generally not very communicable
Tx- tetracyclines such as doxycycline |
|
|
Term
|
Definition
causes upper and lower respiratory tract infection, especially bronchitis and pneumonia in young adults
Tx- tetracyclines such as doxycycline |
|
|
Term
|
Definition
very shorts barely visible under light microscope, Structurally they resemble Gram negative bacteria, obligate intracellular pathogens, divide by simple binary fission, R. rickettsii, R. tsutsagamushi and R. prowazekki express proteins that cross react the proteins OX strains of Proteus vulgaris (xreactivity-Weil-felix test), infects endothelial cells and causes vasculitis, Characterized by rash, edema and hemorrhage due to vascular permeability, In severe cases there is intravascular coagulation and vascular collapse, And this is mediated by endotoxins, There is evidence of exotoxin production by the bacteria.
Dx- ELISA and indirect immunofluorescence are two commonly used serological tests that are used for diagnosis, Weil Felix is a historical test that is not been used nowadays, The principle is based on the cross reaction of antibodies against rickettsial antigens to the antigens of OX strains of Proteus vulgaris
Tx- choice of treatment for all rickettsial diseases include tetracycline along with chloramphenicol |
|
|
Term
|
Definition
spore like stage that is resistant to drying and is very infective, causes Q fever which is transmitted by inhalation of aerosol particles of the bacteria (only rickettsia that is not vector born), The bacteria infects cattle, And are present in large quantities in the placenta, amniotic fluid, urine and feces, causes both upper and lower respiratory-track infections, The bacteria migrates from lungs to other parts of the body, Common symptoms include fever, cough, head ache and myalgia, Skin rash is in uncommon, Pneumonia along with hepatitis is an indication of Coxiella infection can be severe and lead to endocarditis, not communicable
Tx- In most cases the individuals recover before antibiotic treatment. tetracycline along with chloramphenicol. • Veterinarians, people who work in dairy and abattoir, who are at risk for Q fever should receive a vaccine that consists of killed organism |
|
|
Term
|
Definition
| Rocky Mountain Fever, The bacteria is maintained in the tick Dermocenter variablis, tick bites, local lesion develops bacteria enters the circulation and infects the endothelial cells causing redness, swelling and edema, The bacteria spreads to the different parts of the body, • The lesion usually appears on the hand and legs and spreads to the trunk, The onset of disease is characterized by non-specific symptoms such as myalgias, headache and fever, As the disease advances the symptoms will include coma and dilerium, In severe cases there is intravascular coagulation and vascular collapse, no person-person to transmission |
|
|
Term
|
Definition
Typhus, The bacteria is maintained inside human louse Pediculus, There is no animal reservoir, When the louse bites a new individual for a blood meal it defecates during the act of biting and the bacteria is auto-inoculated into the body while scratching the bite, The lesions first appear in the trunk and spread to the hand and legs, Face, palm and soles are spared, Patient may experience delirium and coma, in untreated cases there will be vascular collapse, recurrent form of typhus is called Brill Zinser disease is common among elderly people in the United States
Tx-tetracycline along with chloramphenicol, formalin killed vaccine available for typhus and it is available to military staff and not to civilians |
|
|
Term
|
Definition
used to be the leading cause for meningitis in children, causative agent for upper respiratory tract infections (sinusitis and otitis media- nonencapsulated form) and sepsis in children, pneumonia in adults with obstructive lung disease, encapsulated and causes invasesive disease, type B capsule (made of polyribosyl phosphate) is considered extremely virulent, need chocolate agar (agar+heated blood) supplemented with factor V (NAD) and factor X (heme compound), inhaling aerosol droplets, IgA protease to degrade the host IgA and thereby attach firmly to the respiratory epithelial cells, the bacteria invade the lungs and go to different parts of the body to cause meningitis and sepsis. Capsulated strains cause invasive meningitis and sepsis. Non-encapsulated strains are non-invasive and cause upper respiratory tract infections. Pathogenesis involves antiphagocytic capsule and endotoxin. No exotoxin is produced.
Tx-ceftriaxone since the bacteria are resistant to penicillin, respiratory tract infections can be treated with amoxicillin-clavulanate or trimetheoprim-sulfamethoxazole, capsular polysaccharide of H. influenza conjugated to carrier protein is highly effective vaccine, Meningitis can be prevented in close contacts of the patients by treating with rifampicin |
|
|
Term
|
Definition
coccobacillary, encapsulated Gram negative bacteria, causes whooping cough, inhalation of aerosol particles, attaches to the ciliated epithelial cells with hemagglutinin in the upper respiratory tract but do not invade, Decreased ciliary activity following death of cilated epithelial cells is an important aspect of pathogenesis, pertusis toxin that induce ADP-ribosylation of inhibitory subunit of G protein leading to activation of adenyl cyclase. Activated adenyl cyclase induces cyclic AMP synthesis and cyclic AMP (also taken up the macrophages where it inhibits the antimicrobial mechanisms) activates cyclic AMP dependent protein kinase (induces mucous production in the lungs and inhibits the signal transduction by chemokine receptors causing lymphocytosis),cyototoxin produced by the bacteria is a fragment of the bacterial peptidoglycan and in concert with endotoxin induce nitric oxide production that kills the ciliated epithelial cells.
Dx-cultured in Bordet-Gengou medium. Since the organisms grow slowly fluorescent antibody staining is often used in diagnosing the infection. PCR tests are also available.
Tx-Erythromycin, heat killed vaccine and the other is a acellular vaccine(modified pertussis toxoid where the amino acids that induce ADP-ribosylation are changed and other proteins in the acellular vaccine include hemagglutinin- if have antibodies to hemagglutinin bacteria can't invade) |
|
|
Term
|
Definition
causes atypical pneumonia, requires special nutrients for growth; cultured in charcoal-yeast media supplemented with iron and cysteine, Infection occurs by inhalation of bacteria, causes atypical pneumonia, In severe cases, bacteremia occurs where the organisms can go to multiple organs and cause infection, the major virulence factor is endotoxin, No exotoxins are produced, Cell mediated immunity plays an important role in controlling legionella infection, mild influenza like symptoms to a severe pneumonia accompanied by mental confusion, diarrhea and proteinurea. Although cough is common, the sputum is usually non-purulent. The disease usually resolves spontaneously,
Dx-can be grown in charcoal-yeast media supplemented with iron and cysteine. Samples can be stained with fluorescent antibody. ELISA can be performed in urine samples to detect the presence of antigens
Tx-drug of choice are erythromycin and Fluoroquinolones. Prevent generation of aerosols from water sources. Outbreak of legionella in the hospitals can be prevented by heating the water and by treating the water with chlorine. |
|
|
Term
|
Definition
Gram negative bacteria lacking capsules. Three main human pathogens and their animal reservoirs include: 1. B. melitensis (goats and sheep) 2. B. abortus (cattle) 3. B. suis (pigs). causes brucellosis (undulant fever), infection- consumption of contaminated milk or dairy products or by direct contact with the skin, infection localizes in the reticuloendothelial system namely lymph nodes, liver and spleen. They live inside the macrophages. The host immune responses to infection include formation of granuloma. The granuloma is made of lymphocytes, macrophages, giant cells and epitheleoid cells. The granuloma can progress to caseating abscess.when the O antigen is lost from the endotoxin there is loss in the virulence. After three weeks of incubation, the initial symptoms are non-specific which include fever, chills and fatigue. The characteristic symptom is the undulating fever with concomitant enlargement of liver, spleen and lymph nodes
Dx-Agglutination test. Serological test are often used to determine whether or not the individual is infected with Brucella
Tx-drug of choice is rifampicin+tetracycline, no vaccine |
|
|
Term
|
Definition
causes tularemia or ulceroglandular disease. zoonotic (vector- dermocenter tick) infects the reticulo-endothelial system leading to enlargement of liver, spleen and lymph nodes,granuloma formation and caseation. The onset of disease is characterized by non-specific flu-like symptoms such as myalgias, headache and fever. The endotoxin produced by the organisms is believed to contribute to the pathogenesis. There is no exotoxin
Tx- Tuleremia is treated with streptomycin |
|
|
Term
|
Definition
Gram-negative bacteria, exhibits bipolar staining (resembles a safety pin), outer capsule made of polysaccharide and proteins and is responsible for virulence, zoonotic,blood clots inside the gut of the flea due to the production of coagulase by the bacteria and gets tangled inside the fibrin of the blood, cannot feed, host specificity is lost, bites humans organism spreads to lymph nodes where it causes pathogenesis leading to swollen and tender lymph nodes. virulence factors-
1. the envelope capsular antigen called F-1 that inhibits phagocytosis
2. endotoxin that mediates disseminated intravascular coagulation and vascular collapse
3. exotoxin such as V and W antigens that allow the organism to survive inside the macrophages
4. Yersinia outer protein (YOP) that is inserted into the bacterial cell by type III system.
4. yersinia outer protein inhibit the cytokine signaling leading to impaired production of TNF-α. Bubonic plague is characterized by swollen and tender lymph nodes and referred as bubos. Pneumonia and septic shock are the life threatening events that follow. Pneumonic plague result due to inhalation of the aerosol containing bacteria or due to dissemination of the Y. pestis from lymph nodes to lungs
Dx-Lymph node smears should be stained with Giemsa or Wayson for a safety pin shaped bacteria. Immuno-fluorescence staining of the bacteria and antibody titer
Tx- streptomycin and tetracycline, vaccine containing formalin containing organism provide partial protection against bubonic but not pneumonic plague. |
|
|
Term
|
Definition
smallest and simplest self-replicating bacteria,lack a rigid cell wall and are bound by a single membrane, smallest genome size and, as a result, lack many metabolic pathways and require complex media for their isolation, facultative anaerobes, except for M. pneumoniae, which is a strict aerobe, cell membrane rich in cholesterol, slow growing,
1. Mycoplasma pneumoniae that cause atypical pneumonia
2. Mycoplasma hominis that cause pelvic inflammatory disease
3. Mycoplasma urelyticum that cause urethritis
Mycoplasmas can activate macrophages and stimulate cytokine production (by CD14 independent mechanism) and lymphocyte activation (M. pneumoniae is a superantigen, Mycoplasmas are mostly extracellular pathogens with the exception of Mycoplasma penetrans which has been shown to exist in the intracellular compartment of the host cells, infection antibodies are produced against mycoplasma antigens that cross react with the antigens in the RBC, brain, heart and liver. This is called cold-agglutinin and forms an important basis for sero-diagnosis |
|
|
Term
|
Definition
inhalation of aerosol particles containing bacteria,rod shaped with tapering end with which they attach to the respiratory epithelial cells, not invade respiratory mucosa however the ciliary movement is inhibited, tip contains cytoadhesins which binds to the scialic acid, results in initiation of inflammation and necrosis of epithelial cells and hydrogen peroxide is involved, shown to inhibit host cell catalase, thereby increasing the peroxide concentrations, is a superantigen, atypical/walking pneumonia- atypical because the organism cannot be isolated in the routine culture media that is used in the clinical laboratories. Furthermore the disease is less severe than the conventional pneumonia and the causative agent is neither streptococcus nor haemophilus. The most common clinical syndrome following infection with M. pneumoniae is tracheobronchitis, X-ray examination will show signs of pneumonia even before respiratory symptoms appear
Dx-Culture is essential for a definitive diagnosis. Mycoplasma can be grown in vitro in special media enriched with lipids. It may take one to three weeks for the colonies to develop.
Serology
-Complement fixation test - There is a good complement fixation test that has good sensitivity and specificity, titers indicate recent but not current infection
-Cold agglutinins-are antibodies that agglutinate human erythrocytes at 4 degrees C but not at 37 degrees C. The antigen to which the antibodies are directed is the I antigen. These antibodies arise before the complement fixing antibodies and they decline faster, CGs not specific for M. pneumoniae infections
-. ELISA - There is a new ELISA for IgM that has been used for diagnosis of acute infection. It is sensitive and specific. However, it is not yet commercially available
Tx-the penicillins and cephalosporins are ineffective. The antibiotics of choice are tetracycline (adults only) and erythromycin. no available vaccine |
|
|
Term
| M. hominis and U. urealyticum |
|
Definition
| M. hominis is associated with pyelonephritis, pelvic inflammatory disease and post-partum fevers. U. urealyticum is associated with non-gonococcal urethritis. Colonization with M. hominis and U. urealyticum can occur during birth but in most cases the infection will be cleared. Only in a small number of cases does colonization persist. However, when individuals become sexually active, colonization rates increase. Approximately 15% are colonized with M. hominis and 45% - 75% with U. urealyticum. The carriers are asymptomatic but the organisms can be opportunistic pathogens. M. urealyticum produces urease and in the presence of urea forms ammonia which can be detected using a pH indicator and this forms the important basis for diagnosing M. urealyticum. |
|
|
