Gram Negative Bacteria PDF

Gram Negative Bacteria 1 Asst. Prof. Dr. Ayha Mehmetoğlu [email protected]  Gram Negative Bacteria Cocci/coccobacilli Bacilli Neisseria...

Gram Negative Bacteria 1 Asst. Prof. Dr. Ayha Mehmetoğlu [email protected]  Gram Negative Bacteria Cocci/coccobacilli Bacilli Neisseria Facultative Anaerobic Moraxella Bacteroides Haemophilus Prevotella Bordatella straight curved Brucella Enteric bacteria Campylobacter Legionella Helicobacter Yersinia Vibrio Francisella Pasteurella Pseudomonas Acinetobacter  a. Gram-negative Cocci Neisseria Gonorrhea Meningitidis 3  b. Gram-negative Rods (bacilli) Gram-negative Rods Straight Curved Aerobic Anaerobic Respiratory organisms Zoonotic organisms Enteric and related organisms 4 Neisseria 5  The genus Neisseria consists of gram-negative, aerobic cocci. Two Neisseria species are pathogenic for humans ”Neisseria gonorrhoeae (commonly called Overview gonococcus), the causal agent of gonorrhea; and Neisseria meningitidis (commonly called meningococcus), a frequent cause of meningitis. Gonococci and meningococci are nonmotile diplococci that cannot be distinguished from each other under the microscope. 6  Gonorrhea is one of the most frequently reported infectious diseases. The causal agent, N. gonorrhoeae, a gram- negative diplococcus, is frequently observed inside polymorphonuclear leukocytes of clinical samples obtained from infected patients. I. Neisseria N. gonorrhoeae is usually transmitted during sexual contact or, more rarely, during the Gonorrhoeae passage of a baby through an infected birth canal. It does not survive long outside the human body because it is highly sensitive to 7 dehydration.  Pili Pili enhance attachment of the organism to host epithelial and mucosal 8  Genitourinary tract infections: Symptoms of gonococcal infection are more acute and easier to diagnose in males. The patient typically presents with a yellow, purulent urethral discharge and painful urination. In females, infection occurs in the endocervix and extends to the urethra and vagina. A greenish-yellow cervical discharge is most common, often accompanied by intermenstrual bleeding. The disease may progress to the uterus, causing salpingitis (inflammation of the fallopian tubes), pelvic inflammatory disease (PID), and fibrosis. Infertility occurs in approximately twenty percent of women with gonococcal salpingitis, as a result of tubal scarring. Rectal infections and Pharyngitis 9  Ophthalmia neonatorum Ophthalmia neonatorum is an infection of the conjunctival sac that is acquired by a newborn during passage through the birth canal of a mother infected with gonococcus. If untreated, acute conjunctivitis may lead to blindness. Treatment is with erythromycin because the antibiotic also eradicates Chlamydia trachomatis, if present. [Note: Gonococcal conjunctivitis can also occur in adults.] 10  N. meningitidis is one of the most frequent causes of meningitis. Infection with N. meningitidis can also take the form of a fulminant meningococcemia, with intravascular coagulation, circulatory collapse, and potentially fatal shock, but without meningitis. In each case, symptoms can occur with extremely rapid onset and great intensity. Outbreaks of meningitis, most common in winter and early spring, are favored by close contact between individuals; for example, in schools, institutions, and military barracks. II. N. Severe epidemics also occur periodically in meningitidis developing nations, for example, in sub- Saharan Africa and Latin America. N. meningitidis tends to strike young, previously well individuals and can progress over a 11 matter of hours to death. Polysaccharide capsule When meningococcus is isolated from blood or spinal fluid, it is invariably encapsulated. The meningococcal polysaccharide capsule is antiphagocytic and, therefore, the most important virulence factor. 12  Clinical significance N. meningitidis initially colonizes the nasopharynx, resulting in a largely asymptomatic meningococcal pharyngitis. In young children and other susceptible individuals, the organism can cause disseminated disease by spreading through the blood, leading to meningitis and/or fulminating septicemia. N. meningitidis is currently a leading cause of meningitis. 13  Meningitis Meningococci enter the bloodstream where they rapidly multiply (meningococcemia). It can infect the meninges. Joint symptoms and a petechial rash are also commonly observed in meningococcal infections. Within several hours the initial fever and malaise can evolve into severe headache, a rigid neck, vomiting, and sensitivity to bright lights symptoms characteristic of meningitis. Coma can occur within a few hours. 14 15  Septicemia: Meningococci can cause a life-threatening septicemia in an apparently healthy individual in less than twelve hours. Acute, fulminating meningococcal septicemia seen mainly in very young children. 16  Vaccines: A conjugate meningococcal vaccine (MCV4) was approved in the United States in 2005 for use in adolescents and adults 11 to 55 years of age and has replaced the quadrivalent polysaccharide vaccine. MCV4 is a tetravalent vaccine that contains capsular polysaccharides from serogroups A, C, W-135, and Y. 17  Updated data from CDC Vaccines can help prevent meningococcal disease, which is any type of illness caused by Neisseria meningitidis bacteria. There are 2 types of meningococcal vaccines available in the United States: Meningococcal conjugate or MenACWY vaccines (Menactra®, Menveo®, and MenQuadfi®) Serogroup B meningococcal or MenB vaccines (Bexsero®and Trumenba®) 18  Members of the genus Moraxella are Coccobacilli nonmotile, gram-negative coccobacilli that are generally found in pairs. This organism can cause infections of the respiratory system, middle ear, eye, CNS, and joints. I. Moraxella 19 Coccobacilli Members of the genus Acinetobacter are nonmotile coccobacilli. They are important nosocomial (hospital- acquired) pathogens. II. Acinetobacter 20 Gastrointestinal Gram-negative Rods  All of the organisms are routinely found in the gastrointestinal (GI) tract of humans or other animals. All grow well in the presence of oxygen, being true facultative anaerobes. I. They contain lipopolysaccharide (LPS) (endotoxin). Overview They constitute only a fraction of the total microbiota of the GI tract (most bowel organisms are either gram-positive or gram- negative anaerobes). 22  Diseases Different enteric gram-negative rods cause diseases in the GI tract, outside the GI tract, or in both locations. For example, diseases caused by members of the genera Escherichia, Salmonella, Yersinia, and Campylobacter can be both gastrointestinal and extraintestinal, those caused by members of the genera Shigella, Helicobacter, and Vibrio are primarily gastrointestinal, and those caused by members of the genera Enterobacter, Klebsiella, Serratia, and Proteus are primarily extraintestinal. Fecal contamination is frequently important in the transmission of those organisms that cause GI diseases. 23  Escherichia Salmonella Shigella Entero Yersinia Klebsiella Proteus bacter Enterobacter Providencia iaceae Morganella hafnia Citrobacter Edwardsiella Serratia Pathogen: Salmonella Shigella Yersinia Oportunistic pathogen: E.coli Klebsiella Serratia Proteus Enterobacter 25  E. coli is part of the microbiota of the colon in humans and other animals but can be pathogenic both within and outside of the GI tract. E. coli has fimbriae or pili that are frequently important for adherence to II. host mucosal surfaces. E. coli produces both acid and gas Escherichia during fermentation of carbohydrates. Coli 26  Clinical significance/intestinal disease Transmission of intestinal disease is commonly by the fecal/oral route, with contaminated food and water serving as vehicles for transmission. At least five types of intestinal infections that differ in pathogenic mechanisms have been identified. Enterotoxigenic (ETEC) Enteropathogenic (EPEC) Enterohemorrhagic (EHEC) Enteroinvasive (EIEC) Enteroaggregative (EAEC) 27  Enterotoxigenic E. coli (ETEC): ETEC are a common cause of traveler's diarrhea. Transmission occurs through food and water contaminated with human waste, or by person-to-person contact. 28  Enteropathogenic E. coli (EPEC): EPEC are an important cause of diarrhea in infants, especially in locations with poor sanitation. 29  Enterohemorrhagic E. coli (EHEC): EHEC bind to cells in the large intestine, where they produce an exotoxin (verotoxin, or Shiga-like toxin), causing a severe form of copious, bloody diarrhea (hemorrhagic colitis) in the absence of mucosal invasion or inflammation. Serotype O157:H7 is the most common strain of E. coli that produces verotoxin. This strain is also associated with outbreaks of a potentially life-threatening, acute renal failure (hemolytic uremic syndrome, HUS). 30  The bacteria will be much more deadly if they have the features of both E. coli strain EAEC and EHEC O104:H4 which is the case of the current strain of E. coli (Walsh 2011). 31  Other E. coli infections: Enteroinvasive E. coli (EIEC) cause a dysentery-like syndrome with fever and bloody stools. Enteroadherent E. coli (EAEC) also cause traveler's diarrhea and persistent diarrhea of young children. 32 Clinical significance/ extraintestinal disease The source of infection for extraintestinal disease is frequently the patient's own flora, in which the individual's own E. coli is nonpathogenic in the intestine. However, it causes disease in that individual when the organism is found, for example, in the bladder or bloodstream (normally sterile sites). 33  Urinary tract infections (UTI): E. coli is the most common cause of UTI, including cystitis and pyelonephritis. Women are particularly at risk for infection. 34 Dr. Ayham Abulaila 35  Others Neonatal meningitis: E. coli is a major cause of this disease occurring within the first month of life. Nosocomial (hospital-acquired) infections: These include sepsis/bacteremia, endotoxic shock, and pneumonia. 36 Dr. Ayham Abulaila 37  Members of the genus Salmonella can cause a variety of diseases, Salmonella including gastroenteritis and enteric (typhoid) fever. 38  Clinical significance/ Gastroenteritis Salmonella infection can cause both intestinal and extraintestinal diseases (for example, typhoidal salmonella). It is characterized by nausea, vomiting, and diarrhea. Fever and abdominal cramping are common. 39 Clinical significance/ Enteric (typhoid) fever This is a severe, life-threatening systemic illness, characterized by fever and, frequently, abdominal symptoms. It is caused primarily by serotype typhi (typhoidal salmonella). Nonspecific symptoms may include chills, sweats, headache, anorexia, weakness, sore throat, cough, myalgia, and either diarrhea or constipation. About thirty percent of patients have a faint maculopapular rash on the trunk (rose spots). Mortality is approximately fifteen percent 40 Dr. Ayham Abulaila 41 42  Members of the genus Campylobacter are curved, spiral, or S-shaped organisms that microscopically resemble vibrios. Campylobacter infect the intestine, and can cause ulcerative, inflammatory lesions in the Campylobacter jejunum, ileum, or colon. C. jejuni typically causes an acute enteritis in otherwise healthy. Bacteremia may occur. 43 Dr. Ayham Abulaila 44  Shigella species cause shigellosis (bacillary dysentery) a human intestinal disease that occurs most commonly among young Shigella children. species 45  Pathogenesis and clinical significance An exotoxin (Shiga toxin) with enterotoxic and cytotoxic properties. Shigellae cause classic bacillary dysentery, characterized by diarrhea with blood, mucus, and painful abdominal cramping. 46 Dr. Ayham Abulaila 47  Members of the genus Vibrio are Vibrio short, curved, rod-shaped organisms. 48 Dr. Ayham Abulaila 49 50  Clinical significance Full-blown cholera is characterized by massive loss of fluid and electrolytes from the body. After an incubation period ranging from hours to a few days, profuse watery diarrhea (rice-water stools) begins. Untreated, death from severe dehydration. 51 Dr. Ayham Abulaila 52  The genus includes three species of medical importance: Y. enterocolitica and Y. pseudotuberculosis, both potential pathogens of the GI tract Yersinia Y. pestis, the etiologic agent of bubonic plague 53 Dr. Ayham Abulaila 54  The genus Yersinia is a member of the family Enterobacteriaceae. The most clinically notorious member of this genus is Yersinia pestis, which causes Yersinia plague, rather than enteric disease. Pestis 55 Dr. Ayham Abulaila 56  Clinical significance Plague may present several clinically different pictures. Most common is the bubonic/septicemic form. Pneumonic plague may develop during epidemics. 57 Dr. Ayham Abulaila 58  Members of the genus Helicobacter are curved or spiral organisms. They have a rapid, corkscrew motility Helicobacter resulting from multiple polar flagella. It causes acute gastritis and duodenal and gastric ulcers. 59 Dr. Ayham Abulaila 60  Respiratory organisms Haemophilus : Meningitis Bordetella : Whooping cough Legionella: Pneumonia 61 Dr. Ayham Abulaila 62  Clinical significance H. influenzae has been a leading cause of bacterial meningitis, primarily in infants and very young children, frequently in conjunction with an episode of otitis media. A vaccine against H. influenzae type b, administered to infants, has dramatically decreased the frequency of such infections. Clinically, H. influenzae meningitis is indistinguishable from other purulent meningitides, and may be gradual in onset or fulminant (sudden onset with great severity). 63 Dr. Ayham Abulaila 64  Bordetella Bordetella pertussis and B. parapertussis are the human pathogens of this genus. The former causes the disease pertussis (also known as whooping cough), and the latter causes a mild pertussis-like illness. 65 Dr. Ayham Abulaila 66  IV. Legionella Dr. Ayham Abulaila 67  Legionella Legionellaceae are facultative intracellular parasites that cause primarily respiratory tract infections. 68 Dr. Ayham Abulaila 69  Pseudomonas Pseudomonas aeruginosa, the primary human pathogen in the genus Pseudomonas, is widely distributed in nature A significant opportunistic pathogen and a major cause of nosocomial (hospital-acquired) infections. 70 Dr. Ayham Abulaila 71 Dr. Ayham Abulaila 72  Brucella Members of the genus Brucella are primarily pathogens of animals (domestic and feral). Thus, brucellosis (undulant fever) is a zoonosis (a disease of animals that may be transmitted to humans under natural conditions). Different species of Brucella are each associated with particular animal species; for example, B. abortus (cattle), B. melitensis (goats and sheep), B. suis (swine), B. canis (dogs), and B. ovis (sheep). All but B. ovis are known to cause disease in humans. 73 Dr. Ayham Abulaila 74 Dr. Ayham Abulaila 75  Francisella Tularensis Francisella tularensis is primarily a pathogen of animals. Thus, tularemia (also known as rabbit fever and deerfly fever) is a zoonosis. 76 Dr. Ayham Abulaila 77  Anaerobic Gram-negative Rods (bacilli) Bacteroides : Peritonitis 78 Dr. Ayham Abulaila 79 Dr. Ayham Abulaila 80  For any question [email protected] Dr. Ayham Abulaila 81