Medically Important Gram-Negative Bacteria PDF

MEDICALLY IMPORTANT GRAM- NEGATIVE BACTERIA dr. I Ketut Agus Indra A., Sp.MK Departemen Mikrobiologi FK UNUD RS Universitas Udayana OUTLINE INTRODUCTION Enterobacteriaceae: Non Lactose fermenter Salmonella Shigella Yersinia Proteus Enterobacteriaceae: Lactose ferment...

MEDICALLY IMPORTANT GRAM- NEGATIVE BACTERIA dr. I Ketut Agus Indra A., Sp.MK Departemen Mikrobiologi FK UNUD RS Universitas Udayana OUTLINE INTRODUCTION Enterobacteriaceae: Non Lactose fermenter Salmonella Shigella Yersinia Proteus Enterobacteriaceae: Lactose fermenter Eschericia coli Klebsiella Citrobacter Enterobacter spp. Serratia Other Non Lactose fermenter Pseudomonads Vibrio Acinetobacter  Gram Negative bacteria (all) Bacteria use biochemical pathways to catabolize carbohydrates and produce energy by two mechanisms Fermentation is an anaerobic process à obligate, facultative, and aerotolerant anaerobes. Aerobic respiration (oxidation)à Obligate aerobes and facultative anaerobes. Mahon CR, Lehman DC, Manuselis G. 2019. Textbook of Diagnostic Microbiology. 6th Edition. China : Elsevier, Saunders CULTURE growth MacConkey Agar (MAC) is a selective and differential medium designed to isolate and differentiate enterics based on their ability to ferment lactose. Bile salts and crystal violet inhibit the growth of Gram positive organisms or other commensal bacteria. Lactose provides a source of fermentable carbohydrate allowing for differentiation.  Escherichia Taxonomy Domain: Bacteria Phylum: Proteobacteria Class: Gammaproteobacteria Order: Entreobacterales Family: Entrobacteriaceae Genus: Escherichia https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&id=561&lvl=3&p=mapview&p=has_linkout&p=blast_url&p=genome_blast&lin=f&keep=1&srchmode=1&unlock  Escherichia coli General Characteristics Commonly isolated from colon biota, therefore, used as a primary marker of fecal contamination in water quality testing. Mostly motile. Possess adhesive fimbriae and sex pili and O, H, and K antigens. O antigens have remarkable cross-reactivity with Shigella spp. Mahon C.R., Lehman D.C. in Textbook of Diagnostic Microbiology 6th edition. Elsevier; 2019  Escherichia coli General Characteristics – Virulence Factor Mahon C.R., Lehman D.C. in Textbook of Diagnostic Microbiology 6th edition. Elsevier; 2019  Escherichia coli General Characteristics Mahon C.R., Lehman D.C. in Textbook of Diagnostic Microbiology 6th edition. Elsevier; 2019  Escherichia coli Uropathogenic E. coli The most common cause of UTIs in humans. Strain that cause UTIs in immunocompetent and immunocompromised patients are different. Strain that cause UTIs produce factors (pili) that allow them to attach to the urinary epithelial mucosa. Other virulence factors are cytolysins and aerobactins. Cytolysins (hemolysins) can kill immune effector cells and inhibit phagocytosis and chemotaxis of certain WBCs. Aerobactin allows the bacterial cell to chelate iron; free iron is generally unavailable within the host for use by bacteria. Mahon C.R., Lehman D.C. in Textbook of Diagnostic Microbiology 6th edition. Elsevier; 2019  Escherichia coli Gastrointestinal E. coli Based on virulence factors, clinical manifestation, epidemiology, and different O and H serotypes, there are 5 major categories of diarrheagenic E. coli. ETEC 1 2 EIEC EPEC 3 4 EHEC Enteroadherent à EAEC and DAEC 5 Mahon C.R., Lehman D.C. in Textbook of Diagnostic Microbiology 6th edition. Elsevier; 2019  Escherichia coli Gastrointestinal E. coli ETEC 1 The most common cause of traveler’s diarrhea, especially in subtropical and tropical climates. Stomach acidity à protective mechanism against infection. Produce a heat-labile toxin (LT) à similar to Vibrio cholerae toxin. The toxin consist of 2 fragments (A & B) and activating the cellular adenylate cyclase causing ATP à cAMP. End results: hypersecretion of electrolytes and fluids into the intestinal lumen. Self limiting disease, characterized by watery diarrhea, abdominal cramps, and sometimes nausea without vomiting or fever. Diagnosis by symptoms, isolation of solely lactose-fermenting on differential media, immunologic assays, multiplex PCR. Mahon C.R., Lehman D.C. in Textbook of Diagnostic Microbiology 6th edition. Elsevier; 2019  Escherichia coli Gastrointestinal E. coli EIEC 2 Rare in US and less commonly in developing countries than ETEC or EPEC. Produce dysentery with direct penetration, invasion, and destruction of the intestinal mucosa à very similar to diarrhea by Shigella spp. à easily misidentified. Transmission via fecal-oral route. Symptoms characterized by fever, severe abdominal cramps, malaise, and watery diarrhea. The strains can be nonmotile and generally do not ferment lactose. Detection with DNA probes kits. Mahon C.R., Lehman D.C. in Textbook of Diagnostic Microbiology 6th edition. Elsevier; 2019  Escherichia coli Gastrointestinal E. coli EPEC 3 The strain has adhesive property. Adherence to human epithelial-2 (Hep-2). Symptoms characterized by low-grade fever, malaise, vomiting, and diarrhea contain mucus but no blood. Cause severe diarrhea in children younger than 1 year old. Rarely seen in adults. Detected by nucleic acid-based assays, serologic typing. Mahon C.R., Lehman D.C. in Textbook of Diagnostic Microbiology 6th edition. Elsevier; 2019  Escherichia coli Gastrointestinal E. coli EHEC 4 Strain serotype O157:H7. Associated with hemorrhagic diarrhea, colitis, and HUS (low platelet count, hemolytic anemia, and kidney failure. Produces 2 cytotoxins: verotoxin I & II. Symptoms characterized by watery to bloody diarrhea, abdominal cramps, and lo-grade fever or no fever. Identified by: stool culture, detecting shiga toxin in stool filtrates, toxin- neutralizing antibody titer. ELISA and latex agglutination test can be used to detect O157 antigen. Mahon C.R., Lehman D.C. in Textbook of Diagnostic Microbiology 6th edition. Elsevier; 2019  Escherichia coli Gastrointestinal E. coli Enteroadherent à EAEC and DAEC 5 Associated with diarrheal syndromes and UTIs. DAEC strains are associated with cystitis in children and acute pyelonephritis in pregnant women, and also pediatric diarrheal disease. EAEC strains are found to adhere to Hep-2 cells, packed in an aggregative “stacked-brick” pattern. This strains cause watery diarrhea, vomiting, dehydration, and occasionally abdominal pain, mostly in children. Identification with stacked-brick growth pattern on monolayer cell cultures and DNA probes for virulence genes. Mahon C.R., Lehman D.C. in Textbook of Diagnostic Microbiology 6th edition. Elsevier; 2019  Escherichia coli Extraintestinal Infections The most common cause of septicaemia and meningitis among neonates, accounting for about 40% of the cases of gram-negative meningitis. A newborn usually acquires through the birth canal. The capsular antigen K1 presents in some strains that cause neonatal meningitis. It is identical to the capsular antigen of N. meningitidis group B. Mahon C.R., Lehman D.C. in Textbook of Diagnostic Microbiology 6th edition. Elsevier; 2019  Escherichia coli Control and Management Control by: Preventing the entry of bacterium into the food chain and water supply. Management: Bismuth salicylate (Pepto-Bismol) which both counteracts toxins and provided an antimicrobic effect is the best treatment. Fluid replacement + antibiotics (if needed). Choice of antibiotic: sulphonamides, ampicillin, cephalosporins, aminoglycosides, and tetracyclines. Talaro 10th edition.  Klebsiella Characteristics Domain: Bacteria Phylum: Proteobacteria Class: Gammaproteobacteria Order: Entreobacterales Family: Entrobacteriaceae Genus: Klebsiella https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&id=570&lvl=3&p=mapview&p=has_linkout&p=blast_url&p=genome_blast&lin=f&keep=1&srchmode=1&unlock  Klebsiella spp. Characteristics Usually found in the intestinal tract of humans and animals or free-living in soil, water, and on plants. It is important for normal bowel health and function. The problem with Klebsiella bacteria occurs when it gets outside of the human colon where serious infection can occur. K. pneumoniae à the most commonly isolated species and has a large polysaccharide capsule. Associated with Hospital Acquired Infections (HAIs), pneumonia, wound infections, and Urinary Tract Infections (UTIs). Mahon C.R., Lehman D.C. in Textbook of Diagnostic Microbiology 6th edition. Elsevier; 2019  Klebsiella spp. Characteristics Gram-negative rods, size about 2,0 – 3,0 x 0,6 µm. Non-motile. Possess a polysaccharide capsule. Lactose fermenting Facultative anaerobe. Mahon C.R., Lehman D.C. in Textbook of Diagnostic Microbiology 6th edition. Elsevier; 2019  Klebsiella spp. Characteristics Capsule is responsible for the moist, mucoid colonies characteristic of K. pneumoniae on MAC agar. Mahon C.R., Lehman D.C. in Textbook of Diagnostic Microbiology 6th edition. Elsevier; 2019  Klebsiella spp. Characteristics – Culture Media On MAC agar à red/ pink colonies Mahon C.R., Lehman D.C. in Textbook of Diagnostic Microbiology 6th edition. Elsevier; 2019  Klebsiella spp. Characteristics – Culture Media On blood agar à slimy appearance Mahon C.R., Lehman D.C. in Textbook of Diagnostic Microbiology 6th edition. Elsevier; 2019  Klebsiella spp. Characteristics – Gram stain Mahon C.R., Lehman D.C. in Textbook of Diagnostic Microbiology 6th edition. Elsevier; 2019  Klebsiella spp. Diseases UTIs Pneumonia Septicemia https://www.cdc.gov/hai/organisms/klebsiella/klebsiella.html  Klebsiella spp. Transmission https://www.cdc.gov/hai/organisms/klebsiella/klebsiella.html  Klebsiella pneumoniae Symptoms https://www.cdc.gov/hai/organisms/klebsiella/klebsiella.html  Klebsiella spp. KPC Carbapenemases !"#$%&$'$()( *+,-./+0)1penicillins, cephalosporins, monobactams, and carbapenems. !"#$%& '()"#$%&  Klebsiella pneumoniae Management Antibiotics à Aminoglycosides, Polymyxins, Tigecycline, Fosfomycin. Infections caused by KPC-producing bacteria can be difficult to treat because fewer antibiotics are effective against them. https://www.cdc.gov/hai/organisms/klebsiella/klebsiella.html  SALMONELLA Salmonellae are gram-negative, facultatively anaerobic bacilli that morphologically resemble other enteric bacteria. On selective and differential media (e.g., MAC), salmonellae produce clear, colorless, non–lactose fermenting colonies Colonies with black centers are seen if the media (e.g., HE or XLD) contain indicators for H2S production Produce significant infections in humans and in certain animals. Except Salmonella Typhi and Salmonella Paratyphi, salmonellae organisms infect various animals that serve as reservoirs and sources of human infections. (rodents and birds) Mahon CR, Lehman DC, Manuselis G. 2019. Textbook of Diagnostic Microbiology. 6th Edition. China : Elsevier, Saunders Epidemiology  Antigenic structures Salmonellae possess antigens similar to antigens of other enterobacteria. The somatic O antigens and flagellar H antigens are the primary antigenic structures used in serologic grouping of salmonellae. A few strains may possess capsular (K) antigens, designated Vi antigen. Mahon CR, Lehman DC, Manuselis G. 2019. Textbook of Diagnostic Microbiology. 6th Edition. China : Elsevier, Saunders  Clinical Infection Gastroenteritis Etiology and Pathogenesis Clinical manifestation Contaminated food. The symptoms appear in 8 to 36 hours The Salmonella gastroenteritis are usually Nausea, vomiting, fever, and chills, strains found in animals (S. enterica subsp. accompanied by watery diarrhea and Enterica). abdominal pain. Source: Self-limiting. Symptoms usually disappear Insufficiently cooked poultry, milk, eggs, and within a few days, with few or no egg products as well as to handling pets complications except: (calves and poultry at petting zoos). Patients with sickle cell disease and other Contaminated Cooking utensils. hemolytic disorders, ulcerative colitis, and Direct transmission from person to person. malignancy The infective dose necessary to initiate the Very young children, elderly adults, and disease- 106 bacteria. patients with other underlying disease. Mahon CR, Lehman DC, Manuselis G. 2019. Textbook of Diagnostic Microbiology. 6th Edition. China : Elsevier, Saunders  Enteric fever Etiology Clinical manifestation Contaminated food Prolonged fever Enteric fever caused by Salmonella Bacteremia Typhi is known as typhoid fever Involvement of the Typhoid fever develops in reticuloendothelial system, (liver, approximately 9 to 14 days spleen, intestines, and mesentery) Other enteric fevers include paratyphoid Dissemination to multiple organs fevers, which may be due to Salmonella The clinical manifestations of serotypes Paratyphi A, B, and C and paratyphoid fevers are similar to Salmonella serotype Choleraesuis. typhoid fever but are less severe, and the fatality rate is lower. Mahon CR, Lehman DC, Manuselis G. 2019. Textbook of Diagnostic Microbiology. 6th Edition. China : Elsevier, Saunders  Conditions cause by Salmonella Brooks G.L et al. Jawetz, Melnick, & Adelberg’s Medical Microbiology. Ed 27. New York. 2016. Lange.  Diagnosis Specimen Blood culture must be taken repeatedly (results are often positive in the first week of the disease). Bone marrow cultures Urine culture results may be positive after the second week. Stool specimens also must be taken repeatedly In enteric fevers, positive results from the second or third week In enterocolitis, positive results during the first week A positive culture of duodenal drainage establishes the presence of salmonellae in the biliary tract in carriers. Brooks G.L et al. Jawetz, Melnick, & Adelberg’s Medical Microbiology. Ed 27. New York. 2016. Lange.  Treatment Uncomplicated enterocolitis: No need antibiotic, It is believed to prolong the carrier state. Only supportive treatment (Fluid replacement therapy). Antidiarrheal agents are also restricted Encourage adherence and further invasion. Antimicrobial treatment of Salmonella enteritis in neonates is important. Choice: chloramphenicol, ampicillin, and trimethoprim- sulfamethoxazole. Susceptibility testing In most carriers, the organisms persist in the gallbladder (particularly if gallstones are present) and in the biliary tract. Some chronic carriers have been cured by ampicillin alone, but in most cases cholecystectomy must be combined with drug treatment. Brooks G.L et al. Jawetz, Melnick, & Adelberg’s Medical Microbiology. Ed 27. New York. 2016. Lange.  Treatment (Typhoid fever or Enteric fever) Infection NOT acquired Resistant Infection acquired in India, Alternative Regimens in Asia: Pakistan or elsewhere in Asia: Ciprofloxacin 400 Avoid empiric treatment with Azithromycin 1 gm po x 1 mg IV/750 mg po fluoroquinolones because of dose, then 500 mg po q12h or resistance q24h x 5-7 days OR Levofloxacin 750 Uncomplicated (GI manifestations mg IV/po q24h only) Ceftriaxone 2 gm IV q24h Azithromycin 1 gm po x 1 dose, x 7-14 days for then 500 mg po q24h x 5-7 days uncomplicated infection. Treat for 7-10 days Complicated (e.g., bowel perforation, mycotic aneursym, shock) or severe infection Chloramphenicol 500 mg IV/po q6h x 14 days Meropenem 1-2 gm IV q8h (probably inferior to Sanford Guide. 2019. Antimicrobial Therapy. Consider use of dexamethasone other agents). for severely ill  Shigella Shigella spp. are not members of the normal GI microbiota All Shigella spp. can cause bacillary dysentery. The genus Shigella is named after the Japanese microbiologist Kiyoshi Shiga, who first isolated the organism in 1896. The genus consists of four species that are biochemically similar. Mahon CR, Lehman DC, Manuselis G. 2019. Textbook of Diagnostic Microbiology. 6th Edition. China : Elsevier, Saunders  Shigella Characteristic Do not hydrolyze urea. Do not produce H2S. Do not decarboxylate lysine. Cornelissen C.N., Fisher B.D., Harvey R.A. 2001. Lippincott’s Illustrated Reviews: Microbiology. Ed 3. Philadelphia. Lippincott.  Clinical Infections Shigellosis including Bacillary dysentery and Asymptomatic carrier. In the United States, S. sonnei is the predominant isolate followed by S.flexneri. Short, self-limiting disease characterized by fever and watery diarrhea Mostly young children to one producing infections in young adults (approximately 25 years old). Humans are the only known reservoir of Shigella spp. Transmission can occur by direct person-to-person contact, and spread can take place via the fecal-oral route, with carriers as the source (flies). Personal hygiene plays a major role in the transmission Shigella is also seen in people living in crowded and inadequate housing (also passengers on cruise ships). People who participate in anal-oral sexual activityà gastroenteritis in men who have sex with men. Less than 100 bacilli are needed to initiate the disease in some healthy individuals. Mahon CR, Lehman DC, Manuselis G. 2019. Textbook of Diagnostic Microbiology. 6th Edition. China : Elsevier, Saunders  Diagnosis Specimens Specimens include fresh stool, mucus flecks, and rectal swabs for culture. Large numbers of fecal leukocytes and some red blood cells often are seen microscopically. Culture The materials are streaked on differential media (eg, MacConkey or EMB agar) and on selective media (Hektoen enteric agar, SS or xylose-lysine-deoxychocolate agar), which suppress other Enterobacteriaceae and gram-positive organisms. Shigella and E coli cannot be differentiated by MALDI-ToF MS. Serology Healthy persons often have agglutinins against several Shigella speciesà serial determinations of antibody titers may show a rise in specific antibody. Serology is not used to diagnose Shigella infections. Nucleic Acid Amplification Tests Brooks G.L et al. Jawetz, Melnick, & Adelberg’s Medical Microbiology. Ed 27. New York. 2016. Lange.  Shigellae are fragile organisms. They are susceptible to the various effects of physical and chemical agents, such as disinfectant and high concentrations of acids and bile. They are susceptible to the acid pH of stoolà suspected faeces should be plated immediately onto laboratory media to increase recovery of the organism. Mahon CR, Lehman DC, Manuselis G. 2019. Textbook of Diagnostic Microbiology. 6th Edition. China : Elsevier, Saunders  Therapy Shigellosis is a self-limited infection, lasting 5-7 days. Treatment shortens course of illness by only a day or two, promotes resistance, and may prolong shedding. Reserve therapy for more severely ill patients or for use in an outbreak setting if so advised by public health officials. Adult: Pediatric: Alternative Regimens Ciprofloxacin 750 mg po once daily (or bid) x 3 days or Azithromycin 500 mg po once Levofloxacin 500 mg po once Azithromycin 10 mg/kg/day (max dose 1 gm) once daily x 3 days. daily x 3 days (adults) daily x 3 days; If severely ill, can use For severe disease: Ceftriaxone TMP-SMX 160/800 mg po bid Ciprofloxacin or Levofloxacin 50–75 mg/kg/day x 2–5 days or for 5 days (only if isolate is IV or Ceftriaxone 1-2 gm IV Ciprofloxacin suspension 10 confirmed to be susceptible). once daily x 5 days. mg/kg bid x 5 days. If patient is immunocompromised Sanford Guide. 2019. Antimicrobial Therapy. (adult or child) treat for 7-10 days.  The Pseudomonad Group The pseudomonads are Gram-negative, motile, aerobic rods, some of which produce water-soluble pigments. The pseudomonads occur widely in soil, water, plants, and animals. The classification of pseudomonads is based on rRNA/DNA homology and common culture characteristics. P.aeruginosa is frequently present in small numbers in the normal intestinal flora and on the skin of humans, and is the major pathogen of the group. Other pseudomonads infrequently cause disease. Some produce biofilm Cornelissen C.N., Fisher B.D., Harvey R.A. 2001. Lippincott’s Illustrated Reviews: Microbiology. Ed 3. Philadelphia. Lippincott. Brooks G.L et al. Jawetz, Melnick, & Adelberg’s Medical Microbiology. Ed 27. New York. 2016. Lange.  Pseudomonas aeruginosa Small, gram-negative rods with a single polar flagellum. Aerobic and does not ferment lactose (traits that distinguish it from members of the Enterobacteriaceae). Oxidase positive. Cultures typically produce a greenish pigment that fluoresces under ultraviolet light, as well as a distinctive odor. P. aeruginosa is commonly found in soil and water and is an intestinal resident of about 10% of healthy people. Talaro K.P., Chess B. 2012. Foundation in Microbiology. Ed 8. Pasadena. Mc Graw Hill. Brooks G.L et al. Jawetz, Melnick, & Adelberg’s Medical Microbiology. Ed 27. New York. 2016. Lange. Cornelissen C.N., Fisher B.D., Harvey R.A. 2001. Lippincott’s Illustrated Reviews: Microbiology. Ed 3. Philadelphia. Lippincott. Talaro K.P., Chess B. 2012. Foundation in Microbiology. Ed 8. Pasadena. Mc Graw Hill. Brooks G.L et al. Jawetz, Melnick, & Adelberg’s Medical Microbiology. Ed 27. New York. 2016. Lange.  Virulence factor Virulence factors include Flagella Pili that aid in attachment of the bacterium to host cells. A phagocytosis-resistant slime layer that contributes to the formation of biofilms. Enzymes that degrade host tissues, and exotoxins (exotoxin A) that damage or destroy neutrophils and lymphocytes. The LPS layer of the outer membranes also causes endotoxic shock. P aeruginosa produces four type III–secreted toxins that cause cell death or interfere with the host immune response to infection. Exoenzyme S and Exoenzyme T are bifunctional enzymes with GTPase and ADP-ribosyl transferase activity Exoenzyme U is a phospholipase Exoenzyme Y is an adenylyl cyclase Talaro K.P., Chess B. 2012. Foundation in Microbiology. Ed 8. Pasadena. Mc Graw Hill. Brooks G.L et al. Jawetz, Melnick, & Adelberg’s Medical Microbiology. Ed 27. New York. 2016. Lange.  Clinical manifestation P. aeruginosa is a prime example of an opportunistic pathogen, with the most serious infections seen in patients with severe burns, neoplastic disease, or cystic fibrosis. In many cases leading to endocarditis, bronchopneumonia or meningitis (If penetrate respi track). Might cause necrotizing pneumonia in CF Hemorrhagic necrosis of skin occurs often in sepsis caused by P aeruginosa; the lesions, called ecthyma gangrenosum, are surrounded by erythema and often do not contain pus. Otherwise-healthy persons may acquire skin rashes, wound with blue-green pus, urinary tract infections, or outer ear infections Often connected to the use of community hot tubs and swimming pools. Talaro K.P., Chess B. 2012. Foundation in Microbiology. Ed 8. Pasadena. Mc Graw Hill. Brooks G.L et al. Jawetz, Melnick, & Adelberg’s Medical Microbiology. Ed 27. New York. 2016. Lange.  Treatment The metabolic versatility of Pseudomonas makes controlling the bacterium difficult. Traditionally, significant infections have not been treated with single-drug therapy because the success rate is low and the bacteria can rapidly develop resistance when single drugs are used. An extended spectrum penicillin such as piperacillin is used in combination with an aminoglycoside, usually tobramycin. Aztreonam; carbapenems such as imipenem or meropenem and fluoroquinolones, including ciprofloxacin. Effective drugs include third- and fourth-generation cephalosporins (antipseudomonas) Ceftazidime, cefoperazone, and cefepime are active against P aeruginosa; ceftazidime is often used with an aminoglycoside in Sensitivity test is obligated primary therapy of P aeruginosa infections, especially in patients with neutropenia. Multidrug resistance has become a major issue in the management of HAIs due to Acquisition of chromosomal β-lactamases, extended-spectrum β-lactamases, porin channel mutations, and efflux pumps. Talaro K.P., Chess B. 2012. Foundation in Microbiology. Ed 8. Pasadena. Mc Graw Hill. Brooks G.L et al. Jawetz, Melnick, & Adelberg’s Medical Microbiology. Ed 27. New York. 2016. Lange. Taxonomy ACINETOBACTER DOMAIN : BACTERIA KINGDOM : BACTERIA PHYLUM : PROTEOBACTERIA CLASS : γ-PROTEOBACTERIA ORDER : PSEUDOMONADALES FAMILY : MORAXELLACEAE GENUS : ACINETOBACTER SPECIES : A. BAUMANNII  General Characteristic Acinetobacter (Latin word) for “motionless” è because the lack of cilia or flagella with which to move Have 34 species : A.baumannii and A. Iwoffii are most commonly Ubiquitous in the environment – hospital Gram-negative, non fermenting, coccobacilli (stationary phase) or rod shape (growth phase), non motile Oxidase – , Catalase + , Aerobic 2 groups : saccharolytic (glucose oxidizing) & asaccharolytic species Jawetz, Melnick, & Adelberg’s Medical Microbiology 27th edition. Lange: 2016. Mahon CR, Lechman DC, Manuselis G. Textbook of Diagnostic Microbiology. 6th Edition. Elsevier : 2019.  Epidemiology HABITAT (RESERVOIR) In nature à hospital environment Skin and respiratory microbiota of patients (prolonged period) MODE OF TRANSMISSION Colonization of hospitalized patients from environmental factors Medical instrumentation : organism to normally steril sites Bailey & Scott’s Diagnostic Microbiology Fourteenth Edition. Elsevier; 2017.  Virulence factor Opportunistic pathogen Tend to infect ICU patients (long term care fasilities) Risk factors related to colonization or infection among adult patients, including : mechanical ventilation, tracheostomy, CVC and enteral feeding. Posses several key factors that contribute to the genus virulence : a. ability to produce a lipopolysaccharide capsule b. survival in dry environments c. adherence to mucosal epithelium via fimbriae Bailey & Scott’s Diagnostic Microbiology Fourteenth Edition. Elsevier; 2017.  Clinical Infections Vast majority of infections are health-care associated Most commonly involve : a. UG tract infections b. Respiraory tract infections (VAP, tracheobronchitis,) c. SSTI (selulitis) d. Endocarditis e. Meningitis f. Bacteremia (sepsis) g. Ocular infections (endoftalmitis, conjunctivitis) Bailey & Scott’s Diagnostic Microbiology Fourteenth Edition. Elsevier; 2017. Mahon CR, Lechman DC, Manuselis G. Textbook of Diagnostic Microbiology. 6th Edition. Elsevier : 2019.  Laboratory Diagnosis Gram stain à coccobacil/bacil Gram (-) Media of Choice : ü SBA : smooth, opaque, raised, creamy, smaller than Enterobacter ü MacConkey : non-lactose fermenter, purplish hue ü Nutrient broth, e.g: thyoglycolate, BHI Incubated at 35-37ºC in aerobic condition or 5% CO2 for 24 hours Identification of Acinetobacter spp à growth on AMA, incubated at 37ºCfor 72-96 hours Bailey & Scott’s Diagnostic Microbiology Fourteenth Edition. Elsevier; 2017. Mahon CR, Lechman DC, Manuselis G. Textbook of Diagnostic Microbiology. 6th Edition. Elsevier : 2019. Colonial Appearance aasdf Acinetobacter baumannii on SBA Mahon CR, Lechman DC, Manuselis G. Textbook of Diagnostic Microbiology. 6th Edition. Elsevier : 2019.  Treatment & Therapy Typical frst-line agents : broadspectrum cephalosporin (e.g., ceftazidime or cefepime), a beta-lactam/beta-lactamase inhibitor combination agent (e.g., ampicillin/sulbactam), or a carbapenem, a fluoroquinolone (e.g., levofloxacin) or an aminoglycoside (e.g., gentamicin or tobramycin). Ertapenem (-) because of their intrinsic resistance. May be MDR or XDR Potential resistance to beta-lactam, carbapenems (CRAB), aminoglycosides, and quinolones For drug-resistant infections, polymyxins (e.g., colistin), minocycline, or tigecycline are the main therapeutic options. Bailey & Scott’s Diagnostic Microbiology Fourteenth Edition. Elsevier; 2017.  Prevention Ensure that health care settings and patient environments are cleaned regularly to prevent environmental contamination. Follow the proper aseptic techniques for the insertion of CVC and other indwelling medical devices. All reusable medical equipment should be properly decontaminated or sterilized. Bailey & Scott’s Diagnostic Microbiology Fourteenth Edition. Elsevier; 2017.  References: Murray PR, Baron EJ, Jorgensen JH, et al. 2007. Manual of Clinical Microbiology. 9th Edition. Washington DC : ASM Press. Mahon CR, Lehman DC, Manuselis G. 2019. Textbook of Diagnostic Microbiology. 6th Edition. China. Elsevier, Saunders. Talaro K.P., Chess B. 2012. Foundation in Microbiology. Ed 8. Pasadena. Mc Graw Hill. Cornelissen C.N., Fisher B.D., Harvey R.A. 2001. Lippincott’s Illustrated Reviews: Microbiology. Ed 3. Philadelphia. Lippincott. Brooks G.L et al. Jawetz, Melnick, & Adelberg’s Medical Microbiology. Ed 27. New York. 2016. Lange. Stephen H. Gillespie and Peter M. Hawkey 2006 Principles and Practice of Clinical Bacteriology Second Edition John Wiley & Sons, Ltd Tille P.M. 2017. Bailey & Scott’s Diagnostic Microbiology: Bacterial Genetics, Metabolism, and Structure. Ed 14. Missouri. Elsevier. Sanford Guide. 2019. Antimicrobial Therapy.