Gram Negative Bacteria Flashcards
General Gram Negative characteristics
2 membranes, thin peptidoglycan layer in periplasm, LPS antigen on membrane,
Classes of aerobic gram negative bacilli
Enterobacterales/coliforms (eg E Coli, Klebsiella Pneumoniae, Salmonella and Shigella) and pseudomonas aeruginosa
Aerobic Gram Negative Cocci
Neisseria (N. meningitides and N gonorrhea)
Microaerophilic gram negatives
H pylori and campylobacter
Enterobacterial General Characteristics
Non-spore forming, motile with peritrichous flagella (except Kleisella and shigella), oxidase negative (reduce nitrates), ferments glucose. Species within genus are differentiated based on ability to ferment lactose. Part of intestinal flora
Enterobacterial Clinical Significant
Effect immuno compromised and competent. Isolated from urine, blood, intestinal and respiratory tissues. Extended spectrum beta-lactamases (ESBLs) and Carbepenemase (CPE) present. Can progress to BSIs
E. Coli UTI Infection
Moves from perianal area moves from ureter to bladder. May progress to BSI (<10% of patients), pilli attach to epithelial cells. may progress to pyelonephritis (kidney infection)
EColi Intraabdominal Infections
appendicitis, acute cholecystic, peritonitis, sub-phrenic abscess and liver abscess
5 Types of E.Coli
Enterotoxigenic, enterohaemorrhagic, enteropathogenic, enteroinvasive and enteroaggregative
Enterotoxigenic E Coli
Travellers Diahorrea (watery, non-bloody diahorrea and minor discomfort to severe cholera). Heat liable toxin (increased water secretion) and heat stable toxin (decreased water secretion). Self limiting, treat dehydtration
Enterohaemorrhagic E Coli
Bloody diahorrea and acute inflammation response resulting in tissue damage. Originate from undercooked meats and animals. Survives up to 24-48 hours in enviorment. Self-limiting, treat dehydration symptoms
E Coli Treatment Infections
empiric, cefuroxime (2nd Gen cephalosporin) and co-amoxiclav (amoxicillin + clauric acid)
If confirmed ESBLs Treatment
Carbapenems (very broad spectrum, beta lactamases), aminoglycosides (eg gentamicin) and quinolone (eg ciprofolaxin)
If confirmed CPE (carbepenemase)
Colistin (highly toxic)
Klebsiella Outline
May produce ESBLs and CPE. Causes UTI, BSI, appendicitis, cholecystisis, SSI and ventilator associated pneumonia. Faculative anaerobe and lactose fermenting
Klebsiella Pneumonia Symptoms
Red-jelly like sputum, may cause abcesses (tissue damage) of upper lobe. Caused by ventilator associaed pneumonia and alcoholism is a risk factor
Carbapenem Resistance Outline
Produces carbapenems eg OXA48 and NDM1 (destroys beta lactam ring of antibiotics of carbapenems). Permanently reduced by porin expression
Proteus Outline
Normal GIT flora that becomes pathogenic by migration. May cause UTI, BSI, appendicitis, cholecytisis and SSI. Common is patients with urinary catheters
Proteus Spp Lab Classification
Colonies swarm together (due to peritrichous flagella) , non-lactose producing wiyth characteristic fishy smell
Pseudomonas Aeruginosa Outline
Found in moist areas in enviorment (Big HCAI). Multidrug ressistance. Have pilli, slime layer and LPS. Msy cause pnuemonia, surgical site infections, complicated UTIs, BSIs, otitis and eye infections
Non-enteric fever samonealla Outline
Sourced from uncooked poultry, eggs and unpasteurized milk and ocassionally passes fecal-oral route. High infectious dose is required as stomach acid kills them
P Aeruginosa Treatment
penicillin-tazobactum, ceftazidime (3rd gen cephalosporin), ciprofloxacin (quinolone, inhibits DNA gyrase), aminoglycosides and carbapenems
Shigella Outline
Highly transmissible (low infectous dose). Food and water may be source. Identified by O antigen and biochemistry. Shiga toxin causes dysentery (bloody diahorrea) and bowel ulceration
Neisseria Meningitidis Outline
Transmission by droplets. Vaccine is used for prevention. Common cause of community sepsis, meningitis and septic arthritis. Has LPS and adhesion proteins. Incubation period of 1-10 days. PCR is used in samples of cerebrospinal fluid, blood and joint fluid
Neisseria Gonorrhea Outline
STI, mainly localised to mucus membranes of genital tracts. Other sites: conjunctivitis, BSI. Incubation period 2-7 days
Gonorrhea Symptoms
Male: Symptomatic, Urethritis and Epididymitis. Female: Asymptomatic, salpingitis (fallopian inflammation) and cervitis
Campylobacter spp
Tranmitted by undercooked foods, main cause of bacterial food poisoning in developed countries. Cause of gastro-enteritis in animals. Curved motile flagella.
