Microbiology PHT 123Entrobacteriaceae

2010-20112nd Term 2nd Semester

Properties of EnterobacteriaceaeFound in intestines of humans and animalsG+C ration is 39-59%Phylogenetically closely relatedType genus is Escherichia coli Gram-negative facultative anaerobic rodsMotile except Shigella and KlebsiellaOptimum Temp 35oC-37oCFermentation prefered:

Oxidation-reduction of glucose anaerobicaly generating alcohols, acids, CO2 gas

Oxidase negative, Catalase positiveNitrate is reduced

extract oxygen from NO3 reducing it to (NO2)

Enterobacteriaceae: Major Genera

EscherichiaShigellaSalmonella EdwardsiellaCitrobacter YersiniaKlebsiellaEnterobacterSerratiaProteusMorganella Providencia

Enterobacteriaceae: Types of Infectious DiseaseIntestinal infections (diarrheal, dysentery, colitis…etc)

Shigella dysentriae (dysentery)Salmonella enteritidis (gastroenteritis)Salmonella typhimurium (gastroenteritis)Escherichia coli O157:H7 (hemorrhagic colitis, hamburger disease)Yersinia enterocolitica (enterocolitis)

Extra-intestinal infectionUrinary tract (primarily cystitis)

Escherichia coli, Klebsiella pneumoniae, Enterobacter spp., and Proteus mirabilis

Respiratory (nosocomial pneumonia) Enterobacter spp., Klebsiella pneumoniae, Escherichia coli, and Proteus mirabilis

Wound (surgical wound infection)Bloodstream (gram-negative bacteremia)Central nervous system (neonatal meningitis)

Nosocomial (hospital) Infections Escherichia coli Enterobacter spp. Klebsiella pneumoniae Proteus mirabilis Serratia marcescens Citrobacter spp1

Enteric Reference Laboratory, CDC

Types of E. coliTypes of E. coli

Enteropathogenic E.coli

(EPEC)

Entrotoxigenic E. coli (ETEC)

E. coli enteroinvasive

(EIEC)

E. coli enterohemmoragic(EHEC O157:H7, Humpergur

E. coli enteroaggregative

(EAEC)

DiagnosticsEnteroScreen 4™single test for non-lactose-fermenting, oxidase-negative, enteric pathogens

Urease

Lys decooHase

H2S

Lys deNH3

MacConkey Agar and Eosin Methylene Blue (EMB) agar both are:

Differential medium for lactose fermentationDifferentiates lactose fermenters and non-fermenters

Selective mediumSelects enteric gram negatives and Inhibit gram positives

Specimens: Feces,, sputum, urine, wound, peritoneal flulids: MAC or EMB

EMB MacConkey

Salmonella-Shigella (SS) AgarSelective for Salmonella and Shigella speceis

black colonies

Biochemical testsIndole, Methyl Red, Voges-Prosakaur, Citrate

(IMViC) Tests detects:Glucose fermentation resulting in mix-acidsOR neutral pathways producing AcetoinCitrate and urease utiliztions

Most tests are included in recent technologies like API, Vitek,

Advanced Identification kits

2. Vitec Kits: All media or antibiotics are tested in this cardAnd the computer reads out the card after 8-12 hours

Card

1. ABI kit

Pseudomonas aeruginosa

Properties

Gram-negative rods.

Motile with polar flagella.

Obligate aerobe.

Oxidase-positive.

Do not ferment carbohydrates.

Resistant to multiple drugs.

P. aeruginosaClinical Diseases

Infection of wounds and burns (blue-green pus).

Skin and nail infections

Pulmonary infection Necrotizing pneumonia in Cystic Fibrosis patients

Eye infections: corneal ulcer.

Ear infections Otitis externa: swimmers

Endocarditis

Urinary tract infection

Forms fluorescent greenish colonies, sweet odor, and b-hemolysis.

• Pyocyanin- nonfluorescent bluish pigment;

• pyoverdin- fluorescent greenish pigment;

• pyorubin, and pyomelanin

• Some strains have a polysaccharide capsule.

• Identification of P. aeruginosa is usually based on colonial morphology, b-hemolysis, oxidase positivity, the presence of characteristic pigments and sweet odor, and growth at 42 oC.

P. aeruginosa

Brucellosis: Brucella spp. 1887 by Dr. David Bruce.

Zoonotic diseaseTransmitted by animals and their productsGram negative, coccobacilli bacteriaFacultative, intracellular organismEnvironmental persistence

Temperature, pH, humidityFrozen and aborted materials

Brucella: PropertiesHighly contagious zoonotic diseaseAlso known as undulant fever(intermittent), Malta

fever, Gibraltar fever, Bang's disease, or Mediterranean fever,

Brucellosis mostly is occur in people who work with livestock

It is an intracellular parasite, and can be congenitalZoonotic Species in animals

B. abortus in cattle B. suis in hogs B. melitensis in goats and sheep

Symptoms :intermittent fever, sweating, chills, aches, and mental depression.

Center for Food Security and Public Health, Iowa State University, 2008

Diagnosis in HumansIsolation of organism

Blood, bone marrow, other tissuesSerum agglutination test

Four-fold or greater rise in titerSamples 2 weeks apart

ImmunofluorescenceOrganism in clinical specimens

PCRTreatment

tetracyclines (with streptomycin), co-trimoxazole, and sulfonamides, is effective. Bed rest is also imperative

Bordetella pertussis: Whooping Cough Well known

Infects only man, (child hood disease)Aerobic, Gram negative coccobacillihighly communicable through Respiratory tract

Whooping cough. Produce endotoxin, pertusis toxinThree stages of disease

Catarrhal: runny nose, low fever, and mild cough 1-2wksParoxysmal stage: repetitive coughing 1-6 wksConvalescent stage: final, weeks to months

DiagnosisIsolation, PCR, direct fluorescent antibody, and serology

TreatmentErythromycin, Azithromycin, and clarithromycin

Vaccine: part of regular vaccination schedule (See

tetanus, DTP)

Haemophilus Spp (Blood/heme loving)Small, nonmotile, pleomorphic, Gram negative, coccobacilli,

obligate parasites of man and animalsIsolated in an influenza Pandemic 1890 and was mistakenly

considered the cause of influenza until Influenza virus was confirmed. Contrary to what the name suggests, the bacterium does not cause influenza

Occurs in two forms virulent capsulated and noncapsulatedAerobic, could be facultative anaerobic, fastidious require X factor

(i.e., hemin) and V factor (NAD or NADP)to growchocolate blood agar which is prepared by adding blood to an agar

base at 80oC. The heat releases X and V factors from the RBCs and turns the medium a chocolate brown color.

H. Influenza type b is the major pathogen (95% of human disease)Man and animals are only natural hosts, highly adapted to man

H. Ducreyi STD (soft chancroid) not common

Opportunistic pathogens with uncommon or rare infections include:H. Aphrophilus, H. Parapgrophilus, H. Parainfluenza, H. haemolyticus,

H. Parahemolyticus, H. segnis

H. Influenza have no specific

syndrome but can cause:

meningitis, conjunctivitis,

sinusitis, cellulitis, otitis, epiglottitis,

pneumonia,

Health Canada and www.cdc.gov/vaccines/pubs

According to WHO 3 million serious illnesses, 386 000 deaths uder age of 5, per year by meningitis and pneumonia

Important secondary invader to influenza virusIn swine influenza in pigs, association between the virus and

Haemophilus suis is necessary for the disease.Similar association between human influenza virus and H.

influenzae seen in chick embryos and infant rats. The fight between Streptococcus pneumoniae

In vitro Strep pneumoniae winsIn vivo H. Influenza winsIn vivo H. Influenza signals host immune system against S.

pneumoniae, the former is not well affected

One of the most transformable genomes: First genome 1995

H. Influenza was the first free living organism to have the complete genome sequenced in 1995 by The Institute for Genomic Research (TIGR) now the J. Craig Venter Institute

Why is it highly adaptedTransformable by many ways, by first making “blebs” in outer

membraneThe genome consists of 1,830,140 base pairs of DNA in a

single circular chromosome that contains 1740 protein-coding genes, 58 transfer RNA genes tRNA, and 18 other RNA genes. The sequencing method used is whole-genome shotgun, which was completed and published in Science in 1995 and conducted at The Institute for Genomic Research.[12

Diagnosis

Microscopy to detect in CSF, synovial fluids, Culturing, difficult, may be not sensitivelatex particle agglutination test (LAT)PCR

cefotaxime , ceftriaxone, ampicillin and sulbactam, cephalosporins of the second and third generation, or fluoroquinolones are preferred.

Hib conjugate vaccineHib is preventable, The two major obstacles to

prevention of Hib disease are a shortage of information and a shortage of moneyShortage of info: difficult to diagnose, it causes death

without being recognizedHib vaccine is expensive in 2005, it costs roughly

seven times the total cost of vaccines against measles, polio, tuberculosis, diphtheria, tetanus, and pertussis.

H.influenza: Hidden disease, diagnostics, and treatment dilema. How Hib goes undergoundDoes not cause a unique disease syndrome, but deadly

forms are pneumonia and meningitis But other bacteria also cause pneumonia and meningitisDoctors respond first with Antibiotics to childhood

pneumonia or meningitisHowever, to confirm a case of Hib samples must be taken:

a blood specimen in the case of pneumonia,a spinal-fluid specimen by lumbar puncture in the case of meningitis and the bacteria must then be isolated from those specimens in a

laboratory...a challenge even for sophisticated laboratories In developing countries, these tests may not be made at all, or

laboratories may fail to carry them out correctly, or Hib's presence may be masked because antibiotics were given before the samples were taken

The hidden nature of Hib...this is how Hib is underestimated

A "Rapid Assessment Tool" has been developed by WHO and CDC to make sensible estimates of Hib