09/22/2017

MICROBIOLOGY mci screeningt test and indian medical examz high yield important topics study tips

By Live Dr - Wed Feb 11, 2:48 am

MICROBIOLOGY

bacteria fungi
They are prokaryotes; nucleus and cytoplasm not well developed Eukaryotes;  nucleus and cytoplasm are well developed
Divide by binary fission Divide by sexual and asexual methods of reproduction
Do not show true branching except actinomycetes They do show true branching
Sterols absent Sterols present.

*Chemical present in gram positive bacterial wall but absent in gram negative bacteria is Teichoic acid.

*Quelling reaction-

When a suspension of a capsulated bacterium is mixed with its specific anticapsular serum, and examined under microscope, capsule becomes very prominent and appears swollen.

Thermophilic bacteria Grow best at high temperatures 55-80 degrees
Mesophilic bacteria Grow best at 25-40 degrees
Psychrophilic bacteria Grow best below 20 degrees
Transformation Transfer of genetic information through the agency of free DNA
Transduction Transfer of a portion of DNA from one bacterium to another through the agency of a bacteriophage.
Transposons Jumping genes consisting of inverted repeat sequences, responsible for transferable drug resistance.
Conjugation Transfer of genetic elements after actual physical contact between a male donor bacterium and female recipient.

Physical methods of sterilization

Hot air oven 160 degrees for 1 hour

Used for sterilizing glassware, sharps, all glass syringes, swabs, liquid paraffin, dusting powder, fats, silicone rubber.

Sterilization control- Spores of nontoxigenic strain of clostridium tetani are used to test the efficiency of sterilization

Also Browne’s tube is used

Vaccine baths 60 degree for 1 hr.

For vaccines of nonsporing bacteria

QUOTE CORNER

I am prepared for the worst, but hope for the best.-Bejamin Disraeli

ELEVENTH HOUR MICROBIOLOGY                                                                                                       56

Physical methods of sterilization CONTINUED…

Pasteurization Holder method- 63 degrees for 30 min

Flash method- 72 degrees for 15 seconds followed by rapid cooling to 13 degrees or lower.

Used in pasteurization of milk

Inspissator 80-85 degrees for ½ hour on 3 successive days

Used for sterilizing LJ medium and Loeffler’s serum slope

Tyndallisation 100 degrees for 20 minutes on 3 successive days

For sterilization of media containing sugar or gelatin.

Autoclaving 120 degrees for 20 minutes.

Sterilization control- spores of Bacillus stearothermophilus

Sterilization of culture media, masks and caps, surgical instruments.

Infrared radiation Used for rapid mass sterilization of  prepacked items such as syringes and catheters
UV rays Disinfecting entryways, operation theaters, laboratories.
Gamma rays Sterilizing plastic syringes, swabs, catheters,

CHEMICAL DISINFECTANTS

70 % Ethyl alcohol and isopropyl alcohol Skin antiseptics
Glutaraldehyde Sterilizing, endoscopes, anesthetic tubes, endotracheal tubes
Ethylene oxide Sterilizing heart -lung machine, respirators, suture, dental equipments
Formaldehyde gas Fumigation of operation theaters
Betapropiolactone Fumigation of operation theaters
liquid media solid media
Do not exhibit specific characteristics for identification Do exhibit
Difficult to isolate different types of bacteria from mixed population Easy to isolate
Large volumes of substances can be tested Not so
Bulk cultures of Ig and vaccines can be prepared Not so
Bacteria grow diffusely in liquid media Bacteria produce discrete visible growth

TRIVIAL TRUTH

Laughing lowers levels of stress hormones and strengthens the immune system. Six-year-olds laugh an average of 300 times a day. Adults only laugh 15 to 100 times a day.

ELEVENTH HOUR MICROBIOLOGY                                                                                                       57

Characteristics of various media

Simple media Contains simple substances , like nutrient agar and nutrient broth
Complex media Have ingredients which are added to bring out specific characteristics
Synthetic media / Defined media Prepared from pure chemical substances
Enriched media Nutritive substances like blood or egg are added  for the growth of bacteria with exacting nutritional needs
Enrichment media Liquid media in which growth promoting or substances which are growth inhibiting for non desired bacteria are added
Selective media Substances inhibiting growth of unwanted bacteria are added to solid media
Indicator media An indicator which changes color on growth of a bacterium is added
Differential medium A substance is added which enables to bring out differing characteristics of bacteria to aid in their identification
Sugar media Sugar is added to media
Transport medium To enable viability of delicate organism during travel, and to inhibit growth of  nonpathogens

*Medium for antibiotic sensitivity test- Mueller Hinton agar

*Swarming is prevented by adding 6 % agar to culture media.

*Lawn culture is used for bacteriophage typing.

*Indicator used in anaerobic jar-

Reduced Methylene blue

Reduced Resazurin

exotoxin endotoxin
Proteinaceous Lipopolysaccharides
Actively secreted by bacteria Part of cell wall
Enzymatic action Not enzymatic action
Specific pharmacological effect for each toxin Nonspecific effect
Specific tissue affinity No specific tissue affinity
Highly antigenic Weakly antigenic
Action neutralized by specific antibody Not neutralized by antibody
Can be toxoided Cant be toxoided
Mostly by gram positive bacteria Mostly by gram negative bacteria

QUOTE CORNER

It is a thousand times better to have common sense without education than to have education without common sense.- Robert G. Ingersoll

ELEVENTH HOUR MICROBIOLOGY                                                                                                       58

Mechanism of action of toxins

Irreversible protein synthesis inhibition Shiga toxin(shigella dysentriae -1), EHEC, diphtheria toxin, exotoxin A (pseudomonas aeruginosa)
ADP ribosylation of G-protein Pertussis toxin
Activation of cyclic amp LT (ETEC), cholera toxin.
Activation of cGMP Heat stable E.coli toxin.

Types of hypersensitivity reactions

type description
Type 1 Ig E mediated, e.g. atopy, anaphylaxis
Type 2 Cytolytic, cytotoxic, e.g. antibody mediated.
Type 3 Immune complex mediated, e.g. arthus reaction, serum sickness, rheumatoid arthritis, SLE
Type 4 Delayed hypersensitivity, e.g. contact dermatitis, Mantoux test.

IMMUNODEFICIENCIES

HUMORAL IMMUNODEFICIENCIES

X linked agamma-globulinemia Pyogenic bacterial infections

Live vaccines are contraindicated

Management-gamma globulin administration

Common variable immunodeficiency Late onset hypogammaglobulinemia

Infection with Giardiasis

CELLULAR IMMUNODEFICIENCIES

Di George syndrome Thymus hypoplasia

Fallot’s tetralogy

Neonatal tetany

Viral, fungal and bacterial infections.

COMBINED IMMUNODEFICIENCIES

Nezelof syndrome Cellular immunodeficiency with abnormal Ig G synthesis
Ataxia telengiectasia Ig A decreased
Wiskott-Aldrich syndrome X-linked

Thrombocytopenia

Eczema

Recurrent infections

Decreased cell mediated immunity

Decreased Ig M

Subacute chronic immunodeficiency Adenosine deaminase deficiency

TRIVIAL TRUTH

Mosquitoes prefer children to adults, and blondes to brunettes.

ELEVENTH HOUR MICROBIOLOGY                                                                                                       59

PHAGOCYTOSIS DEFECTS

Chronic granulomatous disease Hydrogen peroxide deficiency

Nitroblue tetrazolium negative

Chediak-Higashi syndrome Decreased pigments

Photophobia

Nystagmus

Peroxidase positive inclusion in WBC

Job’s syndrome Cold staphylococcal abscesses
Lazy leucocyte syndrome Peripheral neutropenia

Decreased phagocytosis

CHARACTERISTICS OF IMMUNOGLOBULINS

Ig

CHARACTERISTICS

Ig G

Binds to microorganism and enhances phagocytosis active in blood an tissues

Ig A

Inhibits the adherence of microorganism to the surface of mucosal calls by covering the organism and thereby preventing entry in body tissues

Ig M

Protection against blood invasion by microorganism

Ig D

Specific stimulation of B cells, either activation, cloning, antibody production or suppression

Ig E

Protection against pathogens by most cell degranulations, release of inflammatory cytokines;  defense against helminthic infections

*Highest serum concentration- Ig G

2nd most common -Ig M

Shortest half-life Ig E

primary immune response secondary immune response
Slow, sluggish, short-lived Prompt, powerful, prolonged
Long log phase Short log phase
Low titre of antibody High titre of antibody
Antibody doesn’t last long Antibodies last long
Ig M  is secreted I g G is produced
No negative phase Negative phase may be seen
Produced after one dose Produced after multiple doses
Level of antibody is not effective Effective
Prozone Antibody excess
Zone Equivalent amounts of antibody and antigen
Post zone Antigen excess

QUOTE CORNER

Keep your face to the sunshine and you cannot see the shadow. It’s what sunflowers do.- Helen keller

ELEVENTH HOUR MICROBIOLOGY                                                                                                       60

INCUBATION PERIOD OF FOOD POISONINGS / GASTROENTERITIS

AGENT

TIME INTERVAL

Bacillus cereus (emetic form, Chinese restaurant syndrome)

1-5 hr.

Staphylococcus aureus

1-6 hr.

Bacillus cereus ( diarrhoel form)

8-16 hr.

Clostridium perfringens

8-16 hr.

Salmonella food poisoning

12-24 hr.

E. coli

16 hr.

Rota virus

2-3 days

Shigella

2 days

Vibrio cholera

1-5 days

Salmonella typhi

1-2 weeks

Staphylococcus
Spherical cocci

Grape like clusters

Nonmotile, nonsporing

Gram positive

Aerobes and facultative anaerobes

Grow on ordinary media

On nutrient agar- large, smooth, circular, shiny colonies.

Produce golden yellow pigment

On nutrient agar slope-oil paint appearance

On blood agar-beta hemolysis

Mac Conkey’s agar-pink colonies

Ferment sugar producing acid but no gas

Mannitol is fermented anaerobically by S. aureaus but not by other species

Catalase positive S. aureus gives prompt phosphatase , while S. epidermidis gives negative or weakly positive result

Non coagulase staphylococci include-

S. epidermidis

S. saprophyticus

S. epidermidis is the most common cause of infection of central nervous system shunts

S. saprophyticus causes urinary tract infection in sexually active young women.

Toxin induced diseases by S. aureus
Staphylococcal food poisoning

Toxic shock syndrome

Staphylococcal scalded skin syndrome-Ritter’s disease, toxic epidermal necrolysis, Pemphigus neonatorum, bullous impetigo

TRIVIAL TRUTH

More people are allergic to cow’s milk than any other food.

ELEVENTH HOUR MICROBIOLOGY                                                                                                       61

Streptococcus pyogenes
Spherical, arranged in chains

Nonmotile, nonsporing

Gram positive

Aerobes and facultative anaerobes

Doesn’t grow on simple, media, require blood or serum, sugars

Blood agar- circular, small, colonies with area of hemolysis around them.

Virulent forms give matt/ granular colonies, while avirulent give glossy colonies

Ferment sugar producing acid but no gas

Catalase negative

Do not ferment inulin

*Bacteriocin- highly specific antibiotic like substances produced by certain strains of bacteria, which are active against other strains of the same or different species.

Retrospective diagnosis of streptococcal infection is done by
Anti streptolysin O

Antistreptokinase antibody

Anti DNA-ase B

Antihyaluronidase

Anti NADase

Alpha hemolytic streptococci/ viridans streptococci Greenish discoloration with partial hemolysis
Beta hemolytic streptococci Sharply defined colorless zone of hemolysis
Gamma / nonhemolytic Streptocooci /indifferent Streptococci/ Enterococci No change in medium

CLASSIFICATION OF STREPTOCOCCI

Lancefield groups Hemolytic streptococci are classified by Lancefield , based on nature of carbohydrate antigen  C on the cell wall
Griffith typing Those belonging to group A streptococcus pyogenes are further subdivided based on the protein (M, T, R) antigens present on cell surface
GONOCOCCUS
Kidney shaped

Aerobic and facultatively anaerobic

N gonorrhea ferments glucose, but not maltose

N. meningitides ferments both.

QUOTE CORNER

Sometimes we stare so long at a door that is closing that we see too late the one that is open.-Alexander Graham Bell

ELEVENTH HOUR MICROBIOLOGY                                                                                                       62

Neisseria meningitides
Gram negative, aerobic, nonsporing, nonmotile,

Oxidase positive

Exacting growth requirements

Strict aerobes

Solid media- round, bluish grey, smooth, glistening, butyrous.

Weak hemolysis on blood agar

Pneumococcus
Small, lanceolate, diplococci

Capsulated

Gram positive

Grow only in enriched media

Aerobes and facultative anaerobes

Blood agar- under aerobic conditions, small, dome shaped, shiny colonies with greenish discoloration (alpha hemolysis), with central umbonation, giving carom coin or draughtsman appearance

Under anaerobic conditions-they show beta hemolysis

Ferment sugars forming acid but no gas

Ferment inulin , bile soluble

Catalase and oxidase negative

Sensitive to optochin

Corynebacterium diphtheriae/ Klebs Loeffler bacillus
Slender rod, clubbing at end, pleomorphic, nonsporing, nonmotile, noncapsulated, gram positive

Metachromatic granules composed of polymetaphospahate, stained with Loeffler’s Methylene blue, give bluish purple color.

Also called volutin or Babes Ernst granules, or polar bodies.

Bacilli are arranged in Chinese letter or cuneiform pattern

Loeffler’s serum slope-growth within 8 hours.

Tellurite blood agar is the selective medium-grey or black colour colonies.

Ferment sugar producing acid but no gas.

Bacillus anthracis
Large capsulated bacilli

Polypeptide capsule

Arranged in long chains, giving bamboo stick appearance.

Sporing

TRIVIAL TRUTH

In ancient Egypt, Priests plucked every hair from their bodies, including their eyebrows and eyelashes.

ELEVENTH HOUR MICROBIOLOGY                                                                                                       63

BACILLUS ANTHRACIS CONTINUED…
M’Fadyen’s reaction-when blood films containi8ng anthrax bacilli are stained with polychrome-Methylene blue, and examined under microscope, capsule is detected as amorphous purplish material around the bacilli

Aerobic and facultatively anaerobic

Grows on ordinary media

Agar-round, grayish colonies with frosted glass appearance, which under low power resembles locks of matted hair, called medusa head appearance.

Gelatin swab culture- inverted fir tree appearance

String of pearls reaction- when grown on solid media containing penicillin, cells become large spherical and in chains.

Clostridium perfringens / Cl. welchii / Bacillus aerogenes capsulatus / bacillus phlegmonis emphysematous
Gram positive bacillus

Subterminal spores, resembling club shape.

Straight bacillus, pleomorphic, capsulated nonmotile.

Anaerobe

Robertson’s cooked meat medium

Predominantly saccharolytic

In litmus milk fermentation of lactose, formation of acid, , clot and gas is seen. Stormy fermentation.

Blood agar- target hemolysis.

Ferments sugar to produce acid but no gas

Nagler reaction- when grown on agar with antitoxin spread on one half there will be no opacity around the colonies on the half of plate having antitoxin, due to specific neutralization of alpha toxin.

Clostridium tetani
Gram positive, slender with spherical bulging, spores at the ends, giving a drumstick appearance( tennis racket appearance is given by Cl. tertium )

Obligatory anerobe

Grows on ordinary media

Deep agar shake agar cultures- spherical fluffy balls colonies

In gelatin swab-fir tree type of growth

Robertson’s cooked meat broth, turbidity and gas, proteolytic.

Blood agar- alpha hemolysis, which later develops into beta hemolysis, due to tetanolysin.

QUOTE CORNER

You may never know what results come of your action, but if you do nothing there will be no result.- Mahatma Gandhi

ELEVENTH HOUR MICROBIOLOGY                                                                                                       64

E coli
Gram negative, straight rod, motile by peritrichate flagella.

Aerobe and facultatively anaerobe

Hemolytic on blood agar

Mac Conkey’s medium-bright pink colonies, due to lactose fermentation.

Ferments sugars with the production of acid and gas.

Proteus mirabilis.
Lactose fermenters

Produces urease, rapidly hydrolyses urea to ammonia and carbon dioxide.

Gram negative, noncapsulated, pleomorphic, motile rod.

Cultures give a fishy or seminal odour.

Swarming growth.

Mac Conkey’s medium-colour less medium.

Weil Felix reaction-heterophilic agglutination due to the sharing of carbohydrates hapten by proteus and rickettsiae.

Shigella
Gram negative, rods, nonmotile, nonsporing, noncapsulated,

Aerobes and facultative anaerobes.

Grow on ordinary media

Mac Conkey’s- colorless colonies, except shigella sonie which is late lactose fermenter.

Deoxycholate citrate agar, selective medium.

vibrio cholera
Gram negative, comma shaped, actively motile by polar flagella, characteristic vibratory/ darting motility, like a swarm of gnats.

Nonsporing , noncapsulated

In stained films show, fish in stream appearance,

Strongly aerobic, Mac Conkey’s colour less colonies.

Blood agar, colonies show surrounding zone of greening, followed by clearing, due to hemodigestion

Gelatin stab culture- funnel shaped or turnip shaped liquefaction.

Venkatraman- Ramakrishnan medium- and Cary Blair medium- is the holding or transport medium.

Alkaline peptone water and Monsur’s taurocholate tellurite peptone water are transport and enrichment medium.

Tcbs is the preferred plating medium- yellowish green colonies.

TRIVIAL TRUTH

The kerosene fungus can live in jet fuel tanks. If there is a minute amount of water in the tank, the fungus can use the fuel as food.

ELEVENTH HOUR MICROBIOLOGY                                                                                                       65

Salmonella
Gram negative, motile with peritrichate flagella.

Aerobic and facultatively anaerobic.

Mac Conkey’s agar-and Deoxycholate citrate – colonies are colorless due to absence of lactose fermentation.

Wilson and Blair medium- jet black colonies, due to H2S production.

Selenite F broth and tetra thionate broth are enrichment media

Ferment sugars producing acid and gas, except salmonella typhi which is anerogenic.

Carriers in typhoid
3weeks to 3 months- convalescent carrier

3 months to 1 year- temporary carrier

More than 1 year- chronic carrier

Pseudomonas aeruginosa
Aerobic, nonsporing, gram negative, motile by polar flagella,

Obligate aerobe.

Grows on simple media- colonies give musty or earthy smell.

Mac Conkey’s and dca colorless colonies.

Produces pigments-pyocyanin-bluish green, fluorescin /pyoverdin-greenish yellow, pyorubin-red, pyomelanin- brown.

Pseudomonas

Are capable of surviving and multiplying in hot water

Causative agent of hot tub folliculitis

Yersinia pestis
Gives safety pin appearance (Bipolar staining)

Similar safety pin appearance in Burkholderia pseudomallei

Ghee broth culture-stalactite growth is seen.

Reservoir of plague

Tatera indica

Haemophilus influenzae/ Pfeiffer bacillus
Gram negative, capsulated.

Fastidious growth requirements, require accessory growth factors, named X and V

Haemophilus ducreyi
Shows bipolar staining

Bacilli are arranged in whorls or parallel chains, giving school of fish or rail road track appearance.

QUOTE CORNER

It is sometimes as dangerous to be run into by a microbe as by a trolley car.-J.J. Walsh

ELEVENTH HOUR MICROBIOLOGY                                                                                                       66

antigenic drift antigenic shift
Gradual, sequential Abrupt discontinuous
New antigens are related to previous antigens New antigens are unrelated to previous ones
Cause periodical epidemics Cause major epidemics or pandemics
Accounted to mutation and selection Cannot be accounted to mutation
Bordetella pertussis/ Bordet Gengou bacillus
gram negative, strict aerobes,  produce toxins., capsulated

In culture films, thumb print appearance.

Bordet-Gengou glycerin -potato-blood agar-selective medium-

Dome shaped smooth, opaque, grayish white colonies, –bisected pearls or mercury drops appearance.

Colonies are surrounded by a hazy zone of hemolysis; confluent growth gives aluminum paint appearance.

Brucella
Brucellosis is also known as Mediterranean fever, Malta fever, undulant fever.

Transmitted through unpasteurised milk.

Gram negative, strict aerobic,

Catalase, oxidase and urease positive

Antigenic cross reactions between Brucella and vibrio cholera.

Mycobacterium tuberculosis
Acid fast

Due to presence of mycoloic acid.

Generation time is 14-15 hours.

Lowenstein Jensen medium is the most widely used solid medium.

Collies are rough, tough and buff.

On liquid media, gives a surface pellicle.

*Mantoux test

0.5 ml of PPD, having 5 tu is injected intradermally, on the flexor aspect of forearm,

Result is read after 72 hours.

Positive tuberculin test indicates hypersensitivity to tuberculin protein due to infection with tubercle bacillus or bcg immunization

Induration > 10 mm Positive
5 mm or less Negative
6-9 mm Equivocal

TRIVIAL TRUTH

There are more living organisms in one average human body than there are humans in the whole world.

ELEVENTH HOUR MICROBIOLOGY                                                                                                       67

False negative test Miliary tuberculosis

Convalescence from measles, lymphoreticular malignancy, severe malnutrition, immunosuppression, immunodeficiency.

False positive Infection with atypical bacteria.

SENSITIVITY OF DETECTION METHODS

Liquid broth 1-10 bacteria
Solid media 100 bacteria
Staining 10000-100000.

Grading of smears

1+ 1-10 in whole slide
2+ 1-10 in 100 oil fields
3+ 1-10 in 10 oil fields
4+ 1-10 in every filed

atypical mycobacteria

Photochromogens No pigment in dark, but on exposure to light.

e.g. M. kansasii, M. marinum, M. simiae.

Scotochromogens form pigment even in the dark

M. scrofulaceum

M. gordonae.

M. szulgai

Non-Photochromogens M. avium.

M. intracellulare/ Battey bacillus

M. ulcerans

M. xenopi

Rapid growers Colonies appear within 7 days.

M. fortuitum.

M. chelonae.

M. ulcerans Ulcers on legs and arms, produces toxin
M.marinum/ M. balnei Causes swimming pool granuloma
Neutral red test Differentiates virulent from non virulent
Niacin test Positive with human type
Arylsulfatase Positive with atypical
Catalase- Peroxidase Differentiates typical from atypical

sensitivity to Isoniazide

QUOTE CORNER

A wise man learns by the mistakes of others, a fool by his own. Latin Proverb

ELEVENTH HOUR MICROBIOLOGY                                                                                                       68

AFB positive structures
Mycobacterium tuberculosis

Mycobacterium leprae

Nocardia

Bacterial spores

Sperm head

Ascospores of some yeasts

mycobacterium leprae
Gram positive and acid fast

Morphological index-live bacilli appear solid and uniformly stained, whereas dead bacilli appear fragmented.

The percentage of uniformly stained bacilli is called morphological index.

Bacteriological index-

Number of bacilli in tissues.

They frequently agglomerate; these masses are known as, globi.-giving a cigar bundle appearance.

They are not cultivable.

Can be grown in footpads of mice kept at 20 degrees.

And in nine banded armadillo

Generation time is 12-13 days.

Grading of smears

1+ 1-10 bacilli in 100 fields
2+ 1-10 bacilli in 10 fields
3+ 1-10 bacilli per field
4+ 10-100 bacilli in every filed
5+ > 100 bacilli in every field, clumps and globi

GRADING FOR BACTERIAL INDEX

Negative No bacilli in 100 fields
+ 1 or less in each field
++ Bacilli in all fields
+++ Many bacilli in all fields

G- globi

Bacterial index = total numbers of + for each smear divided by the number of smears

Minimum 7 sites should be smeared

In paucibacillary, it is < 2

In multibacillary > 2

TRIVIAL TRUTH

Vaccination was discovered by English physician Edward Jenner, after he observed that milkmaids would not catch smallpox since they caught benign cowpox first.

ELEVENTH HOUR MICROBIOLOGY                                                                                                       69

Spirochetes

Treponema pallidum
Thin, spiral.

It can be seen in low microscope by negative staining with India ink.

Morphology and motility can be seen under dark ground or phase contrast microscope.

It can be stained with silver impregnation method

Leptospira
Actively motile

Coiled appearance seen under dark ground microscopy

Their ends are hooked, resembling umbrella handles.

Generation time is 12-16 hours.

Mycoplasma
Devoid of cell wall, pleomorphic.

Show true branching.

Gram negative.

Aerobic and facultatively anaerobic.

Biphasic colonies, with a fried egg appearance

Hemolytic.

Require cholesterol for growth.

*Rickettsiae are obligate intracellular parasites, transmitted by arthropod vectors.

*Chlamydiae are obligate intracellular parasites.

Called energy parasites.

Occur in two forms

Elementary body- extracellular, infective form

Reticulate body/ initial body.-intracellular, growing and replicative form.

Differences between classical and Eltor vibrio

characteristic classical vibrio Eltor vibrio
Hemolysis

+

Vogs Proskauer reaction

+

Chick RBC agglutination

+

Eltor phage 5 susceptibility

+

Polymyxin b sensitivity

+

Group 4 phage susceptibility

+

QUOTE CORNER

When it is obvious that the goals cannot be reached, don’t adjust the goals, adjust the action steps.- Confucius

ELEVENTH HOUR MICROBIOLOGY                                                                                                       70

UREASE POSITIVE BACTERIA
Klebsiella

Proteus

H pylori

species disease vector
R. prowazekii Epidemic typhus

Brill-Zinser disease

Louse
R. typhi

R. felis

Endemic typhus Rat flea / Cat flea
R. ricketsii Rocky mountain spotted fever Tick
Orientia tsusugamushi Scrub typhus Trombiculid mite
R. Quintana Trench fever Louse
R. akari Rickettsial pox Mite
Coxiella burnetti Q fever
Eaton agent Mycoplasma pneumoniae
Johne’s bacillus Mycobacterium pseudo tuberculosis
Eberth Gaffky bacillus Salmonella typhi
Koch Week’s bacillus Haemophilus aegypticus
Whitmore bacillus Pseudomonas pseudomallei

*Paul Bunnel test is used for diagnosing infectious mononucleosis.

Kissing disease-infectious mononucleosis, as kissing is the predominant mode of transport.

fungus type morphology examples
Yeast Unicellular fungi Cryptococcus
Yeast like fungi Partly yeast partly hyphae Candida
Moulds / filamentous fungi True mycelia Dermatophytes
Dimorphic Filaments and yeasts at different temperatures.

Yeast at 37 degrees and mould at 22 degrees

Coccidiodes, blastomyces, Paracoccidiodes, histoplasma
Chorioallantoic membrane Pocks
Allantoic cavity Vaccine production of influenza
Amniotic cavity Primary isolation of influenza
Yolk sac Chlamydia, Rickettsia

TRIVIAL TRUTH

A dentist invented the electric chair.

ELEVENTH HOUR MICROBIOLOGY                                                                                                       71

BLOT TESTS WITH STRUCTURES DETECTED BY THEM

TEST STRUCTURE
Western blot Protein
Southern blot DNA
Northern blot RNA

* Southern was the name of a scientist.

inclusion bodies virus
Negri bodies Rabies
Guarneri bodies Vaccinia
Bollinger bodies Fowl pox
Cowdry A inclusion bodies (Lipschultz) Herpes, yellow fever
Cowdry B inclusion bodies Adenovirus polio virus
Molluscum bodies Molluscum contagiosum
Torres bodies / councilman bodies Yellow fever
Warthin Finkeledy cells Measles

*Universal precautions apply to blood csf, synovial fluid, pleural fluid, pericardial fluid, amniotic fluid, saliva , breast milk, semen, vaginal secretions,

Does not apply to feces, nasal secretions, sputum, sweat, tears, urine, and vomitus.

Differences between P. vivax and P. falciform

characteristic P.vivax p.falciparum
Incubation period 14 days 12 days
RBC size Enlarged Not enlarged
Dots Schuffner’s dots Maurer’s dots
Infection Usually single per rbc Multiple infections
Stages All stages seen Only rings and gametocytes
Special forms None Accole, wing, marginal
Hypnozoites Present Absent
Resistance No resistance Drug resistance widespread
CNS involvement Absent Present
Anaemia Absent Present
Parasites found in blood
Plasmodium malariae

Trypanosoma cruzi

Leishmania donovani

Babesia microti

Microfilaria

QUOTE CORNER

It is hard to fail, but it is worse never to have tried to succeed.- Theodore Roosevelt

ELEVENTH HOUR MICROBIOLOGY                                                                                                       72

Parity of nematodes

oviparous viviparous ovo-viviparous
Ascaris

Hookworm

E. vermicularis

T. trichura

W. bancrofti

B. malayi

T. spiralis

S. stercoralis
African trypanosomiasis Sleeping sickness Tsetse fly T. brucei
American trypanosomiasis Chaga’s disease Reduvid bug T. cruzi
Man is the secondary host for
Echinocooccus

Malaria

Toxoplasmosis

Visceral larva migrans Toxocara canis
Larva currens S. stercoralis
CHARACTERISTIC classical filariasis occult filariasis
Cause Developing worms and adults Microfilariae
Organs involved Lymphatic system Lymphatic system, lungs, liver and spleen
Therapeutic response No response Responds to DEC
Microfilaria Present in blood Present in affected tissues
Eggs which do not float in saturated solution of common salt
Unfertilized eggs of Ascaris lumbricoides

Eggs of Tenia solium and Tenia saginata

All trematodal eggs

Larvae of strongyloides

Calabar swelling Loa Loa affection of eyes
Onchocercomas Subcutaneous fibrous nodules in case of O. volvulus

*Occult filariasis / Mayers-Kouwenaar syndrome

Loa Loa-microfilaria are detected in blood in daytime

PARASITE DOC
Tenia solium Praziquantel
Neurocysticercosis Albendazole- Praziquantel
Tenia saginata Praziquantel- Niclosamide

*Niclosamide is not used in infection with Tenia solium as ova released from the damaged worms causes Cysticercosis

TRIVIAL TRUTH

Powdered tea was once used as a snuff to stop bleeding noses.

ELEVENTH HOUR MICROBIOLOGY                                                                                                       73

Wishing you all great success in life.
Zakirhusain Shaikh

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