InstituteInstitute for for Microbiology, Medical Faculty of Masaryk University Microbiology, Medical Faculty of Masaryk University and St. Anna Faculty Hospitaland St. Anna Faculty Hospital in Brno in Brno

Miroslav VotavaMiroslav VotavaOndřej ZahradníčekOndřej Zahradníček

MORPHOLOGY AND STRUCTUREMORPHOLOGY AND STRUCTUREOF BACTERIAL CELLOF BACTERIAL CELL

Lecture for 2nd-year studentsLecture for 2nd-year studentsFebruary 2February 233, 200, 20099

Shape of bacteria – I Shape of bacteria – I Spherical shape: Spherical shape: coccicocci

regular sphere:regular sphere: staphylococci staphylococci flattened:flattened: gonococci, meningococcigonococci, meningococci

pointed pointed (lancet-like):(lancet-like): pneumococci pneumococciElongated shape:Elongated shape: rods rods

straight:straight: majority (e.g. majority (e.g. Escherichia coliEscherichia coli))short (coccobacilli):short (coccobacilli): acinetobacters acinetobacterslong (fibers):long (fibers): mainly old cultures mainly old culturesslender:slender: Mycobacterium tuberculosisMycobacterium tuberculosisrobust:robust: lactobacilli, lactobacilli, ClostridiumClostridium

perfringensperfringens, Bacillus, Bacillus(to be continued)(to be continued)

Shape of bacteriaShape of bacteria – II – II

(rods, continued)(rods, continued)

with split ends:with split ends: bifidobacteria bifidobacteria

branching:branching: nocardiae, actinomycetes nocardiae, actinomycetes

curved:curved: vibria, campylobacters vibria, campylobacters

with flat ends:with flat ends: Bacillus anthracisBacillus anthracis

spindle-shaped:spindle-shaped: fusobacteria fusobacteria

club-shaped:club-shaped: corynebacteria corynebacteria

pleomorphic: pleomorphic: haemophilihaemophili

spiral:spiral: HHelicobacterelicobacter, Spirillum, Spirillum ( (they are they are not spirochetsnot spirochets))

Shape of bacteriaShape of bacteria – III – III

SpiralSpiral bacteria (spirochetes) bacteria (spirochetes)::

uneven: uneven: BorreliaBorrelia

delicate, regular: delicate, regular: TreponemaTreponema

slender with bent ends: slender with bent ends: LeptospiraLeptospira

Size of bacteriaSize of bacteriaPathogenic bacteria: mainlyPathogenic bacteria: mainly around 1 – 5 around 1 – 5 μm μm

(1 μm = 10(1 μm = 10-3-3 mm) mm)Staphylococcus:Staphylococcus: the diameter circa the diameter circa 1 μm 1 μm RelativelyRelatively largelarge: : genera genera Bacillus Bacillus and and Clostridium Clostridium

(robust rods around 1 × 10 μm) (robust rods around 1 × 10 μm) Relatively Relatively long:long: old cultures of most rods old cultures of most rods

(fibers up to 50 μm long)(fibers up to 50 μm long)Relatively Relatively small: small: genus genus Haemophilus Haemophilus

(in the sputum approximately 0.3 × 0.6 μm)(in the sputum approximately 0.3 × 0.6 μm)Even smaller:Even smaller:

rickettsiae (circa 0.5 μm) rickettsiae (circa 0.5 μm) chlamydiae (elementary bodies circa 0.3 μm) chlamydiae (elementary bodies circa 0.3 μm) mycoplasmas (circa 0.2 – 0.25 μm ) mycoplasmas (circa 0.2 – 0.25 μm )

Arrangement and shape of cocciArrangement and shape of cocci

a)a) in in clumps:clumps: Staphylococcus aureusStaphylococcus aureus

b)b) in in chains:chains: Streptococcus pyogenesStreptococcus pyogenes

c)c) lancet-like lancet-like diplococci:diplococci: Streptococcus Streptococcus pneumoniaepneumoniae

d)d) flattened flattened diplococci:diplococci: Neisseria gonorrhoeaeNeisseria gonorrhoeae

e)e) cocci in cocci in tetrads:tetrads: Micrococcus luteusMicrococcus luteus

Arrangement and shape of rodsArrangement and shape of rods – I – I

a)a) absoluteabsolute majority majority of rods: e.g. of rods: e.g. Eschericha coliEschericha coli

b)b) delicate delicate streptobacillistreptobacilli: : Haemophilus ducreyiHaemophilus ducreyi

c)c) coccobacilli in pairs or coccobacilli in pairs or diplobacillidiplobacilli: : MoraxellaMoraxella lacunatalacunata

d)d) robust rods, robust rods, rounded endsrounded ends: : Clostridium perfringensClostridium perfringens

e)e) robust rods, robust rods, flatflat up to concave up to concave endsends, bamboo cane-like , bamboo cane-like chains:chains: Bacillus anthracis Bacillus anthracis

Arrangement and shape of rodsArrangement and shape of rods – II – II

f) f) club-like in club-like in palisadespalisades: : Corynebacterium diphtheriaeCorynebacterium diphtheriae

g) slender, hinted g) slender, hinted palisadespalisades: : Mycobacterium tuberculosisMycobacterium tuberculosis

h) h) branchedbranched, fragmented: , fragmented: Nocardia asteroidesNocardia asteroides

i) i) spindle-likespindle-like: : Fusobacterium fusiformeFusobacterium fusiforme

j) minute, j) minute, pleomorphicpleomorphic: : Haemophilus influenzaeHaemophilus influenzae

Curved and spiral rodsCurved and spiral rods

a) a) curvedcurved rods, crescent-shaped: rods, crescent-shaped: Vibrio choleraeVibrio cholerae

b) b) thickthick spirals: spirals: Spirillum minusSpirillum minus

c) c) unevenuneven spirals: spirals: Borrelia recurrentisBorrelia recurrentis

d) d) delicate, regulardelicate, regular spirals : spirals : Treponema pallidumTreponema pallidum

e) e) very finevery fine spirals with bent ends : spirals with bent ends : Leptospira Leptospira icterohaemorrhagiaeicterohaemorrhagiae

Outline of bacterial cellOutline of bacterial cellcapsulecapsule

cytoplasmic membranecytoplasmic membrane bacterial cell wallbacterial cell wall

fimbriaefimbriaenucleoidnucleoid

ribosomesribosomes

plasmidsplasmidsgranulagranulavacuolevacuole

flagellumflagellum

Bacterial cell wallBacterial cell wallG+G+ G–G– lipoteichoic acidlipoteichoic acid O-antigenO-antigen lipopoly-lipopoly-

inner polysaccharideinner polysaccharide saccharidesaccharide

lipidlipid AA (endotoxin)(endotoxin)

mureinmurein

porinporin

outerouter

membranemembrane

lipoproteinlipoprotein

periplasmaticperiplasmatic

space space

innnerinnner membranemembrane

cytoplasmic membrane (G+)cytoplasmic membrane (G+) (G–)(G–)

Gram stainingGram staining

G+ G+ G–G–

1.1. Fixation by flame Fixation by flame 3–53–5 times times

2.2. Gram stain 20 sGram stain 20 s

3.3. Lugol solution 20 sLugol solution 20 s

4.4. Alcohol max. 20 sAlcohol max. 20 s

5.5. Tap waterTap water rinse rinse

6.6. Safranin 1 minSafranin 1 min

7.7. Tap waterTap water rinse rinse

8.8. DryingDrying, immersion microscopy (1000 ×), immersion microscopy (1000 ×)

Basis of Gram-positivenessBasis of Gram-positiveness

Rather a Rather a puzzlepuzzle – but it is connected with the – but it is connected with the structure structure of cell wallof cell wall

1st theory:1st theory:Thick peptidoglycane (murein) layer contracts after the Thick peptidoglycane (murein) layer contracts after the

alcohol and slows down the washing of crystal alcohol and slows down the washing of crystal violet and iodine complex out of G-positive cellsviolet and iodine complex out of G-positive cells

2nd theory:2nd theory:Cell wall of Gram-negative bacteria contains more Cell wall of Gram-negative bacteria contains more

lipids, therefore the alcohol forms pores in the wall lipids, therefore the alcohol forms pores in the wall and the colored complex can be washed out easierand the colored complex can be washed out easier

Examples of G+ and G– microbesExamples of G+ and G– microbes

Gram-positivesGram-positives

StaphylococcusStaphylococcus

StreptococcusStreptococcus

BacillusBacillus

LactobacillusLactobacillus

ClostridiumClostridium

ListeriaListeria

CorynebacteriumCorynebacterium

Yeasts and mouldsYeasts and moulds

Gram-negativesGram-negatives

EscherichiaEscherichia

SalmonellaSalmonella

VibrioVibrio

Haemophilus Haemophilus

PseudomonasPseudomonas

All spiralsAll spirals

MycoplasmaMycoplasma

Rickettsiae Rickettsiae && chlamydiae chlamydiae

Sensitivity to antibioticsSensitivity to antibiotics

Effect Effect mostly mostly

on Gram-positiveson Gram-positives::

beta-lactams (beta-lactams (penicillinpenicillin,,

oxacillin oxacillin = = methicillin)methicillin)

macrolides (erytromycin)macrolides (erytromycin)

lincosamides lincosamides (lincomycin)(lincomycin)

glycopeptides glycopeptides (vancomycin)(vancomycin)

Effect Effect mostly mostly on Gram-negativeson Gram-negatives::

polypeptides (colistin)polypeptides (colistin)aminoglycosides aminoglycosides

(gentamicin)(gentamicin); ; but G+ but G+ staphylococci toostaphylococci too

monobactamsmonobactams ( (aztreonamaztreonam)) + +3rd gen. cephalosporins 3rd gen. cephalosporins

(cephtriaxon)(cephtriaxon) – rather – rather broad spectre antibiotics, broad spectre antibiotics, but for G- more than G+but for G- more than G+

Recommended reading materialRecommended reading material

Paul de Kruif: Microbe HuntersPaul de Kruif: Microbe Hunters

Paul de Kruif: Men against DeathPaul de Kruif: Men against Death

Thank you for your attentionThank you for your attention