Miscellaneous

Spirochaetes characteristics

Corkscrew winding

Gram negative bacilli cell wall

Long

Slender

Double membranes

Helically curved bacilli

Spirochaetes genera (morphology)

Treponema- slender with tight coils

Borrelia- thicker with fewer and loose coils

Leptospira - resembles borrelia except hooked ends

Brachyspira- comma shaped

Treponema characteristics

Spiral

Width is less than 0.2um

Not visible on wet mount

Has G- cell wall

Pathogenic species is microaerophilic

Identify

Treponema

Identify

Borrelia

Disease caused by borrelia

1. Relapsing fevers

2. Lyme disease

Two types of relapsing fevers

Epidemic louse borne

Endemic tick borne

Epidemiology of epidemic louse borne relapsing fever

Caused by Borrelia recurrentis

Occurs in Africa and South America

Poor hygiene and sanitation

Increase with wars and conditions of social upheaval

Transmitted when pathogen from crushed lice enters broken skin/ mucous membrane

NB : B. recurrentis there is no transovarian transmission and not shed in saliva / excreta of lice

Epidemiology of endemic tick-borne relapsing fever

Caused by B.duttoni

Shed in saliva/excreta as the tick feed on host because the borrelia invades all tissues of the tick

There is transovarian transmission

Borrelia staining technique

Giemsa stain of thick and thin blood smear

Commonest serovars of L. Interogan sensu stricto

Ictohaemorrhagiae

Canicola

Pomona

NB: destroyed by extreme pH,>40 degree Celsius,dessication

General characteristics of mycoplasmas

Smallest known free living prokaryote

Ubiquitous in plants/ animals

Microbial flora (URT,GUT)

Lack cell wall

Lack peptidoglycan precursors

Lack turbidity in broth culture

Highly fastidious

Slow growing

Require microscope to visualize colonies

Most are facultative anaerobes

Family and genera of mycoplasma

Family; mycoplasmataceae

Genera: mycoplasma, ureaplasma

Major species of mycoplasmas

Mycoplasma fermentans: children/immunocompromised

Mycoplasma genitalium: 15-20% non gonococcal urethritis

Mycoplasma hominis:

Mycoplasma pneumonia:community acquired atypical pneumonia

Ureaplasma parvum:

Ureaplasma urealyticum:

Transmission of mycoplasmas

Direct contact: mother to offspring, aerosol, nosocomial acquisition through tissue transplant