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Because biofilms vary in composition and are difficult to replicate in the lab, they are still not thoroughly understood. The extracellular matrix of a biofilm consists of polymers such as polysaccharides, extracellular DNA, proteins, and lipids, but the exact makeup varies. The organisms living within the extracellular matrix may include familiar pathogens as well as other bacteria that do not grow well in cultures (such as numerous obligate anaerobes). This presents challenges when culturing samples from infections that involve a biofilm. Because only some species grow in vitro , the culture may contain only a subset of the bacterial species involved in the infection.

Biofilms confer many advantages to the resident bacteria. For example, biofilms can facilitate attachment to surfaces on or in the host organism (such as wounds), inhibit phagocytosis, prevent the invasion of neutrophils, and sequester host antibodies. Additionally, biofilms can provide a level of antibiotic resistance not found in the isolated cells and colonies that are typical of laboratory cultures. The extracellular matrix provides a physical barrier to antibiotics, shielding the target cells from exposure. Moreover, cells within a biofilm may differentiate to create subpopulations of dormant cells called persister cells. Nutrient limitations deep within a biofilm add another level of resistance, as stress responses can slow metabolism and increase drug resistance.

Bacterial infections of the eyes

A number of bacteria are able to cause infection when introduced to the mucosa of the eye. In general, bacterial eye infections can lead to inflammation, irritation, and discharge, but they vary in severity. Some are typically short-lived, and others can become chronic and lead to permanent eye damage. Prevention requires limiting exposure to contagious pathogens. When infections do occur, prompt treatment with antibiotics can often limit or prevent permanent damage. [link] summarizes the characteristics of some common bacterial infections of the eyes.

Table titled: Bacterial Infections of the Eyes. Columns: Disease, Pathogen, Signs and Symptoms, Transmission, and Antimicrobial Drugs. Acute bacterial conjunctivitis, Haemophilus influenza, Inflammation of conjunctiva with purulent discharge, Exposure to secretions from infected individuals, Broad-spectrum topical antibiotics. Bacterial keratitis, Staphylococcus epidermidis, Pseudomonas aeruginosa, Redness and irritation of eye, blurred vision, sensitivity to light; progressive corneal scarring, which can lead to blindness, Exposure to pathogens on contaminated contact lenses, Antibiotic eye drops (e.g., with fluoroquinolones). Neonatal conjunctivitis Chlamydia trachomatis, Neisseria gonorrhoeae, Inflammation of conjunctiva, purulent discharge, scarring and perforation of cornea; may lead to blindness, Neonate exposed to pathogens in birth canal of mother with chlamydia or gonorrhea Erythromycin. Trachoma (granular conjunctivitis), C. trachomatis, Chronic conjunctivitis, trichiasis, scarring, blindness, Contact with infected individuals or contaminated fomites; transmission by eye-seeking flies, Azithromycin.

Key concepts and summary

  • Staphylococcus and Streptococcus cause many different types of skin infections, many of which occur when bacteria breach the skin barrier through a cut or wound.
  • S. aureus are frequently associated with purulent skin infections that manifest as folliculitis , furuncles , or carbuncles . S. aureus is also a leading cause of staphylococcal scalded skin syndrome (SSSS).
  • S. aureus is generally drug resistant and current MRSA strains are resistant to a wide range of antibiotics.
  • Community-acquired and hospital-acquired staphyloccocal infections are an ongoing problem because many people are asymptomatic carriers.
  • Group A streptococci (GAS) , S. pyogenes , is often responsible for cases of cellulitis , erysipelas , and erythema nosodum . GAS are also one of many possible causes of necrotizing fasciitis .
  • P. aeruginosa is often responsible for infections of the skin and eyes, including wound and burn infections, hot tub rash , otitis externa , and bacterial keratitis .
  • Acne is a common skin condition that can become more inflammatory when Propionibacterium acnes infects hair follicles and pores clogged with dead skin cells and sebum.
  • Cutaneous anthrax occurs when Bacillus anthracis breaches the skin barrier. The infection results in a localized black eschar on skin. Anthrax can be fatal if B. anthracis spreads to the bloodstream.
  • Common bacterial conjunctivitis is often caused by Haemophilus influenzae and usually resolves on its own in a few days. More serious forms of conjunctivitis include gonococcal ophthalmia neonatorum , inclusion conjunctivitis (chlamydial), and trachoma , all of which can lead to blindness if untreated.
  • Keratitis is frequently caused by Staphylococcus epidermidis and/or Pseudomonas aeruginosa , especially among contact lens users, and can lead to blindness.
  • Biofilms complicate the treatment of wound and eye infections because pathogens living in biofilms can be difficult to treat and eliminate.

Fill in the blank

A purulent wound produces ________.

pus

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Short answer

How are leukocidins associated with pus production?

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What is a good first test to distinguish streptococcal infections from staphylococcal infections?

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Questions & Answers

What are antibodies?
Happy Reply
they are immune cells that are released by immune system to fight strangers like microbes
Ahmed
a blood protien produce in response to an counteracting a specific antigen
Pooja
Why salmonella typhi is harmful protozoan?
Saily Reply
because make typhoid that is considered as a food born illness
Ahmed
Name any five modes of transmission.
Happy
what are the scientific names and common names of some microbes
Rich Reply
Staphylococcus aureus - staph Streptococcus pyogenes - strep Botulism - Clostridium botulinum Rocky Mountain spotted fever - Rickettsia rickettsii Diphtheria - Corynebacterium diphtheriae Gonorrhea - Neisseria gonorrhoeae
Tammy
what are the limitations of the Koch's postulate
Naa
how a microorganism growth.
Zubair Reply
Is foetus a parasite to his or her mother? if yes and if no ho
Mashauri Reply
y
Yusri
yes
Yashkin
yes
Zubair
yes it a parasite to the mother because it feeds on the mother for survival
Beatrice
yes
Redwan
no
Elasha
definition of a parasite: an organism that lives in or on an organism of ANOTHER species (its host) and benefits by deriving nutrients at the other's expense
Elasha
no because an organism can inky be a parasite if it causes harm to its HOST. And the fetus does not cause harm to its mother under normal conditions
aliyu
yes
Naa
what is biosensor in microbiology
Raja Reply
What are biosensor
Raja
what's are biosensor
Raja
what is microbiology defination
Rinku Reply
microbiology is the study of small or manuit organisms which cannot be seen with our nacked eyes unless with the aid of the microscope
Brandina
is the study of living organisms which are not directly visible to a direct eye but can only be seen under a microscope
Ipa
ok
Ipa
microbiology is the study of living organisms of microscopic size it is also the study of micro organisms with their form structure reproduction psychology metabolism and classification
Priyanka
what are the importances of Microbiology?
Erick Reply
don't know
SINGLE
we obtained the insulin from the bacteria. and some microorganisms are decomposer in ecosystems.
Zubair
nitrogen in the air is fixed into the soil by microbes example is nitrobactor
Matilda
yes
Zubair
how a weak immune region where microorganisms attack easily?
Zubair Reply
with examples differentiate gram positive from gram negative bacteria
Mary Reply
Differentiate gram positive from gram negative
Mary
I have no idea
Zubair
hello
Kuonain
and example of gram negative is E. coli
Pooja
gram positive stain purple when subjected to gram stain whilst gram positive bacterial has thick wall composed of peptidoglycan
Matilda
ok
Zubair
what is a process of gene expression in eukaryotes ?
Nayyab Reply
pls help us with the answer
Abdussalam
spontaneous generation means
Siddhi Reply
hiii
Siddhi
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eman
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eman
I have a problem with Micro
eman
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eman
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eman
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Siddhi
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yaya
Greeting to everyone in here.
Manka
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Manka
structure of bacterial
Kuyiba
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Zubair
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Kuonain
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suhail
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Angela
rod shape
Priyanka
helical
Priyanka
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esike
spherical
Priyanka
peomorphic
Priyanka
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Priyanka
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suhail
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DIPTI
Are we together pls what's the topic for the day?
esike
what is innate
Lizzy
innate means natural
Pooja
the genetic makeup of an individual
Matilda
pls i need the common names for the following parasites..ENTEROBIUS VERMICULARIS,NECATOR AMERICANUS,ASCARIES LUMBRICOIDES,TRICHURIS TRICHIURA,TRICHOMONAS VAGINALIS,GIARDIA LAMBLIA,ENTAMOEBA HISTOLYTICA,SCHISTOSOMA MANSONI,SCHISTOSOMAHEMATOBIUM,STROGYLOIDES STERCORALIS,AND TRAPANOSOMA BRUCI GAMBIENSE
timothy
ENTEROBIUS VERMICULARIS and STROGYLOIDES STERCORALIS have the same common name which is pin worm and thread worm
Chinedu
I didn't find the common names for TRICHOMONAS VAGINALIS, GIARDIA LAMBLIA, ENTAMOEBA HISTOLYTICA, TRYPANOSOMA BRUCEI GAMBIENSE
Chinedu
NECATOR AMERICANUS - New world hookworm ASCARIS LUMBRICOIDES- Ascarid TRICHURIS TRICHIURA- Whip worm
Chinedu
Hi guys
Chinedu
Why are myeloblasts not present in the bloodstream?
Chinedu
thank u
Dasaah
is blood from capillary puncture suitable for hormonal assays
NANCY Reply
Direct this question to a hematologist for a better answer please.
LAFIA
In most cases the blood is necessary but it's limited from my own Analysis
Lee
u can do but it depends on your sampling blood its enev or not
Ali
Control indications of cipro, doxicyclin, setracyclin, cloxacyclin, erythromycin
Oslen Reply
oo
babinthe
what is sims position
babinthe Reply
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Source:  OpenStax, Microbiology. OpenStax CNX. Nov 01, 2016 Download for free at http://cnx.org/content/col12087/1.4
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