Gram Negative Bacteria Digging Deeper into Microbial Life Part 2 of 3

Gram Negative Bacteria Stain red* Their thin layer of peptidoglycan is surrounded by a cell wall Most are harmful to humans Produce endotoxins that are often deadly – even after the bacteria is destroyed Gram negative microbes cause the most and the worst cases of septicemia** *Using gram staining technique. Note: due to different photography techniques, you may note colors other than expected. **Septicemia is also known as sepsis, septic shock and bacteremia. It is sometimes referred to “blood poisoning” when speaking with laypeople.

Gram Negative Bacteria Types Pseudomonas aeruginosa Klebsiella pneumoniae Haemophilus influenzae Bordatella pertussis Legionella pneumoniae

Pseudomonas aeruginosa Opportunistic aerobic bacillus Found in most non-sterile water Causes respiratory tract infections Most: Strains are antibiotic resistant Common cause of nosocomial infection in patients hospitalized for over one week Common microbe cultured in mucus from cystic fibrosis patients Commonly cultured microbe on respiratory care equipment

P. aeruginosa Has characteristic fermented fruit odor Often described as fetid by the NBRC Creates a blue – green pigment called pyocyanin Augments color of pus Augments color of mucus

P. aeruginosa Blue pigment on an agar created by p. aeruginosa Green pigment on an agar created by p. aeruginosa The colors can be quite interesting which contrasts the strong, fetid odor the microbe creates.

Klebsiella pneumoniae Facultative anaerobe Opportunistic Often antibiotic resistant Common cause of pneumonia Leads to small areas of lung destruction Leads to abscesses Creates mucus that looks like red currant jelly

Haemophilus influenzae Facultative anaerobic bacillus Found in over 75% of upper respiratory systems Opportunistic Cause of upper respiratory infections (URI) Cause of epiglottitis in children Does NOT cause the flu (that’s a virus!) Requires very specific culturing techniques Epiglottitis article: http://www.emedicinehealth.com/epiglottitis/article_em.htm

Bordatella pertussis Coccobacillus Cause of pertussis, aka whooping cough Characterized by long inhalation and choking cough Produces thick, clear mucus Cough and mucus production may last for months Children receive immunization Teens and adults become ill as immunization does not work against new strains Vaccine is in new tetanus shots to protect older population

B. pertussis Healthcare workers often swabbed to check for colonization of Bordatella pertussis. Illustration shows procedure for testing for the microbe.

Legionella pneumoniae Aerobic bacillus Cause of Legionnaire’s disease Pneumonia Victims get contaminated by water supply Often from inhaling steam from showers or hottubs Hospitals, hotels, and cruise ship contamination may cause an outbreak CDC information on Legionnaire’s disease: http://www.cdc.gov/legionella/patient_facts.htm

Gram Negative Summary Like gram positive bacteria, gram negative have the potential to cause serious pulmonary illness. These microbes have a higher chance of being more serious Tend to have more powerful toxins Are less susceptible to antibiotics. Their endotoxins may continue to damage the host after the death of the bacteria.

Study Tool Gram Positive Staphylococcus aureus Streptococcus pneumoniae Corynebacterium diphtheriae Bacillus anthracis Clostridium botulinum Clostridium tetani Gram Negative Pseudomonas aeruginosa Klebsiella pneumoniae Haemophilus influenzae Bordatella pertussis Legionella pneumoniae

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