Lecture Notes on Bacteria and Infections

Announcements and Lab Coordination

  • Instructor will be available on Friday.

    • Encouragement to call with questions about lab work.

  • Lab on Wednesday will be conducted by Jen.

  • Students can FaceTime instructor during lab if they have questions on unknowns.

  • Open lab scheduled for Friday.

Test Materials

  • Instructor will bring test materials to Pramp and Winnemucca.

    • Students in these locations can review their tests.

    • Park has requested a couple of cultures; these will be brought.

    • No demands from Candy in Winnemucca.

Technical Aspects

  • Instruction on operating classroom technology if issues arise.

    • Albert has assured functionality; students are encouraged to troubleshoot if necessary.

Discussion on Bacterial Genera

Beta Proteobacteria

  • Previously discussed Bordetella primarily Bordetella pertussis:

    • Causes whooping cough.

Genus Neisseria

  • Neisseria characteristics:

    • Have fimbriae that adhere to mucous membranes of mammals, facilitating infection.

  • Two key human pathogens:

    1. Neisseria gonorrhoeae (N. gonorrhea)

    • Causes gonorrhea, historically referred to as "the clap."

    • Second most commonly reported communicable disease.

    • Transmitted sexually and can infect various mucosal tissues (urogenital, oral, anal, conjunctiva).

    • Risk of transmission from untreated mothers to infants during childbirth, potentially affecting infant's eyes (treated with silver drops historically).

    • Can lead to pelvic inflammatory disease (PID), no vaccine available, treatable with antibiotics.

    • Historical context: Penicillin was the standard treatment until resistance developed.

    • Some individuals may be asymptomatic carriers.

    1. Neisseria meningitidis (N. meningitis)

    • Causes bacterial meningitis (infection of the meninges).

    • 40% of the population are asymptomatic carriers.

    • Common symptoms include:

      • Fever

      • Bacteremia (presence of bacteria in blood)

      • Severe headache

      • Stiff neck (classic symptom, immobility indicates severity).

    • Rapid progression of symptoms; potential for coma or death within hours.

    • High-risk populations include infants and college students in dormitories.

    • Treatable with antibiotics, complications may include brain damage or hearing loss.

    • Vaccines available, promoted especially before college semesters.

Gamma Proteobacteria

  • This group is diverse, exhibiting various cell shapes, arrangements, metabolic types, and reproductive strategies.

  • Organized into five main subgroups:

    1. Purple Sulfur Bacteria

    • Obligate anaerobes that oxidize hydrogen sulfide to sulfur, creating sulfur granules instead of using oxygen.

    1. Intracellular Pathogens

    • Facultative intracellular parasites that can reproduce inside or outside host cells.

    • Example genus: Legionella (notably Legionella pneumophila, which causes Legionnaires' disease).

    • Found in water systems, hot water tanks, and air conditioning.

    • Responsible for illness during the American Legion convention due to contaminated mists.

    1. Methane Oxidizers

    • Use methane as their carbon source.

Enterobacteriaceae Family

  • Found in human and mammal intestinal tracts; ferment glucose and some produce bacteriocins (antibacterial substances).

  • Includes notable genera and species:

    • Escherichia (including E. coli):

      • Used extensively in microbiology; indicator of fecal contamination.

      • Typically not pathogenic but can cause UTIs and has some strains (E. coli O157:H7) that produce toxins leading to severe disease.

      • At-risk individuals: children and immunocompromised.

    • Salmonella:

      • Mostly pathogenic; carried in intestines of cold-blooded animals and birds.

      • Includes species such as Salmonella enterica and Salmonella bongori.

      • Over 2,500 serovars distinguished only by antigen-antibody tests.

      • Causes Typhoid fever (e.g., salmonella enterica serovar typhi); Mary Mallon ("Typhoid Mary") was an asymptomatic carrier involved in multiple outbreaks.

    • Shigella:

      • Causes shigellosis, with around 450,000 infections/year in the US, costing approximately $93 million in medical care.

      • Symptoms include diarrhea, vomiting, dehydration, and dysentery.

      • Very easily spread through oral-fecal routes; often affects children under five and can occur during travel to unsanitary areas.

    • Yersinia:

      • Notable for causing bubonic plague (Yersinia pestis); highlight of disease history related to the Black Death.

    • Cronobacter:

      • Linked to infant formula recalls in 2021-2022; caused severe infections like necrotizing enterocolitis in infants.

Health Care-Associated Infections

  • Discussion of common bacteria associated with nosocomial infections:

    • Serratia marcescens:

      • Notable for potential to contaminate sterile equipment and respiratory tools.

    • Proteus:

      • Includes species like P. mirabilis and P. vulgaris, commonly found in hospital settings.

Reminder and Conclusion

  • Scheduling reminder regarding the upcoming lab reports and exams, including A&P lab exam.

  • Instructor will check and confirm details on Canvas before the next session.