LECTURE SLIDES 17 - Bacterial Infections of Humans.pdf

BACTERIAL INFECTIONS OF HUMANS CHRISTINE JOYCE M. JAVIER, RMT, MLS(ASCPI)CM 2024 Jul 11 – 13 MICRO PARA LEC CONTENTS Introduction How do Bacteria Cause Disease? Bacterial Infections of the Skin Bacterial Infections of the Ears Bacterial Infe...

BACTERIAL INFECTIONS OF HUMANS CHRISTINE JOYCE M. JAVIER, RMT, MLS(ASCPI)CM 2024 Jul 11 – 13 MICRO PARA LEC CONTENTS Introduction How do Bacteria Cause Disease? Bacterial Infections of the Skin Bacterial Infections of the Ears Bacterial Infections of the Eyes Bacterial Infections of the Respiratory System Bacterial Infections of the Oral Region Bacterial Infections of the Gastrointestinal Tract Bacterial Infections of the Genitourinary System Bacterial Infections of the Circulatory System Bacterial Infections of the Central Nervous System Diseases Caused by Anaerobic Bacteria Diseases Associated With Biofilms Recap of Major Bacterial Infections of Humans Recap of Major Bacterial Pathogens of Humans Appropriate Therapy for Bacterial Infections How Do Bacteria Cause Disease? Adherence and colonization factors Factors that prevent activation of complement Factors that enable escape from phagocytosis by white blood cells Factors that prevent destruction within phagocytes Factors that suppress the host immune system (i.e., factors that cause immunosuppression) Endotoxin (a component of the cell walls of Gram- negative bacteria) Production of exotoxins (e.g., cytotoxins, enterotoxins, neurotoxins) Production of necrotic and other types of destructive enzymes Bacterial Infections of the Skin Acne Propionibacterium acnes and other Propionibacterium spp.; anaerobic Gram + bacilli Anthrax, Woolsorter Disease Bacillus anthracis; a spore-forming, Gram + bacillus Gas gangrene (myonecrosis) Anaerobic bacteria in the genus Clostridium, especially Leprosy C. perfringens (Hansen disease) Mycobacterium leprae; an acid-fast bacillus Staphylococcal skin infections (folliculitis, furuncles, abscesses, etc.) Staphylococcus aureus, a Gram + coccus Streptococcal skin infections (scarlet fever, erysipelas, etc.) Streptococcus pyogenes, a Gram + coccus Diseases Caused by Staphylococcus aureus Diseases Caused by Streptococcus pyogenes Bacterial Infections of the Skin (cont.) Wound infections Result when protective skin barrier is broken as a result of burns, punctures, surgical procedures, or bites Opportunistic indigenous microbiota and environmental bacteria can invade and cause local or deep tissue infections. Pathogens may spread through blood or lymph, causing serious systemic infections. Viral and Bacterial Ear Infections Infections Caused by Haemophilus influenzae Otitis externa (external otitis, ear canal infection, swimmer’s ear) Escherichia coli, Pseudomonas aeruginosa, Proteus vulgaris, Staphylococcus aureus; less commonly caused by a fungus such as Aspergillus Otitis media (middle ear infection) Bacterial causes: S. pneumoniae, a Gram + diplococcus; Haemophilus influenzae, a Gram - bacillus; and Moraxella catarrhalis, a Gram - diplococcus Viral causes: measles, parainfluenza, and respiratory syncytial (RSV) viruses (RSV) Bacterial Infections of the Eyes Bacterial conjunctivitis (pinkeye) Haemophilus influenzae biogroup aegyptius and S. pneumoniae are the most common causes Gonococcal Ophthalmia Neonatorum Chlamydial conjunctivitis (inclusion conjunctivitis, paratrachoma) Certain serotypes (serovars) of Chlamydia trachomatis Trachoma (chlamydia keratoconjunctivitis) Certain serotypes of Chlamydia trachomatis Gonococcal conjunctivitis (gonorrheal ophthalmia neonatorum) Neisseria gonorrhoeae; a Gram - diplococcus; also called gonococcus or GC Bacterial Infections of the Upper Respiratory Tract Diphtheria Corynebacterium diphtheriae; a pleomorophic, Gram + bacillus Transmission occurs via airborne droplets, direct contact, contaminated fomites, and raw milk. Streptococcal pharyngitis (strep throat) Streptococcus pyogenes; beta-hemolytic, catalase- negative, Gram + cocci in chains Transmission is human-to-human by direct contact, usually hands; also via aerosol droplets. Infections of the Lower Respiratory Tract Having Multiple Causes Pneumonia Gram-Positive Streptococcus pneumoniae in a Gram- Stained Smear of a Purulent Sputum. Note the May be caused by Gram + or Gram - diplococci bacteria, mycoplasmas, chlamydias, viruses, fungi, or protozoa Community-acquired bacterial pneumonia is most frequently caused by S. pneumoniae. S. pneumoniae is the most common cause of pneumonia in the world Transmission, in most cases, occurs via infected humans. Bacterial Infections of the Lower Respiratory Tract Legionellosis (Legionnaire disease, pontiac fever) Legionella pneumophila, a poorly staining, Gram - bacillus; transmission is via environmental water sources, ponds, air-conditioning systems, hot tubs, etc. Mycoplasmal pneumonia (primary atypical pneumonia) Mycoplasma pneumoniae, tiny, Gram - bacteria, lacking cell walls; transmission occurs via droplet inhalation, direct contact with an infected person, or contaminated articles. Bacterial Infections of the Lower Respiratory Tract (cont.) Tuberculosis (TB) Primarily Mycobacterium tuberculosis (a slow-growing, acid-fast, Gram-positive to Gram-variable bacillus), occasionally other Mycobacterium spp.; transmission occurs primarily via infected humans (airborne droplets). Whooping cough (pertussis) Bordetella pertussis, a small, encapsulated, nonmotile, Gram - coccobacillus that produces endotoxin and exotoxins; transmission occurs via infected humans (i.e., droplets by coughing). Bacterial Infections of the Oral Cavity Terms relating to infectious diseases of the oral cavity: dental caries, periodontal disease, gingivitis, periodontitis Acute Necrotizing Ulcerative Gingivitis (ANUG); also known as Vincent’s Angina and Trench Mouth A synergistic infection involving two or more species of anaerobic bacteria of the indigenous oral microbiota; most commonly, Fusobacterium nucleatum and Treponema vincentii Bacterial Infections of the GI Tract Bacterial gastritis and ulcers Helicobacter pylori, a curved, microaerophilic, capnophilic, Gram - bacillus Transmission occurs via infected humans; probably by ingestion; presumed to be either oral-oral or fecal-oral. Campylobacter enteritis Campylobacter jejuni (less common, C. coli), curved, S- shaped or spiral Gram - bacillus Transmission occurs via animals, including poultry, cattle, sheep, swine, rodents, birds, kittens, puppies, and other pets. Bacterial Infections of the GI Tract (cont.) Cholera Certain biotypes of Vibrio cholerae serogroup 01, curved, Gram - bacillus that secretes enterotoxin Transmission occurs via infected humans and aquatic reservoirs; fecal-oral route. Salmonellosis Salmonella spp.; members of the family Enterobacteriaceae, Gram - bacilli that invade intestinal cells, release endotoxin, and produce cytotoxins and enterotoxins Transmission occurs via domestic and wild animals; contaminated food, fecal-oral, food handlers, contaminated water Bacterial Infections of the GI Tract (cont.) Typhoid fever (enteric fever) Salmonella typhi, a Gram - bacillus that releases endotoxin and produce exotoxins Transmission occurs via infected humans for typhoid and paratyphoid; some people become carriers after infection (e.g., “Typhoid Mary”). Shigellosis (bacillary dysentery) Shigella dysenteriae, S. flexneri, S. boydii, and S. sonnei; nonmotile, Gram - bacilli, members of the family Enterobacteriaceae Transmission occurs via infected humans. Enterovirulent Escherichia coli Enterohemorrhagic E. coli (EHEC) Diarrhea Escherichia coli O157:H7 is most commonly involved; others include O26:H11, O111:H8, and O104:H21; Gram - bacillus that produces potent cytotoxins. Transmission occurs via cattle feces; also infected humans, fecal-oral route. Enterotoxigenic E. coli (ETEC) diarrhea (traveler’s diarrhea) Many different serotypes of enterotoxigenic E. coli Transmission is via infected humans, fecal–oral route Urinary Tract Infections (UTIs) Many Gram-Negative Bacilli (arrows) and Many Pink-Staining PMNs Can be Seen in This Gram- The most common causes of UTIs are E. coli Stained Urine Sediment From a Patient With and other members of the family Cystitis Enterobacteriaceae (especially Proteus and Klebsiella). Other common causes of UTIs are Enterococcus spp., Staphylococcus spp. (especially S. aureus, S. epidermidis, and S. saprophyticus), and Pseudomonas aeruginosa. UTIs may be acquired either within a healthcare setting (called healthcare- associated UTIs) or elsewhere (called community-acquired UTIs). UTIs are the most common type of healthcare-associated infection. Urinary Tract Infections (UTIs) Gram-Stained Urethral Exudate from a Male Patient with Gonorrhea Genital chlamydial infections (genital chlamydiasis) Certain serotypes of Chlamydia trachomatis; obligate intracellular Gram - bacteria Transmission via infected humans, direct sexual contact, or mother-to-neonate during birth Gonorrhea Neisseria gonorrhoeae; a Gram - diplococcus Transmission via infected humans, usually sexual contact or direct mucous membrane-to-mucous membrane contact Urinary Tract Infections (UTIs) (cont.) Syphilis Treponema pallidum; Gram-variable, tightly- coiled spirochete; too thin to be seen by brightfield microscopy; can be seen by darkfield microscopy Transmission via infected humans, by direct contact with lesions, body secretions, mucous membranes, blood, semen, etc.; usually sexual contact; also blood transfusions and transplacentally from mother to fetus Other Bacterial STDs Bacterial STDs that occur more frequently in parts of the world other than the United States: Chancroid—caused by Haemophilus ducreyi; a Gram - bacterium Granuloma inguinale—caused by Calymmatobacterium granulomatis; a Gram - bacterium Lymphogranuloma venereum—caused by certain serotypes of Chlamydia trachomatis STDs may be transmitted simultaneously; if a patient is diagnosed with one particular type of STD, other types should be sought. Rickettsial and Ehrlichial Diseases of the Cardiovascular System Spotted fever rickettsiosis (tickborne typhus fever) Rash of Spotted Fever Rickettsia rickettsii; a Gram - bacterium; an Rickettsiosis obligate intracellular pathogen Transmission occurs via infected ticks on dogs, rodents, and other animals Endemic typhus fever (murine typus fever, fleaborne typhus) Rickettsia typhi; a Gram - bacterium; an obligate intracellular pathogen Transmission occurs via rats, mice, possibly other mammals, infected rat fleas. Rickettsial and Ehrlichial Diseases of the Cardiovascular System, cont. Epidemic typhus fever (louseborne typhus) Rickettsia prowazekii; a Gram - bacterium; an obligate intracellular pathogen Reservoirs are infected humans and body lice. Erlichiosis Gram-negative coccobacilli, closely related to rickettsias; obligate intraleukocytic pathogens Reservoir unknown; transmission is via tick bite Other Bacterial Infections of the Cardiovascular System Lyme disease (Lyme borreliosis) Borrelia burgdorferi; a Gram -, loosely coiled Lesion of Tularemia spirochete Transmission is via tick bite. Plague (“black death,” bubonic plague, pneumonic plague, septicemic plague) Yersinia pestis; a nonmotile, bipolar-staining, Gram coccobacillus Transmission is via wild rodents and their fleas (flea bite). Tularemia (Rabbit Fever) Francisella tularensis; a pleomophic, Gram - coccobacillus Transmission is via tick bite; associated with rabbits. Bull’s Eye Rash of Lyme Disease Yersinia pestis (arrows) Bacterial Infections of the CNS Listeriosis Listeria monocytogenes; a Gram + coccobacillus Transmission occurs via ingestion of raw or contaminated milk, soft cheeses, and vegetables. Tetanus (lockjaw) Clostridium tetani; a motile, Gram + anaerobic, spore-forming bacillus Transmission occurs via spores of C. tetani entering a puncture wound, burn, or needlestick by contamination with soil, dust, or feces. Human Diseases Commonly Caused by Anaerobes Major Groups of Medically Important Bacteria