Infectious Agents and Associated Syndromes

Infectious Agents and Associated Syndromes

• Gram-Positive Cocci:
• Staphylococcus aureus: Skin infections (furuncles, abscesses), pneumonia, food poisoning, toxic shock syndrome, bacteremia.
• Staphylococcus epidermidis: Often associated with prosthetic device infections.
• Staphylococcus saprophyticus: Common cause of urinary tract infections (UTIs) in young women.
• Streptococcus (Lancefield groups A, B, C, D, G): Strep throat (Group A), neonatal sepsis (Group B), various skin and soft tissue infections.
• Streptococcus viridans: Endocarditis, dental infections.
• Streptococcus pneumoniae: Pneumonia, meningitis, otitis media.
• Enterococcus faecalis, faecium: UTIs, bacteremia, endocarditis, surgical site infections.
• Gram-Positive Bacilli:
• Listeria monocytogenes: Foodborne illness, can be severe in pregnant women, newborns, and immunocompromised individuals; meningitis.
• Gram-Negative Cocci:
• Neisseria meningitidis: Meningitis, meningococcal septicemia.
• Neisseria gonorrhoeae: Gonorrhea (genital infections).
• Haemophilus influenzae: Meningitis, pneumonia, epiglottitis.
• Gram-Negative Bacilli:
• Enterobacteriaceae (E. coli, Klebsiella, Enterobacter, Proteus, Salmonella): UTIs, gastroenteritis, septicemia; Salmonella typhi -> typhoid fever; Salmonella enteriditis -> gastroenteritis
• Pseudomonas aeruginosa: Opportunistic pathogen; pneumonia, UTIs, skin infections, burn wounds, bacteremia.
• Legionella pneumophila: Legionnaires' disease (pneumonia), Pontiac fever.
• Bacteroides spp.: Common in intra-abdominal infections.
• Miscellaneous Bacteria:
• Bartonella hensalae: Cat-scratch disease.
• Borrelia burgdorferi: Lyme disease.
• Chlamydophila pneumoniae: Pneumonia, other respiratory infections.
• Treponema pallidum: Syphilis.
• Rickettsia rickettsii: Rocky Mountain spotted fever.
• Mycobacteria:
• Mycobacterium tuberculosis: Tuberculosis.
• Fungi:
• Candida spp.: Opportunistic fungal infections, including candidiasis (yeast infections).
• Pneumocystis jiroveci: Pneumonia.
• Aspergillus spp.: Opportunistic infections in immunocompromised individuals; aspergillosis.
• Cryptococcus neoformans, Histoplasma capsulatum, Coccidioides immitis: Fungal infections, varying presentation depending on species.
• DNA Viruses:
• HSV1 & 2; CMV, VZV, EBV: Herpes simplex, Cytomegalovirus (CMV), Varicella-zoster (VZV), Epstein-Barr (EBV) infections (cold sores, chickenpox, mononucleosis)
• RNA Viruses:
• Influenza A: Respiratory illness.
• Paramyxovirus (measles, RSV): Measles, respiratory syncytial virus (RSV).
• Retrovirus (HIV-1): AIDS.
• Protozoa:
• Plasmodium falciparum: Malaria.
• Toxoplasma gondii: Toxoplasmosis.
• Helminths:
• Ascaris lumbricoides: Intestinal parasite.
• Strongyloides stercoralis: Intestinal parasite.

Antimicrobial Agents and Mechanisms

(Note: This section provides a brief overview. Full details are beyond the scope, but typical mechanisms are given.)

• Penicillins: Mechanism- Cell wall synthesis inhibition. Toxicity varies, allergic reactions are common.

• Cephalosporins: Mechanism- Cell wall synthesis inhibition, broader spectrum than penicillins. Toxicity- Allergic reactions less common than penicillins.

• Monobactams (Aztreonam): Mechanism- Cell wall synthesis inhibition, narrow spectrum. Toxicity- Mostly well tolerated.

• Carbapenems (Imipenem): Mechanism- Cell wall synthesis inhibition, broad spectrum. More toxic than penicillins, cephalosporins.

• Glycopeptides (Vancomycin, Linezolid, Daptomycin): Mechanism - Cell wall synthesis inhibition. Toxicity - Vancomycin- Red man syndrome (infusion reactions), ototoxicity possible.

• Macrolides (Clindamycin, Azithromycin): Mechanism - Protein synthesis inhibition. Toxicity - Clindamycin associated with colitis.

• Sulfonamides (Trimethoprim-Sulfamethoxizole): Mechanism - Folate synthesis inhibition. Toxicity- Various, including allergic reactions.

• Aminoglycosides (Gentamicin): Mechanism - Protein synthesis inhibition, broad spectrum. Toxicity- Nephrotoxicity and auditory toxicity are major concerns.

• Quinolones (Ciprofloxacin, Moxifloxacin, Levofloxacin): Mechanism- DNA gyrase inhibition. Toxicity- Tendon rupture, central nervous system disorders, arrhythmias.

• Tetracyclines (Doxycycline, Tigecycline): Mechanism- Protein synthesis inhibition. Toxicity- Teeth staining in children, photosensitivity, GI upset.

• Metronidazole: Mechanism- DNA damage. Toxicity- Nausea, vomiting, metallic taste.

• Anti-fungals: Mechanism various depending on agent and class. Toxicity varies considerably.

• Antivirals: Mechanism varies widely. Toxicities also vary considerably.

• Antiretrovirals:Mechanism- Various targets, mostly viral enzyme inhibition. Toxicities- vary substantially across classes and specific drugs.

• Anti-TB: Mechanism- Mycobacterial inhibition. Toxicity varies, some drugs nephrotoxic, hepatotoxic etc.

Other Topics

• Immune Defects and Infection Patterns* (This section presents general information, not specific details)

• Underlying conditions and diseases (e.g., diabetes, neutropenia, asplenia, AIDS) impairing the immune system increase susceptibility to infections. Mechanisms and specifics are extensively covered in immune system studies.

• Organ transplant recipients: Immunocompromised due to suppression therapy; increased risk of opportunistic infections.

• Newborns: Immature immune systems; Increased susceptibility to various pathogens.

• Microbiology and Empiric Therapy for Clinical Syndromes* (This section is too broad. Requires further elaboration)

• In summary, this is a vast area of study; microbiology and empiric therapy for each syndrome would need significant expansion for comprehensive description. Specific infectious agents, their virulence factors and the specific immune response are key components of each syndrome.