Bacterial Diseases Study Guide PDF

- Routes of infection - Contact - Direct- person to person - Indirect- Person to thing to person - Vector: - Mechanical and biologics; - Vehicle - Food, water, air - Types of pathogens - Viruses, bacteria, fungi, protozoa...

- Routes of infection - Contact - Direct- person to person - Indirect- Person to thing to person - Vector: - Mechanical and biologics; - Vehicle - Food, water, air - Types of pathogens - Viruses, bacteria, fungi, protozoa - Gram staining - Positive is purple, negative is pink - Strep- gram positive chains - Staph- gram positive clusters - Reportable diseases - Must be reported to CDC, collects and reports info weekly - Sepsis - Life-threatening organ dysfunction caused by dysregulated host response to infection - Most common type- vasodilatory shock - Septic shock: - Fluid-unresponsive hypotension (below 100 mmHg) - Serum lactate over 2mmol/L - Need for vasopressors to keep MAP above 65 - Serology - Medical science dealing w/blood serum especially in regard to its immunological rxns and properties - Testing of blood serum to detect presence of antibodies against a specific antigen - Sepsis/shock - Etiology: generally due to gram positive or negative bacteria - Can be viruses and fungi - Risk factors: chronic conditions, weak immune systems, sepsis survivors, adults 65+, children younger than 1-year, recent severe illness or hospitalization - Criteria: - Sequential organ failure assessment- poor sensitivity should not be used a single tool - Systemic inflammatory response syndrome - Temp over 100.4, RR over 20, PCO2 below 32, HR over 90, WBC over 12000 - Sepsis: SIRS + Microbial source - Severe sepsis: Sepsis with \> 1 organ system dysfunction - Septic shock: severe sepsis w/hypotension unresponsiveness to fluid resuscitation - Mods: \>1 organ system requiring interventional homeostasis - Workup - CBC- elevated or decreased WBC, increased bands, thrombocytopenia - CMP- electrolytes, glucose, BUN and creatinine may be high - ABP - Coagulation parameters- may be abnormal or disseminated vascular coagulation - Lactate- repeat in 2 hours or after fluids if high - 2 sets of blood cultures prior to antibiotics if possible - Except for pediatrics- 1 set is generally considered adequate - UA with culture - CXR, EKG - Type and cross may be appropriate - Treatment - Advanced cardiac life support first necessary: circulation, airway, breathing - Two large bore Iv's - Consider central line, broad spectrum antibiotics within 1 hour - Volume replacement- 30 mL/kg either normal saline or lactated ringers - 2L bolus is generally appropriate - Pt who are already fluid overloaded (CHF, kidney, liver) go gentle on fluids - Remove source of infection if possible - Vasopressors- norepinephrine, phenylephrine, epinephrine, dopamine, vasopressin, angiotensin II - Central line preferred - Dopamine not recommended unless pt has significant bradycardia - Vasopressin and angiotensin II are adjunct therapies - Norepinephrine is the initial drug of choice to maintain BP in sepsis - 1-2 mcg/min IV infusion, tritiated to maintain MAP of 65 or higher - Max dose 30 mcg/min - Epinephrine is the drug of choice in anaphylactic shock - 1mcg/min IV infusion titrate to response 1-10 mcg/min typical - Prognosis - Monitor and treat evolving infections appropriately - Especially in high-risk populations - Atypical Mycobacterial disease - Nonmotile, nonspore forming, gram-positive, acid-fast bacteria - Mycobacterium avium- most frequent atypical - Disseminated MAC disease is common in HIV but is rare in immunocompetent pts - Atypical mycobacterial disease more common in cystic fibrosis patients - Symptoms - Common: chronic cough, sputum production, fatigue - Less common: malaise, dyspnea, fever, hemoptysis, weight loss - Diagnosis and treatment - Sputum culture - CXR w/progressive. Persistent infiltrates x2 months, cavitary lesions, and multiple nodular densities - Decision to treat depends on severity of disease in immunocompetent pts - HIV-seronegative pts- clarithromycin or azithromycin, rifampim or rifabutin, and ethambutol- x 12 months - Tuberculosis - Mycobacterium tuberculosis- gram positive, acid fast, nonmotile, nonspore forming - Airborne, droplet transmission - Higher in HIV populations, increase in incidence during COVID due to lack of diagnosis and treatment - Primary TB - Inhaled, bacteria evade alveolar macrophages infection results - Infection occurs, lymphatic and hematologic spread occurs - Healthy pts: T-cells and macrophages contain infection, but often do not eradicate it - Bacteria lies dormant in granulomas for years to decades - Latent TB - TB can be reactivated if the immune system is compromised - Occurs in 5-15% of latent TB pts - Results in active TB - Progressive primary TB - Immune system is unable to contain TB, and it spreads - Resulting in both pulmonary and systemic symptoms - Symptoms - Slowly progressive symptoms - Malaise, anorexia, weight loss, fever, and night sweats, chronic cough, often w/blood-streaked sputum - Lymphadenopathy (especially if extrapulmonary infection) - Physical exam - Productive cough with post-tussive rales in apices of lungs, sputum blood tinged - Previously called: consumption, wasting disease, white plague - Extrapulmonary TB - Can cause symptoms outside of lungs: meningitis, arthritis, lymphadenitis, uveitis, renal disease, liver abscesses, Spinal disease, pericarditis - Work up - Diagnosis based on recovery of M tuberculosis from by culture or RNA/DNA amplification - Positive finding of acid-fast bacteria is not diagnostic as other acid-fast bacteria can colonize respiratory tract - Positive Quant-TB is highly specific but cannot distinguish active and latent disease and should be used in conjunction w/CXR, risk assessment and other tests - Follow up a positive test w/susceptibility testing - Imaging does not reliably differentiate between primary and latent disease - Immunocompromised: more likely to have atypical imaging findings such as miliary TB - Testing for latent TB - Mantoux tuberculin skin test or TB skin test - Specificity is 59% for pts who have already been vaccinated with bacillus Calmette-Guerin - Qant gold- interferon gamma release assay (CD4+ T-cell release of interferon gamma in response to M tuberculosis) - Treatment - Report to local, state authorities - Treatment should be conducted by those w/clinical expertise - Minimizes pt risk off morbidity and mortality - Reduces transmission - Prevents emergence of drug-resistant strains (significant worldwide) - Principles of treatment - Administer multiple meds to which the bacteria is susceptible - Provide safest, most effective treatment for the shortest period - Ensure adherence to therapy - Regimens - 4 month- 8 wks rifapentine, moxifloxacin, isoniazid, pyrazinamide then 9 wks of rifapentine, moxifloxacin, and isoniazid - Management of TB in HIV is complex, Monthy follow up of outpatients is recommended - Prognosis - Main cause of treatment failure is noncompliance - Notifiable disease, reporting is mandated - Anthrax - Bacillus anthracis- gram positive spore forming rod - Produces toxin resulting in ulcer w/black eschar in cutaneous anthrax- least deadly - Treatment: PCN, azithromycin or fluroquinolone if allergy - Must be reported to CDC likely agent for bioterrorism - Botulism - Clostridium botulinum: spore forming, anerobic - Symptoms are due to toxin produced - Most commonly from eating contaminated food (home canned) - Patho - Botulism toxin irreversibly inhibits acetylcholine release - Diplopia, blurred vision - Symptoms - Descending flaccid paralysis progressing to respiratory failure and death without treatment - Work up - Send food for testing if possible - This is a reportable disease, CDC should be contacted - Treatment: Equine serum heptavalent botulism anti-toxin (potassium antagonists) - Clostridia tetani - Reportable disease, gram positive spore forming rod - Same genus as botulinum, C tetani is an obligate anaerobe, ubiquitous in soil - Caused by tetanospasmin, a neurotoxin which inhibits inhibitory neurons - Patients often have history of penetrating injury, does not have to be dirty or contaminated wound - Incubation period 5-15 wks averages 8-12 days - Symptoms and physical exam - Generally, in unvaccinated patients: pain or tingling at injury site, local spasticity, stiffness, dysphagia, irritability - Trismus, risus sardonicus (spasms of the facial muscles) - Opisthotonos (spasms back, abdomen, neck) - Painful convulsions w/minimal stimuli - Sensory exam is normal - Workup and treatment - Diagnosis is clinical - Treatment: 500 units human tetanus immune globin IM within 24 hours - Metronidazole 500 mg IV - Bed rest, avoid excess noise/light, sedate w/benzos- paralysis with curare like agents, mechanical ventilation as necessary - Tetanus does not produce natural immunity, and pts will require full immunization after recovery - Complications and prognosis - Airway obstruction, respiratory arrest, cardiac failure - Contaminated wounds on the face and head are more concerning than other areas of the body, mortality rates higher w/shorter incubation period - Active immunization booster every 10 years, women should receive a Tdap w/each pregnancy (27-30 wks) - DtaP for all children under 7 years, Tdap for adults, there is no longer necessary 2-year gap between dosing Td or Tdap - Acute infectious diarrhea - Under two weeks, inflammatory (bloody/purulent/fever), often caused by invasive, toxin-producing bacterium - Noninflammatory - Watery/non-bloody. Mild self-limited, often caused viral noninvasive toxin producing bacterium - Pursue evaluation only if severe or persisting beyond 1 wk - Causes - Rotavirus, norovirus, adenovirus, SARS-CoV-2, Enterotoxin E coli, staph aureus, Giardia, Vibrio cholera - Dysentery - Invasive bacteria - Shigella-shigellosis-report - Salmonella-salmonellosis- report - Campylobacter- report - Yersinia - Toxin production: clostridioides difficile - Diarrhea - Food poisoning- toxin in contaminated foods - Pregnant women- listeria - Day care- Giardia, Cryptosporidium - Camping or swimming in contaminated water- traveler\'s diarrhea - Recent antibiotics- C difficile - HIV-AIDS-associated diarrhea\\ - Patient evaluation - Distinguish mild vs severe illness - PE: evaluate hydration status, mental status, abdominal tenderness - Diagnostic evaluation includes stool studies - Clostridioides difficile if indicated due to recent antibiotic use or hospitalization - Concerning findings: Fever, WBC \>15000, bloody diarrhea, abdominal pain, more than 6 stools/24 hours, dehydration - Treatment - Rehydrate, avoid fatty food, fiber, milk, caffeine, alcohol, Antidiarrheals like loperamide are generally safe - Avoid anticholinergic meds as this can cause toxic megacolon - Antibiotics? Not recommended, unless pt is severeyly dehydrated or immunocompromised - Cipro 500 mg BID x1-3 days or azithromycin 1 gm once or 500 mg x 3 days - Do not give for shiga-toxin-producing E coli as this can cause hemolytic-uremic syndrome especially children - Recommended for: severe salmonella, shigella, cholera, listeria, C difficile - Campylobacter - Motile gram-neg rods - Dairy cattle and chicken both are reservoirs for campylobacter species - Contaminated food is a common cause of disease - Diagnosis: - Stool sample - Treatment: - Azithromycin 1 gm PO once or 500 mg POx3 days - Systemic infections may require IV antibiotics - This is a reportable illness - Campylobacter fetus - Gram negative rods - C fetus can cause systemic infection that can be fatal including sepsis, meningitis, endocarditis, abscesses - Older immunocompromised or medically fragile - Systemic infections require IV antibiotics- gentamycin, carbapenems, fluoroquinolones/cephalosporins in susceptible organisms - Cholera - Secretory diarrhea- driven by secretion of chloride ions - Reportable disease - Fecal-oral transmission - Symptoms - Voluminous secretory diarrhea, rice water stool, without blood, purulent discharge or odor - Dehydration kills - Risk factors: travel to endemic areas, overcrowding, inadequate sanitization - Diagnosis: - PCR- based stool testing - Treatment: - Fluid replacement PO in mild to moderate disease. Antibiotics and IV lactated ringers in severe disease - Prevention: - Oral cholera vaccines (expensive not widely available), clean water, waste disposal, hygiene - Closteridioides - Antibiotic associated diarrhea- most are not due to C difficile, but nearly all colitis is due to C difficile - Pathogenic C difficile produces toxins: enterotoxin and cytotoxin - Pts often have a history of antibiotic use within the last 8 wks or recent hospitalization - Symptoms: - Greenish, foul smelling, watery diarrhea, rarely bloody - PE: mild left lower abdominal tenderness can be present - Severe disease: WBC \>15000 or higher - Fulminant diseases: hypotension, shock, ileus, megacolon. Often abdominal pain, diarrhea, WBC 30000 - Diagnosis: - Stool testing: - Immunoassay for glutamate dehydrogenase - PCR for C difficile toxin gene - Treatment: - Initial: Fidaxomicin 200 mg PO BIDx10days or vancomycin 125 mg PO QIDx10days. 15-25% recurrence rate with fidaxomicin and vancomycin respectively - First recurrence: fidaxomicin as above or Vancomycin taper - Fulminant disease: Vancomycin 500 mg PO QID and metronidazole 500 mg IV TID. Vanco can be administered via rectal tube and enema in case of ileus - Consult surgery early in fulminant disease - Listeria - Motile, gram-positive rod, listeriosis - Transmission: contaminated food especially deli meats and unpasteurized dairy products (vaginal during birth) - Types of infection - In pregnancy- gastroenteritis - Reportable disease - Symptoms: - Fever, diarrhea, Nausea/vomiting, bloody/purulent diarrhea - Treatment - Ampicillin 8-12 g/day IV divided in 4-6 doses - Single gentamycin 5 mg/kg/day - PCN allergy: trimethoprim-sulfamethoxazole 10-20 mg/day (2-3 wks) - Travelers Diarrhea - Benign, self-limited- large differential - E coli, salmonella, shigella, campylobacter - Prevention: - Good hand hygiene, avoidance of fresh foods which cannot be pealed, drink only bottle or boiled water - Provide antibiotics to healthy pts in case of diarrhea (ciprofloxacin 750 mg once and azithromycin 1000mg PO once if bloody or persistent) - Salmonella - Transmission by ingestion of contaminated food and drink - Can cause enteric fever, gastroenteritis, bacteremia or localized infections - Typhoid fever - Typhi and paratyphoid - Cross the epithelial border invades the macrophages and replicate in the Peyer's patches, mesenteric lymph nodes, and spleen - May disseminate, incubation 6-30 days - Symptoms - Malaise, headache, cough, sore throat, often abdominal pain, constipation then pea soup diarrhea, vomiting - Improves over 7-10 days if no complications - Rose spots - Come up during second week of illness, individual spots principally on trunk 2-3 mm, fades w/pressure, disappears in 3-4 days - Work up - No leukocytosis, Leukopenia possible, transaminitis likely - Best diagnosed on blood culture-80% in first wk of illness - Stool cultures are often negative when the illness develops - Treatment - Ceftriaxone 2g IV for 10-14 days or azithromycin 1g PO once and then 500 mg PO daily for 5-7 days - Complications and prognosis - Appearance of leukocytosis and tachycardia indicates these complications - Intestinal hemorrhage, intestinal perforation - Prevention - Vaccination- oral and IM, not always effective, consider for household contacts travelers and during endemic outbreaks - Salmonella gastroenteritis - Fever, chills, nausea, vomiting, abdominal pain, diarrhea - Symptoms 4-7 dyas and generally, self-limited - Diagnosis: stool culture - Severe infections or immunocompromised individuals use Ciprofloxacin 500 mg PO BID or levofloxacin 500 mg daily for 3-14 days. 14 days if immunocompromised - Complications - Sepsis, localized infections: bone, joints, pleural, pericardium, lungs, and other sites - Shigella - S sonnei, S flexneri, S dysenteriar - Highly transmissible, low ineffective dose, fecal-oral- including oral and anal sex - Increasing antibiotic resistance - Symptoms - Often self-limited and mild, abrupt onset of diarrhea, lower abdominal cramping, and tenesmus - Stool often mixed with blood and mucus - Work Up and Complications - Diagnosis: stool culture, blood cultures rarely positive - Complications: proctitis, intestinal obstruction, and perforation of the colon - Treatment: - In severe or immunocompromised cases attempt to establish susceptibility - Use fluroquinolones- ciprofloxacin 750 mg PO or IV BID, Levofloxacin 500 mg PO daily 3-5 days - High rates of resistance among MSM - Viral causes of Diarrhea - Noninflammatory, rotavirus, norovirus, adenovirus, astrovirus, SARS-CoV-2