Board Review: Board Review Paul O’Keefe April 16, 2003


Skin/Soft Tissue Infections: Skin/Soft Tissue Infections Impetigo Cellulitis Fasciitis


Impetigo: Impetigo Group A streptococcus, Staphylococcus arueus Superficial blistershoney colored crusts on erythematous base No systemic signs Mainly in children May be associated with glomerulonephritis Treat with penicillin/antistaphylococcal penicillin


Cellulitis: Cellulitis Deeper infection usually involving skin and subcutaneous tissue Erythema, pain and swelling often with distinct border (erysipelas) Fever and lymphangitis or adenitis common Gp A streptococcus, Staphylococcus aureus most common Treat with antistaphylococcal penicillin unless culture positive


Necrotizing Fasciitis: Necrotizing Fasciitis Streptococcal gangrene (Gp A strept) Deeper infection involving fascia and often muscle Extreme toxicity and rapid spread (“flesh-eating virus”) May have associated toxic shock Treatment – surgical removal of necrotic tissue and antibiotics Penicillin and clinidamycin


A three year old boy presents with an itchy rash that is spreading. Afebrile with numerous cursted lesions in erythematous base involving left shoulder and upper chest and back with few lesions in the right thigh. Culture growing gram positive coccus, beta hemolytic on SBA, catalase negative, inhibited by bacitracin disc. The isolated agent is: Staphylococcus aureus Coagulase negative staphylococcus Streptococcus pyogenes Sterptococcus pneumoniae Enterococcus faecalis A three year old boy presents with an itchy rash that is spreading. Afebrile with numerous cursted lesions in erythematous base involving left shoulder and upper chest and back with few lesions in the right thigh. Culture growing gram positive coccus, beta hemolytic on SBA, catalase negative, inhibited by bacitracin disc. The isolated agent is


Slide7: A 13 year old develops high fever and a severely painful red rash on the right arm beginning at the site of a minor laceration. He has high fever, hypo- tension and extreme toxicity. The arm is red, very swollen, firm and there are areas of black discolor- ation of the skin. The remainder of the skin has a red sunburned appearance. The extreme toxicity is thought to be caused by Streptolysin O Hyaluronidase M Protein Pyrogenic exotoxin Peptidoglycan


Upper Respiratory Tract Infection: Upper Respiratory Tract Infection Pharyngitis Sinusitis Otitis media


Pharyngitis: Pharyngitis Viral Group A streptococcus (S. pyogenes) Corynebacterium diphtheriae Infectious mononucleosis


Characteristics of Pharyngitis: Characteristics of Pharyngitis


Pharyngitis and Fatigue: Pharyngitis and Fatigue Atypical lymphocytosis Positive culture for Group A streptococcus Neutrophilia with left shift Low serum globulin Hematuria A 15 year old presents with fever, sore throat and extreme fatigue. Temperature is 103.2 and there is a yellowish exudate covering both enlarged tonsils. Submandibular, anterior cer- vical, and posterior cervical lymph nodes are enlarged on both sides. Which of the following is most characteristic of infectious mononucleosis?


Sinusitis: Sinusitis Requires neither X nor V factor for growth Requires X factor but not V factor Requires V factor but not X factor Requires both X and V factors Exuberant growth on sheep blood agar A 15 yo woman presents with fever, facial pain and severe nasal congestion. She has been suffering with hay fever. CT showed opacification of the R maxillary sinus and an air- fluid level in the left. Gram stain of material obtained by antral puncture disclosed gram negative coccobacilli. Which of the following characterizes the organism most likely respon- sible for the infection?


Otitis Media: Otitis Media Gp A streptococcus and Gp B streptococcus Neisseria meningitidis and Streptococcus pneumoniae Streptococcus pneumoniae and Haemophilus influenzae Haemophilus parainfluenzae and Gp A streptococcus Staphylococcus aureus and Gp A streptococcus A 9 month old child with fever and congestion is diagnosed with right otitis media. Common causes of this infection are?


Community Acquired Pneumonia: Community Acquired Pneumonia Streptococcus pneumoniae Mycoplasma pneumoniae Legionella pneumophila Haemophilus influenzae Chlamydia pneumoniae Tuberculosis


Community acquired pneumonia: Community acquired pneumonia A 33 year old male presents with fever and cough 3 weeks after his 7 year old son was treated for pneumonia. X-ray shows a patchy bronchopneumonia involving the right middle and lower lung field. Cold agglutinin test is positive What is the likely cause?


Features of Community Acquired pneumonia: Features of Community Acquired pneumonia


Communinty Acquired Pneumonia: Communinty Acquired Pneumonia A 26 year old woman complained of fever, night sweats and cough for 2 months. She had occasional hemoptysis and 15 pound weight loss. Chest x-ray showed fibronodular infiltrates with a cavity in the posterior segment of the right upper lobe. Please answer the following: What type of isolation would you order? What diagnostic tests would you order? Sputum smear returned positive for AFB. What treatment would you order? Why are multiple drugs necessary for treatment of tuberculosis?


Food Poisoning: Food Poisoning


Infectious Diarrhea: Infectious Diarrhea


Cause of diarrhea 4 hours after eating fried rice: Cause of diarrhea 4 hours after eating fried rice B. cereus S. aureus Salmonella Shigella C. jejuni Yersinia enterocolitica Vibrio parahemolyticus


Contaminated poultry is the most likely source of: Contaminated poultry is the most likely source of Salmonella Vibrio cholerae Shigella dysenteriae Campylobacter jejuni S. aureus


An important virulence factor of the organism found on biopsy of the stomach in patients with chornic epigastric pain is: An important virulence factor of the organism found on biopsy of the stomach in patients with chornic epigastric pain is Enterotoxin Polysaccharide capsule Endotoxin Urease Beta-lactamase


Urinary Tract Infection: Urinary Tract Infection Penicillin V Erythromycin Trimethoprim/sulfamethosoxazole Gentamicin Clindamycin A 23 year old woman presents with acute dysuria one day after intercourse. Urinalysis discloses 15-20 WBC’s /HPF. Gram stain discloses gram negative rods. What is the recommended treatment?


Which of the following strongly favors the diagnosis of pyelonephritis?: Which of the following strongly favors the diagnosis of pyelonephritis? Burning on urination Hematuria Suprapubic tenderness Fever WBC casts on urinalysis


Causes of Meningitis by Age: Causes of Meningitis by Age


Meningitis: Beta hemolytic on sheep’s blood agar Inhibited by bacitracin dise Inhibited by optichin disc Beta-lactamase positive Growth on MacConkey agar Meningitis A 6 year old boy presents with fever and lethargy. He has nuchal rigidity on examination. Lumbar puncture discloses many PMN’s and Gram positive cocci in pairs. Which of the following characterizes this organism?


Vaccines are available to prevent meningitis caused by which organisms ?: Vaccines are available to prevent meningitis caused by which organisms ? E. coli and Streptococcus pneumoniae Haemophilus influenzae and Listeria monocytogenes Group B streptococcus and E. coli Neisseria meningitidis and Haemophilus influenzae Streptococcus pneumoniae and Group B streptococcus


Bone and Joint Infections: Bone and Joint Infections Comma-shaped with single polar flagellum Motile and oxidase positive Nonmotile facultative anaerobe Motile and does not ferment lactose Coccobacilli that require X and V factors A 22 year-old woman with sickle cell disease presents with fever and pain in the left upper arm. X-ray of the humerus shows a lytic lesion. Biopsy is growing gram negative Bacilli. Which of the following best describes the organism?


Sexually Transmitted Diseases: Sexually Transmitted Diseases Gram positive coccus, catalase positive Gram positive coccus, catalase negarive, beta-hemolytic Has infectious elementary body and intracellular reticulate body Gram negarive coccus, oxidase positive Gram negarive rod, ixidase negarive lactose fermenting A 16 year old man presents with burning on urination and a scant urethral discharge 3 days after intercourse with a new partner. Gram stain of discharge discloses many PMN’s but no bacteria. The organism most likely responsible for the infection is


Arthritis: Arthritis Catalase positive, gram positive coccus Gram negative coccus that ferments glucose but not maltose Gram negative coccus that ferments glucose and maltose Gram negative coccus that requries X and V factors for growth Gram negative bacillus that ferments lactose A 29 yo female presents with fever, rash and arthritis 5 days after onset of menses. She has a new sex partner. Exam discloses about 25 papular lesions on distal extremities and inflamed tendon sheaths of the wrists and ankles with painful motion but no fluid in the joints. Cultures of blood and endocervix are growing


Neisseria gonorrhoeae undergoes antigenic variation by altering: Neisseria gonorrhoeae undergoes antigenic variation by altering Antigenic structure of pilus or expression of outer membrane protein II Antigenic structure of OMP II or expression of OMP I Expression of polysaccharide capsule Antigenic structure of pilus and expression of OMP I Expression of cytochrome c (Oxidase)


Lesion: Lesion Gram negative coccobacilli Gram positive cocci in clusters Gram negative diplococci Gram negative bacilli Motile corkscrew-shaped organisms on darkfield microscopy A 32 yo homosexual man presents with a painless lesion on the penis of one week’s duration. It developed 3 weeks after unprotected sex with an anonymous partner. The cause of the infection is identified from a specimen obtained from the lesion which shows.


Response to Treatment: Response to Treatment Progressive rise in RPR and reversion of FTA Abs to negative No fall in RPR and reversion of FTA to negative Progressive fall in RPR and reversion of FTA to negative Progressive fall in RPR while FTA remains positive No change in RPR while FTA remains positive A 20 yo asymptomatic woman in the 6th week of pregnancy has a positive RPR of 1:16. FTA Abs is positive. She is treated with 3 doses of benzathine penicillin. Follow up testing after treatment should demonstrate


Discharge: Discharge Doxycycline for 5 days Metronidazole – single dose Ciprofloxacin – single dose Ceftriaxone intramuscular – one dose Benzathine penicillin G IM – one dose A 33 yo sexually active woman complains of vaginal discharge. Examination of the greenish frothy discharge discloses pH of 5.5 with numerous WBC’s and organisms with a jerking motion on saline wet mount. Treatment is best accomplished with


Fever and Abdominal Pain: Fever and Abdominal Pain Neisseria gonorrhoeae Treponema pallidum Chlamydia trachomatis E. coli, Prevotella bivia, enterococcus Herpes simplex An 18 yo woman presents with fever and lower abdominal pain. She has recently had intercourse with a new partner. Pelvic examination discloses vaginal discharge, pain on motion of the cervix and bilateral adnexal fullness. Causes of these symptoms include?


Vaginitis: Vaginitis Metronidazole for 5 days Ciprofloxacin – one dose Doxycycline for 5 days Topical acetic acid Topical miconazole A 35 year old woman complains of scant vaginal discharge and itching. Exam discloses erythema of the vaginal mucosa with patches of white discharge. The pH is 4.3. What is appropriate treatment for this condition?


Zoonoses: Zoonoses


Plague – Yersinia pestis: Plague – Yersinia pestis Highly virulent, encapsulated, small gram negative rod Endemic in wild rodents Europe and Western N. America Transmitted by flea Virulence: endotoxin, exotoxin, proteins Spreads to nodes – Buboes, severe sepsis Pneumonic plague – droplet spread Diagnosis – aspirate bubo, blood (careful in lab) Treatment – Gentamicin, Streptomycin, tetracycline


Pastuerella multocida: Pastuerella multocida Short, gram-negative rod Cellulitis or osteomyelitis following cat bite or dog bite Treatment penicillin


Anthrax – Bacillus anthracis: Anthrax – Bacillus anthracis Gram positive, spore-forming rod with capsule “Box cars”. Spores in soil, on animal productrs Enter through skin, alimentary, respiratory tracts Toxin: Protective antigen, edema factor (cyclase), lethal factor Painless ulcer with marked local edema Pneumonia (mediastinitis) meningitis Necrotizing enteritismeningitis Diagnosis-culture Treatment: ciprofloxacin+clindamycin+rifampin, penicillin if susceptible


Gram Stain - CSF: Gram Stain - CSF


Tularemia: Tularemia Francisella tularensis – small gram negative rod, enzootic in wild animals (rabbit) Transmission – ticks or contact with dead animal Clinical Ulceroglandular – ulcer with swollen regional lymph nodes Typhoidal – fever, adenopathy Pulmonary Diagnosis – Culture dangerous in lab; serology and direct fluorescence Treatment – Gentamicin or tobramycin


Brucellosis: Brucellosis Small, slow growing gram negative rod B. melitensis (goats, sheep), B. abortus (cattle), B. suis (swine) Transmission – Occupation, milk Small granulomas in lymph nodes, spleen, marrow Fever, weakness, fatigue Diagnosis – cluture blood and tissue, serology Treatment – tetracycline, gentamicin


Rocky Mountain Spotted Fever: Rocky Mountain Spotted Fever Tick borne rash illness caused by Rickettsia rickettsii, a small gram negative rod. Obligate intracellular parasite. Eastern and Midwestern US Vasculitis – organism in endothelium Fever, headache, weakness followed by rash, DiC and shock Diagnosis: Clinical, serology, ElISA, Weil Felix (Culture dangerous) Treatment – Doxycycline


Q Fever: Q Fever Coxiella burnetti Transmission – contact with infectious aerosol from cattle, sheep, goats. Parturient cats Fever, headache, cough; frequent hepatitis, endocarditis Diagnosis – serology Treatment – Doxycycline


Lyme Disease: Lyme Disease Borrelia burgdorferi – spirochete transmitted by Ixodes ticks Reservoir – field mice and deer Erythema migrans, meningitis, encephalitis Heart disease, arthritis Diagnosis – Serology ELISA and Western blot Treatment – Doxycycline, amoxicillin, ceftriaxone


Fungi: Fungi


Histoplasmosis: Histoplasmosis Dimorphic fungus – mold in soil, yeast in tissue Ohio and Mississippi river valleys, disturbed soil with bird droppings, bat caves Small oval yeast in macrophages Clinical Pulmonary – acute pneumonia, chronic like tuberculosis Disseminated in immunocompromised – esp AIDS Diagnosis – Culture, Serology, Antigen in urine Treatment – Self limited, Itraconazole, Amphotericin b


Blastomycosis: Blastomycosis Dimorphic fungus – large refractile yeast with broad based budding Ohio, Mississippi, St. Lawrence river valleys, Great Lakes. Soil with decaying organic material Clinical Pulmonary, pneumonia (refractory) Dissemination to skin common Diagnosis – culture, histology Treatment – Itraconazole, Amphotericin b


Coccidioidomycosis: Coccidioidomycosis Dimorphic fungus – mold in soil, spherule in tissue Southwestern US (CA, AZ, NM, TX), Mexico. Arthrospores carried by wind Clinical Valley fever – flu, pneumonitis, erythema nodosum Chronic pulmonary – thin-walled cavity, nodule Disseminated – Filipinos, African Americans, Immunosuppressed, pregnant Skin, bone, joint. CNS common – chronic meningitis Diagnosis – Sperules in tissue, culture (DANGER), serology Treatment – Amphotericin b, fluconazole, itraconazole


Candida: Candida Oval yeast with single bud. ‘Pseudohyphae’ in tissue. Many species. Germ tube distinguish C. albicans from others Impaired defenses: Mucosal disease – mouth, esophagus, vagina, skin (warm, moist areas) Greater immune compromise – dissemination to many organs Diagnosis – seen on KOH, Culture Treatment Topical – nystatin, azoles Systemic – fluconazole, amphotericin b, caspofungin


Cryptococcus neoformans: Cryptococcus neoformans Oval, budding yeast with polysaccharide capsule Ubiquitous in soil containing bird droppings. Inhaled Compromised: AIDS, diabetes, malignancy, transplant Lung infection Aymptomatic nodule Pneumonia Meningitis common Diagnosis – India ink on CSF, Culture, antigen in CSF and serum (follow titer during treatment) Treatment – Amphotericin b + flucytosine, Fluconazole


Aspergillus: Aspergillus Mold (no yeast form), ubiquitous, several species (A. fumigatus most common), Airborne conidia Manifestations Hypersensitivity – sinusitis, asthma-like illness (ABPA) Mycetoma – fungus ball in pre-existing lung cavity Invasive – Severely immunocompromised. sinus and lung Causes thrombosis and infarction Disseminated especially to CNS Diagnosis – culture and histology Treatment – Amphotericin b, Voriconazole, itraconazole


Zygomycosis: Zygomycosis Mucor, Rhizopus, Absidia – saprophytic molds Invade blood vessels in paranasal sinuses or lung Progressive destruction across tissue planes Diagnosis – culture, histology Treatment Surgical debridement Amphotericin b, newer azoles


Fever in Returning Traveler: Fever in Returning Traveler Malaria if exposed Africa – falciparum India – vivix Blood smear Chloroquine plus primaquine, Quinine plus doxycycline Typhoid fever. Fever, rash, splenomegaly Dengue – fever and headache


Scenarios: Scenarios Returned from Philippines and passed a worm? Young Mexican immigrant with headache and new seizure. CT Cysts in brain Sepsis and severe diarrhea in WWII veteran who has just finished chemotherapy for NHL. Eosinophilia and microscopic worm in sputum