Bordetella, Francisella, and Brucella

BORDETELLA:

• Extremely small
  
• Strictly aerobic
  
• Nonfermentative
  
• Gram-negative coccobacilli
  
• Non-motile
  
• Doesn't ferement CH, oxidizes amino-acids
  
• Nicotinamide required for growth
  
• B. pertussis doesn't grow on common media
  
• 3 species:
  
  • B. pertussis: pertussis
    
  • B. parapaertussis: pertussis
    
  • B. bronchiseptica: beonchopulmonary disease
    

FRANCISELLA TULARENSIS:

• Causes Tularemia(glandular fever, rabbit fever, tick fever, and deer fly fever)
  
• Very small, gram-negative coccobacilli
  
• Nonmotile
  
• Fastidious growth requirements: cysteine
  
• Striclty aerobic
  
• Intracellular parasite
  
• Most common reservoir in the US: rabbits, ticks, and muskrats
  
• Most common in MO, AR, and OK
  
• Summer and winter time +++
  
• Different presentations:
  
  • Ulceroglandular
    
  • Oculoglandular
    
  • Glandular
    
  • Typhoidal
    
  • Oropharyngeal
    
  • Pneumonic
    
  • Gastrointestinal
    
• Trt: Streptomycin
  

BRUCELLA:

• 4 causes human Brucellosis: B. abortus, B. melitensis, B. suis, and B. canis
  
• Small, non-motile, nonencapsulated, gram-negative coccobacilli
  
• Strictly aerobic
  
• Grows slowly

Pseudomonas and Related Organisms

• Opportunistic pathogens of plants, animals, and humans
  
• Non-fermentative bacilli
  
• P. aeruginosa
  
• Burkholderia cepacia
  
• Stenotrophomonas maltophilia
  
• Acinetobacter baumannii
  
• Moraxella catarrhalis
  

Pseudomonas:

• Opportunistic pathogen:
  
  • Immunocompromised
    
  • COPD, cystic fibrosis, bronchiectasis
    
  • Burn wounds
    
  • Trauma to eye
    
  • Exposure to contaminated water
    
  • Diabetic, and elderly
    
  • IV drug users
    
• Clinical syndromes:
  
  • Pulmonary infections
    
  • Skin infections
    
  • UTI
    
  • Ear infections: swimmer's ear and malignant external otitis
    
  • Eye infections
    
  • Bacteremia and Endocarditis may cause: ecthyma gangrenosum
    

  BURKHOLDERIA:
  

  • B. cepacia and B. pseudomallei: +++
    
  • B. pickettii:+
    
  • B. gladioli and mallei: are not pathogens
    
  • Commonly associated with nosocomial infections
    

    B. Cepacia: like Pseudomonas but different trt
    

  • Causes:
    
    • Respiratory infections (cystic fibrosis, chronic granulomatous disease)
      
    • UTI
      
    • Catheter related-Septicemia
      
    • Other opportunistics
      
    • P. cepacia is most susceptible to TMP/SMX eventhough other antibiotics may show in vitro activities(poor vivo response)
      

    B. pseudomallei:
    

    • Causes melioidosis
      
    • Rare in the WEST
      

STENOTROPHOMONAS MALTOPHILA:

• S. maltophilia
  
• Opportunistic pathogen
  
• Resistant to most commonly used beta-lactam and aminoglycosides
  
• Patients receiving long term antibiotic therapy at high risk
  
• May cause: bacteremia, pneumonia, meningitis, wound infections, UTI.
  
• Most active agent: TMX/SMX
  
• Other abx: chloramphenicol and ceftazidime.
  

ACINETOBACTER:

• A. baumannii
  

Campylobacter and Helicobacter

Vibrio, Aeromonas, Plesimonas

• Major group of gram-negative, facultative anaerobic
  
• Fermentative bacilli
  
• Difference from Enterobacteriacae:
  
  • Positive oxidase
    
  • Polar flagella
    

  
  

Vibrio Species Associated with human diseases
SPECIES	SOURCE OF INFECTION	CLINICAL DISEASE
V. cholerae	Water, food	Gastroenterits
V. parahaemolyticus	Shellfish, seawater	Gastroenterits, wound infection, cellulitis
V. vulnificus	Shellfish, seawater	Bacteremia, wound infection, cellulitis
V. alginoliyticus	Seawater	Wound infection, external otitis
V. hollisae	Shellfish	Gastroenterits, wound infection, bacteremia
V.fluvialis	Seafood	Gastroenterits, wound infection, bacteremia
V. damsela	Seawater	Wound infection
others

• Vibrio choleae:
  
  • Rice-water-stools
    
• Vibrio parahaemolyticus:
  
  • Explosive diarrhea
    
  • Cellulitis after exposure to seawater
    
• Vibrio vulnificus:
  
  • Particularly virulent
    
  • Rapidly progressive wound infections(seawater contamination)
    
  • Septicemia(raw oysters)
    
  • Most severe in patients with hepatic disease, hematopoietic disease, or CKD, immunosuppressive drugs.
    

• AEROMONAS:
  
  • A. hydrophila, A. caviae, and A. veronii
    
  • Ubiquitous in fresh and brackish water
    
  • Infection by ingestion of water or food
    
  • Opportunistic systemic diseases in immunocompromised patients(liver disease, cancer)
    
  • Chronic diarrhea in healthy adults-when severe may resembles shigellosis(invasive)
    
  • Resistant to PCN, Cephalo, Erythromycins.
    
  • Effective rx: TMP/SMX, Gentamicin, and chloramphenicol
    
• PLESIOMONAS:
  
  • Gram-negative bacilli
    
  • Oxidase positive
    
  • Multiple polar flagella
    
  • Difference from Aeromonas by biochemical reactions
    
  • P. Shigelloides
    
  • Fresh water and estuarine waters
    
  • Infection by contact with fresh water, consumption of seafood, or exposure to amphibians and reptiles.
    
  • Causes gastroenteritis
    
  • RESISTANT to ampicillin, erythromycin, and many aminoglycosides.
    
  • Susceptible to cephalosporins, imipenem, TMP/SMX, fluoroquinolones

Enterobacteriaceae

Neisseria

Listeria, Erysipelothrix, and other gram-positive bacilli

• Aerobic
  
• Gram-positive bacilli
  
• Resembles Corynebacterium organisms
  
• Including:
  
  • Listeria
    
  • Erysipelothrix
    
  • Arcanobacterium
    
  • Gardnerella
    
• LISTERIA:
  
  • Capable of causing meningitis and bacteremia
    
  • Small coccobacilli may resemble:
    
    • Corynebacteria
      
    • Gram positive diplococci(e.g., Strep pneumoniae,, enterococcus)
      
  • Characteristic tumbling motion
    
  • Attack specific populations:
    
    • Neonates
      
    • Elderly
      
    • Pregnant women
      
    • Immunocompromised (cell-mediated)
      
• Erysipelothrix
  
  • E. rhusiopathiae
    
  • Ubiquitous
    
  • Eryssipeloid is an occupational disease: swine and fish workers
    
  • Absence of motility and catalase difference between Listeria
    
• Arcanobacterium
  
  • A. haemolyticus
    
  • Causes pharyngitis with or without scarlet-like fever
    
• Gardnerella
  
  • G. vaginalis
    
  • Part of the normal vaginal flora
    
  • The number of Gardnerella and other obligate anerobes (Bacteroides, Mobiluncus, and peptostreptococcus) significantly increases in bacterial vaginosis
    

Corynebacterium

Corynebacterium Species commonly associated with human disease
Organism	Diseases
C. diphteriae	Diphteria(respiratory, cutaneous)
C. jeikeium (Group JK)	Septicemia, soft tissue infections, other opportunistic infections
C. urealyticum	UTI, opp inf
C. minutissimum	Erythrasma, opp inf
C. Xerosis	Opp inf
C. pseudodiphtericum	Endocarditis, opp inf
C. Striatum	Opp inf

• Non-spore forming
  
• Gram positive bacilli
  
• Called also diphteorids
  

Similar bacterias:

Nocardia

Rhodococcus

Mycobacterium

Bacillus

• Endospore-forming bacteria classified in the family of Bacillaceae
  
• 2 clinically important genera:
  
  • Bacillus
    
  • Clostridium
    
• Aerobic
  
• Most are motile
  
• Catalase positive
  
• Saprophyte
  
• Found in soil worldwide
  

Bacilus Species
ORGANISM	DISEASE
B. anthracis	Anthrax (cutaneous, inhalation, GI)
B. Cereus	Gastroenteritis(emetic, diarrhea), ocular infections, catheter-related spesis, opp
B. circulans	Opportunistic infections
B. licheniformis	Opportunistic infections
B. subtilis	Opportunistic infections

Enterococcus and Other Gram positive Cocci

Classification of Streptococci

Lancfield Group	Representative	Hemolytic	Typical Infections
A	S. pyogenes	β	Pharyngitis, impetigo, cellulitis, scarlet fever
B	S. agalactiae	β	Neonatal sepsis and meningitis, puerperal infection, urinary tract infection, diabetic ulcer infection, endocarditis
C, G	S. dysgalactiae subsp. equisimilis	β	Cellulitis, bacteremia, endocarditis
D	Enterococci: E. faecalis; E. faecium	Usually nonhemolytic	Urinary tract infection, nosocomial bacteremia, endocarditis
	Nonenterococci: S. bovis	Usually nonhemolytic	Bacteremia, endocarditis
Variable or non goupable	Viridans streptococci: S. sanguis; S. mitis	α	Endocarditis, dental abscess, brain abscess
	Intermedius or milleri group: S. intermedius, S. anginosus, S. constellatus	Variable	Brain abscess, visceral abscess
	Anaerobic streptococci: Peptostreptococcus magnus	Usually nonhemolytic	Sinusitis, pneumonia, empyema, brain abscess, liver abscess

Staphylococcus and related organisms

• Catalase-positive genera:
  
  • Staphylococcus
    
  • Micrococcus
    
  • Stomatococcus
    
• Catalase-negative genera:
  
  • Streptococcus
    
  • Enterococcus
    
  • Others
    
• Staphylococcus:
  
  • Nonmotile
    
  • Facultatively anaerobic
    
  • Catalase positive
    
  • Grow in medium containing 10% sodium chloride
    
  • S. aureus colonies are golden, coagulase positive
    
  • Coagulase negative Staphylococcus:
    
    • Epidermidis
      
    • Saprophyticus
      
    • Haemolyticus
      
    • Lugdunensis
      
    • Schleiferi
      
  • Micrococcus almost invariably represents contamination with skin flora
    
  • Stomatococcus mucilaginosus may cause endocarditis, septicemia, and catether related infections
    
    • Mucoid capsule allows adherence to catheters, shunts, valaves, joints.
      

    Human Colonization and diseases
    

Species	Human Colonization	Human disease
Stapylococcus
S. aureus S.epidermidis S.saprophyticus	Common Common Common	Common Common Common
S.haemolyticus S.lugdunensis S.schleiferi	Common Common Common	Uncommon Uncommon Uncommon
S.saccharolyticus S.warneri S. hominis S.auricularis S. xylosus S.simulans S.capitis S.cohini	Common Common Common Common Common Common Common Common	Rare
Micrococcus	Human Colonization	Human disease
M. luteus M.varians	Common	Rare
M.agilis M.kristinae M.lylae M.roseus M.Sedentarius	Uncommon	Rare
Stomatococcus mucilaginosus	Common	Uncommon

Brainstorming infectious diagnosis

When brainstorming bacterial diagnosis think:

Bacteria:

1. Gram positive Cocci
   
2. Gram negative Cocci
   
3. Gram positive bacilli
   
4. Gram negative bacilli
   
5. Anaerobes
   
6. Fungi-like
   
7. Spirochetes
   
8. Atypicals
   
9. Mycobacteria
   
10. Zoonosis(ticks, mosqitos, birds, dogs, cats, meats…)
    
11. STD
    
12. Travel related
    

    Viruses
    

    Fungi:
    

    endemic v/s opportunistic
    

    Parasites

Gram-Negative Cocci and Bacilli

Aerobic Gram negative Cocci	Anaerobic Cocci
Neisseriaceae Neisseria species Moraxella Moraxella Branhamella	Megasphaera species Veillonella species
Aerobic Gram-negative Bacilli	Anerobic Gram-negative Bacilli
Enterobacteriaceae Citrobacter Enterobacter Escherichia Klebsiella Morganella Proteus Salmonella Shigella Serratia Yersinia Vibrionaceae Vibrio species Aeromonadaceae Aeromonas species Plesiomonadaceae Plesiomonas Campylobacteriaceae Campylobacter Arcobacter Pasteurellaceae Haemophilus Actinobacillus Pasteurella Legionellaceae Legionella Miscellaneous genera Acinetobacter Bartonella Bordetella Brucellae Burkholderia Calymmatobacterium Cardiobacterium Eikenella Francisella Helicobacter Kingella Pseudomonas Spirillium Streptpbacillus	Fusobacterium Bacteroides Bilophila Parphyromonas Prevotella

Gram Positive Bacilli

Aerobic Gram Positive bacilli	Anaerobic Gram negative bacilli
Corynebacteriaceae Corynebacterium species Listeria Bacillus Nocardiaceae Nocardia Rhodococcus Gordona Tsukamurella No cell-wall mycolic acids Actinomadura Dermatophilus Nocardiopsis Oerskovia Rothia Streptomyces Tropheryma Thermophilic actinomyc etes: Saccharomonospora Saccharopolyspora Thermoactinomyces Gardnerella Erysipelothrix Arcanobacterium	Clostridium Actinomyces Bifidobacterium Eubacterium Lactobacillus Mobiluncus Propionibacterium

Gram Positive Cocci

Aerobic	Anerobic
Catalase-positive Catalase-negative Staphylococcus     Micrococcus Stomatococcus Streptococcus Enterococcus   Aerococcus Leuconostoc Pediococcus Alloiococcus Gemella Globicatella Helococcus Tetragenococcus Vagococcus	Peptostreptococcus

New Fever in ICU

• Temperature >101 F warrants work-up, lower in immunocompromised
  
• Fever may not reflect an infectious cause all the time
  
• Infections may not cause fever or may even cause hypothermia
  
• Infections may manifest as hemodynamic instability, tachycadria, confusion, rigors, oliguria, leukoctosis
  
• Work-up:
  
  • Blood cultures
    
  • Consider specific cultures for fungal and mycobacteria
    
  • Obtain 3-4 cultures/24h
    
• Line Sepsis:
  
  • Recovery of certain microorganisms in multiple blood cultures, such as staphylococci, Corynebacterium jeikeium, Bacillus species, atypical mycobacteria, Candida, or Malassezia species, strongly suggest infection of an intravascular device.
    
• Pulmonary infections:
  
  • Difficult to diagnose
    
  • Chest x-ray: unilateral air bronchograms have been shown to have the best predictive value for pneumonia.
    
  • CT imaging is also valuable in immunocompromised patients
    
  • Bronchoscopy: especially useful for :Pneumocystis jiroveci, Aspergillus and other filamentous fungi, Nocardia, Legionella, cytomegalovirus (CMV), and Mycobacterium species
    
  • Virtually always pathogebs: Legionella, Chlamydia, M. tuberculosis, Rhodococcus equi, influenza virus, respiratory syncytial virus, parainfluenza virus, Strongyloides, Toxoplasma gondii, P. jiroveci, Histoplasma capsulatum, Coccidioides immitis, Blastomyces dermatitidis, and Cryptococcus neoformans.
    
  • Isolation of enterococci, viridans streptococci, coagulase-negative staphylococci, and Candida species should rarely if ever be considered the cause of respiratory dysfunction
    
• Gastrointestinal infections:
  
  • C difficile infections
    
  • Sending stools for bacterial cultures or ova and parasite examination should generally be avoided as part of a fever evaluation unless the patient was admitted to the hospital with diarrhea, is infected with HIV, or is a part of an outbreak evaluation.
    
  • Consider CMV in solid organ transplant
    
  • Consider Acute neutropenic enterocolitis or typhlitis caused by enteric Gram-negative bacilli (i.e., Pseudomonas species) or anaerobes (i.e., Clostridium septicum) should be sought in cancer or stem cell transplant
    
• Urinary Tract infection:
  
• Sinusitis
  
• Post-operative Fever
  
• Surgical Site Infections
  
• Central nervous system infections
  
• Non-infectious causes of fever:
  
  • Acalculous cholecystitis
    
  • Acute myocardial infarction
    
  • Adrenal insufficiency
    
  • Blood product transfusion
    
  • Cytokine-related fever
    
  • Dressler syndrome (pericardial injury syndrome)
    
  • Drug fever
    
  • Fat emboli
    
  • Fibroproliferative phase of acute respiratory
    
  • Gout
    
  • Heterotopic ossification
    
  • Immune reconstitution inflammatory syndrome
    
  • Intracranial bleed
    
  • Jarisch-Herxheimer reaction
    
  • Pancreatitis
    
  • Pulmonary infarction
    
  • Pneumonitis without infection
    
  • Stroke
    
  • Thyroid storm
    
  • Transplant rejection
    
  • Tumor lysis syndrome
    
  • Venous thrombosis

Original article from IDSA guidelines

Acinetobacter baumannii Infections

• Ubiquitous pathogen
  
• Causes bacteremia, endocarditis, pneumonias, wound infection, urine tract infections and meningitis
  
• Aerobic gram negative bacilli, oxidase negative, catalse positive
  
• MDR resistant A. baumanii is defined as resistance to carbapenem or to 3 different class of antibiotics.
  
• Therapeutic options:
  
  • Sulbactam
    
  • Carbapenem: still drug of choices
    
  • Colistin
    
  • Tigecycline
    
  • Intra-thecal Amikacin for meningitis
    
  • Consider aersolozied colistin for VAP
    
  • Consider combination with Rifampin
    

Fever and Jaundice case

79 year old male who lives in Wisconsin presents for 4 days of fever and jaundice, end up having babesiosis.

Differential Diagnosis of febrile jaundice:

1-Jaundice from Hemolytic anemia:

• Malaria
  
• Babesiosis
  
• Any other infection with drug related hemolysis
  

2-Jaundice from liver disease:

• Acute hepatitis
  
• Ascending Cholangitis
  
• Pancreatic Cancer: paraneoplastic fever and obstructive jaundice
  
• Any infection with prior liver disease: Such as SBP, sepsis, Pneumonia, UTI in an alcoholic cirrhotic patient
  
• With renal failure: Consider Leptospirosis
  

The diagnostic clues during the interview should search for camping, outdoor activities, travel history, alcohol abuse, type of work, medications, known history of gallstones. Ask about urine color and stool color!

The laboratory and imaging will help also such as liver ultrasound, Bilirubin D and indirect, retic count, liver function tests, peripheral blood smear(re:schistocytes).

INR to differentitate between DIC and microangiopathic hemolytic anemia such as in TTP/HUS.

• Babesiosis is transmitted by tick (Ixodes scapularis) and caused by intraerythrocytic protozoa(babesia)
  Babesiosis cases are severe in elderly, splenectomized and immunosuppressed patients.
  Jaundice is not common 
  Prognostic factors: LDH>125, male gender, WBC>5,000
  Diagnosis via Giemsa-stain thin blood smear, indirect immunofluorescence, and serology Ig>64, PCR
  Treatment is not always indicated.
  Concomitant Lyme disease (B burgdorferi )and Human granulocytotropic anaplasmosis (Anaplasma phagocytophilum)is possible because of common vector
  
  

Treatment Protocols:
depends on the species, severity and duration depends on severity, progression, and may need to be repeated.

For B. Microti

• Mild: Atovaquone (750 mg po q12h) and Azithromycin (500-100 mg pox1 then 250 mg po qd)
  
• Severe:Clindaymycin (600 mg q6h) plus quinine (650 mg q 6-8h) – consider exchange transfusion when parasitemia>10%, significant hemolysis, renal, hepatic or pulmonary compromise
  

For B. divergens: frequently severe and rapidly progressive in asplenic patients, more frequently noted in Europe.

• Exchange trasnfusion
  plus
  
• Clindamycin plus quinine
  

Ref: You may refer to the original article in Mayo Clinic Proceedings.

Eryspeloid

Erysipeloid, caused by the bacterium Erysipelothrix rhusiopathiae, is transmissible to humans via contact with domestic or wild fowl. Infection in pet birds can cause sepsis but is rarely seen in veterinary practice.

Human infection typically affects broken skin, causing a dramatic, localized skin infection that is painful and pruritic; at first it is livid-red, then blue-red. The infection can spread to nearby joints. Septicemia and endocarditis in humans are rare complications

Pasteurellosis

Pasteurellosis is caused by Pasteurella multocida, an inhabitant of the healthy nasopharynx of some birds and also the causative agent of avian cholera.

Pasteurella organisms are transmissible to humans via bites or scratches from pet birds.

Infected wounds in humans are usually red and painful, but the physical findings may lead one to underestimate the severity of infection.

Transmission via respiratory droplets is rare but may cause acute or subacute bronchitis, pneumonia, or septicemia.

Diagnosis: skin or soft tissue culture(may be mistaken for other bacterial species)

Treatment: Penicillin VK, amoxicillin, ampicillin, amoxicillin/clavulanate, quinolones, doxycycline, advanced cephalosporins, or carbanapenems.

MICROBIOLOGY:

-Member of the family Pasteurellacae which consists of Haemophilus, Actinobacillus, and pasteurella.

-Small(cocci to small bacilli), Gram negative, non-spore-forming, non motile, and aerobic or facultative anaerobic bacilli. Most have fastidious growth needs.

-Pasteurella Multocida causes 3 classic forms of infections:

• Cellulitis after animal bite, scratch
  
• Exacerbation of chornic pulmonary disease
  
• Systemic infection in immunocompromised patients, particularly those with underlying hepatic disease
  

-Can be readily isolated on blood or chocolate agar, causes musty odor

Pasteurella Species associated with human diseases

SPECIES	PRIMARY DISEASES
P. multocida	Bite wounds, COPD exacerbation, bacteremia, meningitis
P. betti	Opportunistic infections(abscesses, bite woundsm urogenital infections, bacteremia)
P. caballi	Wound infections
P. dagmatis	Bite wounds
P. stomatis	Bite wounds

Giardiasis

Giardiasis is an intestinal protozoal infection caused by Giardia species (primarily G Lamblia) that affect humans and other mammals. The parasite is found in bird droppings, but the role of birds in transmission to humans is unclear. Most infections are transmitted via contaminated surface water supplies, although person to-person transmission has been documented.

Giardia infections in humans are often asymptomatic, but about 50% of patients have diarrhea, abdominal pain, bloating, belching, nausea, and vomiting 3 days to 3 weeks after ingesting the parasite. A clinical clue may be new-onset lactose intolerance. Symptoms usually resolve after a week. Prolonged infection occurs in up to 20% of patients. People with hypochlorhydria or hypogammaglobulinemia, children, and travelers to endemic areas are at higher risk of infection.

Diagnosis: Stool exam and culture

Treatment if needed with Quinacrine, Tinidazole, nitazoxanide, or paromomycin.

Campylobacteriosis

The main reservoirs for Campylobacter jejuni are wild birds and poultry, although this bacterium can also affect other animals and pet birds. The most commonly affected pet birds are psittaciforms (parrots) and passeriforms (finches and canaries).

The organism colonizes the small intestine and colon of birds and can be spread to humans through contact with feces or carcasses of infected animals.

The most important mode of transmission to humans is through handling or consuming chicken, milk, or other products contaminated with feces of carrier animals. However, in up to 24% of cases, the source of infection is unknown.

Human infection with C jejuni most commonly leads to an acute, self-limited gastrointestinal illness characterized by fever, diarrhea, and abdominal cramps. The diarrhea is typically watery or bloody and occurs 8 to 10 times a day at peak illness. Fever can persist for up to a week. Most cases resolve within 7 days, but some patients may have a relapsing diarrheal illness lasting several weeks.

Diagnosis: Stool culture

Treatment if needed with Zithromax, Clarithromycin and erythromycin

Salmonellosis

Nontyphoidal Salmonella species colonize the GI tract of many animals, including birds.

Up to 80% of chicken eggs are contaminated with this gram-negative bacterium.

Spread of nontyphoidal Salmonella to humans is much more common from poultry, poultry products, and pet reptiles than pet birds. Infected birds may be halthy carriers.

Gastroenteritis in humans begin with nausea, vomiting, fever, and non bloody darrhea about 48h after ingestion. Most infections are self limited, with resolution of fever within 48 to 72 h, and resolution of diarrhea within 4-10 days. Systemic infections is more likely in immunosuppressed patients, sickle cell patients, malignant neoplasms, chronic GI tract disease.

Systemic nontyphoidal salmonella may settle in existing fractures, DJD, abnormal lung tissue, organs affected by stones.

Large vessel arteritis should be suspected in person at risk who presents with back, chest, or abdominal pain preceded by gastroenteritis.

Diagnosic tests: stool culture, blood culture if extraintestinal or systemic infections.

Treatment:

Diarrhea is usually self limited.

Antibiotic treatment increases carrier rate.

Ciprofloxacin, ceftriaxone, or TMP/SMX.

In HIV/AIDS: IV quinolones for 1-2 weeks, then orally for 4 weeks.

For those with endovascular infection: IV 3^rd gen cephalosporin or parenteral ampicillin for 6 wks.

MICROBIOLOGY:

Part of the Enterobacteriaceae.

Salmonella are found virtually in all animals.

Serotypes such as S. typhi and S. paratyphi are highly adapted to humans and do not cause disease in nonhuman hosts. Other strains (e.g. S. choleraesuis) are adapted to animals, when they infect human, can cause severe disease.

A large inoculum is required for symptomatic disease. The infectious dose is reduced for people at increased risk of for disease because of age, immunosuppression, or underlying disease (leukemia, lymphoma, sickle cell disease) or reduced gastric acidity.

Q fever

Q fever is caused by Coxiella burnetti, a gram negative pleomorphic bacillus.

Ticks and vertebrates(goats, sheep, and less commonly birds) are natural reservoirs.

Symptoms typically: fever, penumonitis, severe headache and photophobia.

Meningitis, hepatitis and thromboses are seen in more-severe disease.

Diagnosis: PCR, culture of blood or body tissue.

Treatment: usually self limited, doxy if needed.

Newcastle disease(avian pneumoencephalitis)

Organism: Avian paramyxovirus 1, can affect animals, reptiles, birds and people.

Most common in wild birds, but parrots are also highly susceptible. Illegaly imported Amazon parrots are the most likely source of infection for US households.

Human infection: conjunctivitis

Poultry workers are at greatest risk on infection

Diagnosis: PCR, viral culture

Histoplasmosis

Histoplasma capsulatum is a fungus that colonizes the GI tract of birds and contaminates the soil via bird and bat droppings.

Endemic regions: Ohio and Mississippi river valleys. Typical pet birds such as canaries and parrots are not susceptible, but doves and pigeons may become colonized.

Humans commonly acquire the organism by inhalation of disrupted soil. Humans to humans transmission has not been reported.

In more than 90% of cases, the primary infection is minimally symptomatic. Disseminated disease generally occurs in immunocompromised patients and presents with fever, weight loss, hepatosplenomegaly, and pancytopenia.

Diagnosis: Serologic testing, culture.

Treatment: Disease is often self-limited. If trt is needed: itraconazole, Ketoconazole.

For immunosuppressed or severe, disseminated illness: Amphotericin B

Influenza

All subtypes of influenza A virus can infect birds (influenza B virus cannot).

Avian influenza viruses affecting birds and humans called "avian flu".

Person to person transmission has been very rare, limited and unsustained.

Suspect it in people who have been exposed to sick poultry or wild birds. With highly pathogenic viruses such as H5N1, the disease can progress very rapidly from onset to death.

Psittacosis

Known also as ornithosis, parrot fever, chlamydiosis

Caused by Chlamydophila psittaci, which is present in 40% of birds.

Humans are accidental hosts.

Unlike C. pneumoniae, C. psittaci is not transmitted from human to human.

Atypical pneumonia: the most common presentation. The symptoms typically begin 7-14 days after exposure with fever, chills, prominent headaches, photophobia, and cough. Hepatosplenomegaly is clinically detectable in 10-70% of patients. Uncommon serious diseases: pericarditis, myocarditis, culture-negative endocarditis, MS changes.

The combination of pneumonitis and hepatosplenomegaly should prompt the diagnosis!

Diagnosis: Serology. Reportable disease.

Treatment: usually self limited. If treatment is needed: doxycycline, azithromycin, or Clarithromycin

Pet bird-associated infx with GI syndrome

DISEASE	DIAGNOSTIC TESTS	TREATMENT
Salmonellosis	Stool culture Blood culture if bacteremia or non gi infection	Diarrhea is usually self-limited Abx increases carrier state Cipro, Ceftriaxone, or TMP/SMX
Campylobacteriosis	Stool culture (selective media needed, request testing specifically for campylobacter)	Disease is usually self limited Azithromycin, Clarithromycin, and erythromycin>quinolones
Giardiosis	Stool culture	Disease is usually self limited Quinacrine Tinidazole, nitazoxanide, paromomycin

Pet bird-associated diseases as skin problems

DISEASE	DIAGNOSTIC TESTS	TREATMENT
Pasteurellosis	Skin or soft tissue culture	Penicillins, quinolones, doxy, advanced cephalosporins, or carbapenems
Erysipeloid	Culture(May be confused with Lactobacillus or Enterococcus)	Penicillin, Erythromycin
Cryptococcosis	Antigen testing in CSF/serum India ink stain in CSF Culture	Fluconazole
Avian mite dermatitis	Identification of mites on biopsy or skin scraping	Acaricide(pyrethrins) for birds, topical steroids for patient
Non tuberculous mycobacteriosis	AFB and culture	Ethambutol, rifabutin, macrolides

Pet bird-associated with flu-like syndrome

Diseases presenting with Flu-like or pulmonary symptoms

DISEASE	DIAGNOSTIC TESTS	TREATMENT
Psittacosis	Serology	self limited-otherwise:doxy, azithro, Biaxin
Influenza	PCR	Oseltamivir
Histoplasmosis	Serology, culture	Often self limited. otherwise: refer to IDSA
Newcastle disease	PCR, viral culture	self limited
Q fever	PCR, culture B or tissue	self limited, doxy if needed
West Nile virus	Serology in serum/CSF	supportive
Allergic alveolitis	Exclusion	Avoidance

 

Disseminated Gonorrhea

A case presentation: 

32 year old man, presented to the ER with a 2 day history of skin lesions on his hands and feet. The lesions accompanied by fever(102.9F), malaise, diffuse arthralgias and 1 episode of vomiting. 

Physical: 5-6 purpuric papules, each with a central area of necrosis or pustule formation, located on the palmar and dorsal aspects of his hands and feet, and a well defined plaque on his right ankle. 

This patient claimed to be in monogamous relation. 

Differential diagnosis of fever and skin lesions:

1. Rocky Moutain Spotted fever
2. Tick bite fever
3. Tick-borne diseases 
4. Infective endocarditis 
5. Gonococcemia
6. Vasculitis 

Classical presenting picture of disseminated gonoccocemia: (with/without septic arthritis)

1. Fever
   
2. tenosynovitis
3. skin lesions: 5-40 lesions on the extremities, macules-papules that may become hemorrhagic pustules (present mostly in the non septic arthritis form)
4. purulent arthritis 

Diagnosis:

1. Blood cultures: 50% (form without septic arthritis)
2. Synovial cultures:47% (form with septic arthritis)
3. genital, anorectal, pharyngeal infection in 70-80%- all mucosa should be tested! These can be tested by Gram stain(94% positive in symptomatic men), PCR, culture on Thayer Martin media. For cultures, samples should be inoculated directly onto the culture medium.

Test for other STDs such as HIV, Syphyllis, Chlamydia

Management:

• The only drugs currently recommended: Cephalosporins 
• Quinolones are NOT recommended anymore because of rapidly spreading resistance.

Urogenital and anorectal gonorrhea: 

• Ceftriaxone 125 mg IM x1 dose  
• Cefixime(Suprax) 400 mg po  x1 dose
• Others: Ceftizoxime 500 mg, cefoxiting 2 g with 1 g probenecid, cefotaxime 500 mg

Disseminated Gonococcal infection:

• Ceftriaxone 1 g daily - then switch to po cefixime to complete 7 days course. 
• May use IV Cefotaxime, or Ceftizoxime 1 g IV q 8h as alternative

Do Not forget to treat Chlamydia: Azithromycin 1 g pox1 or doxycycline 100 mg po q12hx7 days

Do NOT forget the partner

Microbiology basics:

Nisseria Gonorrhea is a fastidious organism, aerobic, gram-negative cocci, typically arranged in pairs(diplococci) with adjacent sides flattened together. The bacteria are not mobile, and do not form endospores.  Pathogenic strains are usually encapsulated.  

The Nisseria genus has two species N. gonorhoeae and N. meningitidis. The others may cause opportunistic infections.

All species are oxidase positives, most catalase positive. 

Virulence factors in N. gonorrhoeae:

Virulence factor________________Biological Effect

Capsule__________________________Antiphagocytic

Pilin____________________________Mediates initial attachment to epithelial cells

Por(Protein I)_____________________Porin protein-promotes intracellular survival

Opa(Protein II)____________________Mediates firm attachment to epithelial cells

Rmp(Protein III)___________________Protects other surface antigens from antibodies

Tbp1, Tbp2(Trasnferrin)_____________Mediates acquisition of iron for bacterial meabolism 

Lbp(Lactoferrin)___________________Mediates acquisition of iron

LOS____________________________Endotoxin

Ig A1 protease_____________________Destroys Ig A1

Beta-lactamase____________________Hydrolyze beta-lactam ring in PCN

Special predisposing factors: Late complement deficiencies

West Nile Virus

West Nile virus infection is a flavivirus-induced, mosquito-borne illness that occurs in Africa, ME, Asia, australia and parts of Europe. 

Incubation period: 2-15 days

A mild form of disease, a flu-like illness, "West Nile Fever", develops in approximately 20% of infected individuals. 

Classic presentation:

• Anorexia
  
• Vomiting
• Abdominal pain
• Diarrhea
• fever
• Headache
• conjunctivitis
• Eye pain
• Pharyngitis
• facial congestion
• diffuse lymphadenopathy 
• rash

Possible Complications:

• Dehydration
• Arrythmias
• Limb weakness
• Respiratory failure

A more severe form of West Nile virus, neuroinvasive disease, is evident in less than 1% of infected persons, particularly males, elderly, alcoholic, diabetic, immunosuppressed, and hypertensive.

The rash seen in 20% to 60% patients with West Nile virus represents either viremia or host's immune response. Rash is more common in young individuals, women and West Nile fever, and starts in the 3rd day(range 3-12) of illness as small macules, papaules, maculopapules, and vesicles located on the trunk. Lesions spread to the proximal extremities, last for 7-14 days, and resolve without scarring or desquamation. The rash is roseola-like, morbilliform. The  rash may be associated with pruritus, hyperesthesia. 

Unlike dengue virus rash, West Nile rash is ill defined and spares mucous membrane and the face, palm, and soles.

West Nile virus has become the most common cause of encephalitis. 

Treatment is still experimental. 

Infectious exanthem

Infectious exanthem is an aute generalized skin eruption associated with primary systemic infection.

Common causes:

• Adenovirus
• CMV
• Enterovirus
• EBV(infectious mononucleosis) 
• HSV 6 (roseola) 
• HIV (seroconversion syndrome)
• Measles
• Parvovirus B19 (fifth disease)
• Rubella
• West Nile virus

Serious diseases also can trigger such rash are: Meningococcemia, Rickettsioses, secondary syphillis. 

HCAP/VAP/Nosocomial

Risk factors for MDR pathogens:

• Antimicrobial therapy in proceeding 90 d
• Current hospitalization of 5 days or more
• High frequency of antibiotic resistance in the community or in the specific hospital unit
• Risk factors for HCAP:
  
• -Hospitalization for 2 days or more in the preceding 90 d
• -Residence in a NH or extended care facility
  
• -Chronic dialysis within 30 d
• -Home wound care
• -Family member with MDR pathogen
  
• Immunosuppressive disease and/or therapy

HCAP can be missed as a CAP. Good medical questionnaire will reveal prior admits, prior multiple antibiotics use, home wound care, family member with MDR pathogen.

Empirical therapy:

If no risk factors for MDR pathogens: (early nosocomial or ventilator associated pneumonia)

• Ceftriaxone
  
• Levofloxacin, Moxifloxacin
  
• Ampicillin/sulbactam
  
• Ertapenem
  

If risk factrors for MDR pathogens exist:

• Anti-pseudomonal cephalosporin or Carbapenem or beta-lactam/linhibitor
  
• (Cefepime, ceftazidime) (Imi/mero/Doripenem) (piperacillin/tazobactam)
  

PLUS

• Antipseudomonal quinolone or Aminoglycoside
  
• (Levofloxacin, Ciprofloxacin) (Amikacin,Gentamycin, Tobramycin)
  

PLUS

• Linezolid or Vancomycin

Table of apropriate dosages in MDR pathogens

Reference: IDSA guidelines