23 - 154 - GRAN-NEGATIVE COCCAL AND BACILLARY INFECTIONS Flashcards
The single most important factor in the treatment of acute meningococcal infection
early initiation of antibiotics
Ideally, no more than 30 minutes should pass between a presumptive diagnosis and administration of intravenous therapy.
N. meningitidis serogroups that cause life-threatening disease
A, B, C, W-135, X, and Y
hallmark of Acute meningococcemia
petechial rash
When present, petechiae are** small and irregular with a “smudged” appearance,** and may occur all over the body, including palms, soles, mucous membranes, and conjunctiva, although the extremities are the most common location
may occur with severe disseminated intravascular coagulation (DIC) caused by sepsis, characterized by retiform purpura and necrosis of the skin, which may extend to subcutaneous tissues and, occasionally, muscle and bone
Purpura fulminans
- characterized by polymorphous cutaneous lesions, and may fade and recur with intermittent fevers
- Skin findings often occur around painful joints or pressure points
chronic meningococcemia
most common skin findings of chronic meningococcemia
rose-colored macules and papules
life-threatening condition characterized by adrenal hemorrhage and ensuing adrenal crisis, often accompanied by purpura fulminans
Waterhouse-Friderichsen syndrome
With breach of the blood–brain barrier, patients may develop this condition, which is marked by meningism (nuchal rigidity, headache, photophobia), fever, nausea/vomiting, and altered mental status. Kernig and Brudzinski signs may become positive
meningococcal meningitis
can occur while patients are in recovery, which may include a range of symptoms due to sterile arthritis, vasculitis, pleuritis, pericarditis, or episcleritis
delayed immune complex-mediated syndrome
the most common sequela of meningitis
sensorineural hearing loss or deafness
N. meningitidis is known to reside in what part of the body?
What is the mode of transmission?
nasopharynx of healthy individuals, and can be transferred from person to person via respiratory droplets or by direct contact, such as kissing
The single greatest risk factor for disseminated meningococcal disease
lack of bactericidal antibodies
Prior to obtaining antibiotic sensitivity results, patients with meningococcemia should be treated with what antibiotic?
third-generation cephalosporin such as ceftriaxone or cefotaxime
For patients with meningococcemia, If testing reveals a penicillin minimum inhibitory concentration less than 0.1 µg/mL, what medications should be given?
penicillin G or ampicillin
For patients who are allergic to penicillin and cephalosporin, what is an alternative medication?
chloramphenicol
Although not widely available, patients with purpura fulminans may benefit from what?
protein C concentrate
Fill in the blanks
Close contacts are defined as those who have had prolonged contact (>____ hours) within close proximity (<____ feet) of an infected patient, or those who have had direct exposure to the patient’s oral secretions from ____ days before the onset of symptoms until ___ hours following initiation of effective antibiotics
Close contacts are defined as those who have had prolonged contact (>8 hours) within close proximity** (<3 feet) **of an infected patient, or those who have had direct exposure to the patient’s oral secretions from 7 days before the onset of symptoms until **24 hours **following initiation of effective antibiotics
Antibiotics recommended for chemoprophylaxis for meningococcal disease
- rifampin (children and adults; 4 doses given over 2 days)
- ciprofloxacin (adults; single dose), and
- ceftriaxone (children, adults, and pregnant women; single intramuscular dose)
In ideal situations, chemoprophylaxis of meningococcal disease in those meeting criteria should be initiated within how many hours of identification of an index patient?
24 hours
schedule of meningococal vaccination
Ideally, patients should be vaccinated at 11 or 12 years old with a booster at age 16 years
pigment produced by P. aeruginosa
pyocyanin and pyoverdin pigment
- P. aeruginosa produces pyoverdin, a green-yellow pigment that fluoresces under a Wood lamp and is common to all fluorescent Pseudomonas species.
- It also produces pyocyanin, a** blue-green** nonfluorescent pigment specific to P. aeruginosa
a green-yellow pigment that fluoresces under a Wood lamp and is common to all fluorescent Pseudomonas species
pyoverdin
blue-green nonfluorescent pigment specific to P. aeruginosa.
pyocyanin
characterized by nail dyspigmentation that may be greenish-yellow, greenish-blue, greenish-brown, or greenish-black.
Green nail syndrome, or chloronychia
- Dyspigmentation results from the accumulation of debris and pyocyanin, which adheres to the underside of the nail plate
- Many patients present with a triad of dyspigmentation, onycholysis, and paronychia
presents with thickened, macerated skin with a characteristic moth-eaten appearance and yellow-green purulence
P. aeruginosa toe web infection
- presents with discrete, follicular papules and pustules that heal with fine desquamation and hyperpigmented macules.
- Onset is sudden, approximately 24 hours following exposure to contaminated hot tubs or whirlpools and may be associated with pruritus or pain.
P. aeruginosa folliculitis, commonly “hot tub folliculitis,”
- develops following emersion in contaminated wading pools and hot tubs, usually in children
- It presents with acute painful, erythematous, warm plantar nodules.
hot-foot syndrome
- characterized by acute onset of edema and erythema or discoloration of the external auditory canal, sometimes with maceration, discharge and/or regional lymphadenopathy.
- There is often tenderness with tragal pressure or movement of the pinna, and patients may complain of pruritus
Otitis externa, or “swimmer’s ear,”
- In elderly patients, especially those with diabetes, external otitis may progress to what invasive condition leading to skull-base osteomyelitis?
- characterized by an insidious onset with edema, erythema, and persistent discharge from the ear canal with severe pain that appears disproportionate to examination findings.
- Early cases usually lack fever or constitutional symptoms.
- The presence of granulation tissue in the floor of the external auditory canal at the bony–cartilaginous junction is a classic finding, and frank necrosis of the canal also may be present.
- Tympanic membrane visualization is often blocked by discharge and granulation tissue
malignant otitis externa
- may be caused by P. aeruginosa following commercial piercings as a result of contaminated cleansing agents, as well as following trauma or acupuncture
- The ear is typically swollen, erythematous, and tender, and prompt treatment is essential because of rapid progression to cartilage necrosis.
Perichondritis of the ear helix or tragus
- responsible for necrotic cutaneous lesions associated with P. aeruginosa bacteremia, especially in neutropenic patients, although, rarely, bacteremia may be absent
- It begins with a painless, infarcted gunmetal gray macule or papule with surrounding erythema.
- As the it develops, the lesion becomes more **indurated and pustules or hemorrhagic bullae **may develop.
- Over a rapid course of 12 to 18 hours the patient is left with a necrotic, ulcerative eschar with a halo of tender erythema
- lesions most commonly affecting the **anogenital region **(57%), extremities (30%), trunk (6%), and face (6%)
Ecthyma gangrenosum
Folliculitis outbreaks most commonly occur following submersion in water heated above ___°C, as P. aeruginosa is heat tolerant, and infection risk increases with duration of bathing
38
The most frequent P. aeruginosa serotype isolated from pseudomonal folliculitis
O-11
systemic treatment of P. aeruginosa infection
- penicillins (ticarcillin-clavulanic acid, piperacillin-tazobactam),
- cephalosporins (cefepime, ceftazidime, cefoperazone),
- monobactams (aztreonam),
- carbapenems (meropenem, doripenem, imipenem/cilastatin),
- fluoroquinolones (ciprofloxacin, levofloxacin),
- aminoglycosides (gentamicin, tobramycin, amikacin),
- polymyxins (colistin)
Topical antimicrobials for green nail syndrome
- 2% sodium hypochlorite,
- aminoglycosides (eg, tobramycin, gentamicin),
- fluoroquinolones (eg, ciprofloxacin, nadifloxacin),
- polymyxin B, or
- bacitracin
- Application of Castellani (carbol-fuchsin) paint, gentian violet, or acetic acid soaks also may be employed.
Bartonella are facultative intracellular Gram-negative bacilli, that parasitize what cells?
erythrocytes
- responsible for cat scratch disease, bacillary angiomatosis, and endocarditis
- What is the vector?
- What is the reservoir host?
- Bartonella henselae
- cat flea (Ctenocephalides felis)
- cats
- causes trench fever, bacillary angiomatosis, and endocarditis
- Vector
- Reservoir Host
- Bartonella quintana
- human body louse (Pediculus humanus)
- Humans
- etiologic agent of Carrion disease, a biphasic infection with an acute phase known as Oroya fever, followed by a chronic phase, verruga peruana
- Vector
- Reservoir host
- Bartonella bacilliformis
- sand fly (Lutzomyia verrucarum)
- Humans
the most common Bartonella infection
CAT SCRATCH DISEASE
Cat scratch disease (CSD)
Trench fever
Bacillary angiomatosis
Carrion disease
frequently the presenting sign of cat scratch disease
Regional lymphadenitis
- It is characterized by cyclic fevers of approximately 5 days’ duration, and as many as 90% of patients may develop crops of erythematous macules or papules, which may be found across the abdomen, chest, and back
Trench Fever
stains used to visualize Bartonella organisms
Warthin-Starry or Giemsa
Bartonella organisms, which may be found as intracellular inclusions, as well as free organisms in the extracellular matrix
classic cutaneous manifestation of enteric fever
rose spots
aside from enteric fever, rose spots can also be seen in what conditions?
rose spots may be seen to a lesser extent in** psittacosis, leptospirosis, brucellosis, rat-bite fever, and shigellosis**
most serious complication of enteric fever
intestinal perforation
Salmonella carriage confers an increased risk of what carcinoma?
gallbladder carcinoma
rhinoscleroma etiologic agent
Klebsiella rhinoscleromatis
- large vacuolated histiocytes containing K. rhinoscleromatis
- stain to visualize these cells
- Mikulicz cells
- CD68
Mikulicz cells can be visualized with CD68 immunostaining, and WarthinStarry silver stain may show K. rhinoscleromatis residing in Mikulicz cells
Biopsied tissue reveals plasma cells, lymphocytes, Russell bodies, and pathognomonic Mikulicz cells
Rhinoscleroma
Stain that can be used to enhance Russell bodies
Periodic acid–Schiff staining
Haemophilus influenzae is a fastidious, Gram-negative coccobacillus that grows on chocolate agar and requires what substances for growth?
hemin (factor X) and nicotinamide adenine dinucleotide (factor V)
