Neisseria, Moraxella, Haemophilus, Acinetobacter baumannii

Question 1

What are the common clinical syndromes caused by Neisseria meningitidis?

Answer 1

Meningitis and meningococcemia (septicemia). High-risk presentations include purpura fulminans and Waterhouse-Friderichsen syndrome.

The classic triad of meningitis includes:
fever, neck stiffness, and altered mental status.

Look for petechial rash in meningococcemia.

Question 2

What complement deficiency increases the risk of meningitis due to infection with Neisseria?

Answer 2

Terminal complement factors
(C5 to C9)

Question 3

What type of bacteria is Neisseria?

Answer 3

gram-negative diplococci

Question 4

Metabolically, what differentiates Neisseria gonorrhoeae and meningitidis?

Answer 4

• Neisseria meningitidis is capable of metabolizing glucose and maltose.
• Neisseria gonorrhoeae can metabolize glucose.

Question 5

What enzyme is present in both Neisseria gonorrhoeae and meningitidis?

Answer 5

oxidase.

Question 6

What agar is used for Neisseria?

Answer 6

chocolate agar and Thayer-Martin agar, which contains vancomycin, polymyxin, nystatin, and trimethoprim.

Question 7

What key virulence factor exists with Neisseria spp. that allows for surface attachment?

Answer 7

Pili.

Promotes nasopharyngeal colonization (attachment and movement). Both Neisseria meningitidis and Neisseria gonorrhoeae have pili, but they serve different functions. N gonorrhoeae binds to host epithelial cells using pili, proteinaceous projections on the outer surface of the bacteria. Gonococcal pili undergo both phase variation (ie, on-off expression) and antigenic variation, which rapidly alter the antigenic profile of the pilus and limit the development of long-lasting immunity against the organism. Species of N gonorrhoeae that do not express pili are unable to bind host cells and are therefore unable to cause infection. Pili for Neisseria meningitidis is less crucial for immune evasion compared to N. gonorrhoeae. Pili in Neisseria meningitidis is used for adhesion to nasopharyngeal epithelium and allows for bloodstream invasion, yet the pili in Neisseria meningitidis is not as antigenically variable as N. gonorrhoeae, so immunity can develop after infection or vaccination.

Question 8

What enables Neisseria to colonize mucosal surfaces more easily that aids in mucosal adherence.

Answer 8

IgA protease.

Question 9

Which species of Neisseria are encapsulated?

Answer 9

Neisseria meningitidis.

Neisseria gonorrhoeae is NOT encapsulated and instead uses lipooligosaccharides (LOS), which allows for blebbing (spreading).

Question 10

What key virulence factor exists with Neisseria that prevents phagocytosis?

Answer 10

capsule (only Neisseria meningitidis).

Question 11

What highly-inflammatory compound is possessed by Neisseria that is similar to endotoxins?

Answer 11

These proinflammatory agents lead to DIC (capillary leakage, fluid extravasation, hypovolemia, thrombocytopenia, and thrombosis):
- Lipooligosaccharides (LOS)
- OPA (opacity proteins)

Question 12

How is Neisseria meningitidis spread?

Answer 12

respiratory droplets

**Use a face mask in the hospital setting for PPE. **

Question 13

Where is Neisseria most commonly found?

Answer 13

Places that commonly experience outbreaks are college dormitories and military barracks.

Question 14

What endocrine organ is commonly implicated with Neisseria meningitidis?

Answer 14

Adrenal glands

Adrenal involvement in meningococcemia can lead to a syndrome of adrenal insufficiency known as Waterhouse-Friderichsen syndrome.

Adrenal insufficiency → metabolic derangements → hypoglycemia, hyponatremia, HYPERkalemia.

Question 15

What sequelae is commonly seen with an infection with Neisseria meningitidis?

Answer 15

Sequelae of Neisseria meningitidis infection include immune-complex mediated complications (e.g., pericarditis, arthritis).

Question 16

What prodrome is seen with Neisseria meningitidis?

Answer 16

Febrile, flu-like illness with myalgias.

Question 17

What can Neisseria meningitidis mimic?

Answer 17

Neisseria meningitidis infection can resemble strep throat by manifesting as pharyngitis.

Question 18

What skin symptom suggests DIC secondary to Neisseria meningitidis?

Answer 18

Neisseria meningitidis infection can manifest as a petechial rash due to DIC.

Question 19

Neisseria meningitidis is the _____ most common cause of bacterial meningitis.

Answer 19

2nd.

Streptococcus pneumoniae is usually the most common in patients older than 1 month and in neonates, Group B Streptococcus (Streptococcus agalactiae) is the most common cause.

Question 20

What is an effective antibiotic against Neisseria meningitidis?

Answer 20

Ceftriaxone

Question 21

What antibiotic is used for Neisseria meningitidis in penicillin and beta-lactam allergic patients?

Answer 21

Chloramphenicol

Question 22

What antibiotics are used for post-exposure prophylaxis against Neisseria meningitidis?

Answer 22

Rifampin, ciprofloxacin, or ceftriaxone.

Ideally given within 24 hours of exposure.

Children can be given ceftriaxone or Rifampin.

Adults can receive rifampin (600 mg twice daily for two days), ciprofloxacin (single oral 500 mg dose), or ceftriaxone (single IM dose). Ciprofloxacin is not recommended for children or pregnant women due to risks of cartilage toxicity.

Question 23

What antibiotics should be used for post-exposure prophylaxis against Neisseria meningitidis in children?

Answer 23

Drug of Choice for children:
Rifampin alternative is ceftriaxone).

Dose for older children:
10 mg/kg twice daily for two days.

Dose for infants:
5 mg/kg for infants <1 month.

Question 24

What antibiotics should be used for post-exposure prophylaxis against Neisseria meningitidis in pregnancy?

Answer 24

Pregnant patients should be given ceftriaxone.

Azithromycin: A secondary option if ceftriaxone is contraindicated.

Question 25

what are the common medications that increase susceptibility of getting meningitis by Neisseria?

Answer 25

Eculizumab (Soliris): Inhibits C5, blocking MAC formation; used in PNH and aHUS. Ravulizumab: Similar mechanism to eculizumab but with longer duration of action. Corticosteroids: High doses can transiently impair complement function. Immunosuppressive Drugs: Rituximab, mycophenolate mofetil, and cyclophosphamide may indirectly impair complement activity.

Question 26

What are the countermeasures for preventing Neisseria meningitidis when taking immunpsuppressing medications?

Answer 26

Vaccination: Meningococcal vaccines (MenACWY and MenB) prior to starting therapy.

Question 27

How is the vaccination for Neisseria formulated?

Answer 27

A vaccine with capsular polysaccharides of four serotypes of meningococcus with capsular antigens linked to a carrier protein (e.g., diphtheria toxoid). By conjugating the bacterial polysaccharides to a protein carrier, it elicits a robust T-cell-dependent response, leading to longer-lasting immunity. Conjugate vaccines also reduce nasopharyngeal carriage, contributing to herd immunity.

Question 28

What serogroups does the meningococcal conjugate vaccine (MenACWY) protect against?

Answer 28

Serogroups A, C, W, and Y. Administer at age 11-12 years, with a booster at 16 years. It is mandatory for military recruits and travelers to the meningitis belt of sub-Saharan Africa.

Question 29

Who should receive the MenB vaccine?

Answer 29

Adolescents aged 16-18 years (clinical discretion) and high-risk groups (e.g., during outbreaks, individuals with complement deficiencies, or asplenia). Serogroup B is responsible for outbreaks in developed countries, especially in close-living settings like dormitories.

Question 30

What is a mnemonic to remember the Neisseria meningitidis vaccine schedule?

Answer 30

"11-16-Boost": 11 years: First MenACWY dose. 16 years: Booster dose. Boost every 5 years if high-risk.

Question 31

Who requires booster doses of the MenACWY vaccine?

Answer 31

Individuals at persistent high risk (e.g., asplenia, complement deficiencies, microbiologists exposed to N. meningitidis). Boosters are given every 5 years. College freshmen living in dormitories are at increased risk and may also need vaccination.

Question 32

What vaccination is recommended for travelers to sub-Saharan Africa?

Answer 32

MenACWY vaccine, as serogroup A outbreaks are common in the meningitis belt. The vaccine is required for Hajj and Umrah pilgrims in Saudi Arabia.

Question 33

What is the public health strategy for managing meningococcal outbreaks?

Answer 33

Targeted vaccination campaigns with MenACWY or MenB vaccines based on the serogroup causing the outbreak. Prophylactic antibiotics (e.g., rifampin, ciprofloxacin) are also used for close contacts of infected individuals.

Question 34

What are the contraindications for meningococcal vaccines?

Answer 34

Severe allergic reaction (e.g., anaphylaxis) to a prior dose or vaccine component. Minor illnesses (e.g., cold) are not contraindications; vaccination should proceed in these cases.

Question 35

What is the gram staining and morphology of Neisseria gonorrhoeae?

Answer 35

Gram-negative diplococci.

Question 36

What type of intracellular presence does Neisseria gonorrhoeae exhibit?

Answer 36

Facultative intracellular within polymorphonuclear cells (PMNs).

Question 37

Is Neisseria gonorrhoeae encapsulated?

Answer 37

No, Neisseria gonorrhoeae is not encapsulated.

Question 38

How is Neisseria gonorrhoeae transmitted?

Answer 38

Sexually transmitted infection (STI).

Question 39

What is the significance of asymptomatic carriers in Neisseria gonorrhoeae infection?

Answer 39

They can transmit the infection without showing symptoms.

Question 40

How can Neisseria gonorrhoeae affect newborns?

Answer 40

It can be transmitted during birth, causing neonatal eye infections (ophthalmia neonatorum).

Question 41

What are common manifestations of Neisseria gonorrhoeae in men?

Answer 41

Urethritis, prostatitis, and epididymitis.

Question 42

What are common manifestations of Neisseria gonorrhoeae in women?

Answer 42

Cervicitis, pelvic inflammatory disease (PID), and salpingitis. Intermenstrual bleeding, such as post-coital spotting, is an alarming symptom of gonococcal cervicitis

Question 43

What is the name of the syndrome associated with liver capsule inflammation due to Neisseria gonorrhoeae?

Answer 43

Fitz-Hugh-Curtis syndrome.

Question 44

What are symptoms of disseminated gonococcal infection?

Answer 44

Purulent arthritis, tenosynovitis, and dermatitis. Purulent arthritis of the knee (cloudy fluid with a leukocyte count of more that 20,000/mm^3 with 75% neutrophils), oligoarticular joint pain (monoarthritis or asymmetric polyarthritis) or tenosynovitis, and vesiculopustular skin lesions on the extremities, raises suspicion for disseminated gonococcal infection, which is one of the most common causes of septic arthritis in young, sexually active individuals. It is due to the spread of Neisseria gonorrhea from a (usually asymptomatic) genitourinary infection into the systemic circulation. Patients typically present with either purulent arthritis or the triad of polyarthralgia, dermatitis, and tenosynovitis; however, some overlap in these 2 syndromes can occur. Perform an arthrocentesis and gram stain sample with microscopy (can be of blood, urine, or joint fluid sample), which usually reveals gram-negative intracellular diplococci. Treatment is with IV ceftriaxone plus azithromycin or doxycycline (covers concomitant Chlamydia).

Question 45

What diagnostic test is preferred for Neisseria gonorrhoeae?

Answer 45

Nucleic acid amplification testing (NAAT).

Question 46

What is the drug of choice for treating Neisseria gonorrhoeae?

Answer 46

Ceftriaxone.

Question 47

Why is doxycycline or a macrolide added to Neisseria gonorrhoeae treatment?

Answer 47

To cover potential Chlamydia co-infection. If Chlamydia is negative following lab results, only treat Neisseria.

Question 48

What preventive method is emphasized for Neisseria gonorrhoeae?

Answer 48

Consistent condom use.

Question 49

What area is commonly implicated by disseminated gonococcal infection?

Answer 49

Achilles tendon.

Question 50

What is the morphology and Gram-staining of Moraxella catarrhalis?

Answer 50

Moraxella catarrhalis is a Gram-negative diplococcus.

Question 51

Where does Moraxella catarrhalis commonly colonize?

Answer 51

M. catarrhalis commonly colonizes the nasopharynx.

Question 52

What test results are characteristic of Moraxella catarrhalis?

Answer 52

M. catarrhalis is an aerobic bacteria that is catalase-positive, oxidase-positive, and forms biofilms. The "hockey puck sign" refers to the smooth sliding of colonies across agar when nudged with a loop.

Question 53

What enzyme does Moraxella catarrhalis produce that enhances antibiotic resistance?

Answer 53

M. catarrhalis produces beta-lactamase, which breaks down beta-lactam antibiotics.

Question 54

What are common infections caused by Moraxella catarrhalis?

Answer 54

Otitis media (especially in children) Bacterial sinusitis COPD exacerbations (bronchopneumonia in adults)

Question 55

What are the treatments of choice for Moraxella catarrhalis infections?

Answer 55

Cephalosporins Amoxicillin-clavulanate Trimethoprim-sulfamethoxazole (TMP-SMX) Fluoroquinolones

Question 56

Which 2 bacteria are the most common causes of pelvic inflammatory disease (PID)?

Answer 56

Chlamydia trachomatis (subacute; often undiagnosed) Neisseria gonorrhoeae (acute)

Question 57

If gonorrhea/chlamydia is suspected, then treat _________ .

Answer 57

empirically

Question 58

Standard STI screening panel for common infections in both men & women includes:

Answer 58

Neisseria gonorrhea Chlamydia trachomatis HIV Treponema pallidum

Question 59

What is the outpatient treatment regimen for pelvic inflammatory disease (PID)?

Answer 59

IM ceftriaxone (or other cephalosporin) Oral doxycycline Oral metronidazole

Question 60

What type of bacteria is Haemophilus influenzae?

Answer 60

Haemophilus influenzae is a gram-negative coccobacillus.

Question 61

What are the growth requirements for Haemophilus influenzae?

Answer 61

It requires chocolate agar enriched with factor V (NAD) and factor X (hemin).

Question 62

How is Haemophilus influenzae transmitted?

Answer 62

It is transmitted via respiratory droplets (aerosol transmission).

Question 63

What gives Haemophilus influenzae its pathogenicity?

Answer 63

Haemophilus influenzae is a gram-negative coccobacillus that can be either encapsulated (serotypes a-f) or unencapsulated (nontypeable). H influenzae type b (Hib) is the most invasive strain due to its **polyribosy|ribitol phosphate (PRP) capsule**, which inhibits complement-mediated phagocytosis and allows it to invade tissues and survive in the bloodstream.

Question 64

What are the **TOP TWO** diseases caused by Haemophilus influenzae type B?

Answer 64

- Diseases caused by the encapsulated (type B) Haemophilus influenzae bacteria can range from meningitis, epiglottitis, otitis media, pneumonia, septic arthritis. - The top two diseases caused by Haemophilus influenzae type B are **meningitis** and **epiglottitis**. Common symptoms of meningitis caused by Haemophilus influenzae include headache, neck stiffness, photophobia, nausea, and vomiting. Symptoms for epiglottitis include rapidly progressive high fever, toxic appearance, dysphagia, dysphonia, drooling, and a cherry red epiglottis. These patients tend to position themselves in a sniffing or tripod position. These patients tend to have stridor (high-pitch on inspiration). - These diseases and their considerations are important when children are not vaccinated. The Nontypeable Haemophilus influenzae illnesses are acute otitis media, conjunctivitis, sinusitis, pneumonia and the Hib vaccine does do not help prevent these injections. Also, the most common pathogens that cause conjunctivitis, acute otitis media, and sinusitis are Streptococcus pneumonia, Moraxella catarrhalis, and Nontypeable Haemophilus influenzae.

Question 65

Is Haemophilus influenzae the most common cause of epiglottitis or otitis media?

Answer 65

No, infection of the ear canal (otitis media) or the aryepiglottic area (epiglottitis) is most commonly secondary to Streptococcus pneumoniae due to increased vaccination compliance against Haemophilus influenzae type b. Children who get epiglottitis secondary to Haemophilus influenzae infection are likely unvaccinated and might have other missing vaccines. The most common causes of epiglottitis and otitis media is pneumococcus. The other causes are from Staphylococcus aureus and Group A Streptococcus.

Question 66

How is epiglottitis managed?

Answer 66

Manage airway and intubate (endotracheal intubation) if needed. Antibiotics: Augmentin (Amox-Clav) --> covers Haemophilus influenzae Vancomycin or Ceftriaxone --> covers most other bacteria (including Haemophilus influenzae)

Question 67

Is Racemic Epinephrine Used in Epiglottitis?

Answer 67

No, racemic epinephrine is NOT effective for epiglottitis and is NOT part of standard management. Racemic epinephrine works by reducing subglottic swelling (e.g., in croup), but epiglottitis is a supraglottic disease caused by a swollen, inflamed epiglottis. Instead, after securing the airway, initiate antibiotic therapy, such as, IV Ceftriaxone or Cefotaxime (3rd-gen cephalosporins), which covers H. influenzae type B (Hib) and other bacterial causes. Give IV Vancomycin (if MRSA is suspected, though rarely needed). IV fluids is usually initiated if the patient is dehydrated from drooling. Finally provide humidified oxygen the patient remains hypoxia and dexamethasone can be given as optional treatment to reduce airway swelling, but is only used in some cases.

Question 68

What prophylactic treatment is recommended for close contacts of patients diagnosed with What prophylaxis is recommended for close contacts of Haemophilus influenzae type b infections (epiglottitis, otitis media, or meningitis, secondary to Haemophilus influenzae type b)?

Answer 68

Rifampin prophylaxis.

Question 69

When is the first vaccination for Hib given?

Answer 69

The Hib vaccine is administered beginning at age **2 months** to provide continued immunity. The immunization is composed of PRP conjugated with a protein toxoid (eg, tetanus, diphtheria), which induces a T cell-dependent immune response. The production of opsonizing anticapsular antibodies by B-lymphocytes allows for efficient phagocytosis of the bacterium. Without the protection from the vaccine, children are at risk for invasive disease caused by Hib, such as meningitis, bacteremia, pneumonia, and epiglottitis.

Question 70

How are neonates protected from Haemophilus influenzae?

Answer 70

**Passive immunity** During the first months of life, transient immunity to Hib is accomplished by IgG antibodies acquired transplacentally from the mother while in utero.

Question 71

Acinetobacter baumannii most commonly affects ... ?

Answer 71

hospitalized patients patients usually develop pneumonia or bacteremia

Question 72

Why is Acinetobacter baumannii hard to treat?

Answer 72

often this bacteria multidrug resistant

Question 73

How is Acinetobacter baumannii treated?

Answer 73

carbapenem polymyxin cefepime

Question 74

What is Acinetobacter baumannii?

Answer 74

- Gram-negative opportunistic pathogen causing nosocomial infections - Non-lactose fermenting - Oxidase-negative coccobacillus

Question 75

How does Acinetobacter baumannii appear on Gram stain?

Answer 75

It appears as short, gram-negative coccobacilli, often in pairs or clusters.

Question 76

What types of infections does Acinetobacter baumannii commonly cause?

Answer 76

Pneumonia (especially ventilator-associated pneumonia), bloodstream infections, urinary tract infections, wound infections, and meningitis (especially in post-neurosurgical patients).

Question 77

Why is Acinetobacter baumannii significant in hospital settings?

Answer 77

It is highly resistant to multiple antibiotics and can survive on surfaces for long periods, leading to outbreaks in ICUs.

Question 78

What is the primary mode of transmission for Acinetobacter baumannii?

Answer 78

It spreads via contaminated hospital equipment, hands of healthcare workers, and environmental surfaces.

Question 79

What is the preferred treatment for Acinetobacter baumannii infections?

Answer 79

- Carbapenems (e.g., meropenem) are often used, but resistance is common. - Colistin, polymyxins, or tigecycline may be needed for multidrug-resistant strains.

Question 80

What are the risk factors for Acinetobacter baumannii infection?

Answer 80

Mechanical ventilation, prolonged hospital stay, prior antibiotic use, immunosuppression, trauma, and invasive devices (e.g., catheters, endotracheal tubes).

Question 81

How does Acinetobacter baumannii develop antibiotic resistance?

Answer 81

Through beta-lactamase production, efflux pumps, porin mutations, and enzymatic modification of antibiotics.

Question 82

What infection control measures are necessary to prevent Acinetobacter outbreaks?

Answer 82

Strict hand hygiene, contact precautions, environmental disinfection, and antimicrobial stewardship programs.

Question 83

Why is Acinetobacter baumannii a major concern in combat and disaster medicine?

Answer 83

It has been associated with infections in military personnel and disaster victims due to its ability to survive harsh environments and resist multiple antibiotics.