Infectious Disease Committee Flashcards
What factors influence the transmission of HSV infection to newborns?
- Nature of maternal infection 2. Mode of delivery 3. Duration of ROM 4. Use of intrapartum instrumentation
How is maternal genital HSV classified? (Two classifications)
- Newly acquired - Either a first episode PRIMARY infection (mother has no serum antibodies to HSV-1 or -2 at onset) or a first episode NONPRIMARY infection (mother has a new infection with one HSV type in the presence of antibodies of another type) 2. Recurrent Mother has pre-existing antibodies to the HSV type that is isolated from the genital tract
What is the most common route of Neonatal HSV acquisition?
Intrapartum (Although In Utero and Postnatal infections can occur, it is not the most common)
What category of maternal genital HSV (Primary or Recurrent) have the highest risk of HSV transmission? Why?
Categorizing the maternal genital HSV infection as either primary or recurrent is important! Mom who have had an HSV infection transmit HSV-neutralizing antibodies to their infant across the placenta, provided that their infant is not born before 32 weeks Therefore, infants born to moms with a first-episode primary infection at time of delivery are at the highest risk of acquiring HSV, with transmission rates up to 60% because the mom has no pre-existing neutralizing antibodies to transmit Second highest risk = First episode non-primary infection Lowest risk = Recurrent infections
What is the role of elective C/S for NHSV transmission?
Elective C/S markedly reduces but does not eliminate the risk for newborn infection
How are pregnant women with recurrent genital HSV treated during pregnancy?
They are given prophylaxis with acyclovir or valcyclovir from 36 weeks until delivery. This helps lower the recurrence of genital HSV and shedding at delivery BUT we are not sure if this translates to a reduced risk for NHSV infection
Why are infant serologies (HSV IgG and IgM) not useful in diagnosing neonatal HSV infections? (Three reasons)
- Transplancental IgG antibodies cannot be differentiated from IgG produced by the infant 2. Severely affected infants can not make antibodies (it is impaired) 3. HSV IgM antibody assays are variable and limited reliability
What is the duration of therapy for NHSV infections?
Depends on the category of disease. SEM disease - 14 day course of IV acyclovir Disseminated/CNS disease - minimum 21 days of IV acyclovir
What are the side effects of using IV acyclovir for the treatment of NHSV?
Neutropenia, Nephrotoxicity
What is the additional medication you give for an infant with ocular HSV manifestations?
1% Trifluridine with the IV acyclovir
What swabs need to be done for an HSV exposed asymptomatic neonate?
When evaluating NHSV infection in exposed asymptomatic infants, mucous membrane swabs should be obtained from the mouth, nasopharynx and conjunctivae AT LEAST 24 h after delivery. Additional swabs may be obtained (eg, from sites of scalp electrodes, if present).
How do you manage an asymptomatic neonate who was delivered via C/S before ROM by a mom with active HSV lesions that is presumed first-episode primary or first-epsiode non-primary HSV infection?
Risk for NHSV is very low If child is asymptomatic, take mucosal swabs (mucous membranes, NP swab) at 24 hours of life. Do HSV PCR by blood if available. Neonate can be discharged pending results If results are positive, then need to be managed as an HSV case
How do you manage an asymptomatic neonate who was delivered vaginally or C/S after ROM by a mom with active HSV lesions that is presumed first-episode primary or first-episode non-primary HSV infection?
Do type-specific antibodies for HSV on mom. Infant’s mucous membrane swabs be obtained and should be started on IV acyclovir. Do blood HSV PCR if available. If positive results - Do LP to determine acyclovir duration If negative results - check mom’s serologies. If mom’s results are more in keeping with recurrent HSV - stop ACV If mom’s results are not available or in keeping with a first HSV infection, baby needs 10 days of ACV despite negative swabs
How do you manage an asymptomatic neonate who was delivered by C/S by a mom with active HSV lesions, thought to be recurrent HSV?
If child is asymptomatic, take mucosal swabs (mucous membranes, NP swab) at 24 hours of life. Do HSV PCR by blood if available. Neonate can be discharged pending results If results are positive, then need to be managed as an HSV case
How do you manage an asymptomatic neonate who was delivered vaginally by a mom with active HSV lesions, thought to be recurrent HSV?
If child is asymptomatic, take mucosal swabs (mucous membranes, NP swab) at 24 hours of life. Do HSV PCR by blood if available. Neonate can be discharged pending results If results are positive, then need to be managed as an HSV case
How do you manage a neonate born to a mom who does not have active HSV lesions at delivery?
Observe for signs for NHSV and educate parents, but no swabs necessary. Consider swabs if active lesions were seen during the third trimester or near delivery
Historically, what are the three top causes of meningitis prior to the introduction of vaccines?
- Strep pneumo 2. Hemophilus Influenza Type B 3. Neisseria Meningitidis
In which circumstances do you consider listeria meningitis beyond the neonatal period? What antibiotic would you add if you suspected listeria?
- Specific host risk factors (i.e. immunosuppression) 2. Brainstem infection as the initial presentation You would add ampicillin to cover for listeria
What are 4 contraindications in performing an LP on a child you suspect meningitis in?
- Coagulopathy 2. Cutaneous lesions at the proposed puncture site 3. Signs of herniation 4. Unstable clinical status such as shock
Based on one adult study, what are the three factors associated with poor prognosis with meningitis?
- Delay in starting antibiotics 2. Severity of clinical state at presentation 3. Isolation of nonpenicillin-susceptible strep pneumoniae
What is the empiric therapy when meningitis is suspected in a child >1 month old?
Ceftriaxone/Cefotaxime + Vancomycin
What antibiotic do we use to treat the close contacts of a child who had meningococcal or HiB meningitis?
Rifampin
In which clinical situation does research support the use of steroids in acute bacterial meningitis?
HiB meningitis where evidence shows that steroids decrease hearing loss in children if they are administered just before or with the initial antimicrobial therapy
What should the CSF gram stain show before you consider starting IV dexamethasone? How long should you continue IV dexamethasone for?
If there are no contraindications to steroid use for a particular infant or child, when a bacterial meningitis is suspected (especially if CSF gram stain shows gram positive diplococci or gram negative coccobacili), some experts recommend starting IV steroids immediately before, concomitant with, or within 30 minutes after the first dose of antimicrobials. If Strep pneumo or HiB is cultured or identified by molecular testing, steroids should be continued for 2 days but if another etiology is found within 48 hours, then steroids should be discontinued
In which situations do you require repeat CSF sampling for a child with meningitis?
GBS meningitis - some experts recommend documentation of CSF sterilization 24-48 hours after initiation of therapy Gram negative enteric pathogens causing meningitis - require repeat LP at 24-48 hours
When should a formal audiology assessment be done on a child with confirmed bacterial meningitis?
Before discharge or within 1 month of discharge
What is the recommended duration of treatment for: a) Strep pneumo meningitis b) HiB meningitis c) N Meningitidis d) GBS meningitis
Strep pneumo meningitis = 10-14 days HiB meningitis = 7-10 days N Meningitidis = 5-7 days GBS meningitis = 14-21 days, and depends on whether cerebritis is present
In disseminated HSV infections, what organs are most commonly affected?
Liver = Consider NHSV particularly in neonates with sepsis accompanied by liver dysfunction Lung
What are the most common clinical presentations of invasive Group A Strep infections?
- Necrotizing Fasciitis or myositis 2. Bacteremia with no septic focus / Toxic shock syndrome 3. Pneumonia
What is a prominent risk factor for the development of invasive Group A Strep infection in children?
Varicella infections
How do you diagnose streptococcal TSS (toxic shock syndrome)?
Hypotension with at least 2 of the following signs: 1. Renal impairment 2. Coagulopathy 3. Liver function abnormality 4. ARDS 5. Generalized erythematous rash that may desquamate
What’s the difference between a confirmed invasive GAS case versus probable invasive GAS case?
A probable case means that the isolation of GAS was from a nonsterile site; as opposed to a confirmed invasive GAS case which is from a sterile site
Who should be offered chemoprophylaxis if you have a patient with invasive GAS disease?
- Household contacts who have spent at least 4 h per day on average in the previous seven days or 20 h per week with the case. - Nonhousehold persons who share the same bed with the case or had sexual relations with the case. - Persons who have had direct mucous membrane contact with the oral or nasal secretions of a case (eg, mouth-to-mouth resuscitation, open mouth kissing) or unprotected direct contact with an open skin lesion of the case. - Injection drug users who have shared needles with the case. - Selected contacts of long-term care facilities. - Selected contacts in child care settings. - Selected hospital contacts.
When should chemoprophylaxis be offered for close contacts of a patient with invasive GAS disease?
- Should only be offered to close contacts of a confirmed case of severe GAS during the period from 7 days before the onset of symptoms in the case to 24 hours after initiation of antibiotics in the case 2. Chemoprophylaxis of close contacts should be administered as soon as possible and preferably within 24 h of case identification, but chemoprophylaxis is still recommended for up to seven days after the last contact with an infectious case.
What antibiotic is the preferred choice for chemoprophylaxis of close contacts of a patient with invasive GAS disease?
First generation cephalosporin (Cephalexin)
What antibiotics do you use to treat invasive GAS disease?
Penicillin + Clindamycin
In addition to antibiotics, what other treatment do you consider in a patient with streptococcal TSS or severe toxin-mediated disease in the absence of shock?
IVIG
What are three potential risk factors for transmission of blood-borne viruses in child care centres?
- Aggressive behaviour with frequent biting 2. Oozing skin lesions 3. Bleeding disorders
Which kind of bites in the child care setting can potentially transmit HBV?
A bite that breaks the skin has the potential to transmit the virus (the virus is not transmitted by simple contact of saliva or blood with intact skin)
What is the transmission likelihood of HIV by a bite in the child care setting?
Extremely unlikely. There has been no report of HIV transmission in child care. Only rare reports of HIV by severe bites by adults where considerable blood exchange has occurred.
Of HBV, HIV, and HCV; rank the three viruses based on the risk of transmission by a bite in a child care setting
All of these are of low likelihood in general. Risk of transmission is higher with HBV, followed by HCV, and then HIV (lowest likelihood)
Do bites in the child care setting lead to bacterial infections?
Bites from young children rarely lead to bacterial infections. Routine wound care should decrease the risk of infection to almost zero
In the case of a bite that breaks the skin, if either the biter or the one bitten is known to be a HBV carrier, what needs to be done?
If the child is known to be non immune or incompletely immunized, then hepatitis B immunoglobulin and HBV vaccine should be administered
In the case of a bite that breaks the skin, if one child is non immune or incompletely immunized and the status of the other child is unknown, what needs to be done?
Because of the low risk of infection, HBV testing is not justified. The nonimmune child should be given the HBV vaccine
In the case of a bite that breaks the skin, and both children’s HBV status is unknown, what needs to be done?
Because of the low risk of infection, HBV testing is not justified. Both children should be given HBV vaccine, unless already fully immunized
Why is PO erythromycin not used in babies to treat gonorrhea/chlamydia?
Association with pyloric stenosis
What is the CPS stance on neonatal ocular prophylaxis with erythromycin?
May no longer be useful and should not be routinely recommended
What is the management of infants exposed to N gonorrhoeae who appear to be healthy at birth?
They should have a conjunctival culture for gonorrhea and receive a single dose of Ceftriaxone
What is the management of infants exposed to N gonorrhoeae who appear to be unwell at birth?
Take blood and CSF cultures. Consult peds ID
In what situation will a patient have IgG varicella antibodies?
Only when they were naturally exposed. Patients who received the varicella vaccination do not demonstrate an IgG to VZV
Why do we currently give the second varicella vaccine at 4-6 years of age?
To prevent secondary vaccine failure (waxing and waning)
What is the minimum space (duration of time) that is needed before a child can receive the second varicella vaccine?
The two doses must be given a minimum 3 months apart for children less than 12 years old, and 4 weeks apart for older children
For a child who sustained a needle stick injury, what do you do for HBV prophylaxis when a child has not been fully vaccinated against HBV?
For a child who sustained a needle stick injury, what do you do for HBV prophylaxis when a child has been fully vaccinated against HBV?
