Transcript (Ureaplasma) in the Newborn

Genital Mycoplasmal
Disease in the Newborn
John Baier M.D.
University of Manitoba
Characteristics of
Mycoplasmas


Mycoplasmas are the smallest self replicating
organisms
Do not have a cell wall like other bacteria
• Do not Gram stain

Small genome and lack enzymes needed to
synthesize may compounds
•
•
•
•
Complex nutritional requirements
Require host cells and their products
Difficult to culture outside of hosts
Will not grow on routine bacteriologic media
Mycoplasmas in Human
Disease

Difficulties in culturing have made establishing a
pathogenic role of mycoplasmas difficult

Diseases caused by mycoplasmas
• acute Mycoplasma pneumoniae
• often subacute or chronic
• lack well defined clinical presentations
Mycoplasmas in Human
Disease

Diseases potentially caused by mycoplasmas
• Periodontal disease
• Arthritis
• Urethritis, cervicitis
• Prematurity
• Recurrent pregnancy loss
• AIDS related diseases
• Chronic lung disease
Mycoplasma salivarium
Mycoplasma arthitidis, Mycoplasma
fermentans
Mycoplasma hominis, Ureaplasma
urealyticum
Mycoplasma hominis, Ureaplasma
urealyticum
Mycoplasma hominis, Ureaplasma
urealyticum
Mycoplasma penetrans, Mycoplasma
fermentans
Mycoplasma hominis, Ureaplasma
urealyticum
Mycoplasmas Colonizing
the Genital Tract

Ureaplasma urealyticum/ Ureaplasma parvum
•
•
•
•

Mycoplasma hominis
•
•
•
•

premature labor
pneumonia
meningitis
BPD
premature labor
pneumonia
meningitis
BPD?
Mycoplasma fermentans
• no known association with perinatal disease

Mycoplasma genitalium
• Only detectable by PCR
• no known association with perinatal disease
Epidemiology of Genital
Tract Mycoplasmas

Commonly found
• 40-80% pregnancies colonized with Ureaplasma urealyticum
• 5-50% pregnancies colonized with Mycoplasma hominis

Increased colonization with
• increased number of sexual partners
• earlier age of first intercourse
• isolation of other STDs (Chlamydia trachomatis)
Transmission of Ureaplasma
urealyticum to the Newborn

Vertical transmission
• 18-55% in term infants
• 29-55% in preterm infants

Factors that increase chance of transmission to
fetus
• rupture of membranes
• chorioamnionitis
• vaginal delivery


Transmission rate varies with gestational age
Once acquired colonization of respiratory tract
may persist for months untreated
Percent Transmission
Perinatal Transmission of
Ureaplasma to Newborn
100
90
80
70
60
50
40
30
20
10
0
<1500 1501- 2001- 2501- 3001- 3001- >3500
2000 2500 3000 3500 3500
Klein JO 1969
Birth Weight
Consequences of Genital
Mycoplasma Infections in the
Newborn
 Variable
response to infection
• self limited with no long term effects
• acute pneumonia
• chronic inflammatory response may lead to
development of chronic lung disease
Ureaplasma urealyticum as a
cofactor in the development of
BPD

BPD is a multifactorial disease
• Uu is not THE CAUSE of BPD

Conflicting data in the literature
• different culture sites/methods
– single culture vs. multiple culture
– tracheal aspirate vs. nasal aspirate
– reliability of cultures
– PCR vs. culture
• different populations
– not a disease of larger infants
• colonization with Uu is of no significance (generally) in a otherwise
healthy term infant
– different frequencies of organisms causing preterm birth

Overall, isolation of Uu
from airways is
associated with a 2-3
fold increase in the
incidence of oxygen
dependency at 28 days
of age

Associated with a lesser
but still significant
increase in the incidence
of oxygen dependency
at 36 weeks PCA
Percent BPD
Ureaplasma urealyticum as a cofactor
in the development of BPD
100
90
80
70
60
50
40
30
20
10
0
*
LSU 1992-94
*p<0.001
Uu present
Uu absent
Mechanisms of lung injury
caused by Mycoplasmas

Live and heat killed mycoplasmas induce inflammatory
cytokine production in a variety of lung cell types
• mononuclear cells (alveolar macrophages)
• respiratory epithelium
• fibroblasts

In most mycoplasmas the cytokine inducing activity is
been determined to be membrane lipoproteins
• slight similarity to LPS
• utilize LPS receptors (toll like receptors)

The component that stimulates cytokine production has
not been determined for Ureaplasma urealyticum
In vitro infection with U. urealyticum
preterm monocyte cytokine release
Monocytes from preterm cord
blood (24 to 32 weeks) were
incubated with CRPMI-10% FCS
alone, U. urealyticum at 103
CCU (UU3) (low inoculum) or
106 CCU (UU6) (high inoculum),
or LPS (100 ng/ml) with or
without U. urealyticum for 24 h.
(A) TNF- ; (B) IL-6; (C) IL-10;
(D) IL-8. Results are expressed
as percentages of the LPS
positive control value n = 6). *,
P < 0.05 versus medium control;
P < 0.05 versus LPS.
,
Pulmonary Inflammation and isolation of
Ureaplasma urealyticum
MCP-1 pg/ug Sec
3000
No Uu
Uu
2500
2000
1500
1000
500
0
1
3
5
9
Age (Days)
14
21
Induction of CC chemokines by M hominis and U
urealyticum:
Cord blood mononuclear cells
Cytokine (pg/ml)
8000
7000
6000
5000
MIP-1 alpha
MIP-1 beta
MCP-1
MCP-2
MCP-3
4000
3000
2000
1000
0
Control
Uu
Control
Mh
Uu increases inflammatory
responses in animal models

Yoder et al 2003
• Intra-amniotically infected premature baboons
• Increased inflammatory cell infiltrate in Uu +ve animals compared to
controls of Uu – ve animals
• Predominately monocytic cells
Factors determining “pathogenicity” of
Genital Mycoplasmas

Gestational age
• animal models suggest that immature animals develop more severe disease
• clinically this is a disease of the smallest infants
– reduced transfer of maternal IgG
– immature immune responses

Surfactant deficiency
• infants with mature lungs rarely develop problems
• lack of mycoplasmacidal effects of surfactant proteins

Oxygen administration/Mechanical ventilation
• synergistic effect between oxygen and infection

Maternal immune response
• low antibody production in mother increases risk of disease in newborn

Genetic Factors?
• Variations in cytokine or pathogen pattern recognition genes
– IL-1RA (maternal)
– TLR2

Biovar or serotype does not play a role
• no specific pathogenicity factor known
Surfactant protein A: mediation of
mycoplasmacidal activity of alveolar
macrophages
Hickman-Davis et al 1998
Clinical Presentation






Transient colonization
Non resolving HMD/Persistent
colonization
Rapid development of BPD like changes
Pneumonia
PPHN (rare)
Apnea
Transient respiratory
tract colonization



Incidence is not known
May constitute ~ 25% of culture positive infants
Present with mild-moderate respiratory distress
• HMD or TTN
• Positive culture for Uu/Mh incidental



Rapid resolution without sequelae
Culture results return after patient is extubated
and relatively well
Require no treatment
Non resolving HMD/Persistent
colonization




Represents largest proportion of infants
Initial presentation of typical HMD
Incomplete resolution
May have multiple cultures positive
• initial may be negative
Infants with persistent Uu are
more likely to develop BPD
Outcome (percent)
100
O2 at 28 days
O2 at 36 weeks
80
60
40
20
0
Follow up Uu culture
negative or indeterminate
Baier RJ et al 2003
Follow up Uu culture
positive
Rapid development of
BPD like changes

Initial presentation of typical HMD
• does not have to be severe


Poor resolution
Development of cystic appearance by first weeks
of life
• can be confused with PIE
• likely represents pneumonia

Worse prognosis?
Ureaplasmal pneumonia

May present at birth
• indistinguishable from HMD
• pneumonic appearance

May present several weeks after birth
• apnea
• respiratory distress
• may progress to chronic lung disease

No other agent is cultured
Adverse CNS Outcomes in infants with
Ureaplasma urealyticum
70
*
Uu Positive
60
Uu Negative
*
Incidence (%)
50
*
40
30
20
10
0
All IVH
Severe IVH
Hydrocephalus
Shunt
*p<0.02
Incidence (%)
Interaction between isolation of Uu
and IL-1b –511T polymorphism
45
40
35
30
25
20
15
10
5
0
IVH
Uu negative and 511T negative
Uu Positive and 511T neagtive
PVL
IVH or PVL
Uu negative and 511T positive
Uu Positive and 511T positive
Diagnosis and
Management of
Mycoplasmal Infections
Diagnosis of Genital
Mycoplasma infections

Who to culture?
• Routine
– Infants with birth weight less than 1500 grams
– mechanical ventilation
– preterm labor ± ROM, chorioamnionitis
• Suspect genital mycoplasmas
– early BPD like changes
– non resolution of HMD
– culture negative pneumonia
Diagnosis of Genital
Mycoplasma infections

What to culture?
• Tracheal aspirate
• Blood ?
• Little predictive value of positive cultures from nose, throat,
rectum, gastric aspirate

Value of repeated cultures?
• Persistent positive cultures correlate better with development
of BPD
• frequently initial culture at birth may be negative
• 3x during first week if intubated
Diagnosis of Genital
Mycoplasmas

Culture methods
• Mycoplasmas are not hardy
organisms
– fresh specimens
• specialized transport media
– frozen
– blood
– CSF
• frequently there are natural
inhibitors to growth
– serial dilutions
– multiple media
• cultures are difficult to interpret
– require microscopic
examination of colony
formation
– color change in media may
be from other organisms
Diagnosis of Genital
Mycoplasmas


Polymerase Chain Reaction (PCR)
Ureaplasma
• Urease gene
• Multiple banded antigen
– distinguishes between U. urelyticum and U. parvum

Mycoplasma hominis
• 16S rRNA gene
PCR for Ureaplasma based on Urease gene
PCR vs Culture

PCR
• rapid results <24 hours
• biovar information
• very sensitive
– relevance of detecting ~ 10 organisms

Culture
• may take longer than a week for positive ID
• no biovar information
• false negatives may be common depending on lab experience
and specimen handling
• less sensitive
– detects larger numbers of viable organisms
Treatment Strategies
Should
Whom
What
you treat
to treat?
to treat with?
Treatment of Genital
Mycoplasmas


Treatment of genital mycoplasmas is
controversial
No studies have been done to show that it alters
outcome
• diagnosis and treatment is often delayed
– not considered
– cultures take 5-7 days
• distinguishing between colonization and infection
• strains of Ureaplasma may be resistant to antimicrobials
Treatment of Genital
Mycoplasmas: Strategies

Empiric treatment of at risk infants
• no studies
• possible benefit of early treatment
• treatment of infants who won’t develop disease with broad
spectrum antibiotics
– increased risk to develop yeast infections?

Treatment of culture positive or persistently
positive infants
• delay of treatment after much of the damage may be done
• the few studies done show little or no benefit
Treatment of Genital
Mycoplasmas
Ureaplasma urealyticum
• sensitive to macrolide
antibiotics
• erythromycin 30-40 mg/kg/day
– 10-14 days (no studies)
– Failure to clear organism
• azithromycin
– no data
– 10mg/kg day 1 then
5/mg/kg/day x 6days?
• insensitive to clindamycin
• sensitive to chloramphenicol
and tetracyclines
– resistant cases or
meningitis?
100
Positive TA culture (%)

80
60
40
20
0
Day 0
Day 5
Day 10
Day 15
Time after start of treatment
(days)
Baier RJ et al 2003
Treatment of Genital
Mycoplasmas

Mycoplasma hominis
•
•
•
•
insensitive to macrolides
may be sensitive to gentamicin (not reliable)
sensitive to clindamycin
sensitive to chloramphenicol and tetracyclines
– resistant cases or meningitis?
Summary




Genital mycoplasmas frequently colonize and
infect the respiratory tract of preterm infants
Infants may develop self limited disease from
infection or may have chronic inflammation that
may predispose to the development of BPD
Identification and treatment of infants with these
organisms is frequently delayed or missed
because of specialized culture requirements
The benefits of treating these infants have not
been determined although treatment of infants
with pneumonia or chronic inflammation may be
warranted