Choosing Wisely - Rational Antibiotic Usage

1. Choosing Wisely
Dr Matthew Skinner
General/ID Physician
14th June 2018

2. Outline
• Cases to consider:
– Why that antibiotic?
– What would change a choice?
– Where to look when stuck
– Best use of ID service

3. Presenting Complaint
• 41 year old ♀
• 7 days of dry cough with fevers, rigors &
sweats
• 3 weeks of lethargy, myalgias & low grade
fevers
• GP prescribed amoxycillin 10 days prior →
presumed chest infection

4. Emergency Department
• Febrile
• Further examination reported as normal
• Clear chest x-ray
• Urinalysis unremarkable
• Presumptive diagnosis → undifferentiated
viral illness
• Discharged home

5. Next Day
• 15-minute episode of central chest pain:
– Occurred at rest
– Associated mild dyspnoea
– No radiation
– Pain was neither pleuritic nor positional

6. Examination
• Febrile: 37.9ºC
• Tachycardic: 106 bpm
• Hypertensive: 150/80 mmHg
• Cardiovascular examination:
– Splinter haemorrhages
– Diastolic murmur
– No signs of heart failure

7. Initial Tests
• FBE: Hb 108; WCC 13.4; NΦ 11.1; Plt 415
• U&E: Na+ 136; K+ 3.9; Ur 3.1; Cr 56
• LFTs: albumin 39; bilirubin 8; ALT 71; AlkP
141; γGT 230
• CRP: 250
• ESR: 108
• Troponin T <0.01
• ECG normal

8. Further History
• Migrated from Philippines >20 years:
– Last visited at Christmas
• Married with 2 young children
• Mental health care nurse
• Non-smoker & no alcohol
• No recreational intravenous drug use, tattoos
or body piercings

9. Further History
• Her husband had been diagnosed & treated
for gonococcal urethritis a month prior with
ciprofloxacin
• She received ciprofloxacin prophylaxis at that
time (all tests negative)

10. Investigations
• Two further sets of blood cultures were sent
• Transthoracic echocardiogram performed

11. Echocardiogram

12. Echocardiogram

13. Empiric Treatment
• Infective endocarditis:
– Flucoxacillin 2g IV QID
– Ceftriaxone 2g IV daily
• Stat dose of azithromycin 1g oral to cover
possible concurrent chlamydial infection

14. Blood Cultures
• 2 days later → 2 aerobic blood cultures positive for
Neisseria gonorrhoeae
• Therapy rationalised to 2g IV ceftriaxone daily

15. Treatment
• Excellent clinical response:
– Defervescence, night sweat resolution
– Normalisation of inflammatory markers
• Discharged to HITH after a week of inpatient
therapy:
– Total antibiotic course 18 days
– Screening for STIs negative

16. 3 Weeks Later
• Admitted to hospital:
– Exertional dyspnoea → rest
– Significant functional limitations
– Torrential aortic regurgitation

17. Repeat Echocardiogram

18. Outcome
• Aortic valve replacement:
– No growth from valve tissue
– Peri-operative prophylaxis with ceftriaxone
• Discharged home 10 days post procedure:
– Cardiology, cardiothoracic and infectious diseases
follow-up

19. Follow Up
• Husband re-treated for Neisseria gonorrhoeae
(repeat test negative)
• 3 month review:
– STI serology negative (husband & wife)
– Clinically well
– No warfarin complications

20. HEADACHE & FEVER
• A 33 year old lady presented to the ED with
one day of headache, fever and rigor.
• Examination was normal except for a fever of
39ºC
• Investigations revealed neutrophilia and
raised CRP. Blood culture was positive
• Her CT scan is shown
• What does it show?
• What could the organism be?

21. CT brain 28/5/08
Gas in
cavernous
sinus

22. CT bone windows
28/5/08
Sphenoid
sinusutis

23. Gas in
cavernous
sinus
CT brain 28/5/08

24. H Influenzae
Positive blood culture on 28/5/08
Cetriaxone begun 28/5/08

25. Haemophilus influenzae
CULTURE
Note - the satellitism around the staph streak
- XV factors
- sensitivities

26. The next day after IV ceftriaxone the gas
had gone – 29/5/08
Sphenoid
sinusutis

27. The next day after IV ceftriaxone the gas
had gone – 29/5/08

28. The next day after IV ceftriaxone the gas
had gone – 29/5/08

29. PROGRESS
• She responded quickly and was discharged
home on 14 days of ciprofloxacin.
• Note the followup CT scan – all clear.

30. Followup CT scan

31. Cellulitis
• This 39 year old man presented with fever,
rigors and “cellulitis” over his right shin.
• Fevers continued on treatment and he
developed a collection which was drained
twice.
• What does the bone scan show?
• What is the organism?

35. Nuclear bone scan
Flow study Bone study

36. An unusual cellulitis
• This 39 year old man presented to casualty with
fever, rigors and “cellulitis” over his right shin
• He was treated with IV cephazolin on HITH
• Fevers continued on treatment and he developed a
collection which was drained twice as an outpatient
• A bone scan showed the collection but no
osteomyelitis
• Group C streptococcus was isolated twice

40. Beta haemolysis
Group C strep

41. Nuclear bone scan
Flow study Bone study

42. PROGRESS WITH IV CEPHAZOLIN

43. AN UNUSUAL RASH
• This lady cut her foot on coral and sustained a
local infection
• Cultures were not helpful and she was slow to
respond to broad spectrum antibiotics
• Subsequently she developed rash elsewhere as
shown
• Punch biopsies were taken and results are shown
• Photos are shown 2 weeks apart

44. 520_547 Pt EM AH1088925
27-04-05 & 10-05-05
27-04 & 10-05
A.

45. 520_547 Pt EM AH1088925
27-04-05 & 10-05-05
27-04 & 10-05
A.

46. 27-04 & 10-05
C.

47. 27-04 & 10-05
B.
What is rash B seen here and in the following photos?
What caused the improvement?

48. 27-04 & 10-05

49. 27-04 & 10-05

50. 27-04

51. 27-04 & 10-05

52. Sweets Syndrome
This case demonstrates the utility of punch biopsies
The improvement seen is due to prednisolone

53. Case
• This 32 year old man from India presented
with painful nodules on both legs as shown
• They had been present for 4 weeks
• He was not unwell

54. 26/04: Tender & painful

55. 26/4: Tender & painful

56. Spot Diagnosis
• What is this ?
– Erythema nodosum
– Sporotrichosis
– Mycobacterium marinum
– Erythema induratum
– Mycobacterium leprae

57. INVESTIGATIONS
• Biopsy – Erythema induratum
• Quantiferon positive
• ESR 44, CRP 25
• CT chest & abdo:
– no lymphadenopathy
– NAD

58. Erythema Induratum
• Nodular panniculitis (erythema induratum) — Nodular
panniculitis, also called erythema induratum, Bazin disease,
and nodular vasculitis, is the primary alternative diagnosis
in patients with inflammatory nodules of less than eight
weeks duration involving the legs.
• Some case series report clinical distinctions between
nodular vasculitis and EN, with the former more commonly
involving the posterior aspects of the legs, and more prone
to ulceration and recurrence than EN.
• Other series, however, have indicated considerable overlap
between the clinical appearances of these entities.
• Primary tuberculosis is a leading cause of nodular vasculitis.

59. Nodules on the legs. A clinical, histological and immunohistological study of
82 patients representing different types of nodular panniculitis. AUNiemi KM;
Forstrom L; Hannuksela M; Mustakallio KK; Salo OP SOActa Derm Venereol
1977;57(2):145-54.
• Eighty-two cases of nodular panniculitis of the legs were examined clinically, histologically and
immunohistologically.
• Clinically the cases could be divided into four groups: typical erythema nodosum (ENty) (35 cases),
erythema nodosum migrans (ENmi) (11 cases), erythema induratum (EI) (11 cases) and the
remaining 25 cases not consistent with the others as "non-definite panniculitis" (NDP).
• The main histological categories were septal panniculitis and lobular panniculitis, the former
including erythema nodosum, both typical and migrans, the latter EI and NDP.
• Lobular panniculitis was divided into three subgroups in which the most prominent histological
features were epithelioid cell granuloma, vasculitis and palissading granuloma, respectively.
• Immunoglobulins in the vessel walls were found in 5 of the 46 cases of erythema nodosum, in 19 of
the 36 EI and NDP cases and, in the histological groups in 4 of the 43 cases of septal panniculitis and
in 19 of the 35 cases of lobular panniculitis, respectively.
• Fibrin was found in the walls of the papillary capillaries and deep dermal vessels in the majority of
cases of lobular panniculitis.
• In EI and NDP the follow-up time was 40 months, on average.
• Twenty-two patients were treated with antituberculous drugs, 15 became symptomless, as did 5 of
the 12 patients who were not treated at all.

60. Beginning of TB (3 drug Rx)

61. After 2 months of TB (3 drug Rx)

62. Note the improvement after 2 months
of TB treatment

63. Case
• 28 year old Australian woman
• PHx dermatitis
• Visiting Thailand after return from Switzerland
(12/09/06-24/09/06)
• Bangkok(3)-Ko Tang(4)-Bangkok(1)-Ko PiPi(4)-
Bangkok(1); arrived Thailand 24/09/06 left
06/10/06
• No IVDU but sexual contact in Switzerland
• No malaria prophylaxis, no typhoid vaccine
• HepA/HepB vaccinated
• Recalls mosquito bites

64. • October 1, arrival in Ko PiPi
• Unwell with dry cough temperatures,
rhinorrhoea and conjunctivitis (01/10)
• Stayed in bed
• D+2 - facial/palmar rash
• D+5 - truncal macular-papular rash
• Returned to Bangkok October 6
• Attended doctor at airport, im amoxycillin
• Boarded plane for Melbourne???
• Arrived late 06 October; quarantined

65. • Avian influenza excluded on history
• Alfred Hospital 0050 October 07
• Side room 0055
• Ward 7west 07/10 1224 (N 95 mask transit)
• Cough and rash predominant features
• EUC NAD
• ALT 108, CRP 45, Hb 138, WCC 3.28, Neut
2.65, Lym 0.26, N Coags
• BCs, Malaria T+T/ICT, dengue serology
• Stool spec, Nose and throat swabs

66. • Temperature 39ºC
• Normotensive
• Tachycardic
• Conjunctival injection
• Lacrimation
• Flushed
• Hepatosplenomegaly
• Coalescing rash on face
• Diffuse non-blanching, non-pruritic rash on
arms, legs and trunk
• Palmar involvement

76. Case
• WHAT IS THIS ILLNESS?
• HOW WOULD YOU DIAGNOSE IT?
• HOW WOULD YOU TREAT HER?

77. 0582884

78. Impression
• Measles
• Rubella
• Enterovirus
• Rickettsial illness
• Influenza
• Adenovirus
• Dengue fever
• Syphilis
• Typhoid fever
• Malaria
• Drug reaction
Recalled 1 x vaccination for “MMR” in year six

79. • Blood cultures –ve
• Malaria T+T + ICT –ve
• EBV IgG +ve, CMV IgG –ve, Rubella IgG >400,
Influenza A+B <10, Adenovirus IgG 2,560, GpB
Arbovirus IgG –ve, syphilis serolgy –ve; Hep A IgG
+ve, IgM –ve, HepB sAg –ve, sAb 770, HepCAb -ve
• HSV-1 PCR +ve from mouth ulcer
• Throat/Nose swabs RSV/measles PCR +ve
• Measles IgG + IgM +ve

80. Diagnosis and course
• Measles suspected
• Atypical features
– Rash day 2-3
– Antibiotics
– History of vaccination
• Notified 09 October 48 hours after
admission
• Diagnosis; Measles and RSV infection
without pneumonitis

81. Diagnosis and course
• 5 days in hospital
• Recovery of symptoms with supportive treatment
• Neutropenia to 0.42 on day 2 resolved
• Discharged home, well at follow up
• Subsequently identified as genotype D5
• Health Department initiated contact tracing
• No major contacts at Alfred (rash >4 days)

82. Measles
• Paramyxovirus genus Morbillivirus
• RNA virus with 6 structural proteins, 3 complexed to
RNA and three with the viral envelope
• Short survival time (<2hrs in air)
• Highly infectious
• Respiratory droplets
• Infectious from prodrome (3-5 days prior to rash
appearance) and for 4 days after the rash appearance

83. • Incubation period 10-14 days
• Prodrome; fever, cough, coryza,
conjunctivitis
• Rash begins on face and upper neck then
becomes generalised
• Otitis media (severe) in 7%
• Bronchopneumonia in 6%
• Encephalitis 2-10/10,000 cases (mortality
10-15% with 15-40% having severe
permanent neurological sequaelae

84. Koplik spots

85. • Subacute sclerosing panencephalitis (SSPE)
1/100,000 cases; fatal with progressive brain
damage
• Complications more common in chronically ill and
very young children
• 1976-2000 98 deaths in Australia, more than
diphtheria, tetanus, pertussis and poliomyelitis
combined
• 2001 91% of children aged 2 had been vaccinated
• 2 doses of MMR at 12 months and at 4 years of
age
• Adults born during or post 1966 should have two
doses

86. Who not to worry about
• Children aged 1-4 with one dose of vaccine
• Persons over 4 and born since 1966 with
documented evidence of 2 doses of a measles
containing vaccine
• Persons before 1966

87. Conclusions
• Sporadic outbreaks require prompt identification and
containment
• Presentation can vary
• Majority of cases “imported”
• Beware those born since 1966
• Conjunctivitis, corzya, cough and fever are hallmark
features

88. Pneumonic for Rashes
Pneumonic
1. Very
2. Sick
3. People
4. Must
5. Take
6. No
7. Exercise
Conditions
• Varicella
• Scarlet fever
• Small pox
• Measles
• Typhus/Ricketssial diseases
• Nothing (Dengue)
• Enteric fever (Typhoid)

89. Case
• 41 y.o. ♂, returned traveller from Bali, sent in
by GP to the ED with fever and rash:
– Unwell since Day 3 returning
– Presented to GP on Day 8 after returned

90. Presenting Complaint
• Day 1 of illness:
– Coryza symptoms
– Tiredness, malaise
– Mild intermittent headache
• Day 3 of illness:
– Mild “red watery eyes” ? Conjunctivitis
• Day 5 of illness:
– Fever 38˚C – No sweats/rigors
– New rash: Started on trunk, spread centrifugally
to upper and lower limbs

91. Presenting Complaint
• System review:
– No cough, SOB, chest pain
– No sore throat
– No photophobia, neck stiffness
– No nausea, vomiting
– No diarrhoea, abdominal pain
– No urinary symptoms

92. Travel History
• Travelled to Bali with family for 2/52:
– No malaria prophylaxis / travel vaccines
– Visited rural Bali
– Travelled by car around Bali
– Stayed in villa, consumed restaurant food
– Admitted few mosquito bites
– No zoonosis exposure
– No fresh water swimming
– Denied unprotected sexual intercourse & IVDU
– Everyone was well throughout the trip

93. Additional History
• PHx: nil
• Medications: nil
• Allergies: NKA
• SHx:
– Originated from Russia
– Work as a scientist in a
local university
– Wife currently 33/40
pregnant
– Daughter 3y.o. – well
– Non-smoker, no ETOH, no
recreational drug use
– Unsure of immunisation
status

94. Examination
General
• Looked well
• Haemodynamically stable:
– BP 120/75
– HR 88
– RR 16
– SaO2 98% RA
– Afebrile
Organ Specific
• Head & neck:
– Occipital & cervical
lymphadenopathy
– No Koplik spots
• Cardiovascular – unremarkable
• Respiratory – unremarkable
• abdominal – unremarkable
• No arthralgia

95. Examination
• Generalised, blanching
maculopapular
erythematous rash
• Predominantly on
upper torso, but
involved face, upper
and lower limbs

96. DDx
Fever on returned traveller
• Malaria
• Dengue
• Typhoid
• Respiratory infections:
URTI / Influenza / pneumonia
• Gastroenteritis
• Amoebic liver abscess
• Incubation period / Dx / Mx

97. Investigations
• FBE 147 / 3.24 / 140:
– Neutrophils 1.83
– Lymphocytes 0.89
• Malaria thick & thin films
– negative
• Blood culture – no growth
• UEC & LFT normal
• Respiratory viruses PCR –
negative
• MSU – NAD
Serology:
• EBV:
– IgM negative
• Measles:
– IgM negative
– IgG positive
• Rubella:
– IgM positive
– IgG negative

98. Management
• Home isolation – for another day (4 days
after rash onset)
• Wife: 33/40 pregnant
–Congenital Rubella Syndrome – transmission
depends on timing of infection
–Has been adequately vaccinated
–No treatment needed
• Daughter – Due for 2nd MMR
• Department of Health notification

99. Clinical manifestation:
• Can be asymptomatic
• Prodromal symptoms: (1-5 days)
–Malaise
–Low grade fever
–Lymphadenopathy (post cervical/occipital)
• Rash (3-5 days)
–There is variation in the progression, extent,
and duration of the rubella exanthem

100. Rubella
Measles
Photos from Fairfield Hospital slide collection

101. Rash begins on face…
Rubella
Photos from Fairfield Hospital slide collection

102. Then, spreading down
the body centrifugally.
Rubella
Photos from Fairfield Hospital slide collection

103. And to other parts of the
body.
Rubella
Photos from Fairfield Hospital slide collection

104. Management
• Isolation
• DHS notification & Contact tracing
• Pregnancy

105. Rubella prevention: Vaccines
• 2 types:
– MMR vaccine
– Monovalent Rubella vaccine
• Principal aim: Prevent Congenital Rubella
Syndrome
• Target:
– All children – at 12 & 18 months
– Women of child bearing age
– Post-partum seronegative women
– Adolescent & adult males
- born after 1966 – need 2 doses of MMR if no
documented vaccination record
– Healthcare worker & people working with children

106. Case
• 35 yr old reserve bank manager
• In Nukualofa (Tonga) for 3 days 5-8 March
• Became ill on 12th March
• Fevers, headache, sore eyes, back ache, Joint
aches
• Admitted to The Alfred on 13th March
• Later developed a rash

107. 1179838
What does he have ?
How would you prove it ?

108. Dengue fever
• 35 yr old reserve bank manager
• In Nukualofa (Tonga) for 3 days 5-8 March
• Bitten by mosquitoes
• Became ill on 12th March
• Fevers, headache, sore eyes, back ache, joint aches
• Admitted to The Alfred on 13th March
• Later developed a rash
• Lethargy took 5 weeks to resolve

109. 1179838
Dengue
– note the blanching sunburn like rash

110. Case
• This 29 yr old lady presented with a rash on her
left foot 4 weeks after returning from Thailand
• Travel included Bangkok and coastal areas
including swimming
• The rash was itchy and changing daily
• She had tried topical medication with no help

114. Questions
• What is the diagnosis?
• What organism(s) cause this?
• What would you treat her with?

115. CUTANEOUS LARVA MIGRANS
• Cutaneous larva migrans
• Usually due to Ancylostoma braziliense (dog
and cat hookworm )
• Treatment: Albendazole or ivermectin

116. Case
• This young man has spent a few months in the
tropics.
• He presented with this rash.
• Skin scrapings were taken – what does he
have?
• How would you treat him?

120. Malassezia furfur
• M. furfur is a yeast - appearance of “spaghetti and
meatballs” is diagnostic. Culture is difficult (olive oil needed )
• It causes pityriasis versicolor or tinea versicolor. Rarely can
cause catheter related sepsis related to TPN or intralipid.
• Treatment is with selsun shampoo topically or an azole
cream.

121. An Unusual Cause of Diarrhoea
• A 41 yr old man with chronic diarrhoea and
abdominal discomfort for 9 years was referred
for a colonoscopy.
• At colonoscopy a worm was found emerging
from the terminal ileum.
• With “tugging” a small segment was removed
but the private lab could not identify the
parasite.

122. An Unusual Cause of Diarrhoea
Colonoscopy view – forceps

123. An Unusual Cause of Diarrhoea
• After praziquantel the worm was expelled into
the toilet and brought to The Alfred for
identification.
• The patient later admitted to having
symptoms for 9 years since visiting Japan!

124. Eggs
• Worm - ~ 2 metres long

125. • Eggs

126. Eggs – high power

127. • DIPHYLLOBOTHRIASIS: FISH TAPEWORM — Fish tapeworm infections are due to
parasites of the Diphyllobothrium species. Different species are endemic in various parts
of the world. The most common species worldwide is D. latum. It is seen predominantly
in northern Europe and Japan but has also been reported from many other countries.
• Life cycle — Humans are the main definitive host for D. latum and the most important
reservoir of infection. However, some other Diphyllobothrium species primarily infect
birds or mammals and are less common causes of human infection.
• As with Taeniasis, the adult parasites live in the human intestinal tract, and eggs and
proglottids are passed in the faeces. These tapeworms can be very large, measuring up
to 12 m and containing 3000 to 4000 proglottids. When eggs are discharged into
freshwater (D. latum and most other species) or marine water (D. pacificum), they hatch
and release motile embryos which are ingested by minute waterfleas (first intermediate
hosts). Following ingestion by larger crustaceans and fish (second intermediate hosts),
these motile embryos develop into larvae (known as sparganum or plecocercoid larvae),
which are infectious to humans. When raw or undercooked infected fish and crustaceans
are eaten, these larvae are ingested; development into an adult tapeworm in the human
intestine completes the life cycle.
• Many freshwater fish can transmit D. latum infection. People who eat various forms of
raw fish, such as sushi, sashimi, and ceviche, are at risk of infection. Infection is often
associated with raw salmon.
• Passage of eggs begins approximately one month after ingestion of the contaminated
fish (the prepatent period). Each tapeworm can produce more than one million eggs per
day, but egg passage can be intermittent. Eggs are passed from the adult fish tapeworm
via a midline uterine pore. The adult tapeworm survives for approximately 10 years in
the human GI tract.

129. • Clinical symptoms — Most individuals with diphyllobothriasis are asymptomatic. A
proglottid can occasionally be regurgitated or passed in the faeces, but this occurs less
commonly than with Taenia species. Nonspecific symptoms that have been attributed
to infection include fatigue, diarrhoea, numbness, dizziness, and allergic symptoms.
Mechanical obstruction of the intestine can occasionally occur if there are several
worms that become entangled.
• Vitamin B12 deficiency — The classical manifestation of infection with D. latum is
megaloblastic anaemia due to vitamin B12 deficiency. D. latum has a unique affinity for
vitamin B12 and therefore competes with the host for absorption. Deficiency develops
particularly if the host already has marginal B12 levels before acquiring the infection.
• It has been reported that approximately 40 percent of infected individuals have low
B12 levels but that only 2 percent actually develop anaemia . If the B12 deficiency is
severe, pancytopenia, glossitis, dyspnea, and neurologic abnormalities (subacute
combined spinal and peripheral nerve degeneration) can develop.
• A peripheral eosinophilia of 5 to 10 percent may occur in some infected patients.
• Diagnosis — Megaloblastic anaemia and B12 deficiency can be a clue to the diagnosis
of diphyllobothriasis.
• Microscopy — The definitive diagnosis is made by finding characteristic eggs in the
stools or occasionally by finding evacuated segments of proglottids.

130. Differential Morphology of Cestodes: Eggs
Species Size Shape Colour Stage Specific
Features
Taenia saginata,
T. solium
35 μm
31-43 μm
Spherical
with thick
striated shell
Walnut
brown
Embryonated
6-hooked
oncosphere
Proglottids
or scoleces
for
speciation
Hymenolepsis
nana
47x37 μm
40-60 x 30-50 μm
Ovoid with 2
distinct
membranes
Colourless Embryonated
6-hooked
oncosphere
Polar
filaments
Diphyllobothrium
latum
66x44 μm
58-76 x 40-51 μm
Oval or
ellipsoidal
with
operculum
Yellow to
brown
Unembryonated Resembles
hookworm
egg

131. • The eggs of Diphyllobothrium species have an operculum, or lidlike opening, which is
commonly seen in trematode eggs but is not seen with eggs of other cestodes .
• The eggs measure 40 by 60 µm and have a small knob on the end opposite the operculum.
Concentration methods are not necessary for diagnosis in most cases, since there are
typically high numbers of eggs present in the stool.
• The scolex of the adult is spoon-shaped and has characteristic ventral sucking grooves
known as "bothria" with which the worm attaches to the intestinal mucosa. The
proglottids can be differentiated from Taenia proglottids because their width is greater
than length, and there is a characteristic egg-filled uterus that appears as a dark rosette in
the center of mature proglottids. However, it is generally difficult to distinguish among the
species of Diphyllobothrium based upon morphology.

132. • TREATMENT — The first line treatment for all of these tapeworm infections is
praziquantel. Praziquantel — Praziquantel is a synthetic heterocyclic isoquinolone-
pyrazine derivative.
• Mechanism of action — Praziquantel induces ultrastructural changes in the
teguments of parasites, resulting in increased permeability to calcium ions. Calcium
ions accumulate in the parasite cytosol, leading to muscular contractions and
ultimate paralysis of adult worms . By damaging the tegument membrane,
praziquantel also exposes parasite antigens to host immune responses . These
effects lead to dislodgement of worms from their intestinal sites and subsequent
expulsion by peristalsis.
• Dosing based upon species of tapeworms — Different doses of praziquantel are
required for different species :
• 5 to 10 mg/kg in a single dose is administered for taeniasis (T. saginata and T.
solium) and diphyllobothriasis; efficacy is >95 percent.
Results of therapy — After treatment, the proximal parts of the tapeworms
disintegrate. Gravid proglottids can release eggs as they are being destroyed.
Because praziquantel kills adult worms but not eggs, precautions should be taken to
prevent autoinfection, laboratory-acquired infection, or dissemination to others,
particularly for T. solium.
• For treatment of tapeworms to successfully result in cure, the scolex must be
destroyed and eliminated, since a residual scolex can result in regrowth of the entire
tapeworm. With large tapeworms such as Taenia and diphyllobothrium species,
intact or disintegrating segments and eggs may be passed for several days. Following
therapy, stools should be rechecked for eggs at one month to document cure.