420

In common medical practice most patients with increasedjugular venous pressure are likely to have some impairmentof left ventricular function with a normal or good rightventricle. However, the abdominojugular test is not specificfor increased left ventricular filling pressure. Some patientswith raised jugular venous pressure and a positive test willhave isolated right ventricular dysfunction with a normalpulmonary artery wedge pressure. Moreover, the test is notsensitive for diagnosing cardiac failure. In patients withincreased pulmonary artery wedge pressure who havereduced blood volume due to diuretic therapy, or who havebeen treated with venodilating agents such as nitrate drugs,neither a raised jugular venous pressure nor a positiveabdominojugular test will necessarily be present. Theabdominojugular test is a useful clinical sign that needs to becorrectly executed and interpreted.

PENICILLIN ALLERGY IN CHILDHOOD

PENICILLIN allergy in children is overdiagnosed; doctorsseldom question a report that a child is allergic to penicillin,fearing the possibility of fatal anaphylaxis. However, whenchildren said to be allergic to penicillin are given the drug,very few experience adverse reactions.l-4 A few simpleinquiries can often exclude the diagnosis. A rash duringantimicrobial therapy may be caused by an underlyinginfection (eg, measles, rubella), or by a colouring agent orpreservative (eg, tartrazine, benzoic acid) included in aliquid preparation of the antibiotic; loose stools usuallyindicate an underlying viral infection or a disturbance of gutflora. Sometimes parents report penicillin allergy when aside-effect has occurred to a completely different antibiotic.

Degradation products of penicillin may bind with tissueor serum proteins to form an immunogenic complex whichcan elicit an immune response. Penicillin allergy isattributed either to the benzylpenicilloyl hapten (theso-called "major" determinant, because 95% of tissue-bound penicillin is in this form), or to a group of compoundscollectively known as "minor" determinants, which areparadoxically responsible for many of the severest allergicreactions. Adverse reactions to penicillin are most simplyclassified by the timing of their occurrence.5.6 Immediatereactions-within an hour of administration-are usuallydirected against the minor determinant antigens and aremanifested by urticaria, laryngeal oedema, bronchospasm,and anaphylactic shock. Accelerated reactions-1-72 hoursafter administration-have the same clinical features asimmediate reactions, and are usually directed against themajor determinant. Late reactions, the mechanisms ofwhich are generally less well understood, occur more than 72hours after drug administration; maculopapular (measles-like) rash, urticaria, serum sickness, erythema multiforme,haemolytic anaemia, thrombocytopenia, and neutropeniaare included in this group. Rarely, late reactions are due tothe new development of an immediate or acceleratedreaction. Although these reactions are shared by all

1 Brown BC, Price EV, Moore MB. Penicilloyl-polylysine as an intradermal test ofpenicillin sensitivity. JAMA 1964, 189: 599-604

2. Oswald STA. Penicillin allergy a suspect label. Br Med J 1983; 287: 265-66.3. Chandra RK, Joglekar SA, Tomas E. Penicillin allergy antipenicillin IgE antibodies

and immediate hypersensitivity skin reactions employing major and minordeterminants of penicillin. Arch Dis Child 1980, 55: 857-60.

4 Graff-Lonnevig V, Hedlin G, Lindfors A. Penicillin allergy—a rare paediatriccondition? Arch Dis Child 1988, 63: 1342-46

5 Weiss ME, Adkinson NF. Immediate hypersensitivity reactions to penicillin andrelated antibiotics. Clin Allergy 1988, 18: 515-40

penicillin and cephalosporin antibiotics, anaphylaxis is lesscommon with flucloxacillin, dicloxacillin, carbenicillin,ticarcillin, and the cephalosporins.6 Ampicillin can provokethe same allergic reactions as other penicillins, but inaddition is associated with an especially high frequency of anon-allergic maculopapular rash, beginning a week or moreafter starting therapy. 6,7A history of penicillin therapy associated with an

immediate or accelerated onset skin eruption, especially anurticarial rash, or with more serious symptoms such aslaryngeal oedema or anaphylactic shock, suggests penicillinallergy. Readministration of penicillin to such patientscarries the risk of allergic reactions, most importantly fatalanaphylaxis. For this reason, it is essential to inquire aboutpossible penicillin allergy before giving an injection ofpenicillin, but even so not all patients with such an allergyhave a history of penicillin administration8-sensitisationmay have occurred through inadvertent exposure to

penicillin8 in food, milk,9 poliovaccine, or even soft drinks.loWhen there is a firm history of penicillin allergy, the choiceis either to withhold antibiotics or to avoid the use of

penicillins, cephalosporins, or imipenem, which, like thepenicillins, contains a beta-lactam ring and cross-reactsextensively with penicillin." Almost all deaths from

anaphylaxis have resulted from parenteral administration ofthe drug.6,8

Tests to predict whether a patient will react to penicillinare unhelpful in routine clinical practice. Although severalstudies have shown that a negative response to skin tests withthe major determinant and a mixture of minor determinantsis infrequently associated with adverse reactions to

penicillin, mixtures of minor determinants are unstable"and not commercially available, and skin tests themselvescarry a significant risk of anaphylaxis and even death.6.12Such tests also have to be repeated when another course ofpenicillin is contemplated, because the patient may havebecome sensitised meanwhile, and it is possible thatthe skin testing antigens may sensitise the patient.Radioallergosorbent (RAST) testing, like skin testing, needsto be done within a few months of a suspected reaction ;3,13 itis also of little value because the results are not available for at

least a day and there are no RAST tests for minordeterminants. On the very rare occasions in childhood whentreatment with penicillin is essential (eg, in patients withendocarditis), the patient can be desensitised by oral andthen continuous intravenous administration,13 but this

procedure carries a theoretical risk of fatal anaphylaxis.Protection afforded by desensitisation is short lived,although a state of desensitisation can be maintained bylong-term administration of low doses of oral penicillin.14

6. DeSwarte RD Drug allergy. In Patterson R, ed Allergic diseases Diagnosis andmanagement. 3rd ed Philadelphia: Lippincott, 1985: 505-661

7. Shapiro S, Slone D, Siskind V, Lewis GP, Jick H Drug rash with ampicillin and otherpenicillins. Lancet 1969; ii: 969-72.

8. Idsoe O, Guthe T, Willcox RR, De Weck AL Nature and extent of penicillinside-reactions, with particular reference to fatalities from anaphylactic shock BullWHO 1968; 38: 159-88.

9 Dewdney JM, Edwards RG. Penicillin hypersensitivity—is milk a significant hazard?J R Soc Med 1984, 77: 866-77.

10 Wicher K, Reisman RE Anaphylactic reaction to penicillin (or penicillin-likesubstance) in a soft drink. J Allergy Clin Immunol 1980, 66: 155-57.

11 Saxon A, Beall GN, Rohr AS, Adelman DC. Immediate hypersensitivity reactions tobeta-lactam antibiotics. Ann Intern Med 1987; 107: 204-15

12 Dogliotti M. An instance of fatal reaction to the penicillin scratch-test Dermatologica1968, 136: 489-96.

13 Fratft D,Wide L Clinical patterns and results of radioallergosorbent (RAST) and skintests in penicillin allergy Br J Dermatol 1976; 94: 593-601.

14. Stark BJ, Earl HS, Gross GN, Lumry WR, Goodman EL, Sullivan TJ. Acute andchronic desensitisation of penicillin-allergic patients using oral penicillin J AllergyClin Immunol 1987, 79: 523-32