496 DEMONSTRATION OF LEGIONELLA PNEUMOPHILA BY "HALF-A-GRAM" STAIN easy visualisation of Legionella pneumophila by stain procedure reported by Dr de Freitas and colleagues (Feb. 3, p. 270) is accurate but your readers should the observation with caution. As de Freitas et al. irnply any Gram-negative organism is or can be variably Grampositive before decolorisation. This fact is historical. The idea nevertheless is a very useful one for allowing rapid assessment of how many organisms are present in any specimen, their sizes, and morphologies. A methylene-blue staining procedure would accomplish the same ends, but both procedures are much more rapid than a Giemsa, and certainly more rapid than Dieterle’s method. As de Freitas et al. state, their pro-
replace immunofluorescent staining for ultimate
identification. Brownlee Laboratory, Ruchill Hospital, and Patholoev Department,
University of Glasgow, Western Infirmary, Glasgow G20 9NB
JAMES F. BOYD
IgG ANTIBODY AGAINST EARLY ANTIGEN IN SUBCLINICAL CONGENITAL CYTOMEGALOVIRUS INFECTION
SIR,-Cytomegalovirus (c.M.v.) is the commonest known microbiological cause of brain damage.’ Most congenitally infected infants, however, have no clinical manifestations of cytomegalic inclusion disease that might suggest this diagnosis.2 Although the detection of viruria soon after birth is the most reliable method for the diagnosis of congenital c.M.v. infection, virus isolation is too expensive and time-consuming for mass screening. An alternative might be determination of c.M.v.-specific IgM antibody in cord serum. This method is useful in identifying c.M.v. infection in symptomatic infants, but it is not as good as virus isolation for detecting silent infection. Melish and Hanshaw,3 found c.M.v.-specific IgM in 95% SEROLOGICAL AND VIROLOGICAL DATA ON THREE CASES OF CONGENITAL C.M.V. INFECTION AND THREE CONTROLS
of life but no clinical abnormalities were observed; three other infants (cases 4-6) were born to mothers who showed seroconversions to c.m.v. during pregnancy but had escaped intrauterine infection, as judged by negative virus isolation in neonatal period. None of the six infants had IgM antibody detectable in their cord sera. In contrast, EA antibodies were detectable in all cord sera, ranging in titre from 1:10 to 1:40. The important finding was the presence of the higher EA antibody titres in the group of congenitally infected infants, especially when compared with titres in the maternal sera. Although EA antibodies were also detectable in the control group of infants, the titres were the same as or at most twice as great as maternal titres, a finding comparable with the results of complement-fixation tests and not unexpected, bearing in mind the transplacental nature of IgG antibodies. Thus, apart from virus isolation, only determinations of EA antibody titres gave positive results among various serological indices used. Our data suggest that the parallel determination of IgG-EA antibody titres in maternal and cord sera is a useful means of screening for subclinical congenital c.M.v. infections.
Department of Pædiatrics, Sapporo Medical College, Sapporo, Hokkaido 060, Japan
SHUNZO CHIBA MAKOTO KAMADA HISAAKI HANAZONO TAKU MOTOKAWA TOORU NAKAO
Department of Gynæcology and Obstetrics, Sapporo Teishin Hospital
VIRUCIDAL EFFECT OF ALCOHOLS AGAINST ECHOVIRUS 11
SIR,-Alcoholic solutions of chlorhexidine are being increasingly used to disinfect hands’ as a partial substitute for handwashing. How virucidal are they? This question is especially important to neonatal units, in which there have lately been outbreaks of enteroviral infections with tragic conse-
quences.2,3 The method of Drulac et al.,’ in which residual disinfectant activity is neutralised by skimmed milk, was adapted to test the activity of ethanol, industrial methylated spirits B.P. (LM.S.), isopropyl alcohol (isopropanol), and ’Hibisol’ (I.C.I.; a solution of chlorhexidine in 70% w/w isopropyl alcohol) against recently isolated strains of echovirus type 11 and herpes simplex virus (H.s.v.) type I. Freshly made up dilutions of the disinfectants (0-4 ml) were
mixed with 0.05 ml of the virus and 0-05 ml of calf serum and
of infants with symptoms and 44% of symptom-free infants. Thus many congenitally infected infants without overt disease might be missed if the c.M.v.-IgM test were used as the sole means of identifying c.M.v. infection. The indirect fluorescent for IgG antibody to c.M.v. early antigens (EA), developed The et al. provides another means of identifying active c.Nt.v. replication in infected hosts. We have looked for IgG-EA antibodies in infants with congenital c.M.v. infection confirmed by virus isolation (see table). In three infants (cases 1-3) viruria was detected on the second
1. Lancet, 1974, i, 845. 2. Starr, J. G., Bart, R. D., Jr., Gold, E. New Engl. J. Med. 1970, 282, 1075. 3. Melish, M. E., Hanshaw, J. B. Am. J. Dis. Child. 1973, 126, 190. 4. The, T. H., Klein, G., Langenhuysen, M. Clin. exp. Immun. 1974, 16, 1.
held for 1 min at room temperature before adding 4.5 ml of skimmed milk. Ten-fold dilutions were then made and inoculated onto monolayers of human embryo-lung fibroblasts which were observed for 5 days for signs of cytopathic effect. The strengths of the disinfectants referred to in the results are initial concentrations; their final concentrations in the reaction mixture are 4/5th of those figures. The titre of H. s.v. typeI was reduced by at least 105 by hibisol and by isopropanol, ethanol, and i.M.s. at concentrations of 50%, 75% and 95% v/v. Against echovirus type 11, however, the results, shown in the table, indicate that neither hibisol nor isopropanol was effective, but that 95% ethanol or LM.S. caused at least a 1000-fold reduction in virus titre. Tests with poliovirus, another enterovirus, have also demonstrated a similar superiority of i.M.s. over isopropanol (R. A.
Bucknall, personal communication). Where viral as well as bacterial cross-infection is likely it would 1. 2.
Lowbury, E. J. L., Lilly, H. A., Aycliffe, G. A J. Br. med. J. 1974, iv, 369 Nagington, J., Wreghitt, T. F., Gandy, G., Robertson, H. R C., Berry, P J. Lancet, 1978, ii, 725.
3. Davies, O. P.,
Hughes, C. A., McVicar, J., Hawkes, P., Muir, H J. Lancet. 1979, i, 96. 4. Drulac, M., Wallbank, A M., Lebtag, I. J. Hyg., Camb. 1978, 81, 77.