Journal of Infection (1994) 29, 203-205

C A S E R E P O R T

N e o n a t a l o s t e o m y e l i t i s i n D o w n ' s s y n d r o m e d u e t o n o n - e n c a p s u l a t e d Haemophilus influenzae

R u t h W i l l i a m s , ~ V i n c e n t K i r k b r i d e I a n d G e r a r d D . C o r c o r a n ~

1Department of Paediatrics, UCLMS, The Rayne Institute, 5 University Street, London WCIE 6JJ, U.K. and 2Department of Microbiology,

University College Hospital, Gower Street, London WCIE 6A U, U.K.

Accepted for publication 2 7 April I994

S u m m a r y

A case of neonatal osteomyelitis in a baby with Down's syndrome is described. The causative organism was a non-encapsulated Haemophilus influenzae biotype I, which was isolated from pus at the site of infection. This organism has not previously been reported as a cause of neonatal osteomyelitis.

Case report

A I7-day-o ld baby girl p resented with a 24-hour history of lethargy, apparent d iscomfor t on nappy changing and progressive swelling of the left thigh. She had been born by Caesarian section at 36 weeks gestation. Features of D o w n ' s syndrome were not iced at bir th and t r isomy 21 was subsequent ly confirmed on karyotype analysis. She was discharged at 6 days of age. A unilateral sticky eye was not iced on day 8. A swab was sent for culture and she was started on topical chloramphenicol drops. T h e eye swab grew H. influenzae, but the organism was not serotyped.

On admission the baby was afebrile and not unwell. Cardiovascular and respiratory systems examinat ion was unremarkable and the liver and spleen were not enlarged. The re was a firm, fluctuant, almost circumferential swelling of the left thigh and a left foot drop. T h e W B C count was 72"3 x io9/1 and the film showed a leukaemoid reaction. H ip and leg X-rays were consistent with a diagnosis of osteomyelit is . Needle aspiration of the swelling p roduced frank pus and surgical exploration and drainage of the left femur was performed. Gram staining of this fluid showed Gram-negat ive rods and culture confirmed H. influenzae bio type I, not agglutinating with any of the antisera to capsular types a to f, and not p roduc ing iridescent colonies on Levinthal ' s agar. Blood cultures were sterile.

She was commenced on high dose intravenous ampicillin and gentamicin for io days and comple ted a fur ther 5 weeks of oral amoxycill in at home. H e r W B C count re turned to normal within a few days and her recovery was complete and unremarkable .

Address correspondence to: Dr Ruth Williams.

o163-4453/94/o5o2o3 +03 $08.00/0 © 1994 The British Society for the Study of Infection

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204 R. W I L L I A M S E T A L .

Discuss ion

Neonatal osteomyelifis is a relatively uncommon condition which affects males more often than females. Infection is generally thought to occur via the haematogenous route. Frequently reported causative organisms include staphylococci, streptococci and Escherichia coll. Two studies have suggested that the majority of babies who develop osteomyelitis have one or more predisposing factors eg. prolonged rupture of membranes, preceding minor infection and other neonatal complications. 1' 2 Neither series included a child with trisomy 21.

The immune system in Down's syndrome has been investigated extensively. Infants have a higher incidence of respiratory tract infections but are not thought to be predisposed to pyogenic or fungal infections. Subtle defects affecting a number of aspects of immune function have been recognised and it is thought that it is the sum of these defects which contributes to the overall deficiency. The complement activation system and humoral immunity are usually normal while thymic structure and cell mediated immunity are abnormal. Defects of phagocytosis have been described but reports of deep seated infections due to pathogenic organisms typically associated with reduced leucocyte motility or defective killing are not widely reported. 3

H. influenzae is a facultative anaerobe. Six "pathogenic" serotypes (a-f) can be identified amongst the encapsulated strains. Non-encapsulated H. influenzae is generally a non-pathogenic commensal causing only minor infections of the respiratory tract in children. Eight biotypes ( I -VIII ) of H. influenzae have been identified, but the majority of clinical isolates are distributed between three biotypes (I, II, III). Most of the capsulate type b strains isolated from cases of meningitis and epiglottitis belong to biotype I as did the organism in our case. However the absence of iridescent colonies on Levinthal's agar and the failure to agglutinate with capsular antisera a to f demonstrates that the organism in this case was non-capsulate. Non- serotypable strains of H. influenzae may be genetically distinct from, or be non-encapsulated strains. Molecular typing methods are necessary to distinguish these groups. The incidence of non-encapsulated H. influenzae associated disease among neonates has increased since the I97OS. They generally present within the first few days of life with fulminant sepsis and respiratory distress. Low birth weight infants are affected and there is a high mortality. Unlike group B streptococcal disease, signs of meningitis are uncommon. Biotypes II and IV are the most common organisms to be isolated from these babies. 5

In 1975 Granoff and Nankervis reported a case of septic arthritis caused by a non-encapsulated H. influenzae. The child presented at 5 days of age with redness and swelling of fingers and toes. She had been unwell since the first day with respiratory distress and cyanotic episodes initially and increasing lethargy and fever later. Haemophilus was isolated from fluid aspirated from a swelling over the wrist on day 6. Haemophilus was also isolated from CSF but not from blood cultures. No biotype was given. 6

In summary, we have described a case of neonatal osteomyelitis caused by an organism which has not previously been identified as a cause of bone

N e o n a t a l osteomyelitis in Down's syndrome 205

infec t ion , b u t w h i c h m a y rare ly cause severe disease wi th in the first few days o f life.

References

i. Fox L, Sprunt E. Neonatal Osteomyelitis. Pediatrics 1978; 62: 535-542. 2. Knudsen CJM, Hoffman EB. Neonatal osteomyelitis. J BoneJt Surg 199o; 72B: 846-851. 3. Barroeta O, Nungaray L, Lopez-Osuna M, Armendares S, Salamanca F, Kretschrner RR.

Ped Res 1983; 17: 292-295. 4. Falla TJ, Dobson SRM, Crook DWM, et al. Population-based study of non-typable

Haemophilus influenzae invasive disease in children and neonates. Lancet 1993; 341: 851-854.

5- Camponone P, Singer DB. Neonatal sepsis due to nontypable Haemophilus influenzae. Am J Dis Child 1986; I4O: I I7- I2I .

6. Granoff DM, Nankervis GA. Infectious arthritis in the neonate caused by Haemophilus influenzae. Am J Dis Child 1975; I29:73o-733 •