Indian Pediatrics 1999; 36:300-303
Outbreak of Salmonella worthington Meningitis in Neonatal Intensive Care Unit
Rekha H. Udani
Nandkishor S. Kabra
Ruchi N. Nanavati
Salmonella infections in newborns are of special significance since the attack rate as well as morbidity and mortality are higher among the neonates as compared to older children and adults. Even an avirulent strain may cause disease in the newborn infant and low birth weights are more vulnerable(1). Salmonellosis in neonates is a reflection of Salmonella infection in the community. The emergence of multi drug resistant Salmonella infection results in frequent therapeutic failures and is epidemiologically hazardous. We report an epidemic of multi-drug resistant Salmonella worthington meningitis in Level III Neonatal Intensive Care Unit (NICU).
Subjects and Methods
The epidemic occurred in the month of June 1996, Four neonates were symptomatic, four others were asymptomatic and 30 more neonates admitted in nursery were at risk, A full term male infant weighing 2,7 kg, a case of meconium aspiration had multiple episodes of convulsions, fever, feed intolerance, lethargy, apneic spells on the second day of life, The CSF study was suggestive of pyogenic meningitis. The neonate was administered intravenous ceftriaxone and amikacin in appropriate dosage in addition to supportive treatment. The baby rapidly deteriorated and expired on day 6 of life. Within 2 days, 3 more neonates (2 preterm and 1 full term) deteriorated and expired, Feed intolerance, lethargy and convulsions were common features in all the four babies, while apneic spells and abdominal distension were observed in three. Sepsis work-up which included complete blood count, blood culture, gastric aspirate culture, CSF study and chest radiograph was carried out in all symptomatic neonates. Antibiotic sensitivity tests in vitro were performed in all cases, the CSF culture revealed Salmonella species in all. Post mortem examination was done in all four babies. Subsequently all other 30 neonates in NICU were subjected to epidemiological investigations which included stool, blood, gastric aspirate and umbilical cord cultures. Complete surveillance was carried out to find out the source of infection. Swabs from equipments and various places like wash basins, suction catheters, dustbins from NICU and labour ward were sent for culture. Stool culture of NICU staff and nursing personnel were performed.
The clinical observations in the symptomatic and asymptomatic cases are shown in Table I. CSF culture revealed Salmonella species in symptomatic newborns while blood culture did not reveal any organism. In the four asymptomatic newborns, the organism could be isolated from the culture of gastric aspirates. Serological confirmation of Salmonella species, i.e., Salmonella worthington was done at the Central Research Institute, Kasauli, India. The isolated Salmonella worthington was resistant to several antibiotics-Ampicillin, Amoxicillin, Ampitum, Chloramphenicol, Gentamicin, Cefotaxime, Ceftriaxone, Cefazoline, except Ciprofloxacin and Amoxi-clavulanate combination. The postmortem examination including histopathology confirmed 'pyogenic meningitis in all.
Four asymptomatic neonates were given intravenous ciprotloxacin (5 mg/kg/dose twice a day) for 14 days before being discharged. Blood and stool cultures performed after the completion of therapy showed no growth. Complete surveillance in NICU did not reveal any inanimate object as well as any . nursery personnel as source of infection.
A nursery outbreak with Salmonella worthington was identified by us. There are few reports of such outbreaks with this organisms in neonates(2-4). The source of infection has varied from nursery personnel to dust, air and equipments used while in some reports the source of infection could not be identified(1). The mode of transmission of Salmonella infection in our nursery could not be speculated. The mode of acquisition in the index case was difficult to comment upon in the absence of documented evidence.
The clinical spectrum of nursery outbreaks of Salmonellosis have been associated with asymptomatic carriage to septicemia and meningitis. Neonatal Salmonella meningitis has been reported in 49 cases, out of 147 studied in a series(5). The causative serotypes include, in order, S. havana, S. enteritidis, S. typhimurium, S. panama, S. paratyphi B, S. choleraesuis and indeterminate type. (S. worthington belongs to S. enteritidis group). The clinical spectrum of Salmonella infection in newborns includes enterocolitis, bacteremia and localized infection.
In the outbreak of Salmonella worthington reported earlier(2), refusal to feed, diarrhea, convulsions and jaundice were the common presenting features. None of our neonates had diarrhea. In conformity with earlier observations(2), a multiresistant antimicrobial pattern and high mortality were noted in the present study. This is of concern because emergence of resistant strains to newer antibiotics might also limit their usefulness in treatment.
Infection with multi-drug resistant salmonella is associated with mortality ranging from 9.5% to 77.7%(6). A recent study from Mumbai reported 61 % mortality in Salmonella worthington sepsis in neonates(2). In the present epidemic, the mortality in symptomatic group was 100% which highlights the importance of suspecting Salmonella infections in neonates when they deteriorate suddenly.
After this epidemic the following preventive measures were undertaken in addition to the prevention of infection in general in NICU: (a) Stool cultures of all mothers of babies coming to NICU; and (b) Regular epidemiological surveillance for Salmonella from labor ward and NICU.
We are grateful to our Dean Dr. (Mrs.) P.M. Pai for giving us permission to publish this article.