Neonatal meningitis due to Listeria monocytogenes: a case report from Southern IndiaCorrespondence Address :
Department of Microbiology
Amrita Institute of Medical Sciences, Kochi-682041
E-mail:email@example.com, Tel: 08943258743
Introduction: Listeria monocytogenes is an uncommon cause of bacterial meningitis in neonates. The infection due to this organism in the neonates can be categorized as an early onset or a late onset disease. While the early onset neonatal listeriosis is due to an in utero infection, the late onset form primarily occurs due to exposure to the organism during vaginal delivery. Case presentation: Here, we report a 2 week old female child who presented with late onset meningitis due to Listeria monocytogenes and responded adequately to appropriate antimicrobial therapy.
Conclusion: Physicians should always consider Listeria as a possible aetiological agent of meningitis in paediatric patients, regardless of their age or immunological status in a developing country. It is important to differentiate meningitis which is caused due to Listeria monocytogenes from other causes, as cephalosporins which are the most commonly used antimicrobial in bacterial meningitis, are unlikely to elicit a favourable response in such cases.
Listeria, neonatal meningitis
Listeria monocytogenes is a gram positive intracellular pathogen which is associated with a number of clinical entities like septicaemia, abortions, stillbirth, meningitis and meningoencephalitis. The infections by this psychrotrophic organism are commonly seen in pregnant women, newborns, the elderly, in immunocompromised people and in individuals who are in frequent contact with animals (1).Neonatal infections which are caused Listeria spp in Asia are quite under reported(2). A low index of clinical suspicion and the absence of pathognomic clinical features often contribute to this. We illustrate through a case report of late neonatal sepsis, the importance of the identification of Listeria monocytogenes from CSF and blood and its theraupetic implications.
A 2.74 kg, full term, female baby was delivered by an emergency lower segment caesarean section (LSCS) at our hospital. The Apgar scores were 8 at 1 minute and 9 at 5 minutes. The infant progressed fairly until 14 days, after which she developed fever, showed a poor feeding pattern and presented with abnormal movements. On general examination, the patient showed high grade fever, poor feeding with the regurgitation of milk, a vacant stare and a pulse rate of 140/minute. The central nervous system examination showed hypertonia, exaggerated deep tendon reflexes without clonus and tonic posturing with seizures. The patient showed respiratory distress and so, was immediately admitted to the Neonatal Intensive Care Unit (NICU). The patientâ€™s mother was a 22-year-old primi gravida who had presented at 39 weeks of gestation with non progression of labour, as a result of which she was taken up for an emergency caesarean section. The mother did not give any history of fever or any history which was suggestive of any focus of infection. The baby was breast fed till the 14th day of life, when she presented to the paediatric emergency. Laboratory investigations of the infant on admission showed a white blood cell count of 12.0 x 109/L units. The haemoglobin levels and the platelet counts were within normal limits. The cerebrospinal fluid (CSF) showed a glucose concentration of 0.74g/l and a protein concentration of 0.68g/l . The blood glucose level was 0.98g/dl. The gram staining of the CSF showed plenty of polymorphonuclear leucocytes, but no bacteria were visualized. The CSF was inoculated on 5% sheep blood agar, chocolate agar and MaConkey agar. The blood agar was incubated in a CO2 incubator, while the other media were incubated for 24 hours in ambient air at 37Â°C. The blood agar showed large colonies with a narrow zone of beta haemolysis, which was more evident when the colonies were removed. Corresponding growth was seen in chocolate agar, while there was no growth in MaConkey agar. Further tests showed the isolate to be a catalase positive, oxidase negative, gram positive rod, with a tumbling motility at 25Â°C and non motile at 37Â°C. Based on the above findings, the organism was presumptively identified as Listeria spp and it was subcultured on Polymyxin Acriflavine Lithium Chloride Ceftazidime Esculin Mannitol Agar (PALCAM) agar, which is a selective medium for Listeria spp. The next day, black colonies which were characteristic of the Listeria spp were seen. Standard biochemical tests showed the organism to be Listeria monocytogenes. Antimicrobial Susceptibility tests which were done by using the disc diffusion test demonstrated that the organism was susceptible to ampicillin, vancomycin, gentamicin and tetracycline and that it was resistant to cephalosporins. Listeria monocytogenes was isolated from the blood culture of the patient after 5 days of incubation.
On admission to NICU, the patient was started on Ceftriaxone, but did not show any clinical improvement. Following the isolation of Listeria monocytogenes, the patient was started on intravenousampicillin at 200mg/kg/day and gentamicin at 2.5mg/kg/dose, every six hours. Within 48 hours, her clinical condition improved dramatically and the patient was afebrile. Repeat blood and CSF cultures after 48 hours of treatment were negative. Overall, gentamicin was given for seven days and ampicillin was continued for a total of two weeks. The patient showed remarkable improvement and was discharged after 7 days in good condition. The maternal high vaginal swabs were negative for Listeria spp.. No history of potential sources of listeriosis like the intake of unpasteurized milk or partially cooked meat by the mother were elicited.
Listeriosis is an uncommon disease in immunocompetent individuals. However, cases in immunocompetent individuals with serious sequelae like unilateral abducens paralysis and inappropriate anti diuretic hormone secretion, have been described(3). Though it is a rare affliction, listeriosis in immunocompetent infants may also be preceded by gastroenteritis due to the same causative organism(4).Pregnant women are prone to this infection as the placenta provides the causative organism a protective niche for its growth(5). This is evident from the fact that while the incidence of listeriosis in the general population is 0.7 per 100000, it is 17 times higher in pregnant women (12 per 100000)(6). Neonatal listeriosis can occur by transplacental infection or by an infected birth canal. It occurs in two clinical forms, early onset and late onset. The early onset disease presents within the first 5 days of delivery, especially in the preterm infants of symptomatic mothers. The late onset disease presents during the 1st to 4th weeks of life, usually as a purulent meningitis(7). The mother generally remains asymptomatic. Listeriosis during pregnancy may cause severe complications in the neonate. This makes listeriosis a diagnostic concern in febrile pregnant women at any stage of pregnancy. The first-line treatment is based on high-dose amoxicillin, to be used for at least 3 weeks for the treatment of listeriosis during pregnancy. If the foetus survives, a longer therapy until delivery should be given(8).
In this case, the patient showed the features of a late onset disease, with meningitis and septicaemia. Purulent meningitis is a frequent presentation of the late onset disease, although it is also seen in 24% of the early onset disease cases. Misidentification of the Listeria spp from CSF has often been reported. Moreover, cases of neonatal listeriosis in India are usually under reported. In a prospective study which was done in 1981, the prevalence of listeriosis was found to be 0.2% among the total number of births and 2.2% among the meconium stained babies(9). Recent reports from the sub Himalayan belt and other other areas of India indicate that the disease which iscaused by the Listeria spp might be more prevalent in the country than was previously thought(10)(11). It is important to differentiate meningitis which is caused by Listeria monocytogenes from other causes, as cephalosporins which is the most commonly used antimicrobials/antibiotics in bacterial meningitis, is unlikely to elicit a favourable response in such cases. Secondly, due to its morphological similarities to diphtheroids and streptococci, misidentification of the Listeria spp is possible(12). Therefore, the isolation of gram positive rods from CSF should alert the microbiologist to a possibility of Listeria infections.
PALCAM: Polymyxin Acriflavine Lithium Chloride Ceftazidime Esculin Mannitol Agar ; CSF :Cerebrospinal fluid; LSCS Lower Segment Caesarean section ; NICU: Neonatal Intensive Care Unit.
A written informed consent was obtained from the patientâ€™s mother for the publication of this case report. A copy of the written consent is available for review with the Editor-in-Chief of this journal.
It is important to differentiate meningitis which is caused due to Listeria monocytogenes from other causes, as cephalosporins which are the most commonly used antimicrobials in bacterial meningitis, is unlikely to elicit a favourable response in such cases.
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