Case Report

Leuconostoc Lactis as an Early-onset Neonatal Sepsis Agent: A Case Report with the Current Literature Review

10.4274/haseki.galenos.2023.8611

  • Edin Botan
  • Banu Aydin
  • Celik Gultekin

Received Date: 19.07.2022 Accepted Date: 23.01.2023 Med Bull Haseki 2023;61(1):69-71

The patient, who was born spontaneously to a 22-year-old mother as G1P1Y1 with a weight of 2605 g at 37 weeks of gestation, had an Activity, Pulse, Grimace, Appearance and Respiration (APGAR) of 8 and 5, respectively, at the first and fifth minutes APGAR 9. Physical examination revealed that the patient’s general condition was moderate: body temperature was 36.7 °C, respiratory rate was 68 beats per minute, heart rate was 146 beats per minute, blood pressure was 59/33 mmHg, saturation was 92%, both hemithoraxes participated equally in respiration, consciousness was clear, and the sucking reflex was weak. Because the mother had a history of premature membrane rupture for 22 hours, ampicillin and gentamicin were given intravenously after a blood culture. Leuconostoc lactis was grown in a blood culture sent by the patient. On the 12th day of her hospitalization, the patient was discharged with full oral feeding, had started to weigh regularly, and had good general condition, oral intake, and activity. Leuconostoc species should be kept in mind in vancomycin-resistant gram-positive infections. It should be kept in mind that Leuconostoc lactis may be a cause of Early-onset neonatal sepsis, albeit very rarely.

Keywords: Newborn, Leuconostoc lactis, sepsis

Introduction

Early-onset neonatal sepsis (EONS) is an infection that occurs in the first 72 hours of life (1). The most common EONS agents are group B Streptococci and Escherichia coli. Less frequently: Enterobacter, Enterococcus, Klebsiella, Listeria, non-typeable Haemophilus influenzae, other enteric Gram-negative bacilli, Staphylococcus aureus, and Streptococcus viridans (2).

Leuconostoc is a Gram-positive cocci from the Leuconostocaceae family. It belongs to the Streptococceae family, is inherently glycopeptide-resistant, and has intrinsic or chromosomal resistance to vancomycin (3). Although Leuconostoc spp. were not considered pathogens for humans in the past, they have recently been accepted as an infectious agent, especially in immunosuppressed patients (4).

Infections due to Leuconostoc spp. in newborns were described in a few case reports in the literature. As far as we know, Leuconostoc spp. has not been reported as an EONS agent in the literature. Here, a term newborn case with Leuconostoc lactis growth in blood culture as an EONS agent is presented.


Case Report

The patient, who was born spontaneously to a 22-year-old mother as G1P1Y1 with a weight of 2605 g at 37 weeks of gestation, was determined to be in the 1st minute 8 and 5 minutes for Activity, Pulse, Grimace, Appearance, and Respiration (APGAR) 9. Physical examination revealed that the patient’s general condition was moderate: body temperature was 36.7 degrees Celsius, respiratory rate was 68 beats per minute, heart rate was 146 beats per minute, blood pressure was 59/33 (41) mmHg, saturation was 92%, both hemithorax participated equally in respiration, consciousness was clear, and the sucking reflex was weak. The patient with tachypnea was started on oxygen. Ampicillin and gentamicin intravenous (IV) were initiated after a blood culture was taken because the mother had a history of premature rupture of the membranes (PROM) for 22 hours. A bilateral infiltrative appearance was detected on the chest X-ray (Figure 1).

The C-reactive protein (CRP) was 0.54 mg/L, blood biochemistry was normal, hematocrit was 54.1%, platelet count was 114,000/mm3, and leukocyte count was 9640/mm3 in the complete blood count on the first day of the patient’s stay. A peripheral smear examination revealed 5-6 platelets per 100 magnification field. It was learned that the mother’s platelet count was normal. Leuconostoc lactis was grown in a blood culture sent by the patient. The antibiogram showed that the bacteria were sensitive to ampicillin, and the antibiotic treatment was continued. Enteral feeding with 8x5 cc of breast milk was started and increased gradually in the patient, whose general physical examination was normal, and no oxygen was needed on the fourth day. There was no growth in the blood cultures taken twice after the antibiotic treatment was started. The patient’s IV fluid was gradually reduced and stopped as his sucking became more active. In the control blood tests taken on the 10th day, blood biochemical parameters were normal, CRP 0.63 mg/L, hematocrit 52%, platelet count 250,000/mm3, leukocyte count 9780/mm3. On the 12th day of her hospitalization, the patient was discharged with full oral feeding, had started to weigh regularly, and had good general condition, oral intake, and activity.


Discussion

Leuconostoc species were not considered pathogenic to humans until the early 1980s. For the first time, vancomycin-resistant Gram-positive cocci were produced in the blood cultures of two adult immunocompromised patients by Buu-Hoï et al. (5), and this bacterium was identified as Leuconostoc spp.

Leuconostoc spp. it is a member of the Streptococcaceae family. Routine biochemistry and phenotypic identification are ineffective. Sheep agar can be confused with Enterococcus or Streptococcus because it contains non-hemolytic or alpha-hemolytic gram-positive cocci (6).

Leuconostoc species can grow in 6.5% NaCl and hydrolyze esculin in the presence of bile but cannot produce leucine aminopeptidase and pyrrolidonyl arylamidase, leading to the formation of glucose and CO2. Antibiotic susceptibility tests are important for diagnosis. Leuconostoc strains are naturally glycopeptide-resistant (7). In our case, after BD Bactec-FX40 blood culture was incubated in an automated system, the material was inoculated onto blood agar and EMB (eosin methylene blue) agar after an automatic growth signal. Bacteria grown after incubation at 370 °C for 24 h in Oven Nuve 055 were stained by gram staining. Upon the detection of gram-positive cocci, BD Phoenix PMIC/ID-600 bacteria were inoculated into the identification and antibiogram kit. In October, the Phoenix Spec McFurlant 0.5 threshold was used. The test kit was placed in a Phoenix 100 instrument. Results were obtained after 12-24 hours. On the test kit Phoenix 100 instrument, the growth was identified as Leuconostoc lactis. Tigecycline, ampicilline, co-trimaxozol, ceftazidime, ceftriaxone, amoxicillin/clavulonic acid, erythromycin, tetracycline, penicillin, gentamicin, ciprofloxacin, rifampicin, and vancomycin were found to be susceptible and resistant, respectively.

Leuconostoc spp. are considered to have low pathogenic potential for healthy individuals; however, it has been reported recently that they cause fatal infections such as sepsis or meningitis, particularly in immunocompromised patients (8,9). Risk factors for Leuconostoc lactis infection include central venous catheters, parenteral nutrition, surgery, liver failure, chronic renal failure treated with hemodialysis, extensive burns, immunosuppression, and long-term vancomycin therapy (10).

Although pediatric patients who developed infections due to Leuconostoc species have been reported in the literature, there are few case reports in newborns. Janow et al. (11) found that a 26-day-old premature newborn with a gestational age of 24 weeks developed sepsis while receiving vancomycin, he was initially identified as vancomycin-resistant streptococcus in a blood culture, and later it was determined that the growing agent was Leuconostoc spp. They reported that it was fixed. Yossuck et al. (12) reported that three-week-old extremely low birth weight newborn patients infected with vancomycin-resistant Leuconostoc spp. recovered with appropriate antibiotic therapy after removal of the central catheter. Hosoya et al. (13), Leuconostoc lactis is a glycopeptide-resistant, Gram-positive, facultative anaerobic coccus isolated from dairy products, whereas Staphylococcus nepalensis is a coagulase-negative coccus that has not been identified as a human pathogen. Additionally, there was an underlying risk factor in all three cases. The mother in our case had a 22-hour PROM history. In blood culture, the BD Phoenix PMIC/ID-600 bacterial identification system detected Leuconostoc lactis growth, which was vancomycin-resistant in the antibiogram. As far as we know, there are no EONS due to Leuconostoc lactis in the literature. They are often considered a source of entry for intravascular catheters and gastrointestinal tract bacteria (6). In our case, there was no catheter intervention; it was a baby who was given breast milk as soon as she was born.

Although Leuconostoc lactis is not found in the normal human flora, it has been reported to be isolated from the vagina in healthy women of reproductive age (14). A possible source of this in our patient was the vaginal flora of the mother. However, this is speculation since a vaginal culture cannot be obtained from the mother. Management of Leuconostoc infections consists of appropriate antibiotic therapy and removal of the source of infection (catheter removal, drainage of the abscess) (6). Leuconostoc strains are intrinsically glycopeptide-resistant. The most preferred antibiotic in treatment is penicillin with or without gentamicin. In our case, improvement was observed after 10 days of ampicillin treatment.


Conclusion

In conclusion, in vancomycin-resistant Gram-positive infections, it should be kept in mind that Leuconostoc lactis may be the cause of EONS, albeit very rarely. The most common EONS agents are group B Streptococci and Escherichia coli. Less frequently: Enterobacter, Enterococcus, Klebsiella, Listeria, non-typeable Haemophilus influenzae, other enteric Gram-negative bacilli, Staphylococcus aureus, Streptococcus viridans. However, it should be kept in mind that Leuconostoc lactis may be the cause of EONS.

Ethics

Informed Consent: Consent information was obtained from the patient’s family.

Peer-review: Externally and internally peer-reviewed.

Authorship Contributions

Concept: E.B., Design: E.B., G.C., Data Collection or Processing: E.B., B.A., Analysis or Interpretation: E.B., Literature Search: E.B., Writing: E.B., B.A.

Conflict of Interest: No conflict of interest was declared by the authors.

Financial Disclosure: The authors declared that this study received no financial support.


Images

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