Bacteriological Profile and Antibiotic Susceptibility Pattern of Neonatal Septicemia in a Tertiary Hospital in Vadodara, Gujarat

Neonatal septicemia is a major cause of infection and mortality in neonates. Neonatal sepsis is a type of neonatal infection, particularly bacteremia, diagnosed by the presence of microorganisms in blood via microbiological culture tests during the first 4 weeks of birth. Neonatal sepsis is classified into early bacterial neonatal septicemia (less than 72 h) and late bacterial neonatal septicemia (>72 h–28 d) according to age. Isolation of septicemia-causing bacteria from the blood of neonates and investigation of their antibiotic susceptibility pattern for disease management. This study was a retrospective analysis of blood cultures from neonates admitted to the NICU with symptoms of septicemia from June to December, 2019. All samples were processed according to standard microbiological procedures using the BACTEC 9050 automated culture system. Results were reported on the basis of microbial appearance on the culture media and microscopic examination using the Gram staining method, and authentication was performed using standard biochemical reactions. Of the 228 patients, 32.89% were positive for blood culture. Early bacteremia was detected in 64% of the patients, and late bacteremia was detected in 36% of the patients. The most effective drugs against the gram-positive bacteria were linezolid, vancomycin, and ciprofloxacin and against the gram-negative bacteria were tigecycline, imipenem, and amikacin. Coagulase-negative staphylococci and gram-negative organisms such as Klebsiella, Acinetobacter, and Staphylococcus aureus were the major cause of neonatal septicemia in this study, and almost all the isolates were resistant to different antibiotics. Overall, antimicrobial drug resistance was observed in all the positive blood culture samples.


INTRODUCTION
Neonatal septicemia is one of the most common causes of infection and mortality in neonates, due to which 30-50% of neonates die each year in developing nations.Various studies have suggested that bacteremia occurs in 20% of neonates, and approximately 1% die due to neonatal sepsis. 1 According to the National Perinatal Database (NNPD) study, neonatal septicemia occurred in 30 live births out of 1000 in India during 2002-2003. 2The classification of neonatal sepsis is based on the age at infection initiation; according to this classification, it is categorized into early bacterial neonatal sepsis (less than 72 h) and late bacterial neonatal sepsis (>72 h-28 d).Early bacterial neonatal septicemia is diagnosed mostly at the time of fetal delivery and during the nursery period. 4There are various gram-positive and gram-negative bacteria that cause bacterial neonatal septicemia. 5urrently, the appearance of multiple antibiotic-resistant microorganisms poses challenges in the management of neonatal sepsis. 6,7In order to utilize the antimicrobial therapy effectively in septicemia patients to detect the prevalence of bacteria and the related antibiotic drugs, it is important to identify their sensitivity patterns.Early detection and antimicrobial treatment in sepsis are useful for reducing morbidity and mortality. 8This study was performed in an institute to determine the incidence rate and microbiological profile of neonatal sepsis along with the antibiotic susceptibility testing (AST) pattern of the isolates from neonates who were admitted to the NICU of Dhiraj Hospital, Pipariya, Vadodara.

MATERIALS AND METHODS
This study was conducted in the central laboratory of the Department of Microbiology, Dhiraj Hospital, Vadodara (Gujarat) from June to December, 2019.The study evaluated the bacteriological profile and antibiotic susceptibility patterns of 228 neonates clinically suspected of septicemia, admitted to the NICU of Dhiraj Hospital, Piparia, Vadodara (Gujarat) from June to December, 2019.
Blood samples were collected from suspected neonates with septicemia under aseptic conditions after obtaining consent from their relatives.Then, 1-2 ml of the collected venous blood was inoculated in a blood culture bottle containing 40 ml sterile BD BACTEC™ Peds Plus™/F culture vials.All samples were processed according to standard microbiological procedures using the BACTEC 9050 automated culture system.If microbes are present in the collected blood specimen injected into the sterile bd bactec peds plus/f culture vials, CO 2 is generated when the microbes break down the substance present in the vial.The rise in the fluorescence of the vial due to the higher amount of CO 2 released by microbes was monitored using the BD BACTEC 9050 instrument.The positive blood cultures were subcultured on sheep blood agar and MacConkey agar and incubated at 37°C for 24 h.

Statistical analysis
Results were reported on the basis of the appearance of microbial growth on culture media and microscopic examination using the Gram staining method, and interpretation was performed using standard biochemical reaction tests.Several bacteria from the Enterobacteriaceae family have been identified using various biochemical reactions such as indole test, H 2 S production-based catalase test, citrate utilization test, hanging drop test, urease test, oxidase test, sugar fermentation test, and other tests.For gram-positive bacteria, coagulase, catalase, bacitracin, and optochin disk tests and other tests were performed.The correlation of the results was also performed using BioMerieux's VITEK® 2 COMPACT (automated microbial identification system).

RESULTS
A total of 228 suspected neonatal blood samples were collected for blood culture during the study; among these, bacterial sepsis was confirmed in 32.89% (75 out of 228) patients.Of the 75 patients, 48 (64%) had early septicemia (EOS; <72 h of age) and 27 (36%) had late septicemia (LOS; >72 h of age).
Table 2 suggests that the most sensitive antibiotics to gram-positive bacteria were vancomycin and linezolid, followed by ciprofloxacin and gentamicin.Almost all the gram-positive bacteria were resistant to penicillin.
Table 3 suggests that the most sensitive antibiotics to gram-negative bacteria were tigecycline, imipenem, and piperacillin/ tazobactam, followed by ciprofloxacin and amikacin.Almost all the gram-negative bacteria were resistant to ampicillin and co-trimoxazole.

DISCUSSION
This study shows that gram-positive bacteria such as Klebsiella, Acinetobacter, CONS, and S. aureus are the major cause of neonatal septicemia, and most of them are resistant to multiple antibiotics that are routinely used.
Table 4 shows that in the four studies, the prevalence of neonatal septicemia was did not differ considerably, which indicates that the prevalence of neonatal septicemia is high in developing countries such as India.
Table 5 shows that in most of the studies compared, neonatal septicemia was caused by Klebsiella, Acinetobacter, Coagulase-negative Staphylococcus (CONS), and Staphylococcus aureus.The most typical organism was Klebsiella.

Table 1 .
Main Causal bacteria for Neonatal septicemia