| Abstract|| |
Neonatal septicemia is one of the leading causes of neonatal mortality and morbidity worldwide. Hence, the present study was undertaken to isolate the bacteria causing neonatal sepsis and determine their antibiotic susceptibility pattern. Fifty neonates suspected to have septicemia were screened for 2 months (July and August 2014). Out of 50 specimen, 15 (30%) were blood culture positive. Coagulase-negative staphylococci was the most common isolate (10, 66.6%), with 60% (6 isolates) methicillin resistance. In view of the increasing antibiotic resistance, periodic surveillance should be conducted to control the emergence and spread of antimicrobial resistance.
Keywords: Coagulase-negative staphylococci, methicillin resistance, neonatal septicemia
|How to cite this article:|
Shivanna V, Sunkappa S R, Venkatesha D. The rising trend of coagulase-negative staphylococci in neonatal septicemia. Indian J Pathol Microbiol 2016;59:510-2
|How to cite this URL:|
Shivanna V, Sunkappa S R, Venkatesha D. The rising trend of coagulase-negative staphylococci in neonatal septicemia. Indian J Pathol Microbiol [serial online] 2016 [cited 2020 Feb 28];59:510-2. Available from: http://www.ijpmonline.org/text.asp?2016/59/4/510/191806
| Introduction|| |
Neonatal septicemia refers to the systemic bacterial infection with positive blood culture in the first 4 weeks of birth.  It can be classified into two types based on the age of onset: Early-onset septicemia (<72 h) and late-onset septicemia [LOS] (≥72 h 28 days). Early-onset septicemia (EOS) is acquired before birth, during delivery, or after birth.  Neonatal sepsis is caused by a variety of Gram-positive as well as Gram-negative bacteria, and sometimes yeasts. In the last two decades, the isolation of Gram-positive organisms has increased significantly.  The incidence of neonatal sepsis has increased during the recent years, due to invasive procedures and emergence of resistant organisms. 
As neonatal septicemia is a life-threatening emergency and delay in diagnosis and treatment with the appropriate antibiotics may have grave consequences, surveillance is essential to identify the common pathogens as well as the antibiotic susceptibility profile of the pathogens in a particular area.  The present study was undertaken to determine the bacteriological profile and antibiotic sensitivity pattern of neonatal septicemia in a tertiary care hospital in Karnataka, India.
| Materials and Methods|| |
This prospective study was conducted in the Department of Microbiology of a tertiary care hospital for 2 months (July and August 2014). Blood samples were collected from fifty clinically suspected cases of neonatal septicemia admitted to the Neonatal Intensive Care Unit. All neonates who had received antibiotics before admission were excluded from the study. Institutional Ethical Committee clearance was obtained. Informed consent from the parents of all the neonates under study was taken.
Sample collection and processing
About 1 ml of blood was drawn using a sterile syringe under aseptic precautions, and inoculated into 10 ml of brain-heart infusion broth and incubated at 37°C. Subcultures were done on sheep blood agar and MacConkey agar at the earliest visual detection of turbidity or blindly on days 1, 4, and 7 if the bottles did not show turbidity. Isolates were identified by standard Microbiological procedures.  Blood culture broth showing no microbial growth within 7 days was reported as culture negative after subculturing. Blood cultures positive for Corynebacterium sp., Bacillus sp., Streptococcus viridans and coagulase negative Staphylococcus generally were considered to be contaminants, except when two positive blood cultures and/or evidence of a true infection based on clinical course and laboratory data existed. 
Antimicrobial susceptibility testing was performed for all blood culture isolates by Kirby-Bauer disc diffusion method according to the Clinical and Laboratory Standards Institute guidelines (CLSI).  Gram-negative bacteria resistant to the third generation cephalosporins were tested for extended spectrum beta-lactamases production by disc potentiation test  Staphylococci were further screened for methicillin resistance (MR) by Kirby-Bauer disc diffusion method using cefoxitin discs (30 μg) according to the CLSI guidelines. 
| Results|| |
Out of the 50 neonates screened 15 (30%) were blood culture positive. Among the culture positive cases, there were 8 (53.33%) male and 7 (43.67%) female. EOS cases (11 [73.3%]) were found to be three times higher than LOS (4 [26.7%]).
Details of the causative organisms are provided in [Table 1]. These included Gram-positive cocci (12/15, 80%) and Gram-negative organisms (3/15, 20%). Coagulase-negative staphylococci (CoNS) and Klebsiella were the most common Gram-positive and Gram-negative organisms, respectively.
All the CoNS were sensitive to vancomycin and linezolid. MR was seen in 6 (60%) CoNS isolates. Enterococcus was sensitive to ampicillin, amoxicillin, levofloxacin, piperacillin/tazobactam, linezolid, and vancomycin. S. viridans was sensitive to all the antibiotics tested. All the Gram-negative organisms were sensitive to gentamycin, amikacin, imipenem, and meropenem.
The major maternal risk factors were bleeding per vaginum, lower segment cesarean section, premature rupture of membranes, urinary tract infection, and prolonged labor. The most frequent neonatal risk factors were low birth weight, perinatal asphyxia, prematurity, and fetal distress.
| Discussion|| |
In view of the high morbidity and mortality associated with neonatal sepsis, the culture report cannot be awaited to administer antibiotics. Hence, an area-based knowledge of the bacteriological spectrum and their antibiotic sensitivity pattern is essential to formulate an empirical therapy. 
In this study, out of 50 suspected neonatal septicemia cases screened 15 (30%) were blood culture positive. The culture positivity rates in different studies varied from as low as 2.1%  to as high as 62%.  However, the incidence of neonatal septicemia is variable and differs from place to place, as it depends on various factors such as gestational age, fetal birth weight, maternal nutrition, perinatal care and hygienic conditions, and child health-care facilities. 
A slight male preponderance was found in our study which agrees with the previous reports. , The reason for male predominance could be due to sex-dependent genetic factors. 
In this study, early onset septicemia (EOS) (73.3%) was more than late onset septicemia (LOS) (26.7%), which is consistent with earlier studies. ,,, This could be due to prematurity, low birth weight or unhygienic conditions during labor. 
In the present study, Gram-positive organisms (80%) were predominant compared to Gram-negative isolates (20%). Bacteria causing neonatal sepsis continue to change with place and time.  CoNS has been identified as the causative organism for EOS. In a study by Agarwal et al.,  approximately two-thirds of the CoNS sepsis had developed within the first 3 days of life. In our study also, most of the CoNS detected by blood culture were EOS (72.7%). The increasing prevalence of CoNS infections is attributable to their increasing antibiotic resistance and their ability to form biofilms on foreign bodies such as intravascular catheters.
CoNS is often regarded as the contaminant, possibly from the skin, but Ponce de Leon et al.  opined that the presence of this bacterium in blood can no longer be taken as contamination, especially in patients in critical care units. It remains difficult to determine whether CoNS is a significant cause of sepsis or not. The overall clinical picture and other markers of infection may be of assistance.  CoNS have low virulence but associated with morbidities like chronic lung disease and adverse neurodevelopmental outcomes in premature infants. CoNS infections are also associated with prolonged hospital stay and increased hospital costs. 
In this study, prematurity, low birth weight, and perinatal asphyxia were the risk factors more commonly associated with neonatal sepsis. It was concordant with the findings of other studies , and may be attributed to the immature immune system. Hence, close monitoring of the newborns in high-risk categories as soon as they are born is very essential. 
In the present study, high rate of antibiotic resistance was seen among CoNS to commonly used antibiotics and the majority of them were MR (60%), but vancomycin and linezolid were 100% sensitive. The increasing trend in the prevalence of MR-CoNS has also been reported in other studies. ,, This is because of the indiscriminate use of antibiotics. The drawback of this study was low sample size as it was a short-term project under the Indian Council of Medical Research (ICMR).
| Conclusion|| |
CoNS is the leading causative agent of neonatal sepsis in our hospital. A low susceptibility to commonly used antibiotics is a cause for concern. Vancomycin and Linezolid should not be used indiscriminately and be kept as reserve drugs, otherwise resistance to these drugs may develop, thereby threatening treatment. Every hospital should carefully follow the bacterial spectrum and resistance patterns of microorganisms responsible for neonatal infections to design a specific empirical antibiotic regimen.
We sincerely thank ICMR for supporting this study as a short-term research project.
Financial support and sponsorship
The study was supported by ICMR, New Delhi.
Conflicts of interest
There are no conflicts of interest.
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Department of Microbiology, AIMS, B.G. Nagara - 571 448, Mandya, Karnataka
Source of Support: None, Conflict of Interest: None