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research letter

Indian Pediatr 2014;51: 752-753

Antimicrobial Susceptibility Profile of Isolates from Pediatric Blood Stream Infections


Winsley Rose, *Balaji Veeraraghavan, *Agila Kumari Pragasam and Valsan Philip Verghese

From the Departments of Pediatrics and *Microbiology, Christian Medical College, Vellore, India.
Email: [email protected]
 

 


We describe the pathogens and their antimicrobial profile causing blood stream infections in children over a 4-year period. The commonest pathogens were: non-fermenting Gram negative bacilli other than Pseudomonas, Salmonella species, Escherichia coli, Staphylococcus aureus and Klebsiella species. High rates of drug-resistance were observed.

Keywords: Antibiotic, Bacteremia, Resistance.



Blood stream infections are important causes of morbidity and mortality in children [1]. Successful outcome of these infections relies on prompt and timely empiric therapy with broad spectrum antibiotics [2]. Inadequate empiric therapy results in poor outcome with increased mortality rate and emergence of antibiotic resistance [3]. Drug resistant organisms such as extended spectrum beta-lactamase (ESBL) producing organisms and Methicillin - resistant Staphylococcus aureus (MRSA) concern health care providers, especially in the developing countries [4]. Surveillance of prevalence and antimicrobial susceptibility of pathogens is essential for empiric treatment choice in pediatric blood stream infections. We present the distribution of pathogens and their antibiotic susceptibility profile from blood cultures in children who presented with clinical features of sepsis over a 4-year period.

All children aged between 30 days and 15 years of age, who presented to Christian Medical College, Vellore from January 2010 to December 2013 with clinical features of sepsis had their blood samples drawn under aseptic condition. The specimens were inoculated and processed by BacT/ALERT system followed by Gram staining and sub-cultures on MacConckey agar and 5% sheep blood agar. Biochemical identification of the pathogen was done using standard procedures, and followed by antibiotic susceptibility testing as per standard Clinical and Laboratory Standards Institute (CLSI) guidelines. Organisms such as Coagulase negative Staphylococcus aureus (CONS), Diphtheroids and Aerobic spore formers (ASF) were considered contaminants and excluded from analysis.

A total of 41457 blood cultures were done during the study period with positive cultures in 4.8% (n=2015); 3.6% (n=1507) Gram negative bacilli (GNB) and 1.2% (n=508) Gram positive cocci (GPC). Table I shows the predominant pathogens and their antibiotic susceptibility profile. The other pathogens were alpha-hemolytic Streptococci (n=46, 2.3%), beta-hemolytic Streptococci (n=40, 2%) and other Gram negative bacilli (n=29, 1.4%). Non-fermenting Gram-negative bacteria other than Pseudomonas spp. (NFGNB) were commonly isolated. Further characterization showed Acinetobacter spp – 202, Burkholderia cepacia – 41, Sphingobacterium multi-vorum – 6, Ralstonia spp – 4 and undifferentiated NFGNB - 269.

TABLE I Antibiotic Susceptibility Profile for the Predominant Bacteria Isolated from Blood Cultures
Pathogen Number (%) Antibiotic Susceptibility in Percentage
PEN/AMP/OXA P/T GEN AK 3rd gen. Ceph. CIP MER COL TIG VAN LIN
NFGNB 522 (25.9) 75 60 70 73 90
Salmonella spp. 349 (17.3) 95 (AMP) 100 5
E. coli 221 (11) 55 43 83 28 26 92 100 99
Klebsiella spp. 200 (9.9) 56 44 60 31 37 78 100 91
Pseudomonas spp. 128 (6.4) 91 90 90 88
Enterobacter spp. 58 (2.9) 74 43 76 33 64 86 98 98
S.  aureus 217 (10.8) 60 (OXA) 58 32 100 100
Enterococcus spp. 111 (5.5) 50 (AMP) 50 (HLG) 86 100
S. pneumoniae 94 (4.7) 97 (PEN) 98
PEN-Penicillin; AMP-Ampicillin; OXA-Oxacillin; P/T-Piperacillin/tazobactam; Gen-Gentamicin; AK-Amikacin; 3rd gen. Ceph.-3rd generation cephalosporin; CIP-Ciprofoloxacin; MER-Meropenem; COL-Colistin; TIG-Tigecycline; VAN-Vancomycin; LIN-Linezolid; HLG-high level Gentamicin; NFGNB – Non-fermenting Gram negative bacilli other than Pseudomonas.

NFGNB are increasingly being recognized as a source of healthcare associated infections [5]. The hospital- based nature of our study may be a reason for high number of NFGNB in our study. Our study also shows high rates of extended spectrum b-lactamase production (71%) among E. coli and Klebsiella spp. Carbapenemase producing organisms were found in 22% of Klebsiella spp. and 9% of E.coli. Among the Gram positive organisms, 40% of the Staphylococcus aureus were methicillin-resistant. All of them were susceptible to Vancomycin and Linezolid. Among Streptococcus pneumoniae, 97% were susceptible to penicillin compared to 94.1% reported by CDC in 2012 [6]. Fourteen per cent of enterococci in our study were resistant to vencomycin.

To conclude, we documented a high level of drug resistance in gram positive and gram negative bacterial isolates. Urgent efforts are needed to combat increasing drug-resistance in our country.

Contributors: WR and BV: study design; AP: data collection. All the authors were involved in data analysis and manuscript preparation.

Funding: None; Competing interests: None stated.

References

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2. Kollef MH. Inadequate antimicrobial treatment: An important determinant of outcome for hospitalized patients. Clin Infect Dis. 2000;31:S131-8.

3. Behrendt G, Schneider S, Brodt HR, Just-Nübling G, Shah PM. Influence of antimicrobial treatment on mortality in septicemia. J Chemother. 1999;11:179-86.

4. Bhattacharjee A, Sen MR, Prakash P, Gaur A, Anupurba S. Increased prevalence of extended spectrum beta lactamase producers in neonatal septicaemic cases at a tertiary referral hospital. Indian J Med Microbiol. 2008;26:356-60.

5. Malini A, Deepa EK, Gokul BN, Prasad SR. Nonfermenting gram-negative bacilli infections in a tertiary care hospital in Kolar, Karnataka. J Lab Physicians. 2009;1:62-6.

6. Centers for Disease Control and Prevention. 2013. Active Bacterial Core Surveillance Report, Emerging Infections Program Network, Streptococcus pneumoniae, 2012.

 

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