Keywords

Acinetobacter; Antimicrobial resistance; MRSA; Sterile body fluids

Introduction

Infections of the sterile body sites typically have greater clinical urgency and these infections could be life-threatening [1,2]. Different types of microorganisms like bacteria, fungi, virus and parasites may invade and infect the body fluids resulting in severe morbidity and mortality. For potentially pathogenic microorganism, even a single colony may be significant [3]. The common pathogenic bacteria of concern are Escherichia coli, Acinetobacter spp., Klebsiella spp., Staphylococcus aureus and Enterococcus spp. Therefore, it is necessary to monitor the epidemiology of bacterial susceptibility pattern in each area, so that such infections must be treated by the empirical use of antimicrobial drugs as soon as possible to reduce the morbidity and mortality. This study was done for identifying the bacterial pathogens and their antimicrobial susceptibility pattern in the patients admitted in a tertiary care Hospital, New Delhi.

Materials and Methods

This study was done on a prospective basis for a period of one year from Jan 2015 to December 2015 in Department of Microbiology of a tertiary care hospital, New Delhi. A total of 405 samples were analyzed. Pleural, peritoneal, synovial and pericardial fluids were drawn using proper aseptic precautions and sent to Department of Microbiology, within 2 hours of collection.

Sample processing

Pleural fluid, peritoneal fluid, synovial fluid and pericardial fluid were processed in laboratory using standard microbiological procedures. Blood agar, Mac-Conkey agar and chocolate agar (Himedia, Mumbai, India) were used for culture with the purpose of obtaining isolated colonies. The isolated colonies were then identified using standard biochemical tests [3].

Antimicrobial susceptibility test: The antimicrobial susceptibility test was performed for isolated organisms by Kirby Bauer’s disk diffusion method according to clinical and laboratory standard institute (CLSI, 2014) guidelines [4]. The routine antimicrobial sensitivity tests were put for the following antibiotics:

Drugs for GPC pathogen

The antibiotics which were tested for GPC were Cefoxitin (30 mcg), Ciprofloxacin (5 mcg), Tetracycline (30 mcg), Erythromycin (15 mcg), Trimethoprim-sulfamethoxazole (1.25/23.75 mcg), and Linezolid (30 mcg).

Drugs for GNB pathogen

For GNB Ampicillin (10 mcg), Pipracillin/tazobactam (100/10 mcg), Ceftazidime (30 mcg), Ceftriaxone (30 mcg), Cefepime (30 mcg), Ceftazidime/clavulanic acid (75/30 mcg), Amikacin (30 mcg), Gentamicin (10 mcg), Netilmicin (30 mcg), Ciprofloxacin (5 mcg), Imipenem (10 mcg), Meropenem (10 mcg), Aztreonam (30 mcg), Polymyxin B (300 mcg), Colistin (10 mcg), Trimethoprimsulfamethaxazole (1.25/23.75 mcg).

Drugs for Pseudomonas aeruginosa pathogen

Antibiotics used for Pseudomonas aeruginosa were Piperacillin (100 mcg), Piperacillin/tazobactam (100/10 mcg), Ceftazidime (30 mcg), Cefepime (30 mcg), Amikacin (10 mcg), Gentamicin (10 mcg), Ciprofloxacin (5 mcg), Imipenem (10 mcg), Meropenem (10 mcg), Netilmicin (30 mcg), Aztreonam (30 mcg), Polymyxin B (300 mcg), Colistin (10 mcg).

Results

A total 405 different body fluid were collected from suspected patients, which included pleural fluid, peritoneal fluid, synovial fluid and pericardial fluid. Amongst 405 samples, 122 fluids samples showed growth of organisms with an isolation rate of 30% (Table 1). Isolates from different fluids were E.coli, Acinetobacter spp., Klebsiella spp., S. aureus, Enterococcus spp., Pseudomonas spp. and Citrobacter spp. (Table 2). Antibiotic sensitivity pattern of different isolates is shown in (Table 3). Gram negative isolates were mostly sensitive to carbepenems, colistin and polymyxin B (100%) and gram positive isolates were highly sensitive to vancomycin (100%), linezolid (100%) and ciprofloxacin (70%). Acinetobacter was the most resistant pathogens to many antibiotics. About 38.5% of S. aureus isolates in our study were MRSA.

Table 1 Different type of samples.

Table 2 Different organisms isolated from different samples.

Table 3 Antibiotic sensitivity patterns of isolates *MIC determination by E-test.

Discussion

Normally sterile body sites such as pleural fluid, peritoneal fluid, pericardial fluid, synovial fluid etc. can be infected by various pathogens. In this study 30% samples give culture positive result, which is in comparison to other studies conducted on similar lines, were 31% and 24% positive results [5,6]. A total of 405 samples were studied out of which, 156 were peritoneal fluids, 140 were pleural fluids, 93 were synovial fluids and 16 were pericardial fluid samples. In our study, the predominant organisms were E.coli (28.6%) and Acinetobacter spp. (27%), followed by Klebseilla spp. (19.6%), S. aureus (10.6%), Enterococcus spp. (7.3%), Pseudomonas spp. (4.9%) and Citrobacter spp. (1.6%). In our study Acinetobacter spp. and E. coli were the commonest organisms isolated from pleural effusion samples while other studies done by Sujatha et al. [5] and Evan et al. [7] found E. coli and Klebsiella spp. and S.aureus as the most common isolate respectively.

Gram negative organisms (90%) were more commonly isolated from ascitic fluids than Gram positive organisms (9%). Among the Gram negative isolates, E.coli was most common isolate (35%) followed by Acinetobacter spp. (26.8%) and Klebsiella spp. (21.9%). Similarly in several other studies E.coli was found to be the most common cause of ascitic fluid infection [5,8,9].

On synovial fluid, there were many studies conducted by authors [10,11] that found S.auerus as the most predominant isolates 55% and 30% respectively. We found S.aureus, Klebsiella spp. and Entercoccus spp. with the isolation rate of 68.7%, 18.7% and 12.5% respectively. In a study from South Africa, [12] S.aureus and Salmonella spp. were commonly isolated from pericardial fluid samples. In the present study, Klebsiella spp. was isolated in 12% of pericardial fluid samples.

Our study showed that gram negative isolates were mostly sensitive to Carbepenems, Colistin and Polymyxin B (100%). E.coli isolates showed highest resistance to Cephalosporins, Fluoroquinolones and moderate resistance to beta-lactambeta- lactamase inhibitors. According to Barai L et al. [13] E.coli isolates were highly resistant (>80) to Cephalosporins and Fluoroquinolones. In Tullu et al. [14] study too, majority of the isolates were highly resistant (66%-100%) to Cephalosporins. Klebsiella spp. showed least resistance to Carbapenems, Tigecycline and moderate resistance to aminoglycosides, and beta-lactam beta-lactamase inhibitor combination. In our study, more than 95% of Pseudomonas isolates were sensitive to Piperacillin-tazobactam and more than 80% of the isolates were sensitive to Meropenem, Imipenem and Ticarcillin.

We found that Acinetobacter was the most resistant pathogens to many antibiotics as seen in some other studies [15]. Acinetobacter is an important public health problem, especially in patients on broad spectrum antimicrobial therapy and requiring life support [16,17]. A study has shown that multi drug resistant Acinetobacter isolates are commonly seen in ICUs and may cause severe infections with a high mortality rate [18].

In our study, gram positive organisms were found to be highly resistant to erythromycin and tetracycline. The study also showed that S. aureus was found to be highly sensitive to vancomycin, linezolid and ciprofloxacin. About 38.5% of S. aureus isolates in our study were MRSA, which is much similar to other studies performed in India [19,20]. The present study shows antibiotic resistance pattern within India, and has been conducted specifically on sterile body fluids, whereas others were done on a wide variety of sterile and non-sterile clinical specimens [21,22]. Therefore, the present findings can serve as an index of actual antibiotic resistance specifically in sterile body fluids.

The prevalence of MRSA continues to increase worldwide, sometimes accounting for approximately 40-60% of all hospital acquired strains [23]. No vancomycin resistant (VRSA) or Vancomycin-intermediate resistant S.aureus (VISA) isolates were detected in our study. There could be many explanations for such differences, like effective infection control measures, antibiotic prophylaxis and treatments policy in hospital. While there are reports around the world indicating a tendency toward decreasing susceptibility to Vancomycin in S.aureus, [24] we had no VRSA or VISA isolates. This may be due to judicious and controlled use of Vancomycin in our hospital.

Surveillance of the incidence, microbial profile and antibiotic resistance pattern of sterile body fluids infections in a particular population is an essential part for the selection of the most appropriate empiric antibiotic regimen and to prevent selective pressure as well as further development of resistance in these pathogens.

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