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International Journal of Health & Allied Sciences

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Volume 5 / Issue 4 / October-December 2016

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INTRODUCTION

Bloodstream infections (BSIs) are associated with a high mortality rate of 20%–50% and one of the most common health‑care associated infections.[1] It requires rapid and aggressive antimicrobial therapy.[2] The change of prevalence and antimicrobial resistance pattern among bloodstream pathogens is a significant problem worldwide with severe consequences including increased cost of care, morbidity, and mortality.[1,3] The increasing resistance to most commonly used antimicrobials results in a reduction in therapeutic options.[3] Thus, the detection of BSIs must be given priority in all health‑care settings. Clinical laboratory

Bacteriological profile and antimicrobial resistance patterns of bloodstream infections in a tertiary care hospital, Eastern IndiaMuktikesh Dash, Rakesh Kumar Panda, Dharitri Mohapatra, Bimoch Projna Paty, Gitanjali Sarangi, Nirupama ChayaniDepartment of Microbiology, Shri Ramachandra Bhanj Medical College and Hospital, Utkal University, Cuttack, Odisha, India

Original Article

ABSTRACT

Introduction: Bloodstream infections (BSIs) are associated with a high mortality rate of 20%–50%. Blood culture is paramount to identify causative agents of BSIs to choose an appropriate antimicrobial therapy. Objectives: The present study was undertaken to analyze the various microorganisms causing BSIs and study their antimicrobial resistance patterns in a tertiary care hospital, Eastern India. Materials and Methods: A total of 239 blood specimens from clinically suspected cases of BSIs were studied for 6 months from July 2015 to December 2015. Blood specimens were incubated in BacT/ALERT® 3D system (bioMerieux, Durham, NC, USA) a fully automated blood culture system for detection of aerobic growth. Identification and antimicrobial susceptibility testing were conducted on VITEK® 2 (bioMerieux, Durham, NC, USA) as per Clinical Laboratory Standards Institute guidelines. Results: Out of 239 specimens, 41 (17.2%) yielded growth of different microorganisms. From these isolates, 20 (48.8%) were Gram‑negative bacilli, 18 (43.9%) were Gram‑positive cocci and rest 3 (7.3%) were yeasts. Among Gram‑negative bacilli, Klebsiella pneumoniae sub spp. pneumoniae (70%) was most commonly isolated. Coagulase‑negative staphylococci (88.9%)

were the most common isolate among Gram‑positive cocci. All three Candida spp. isolated were nonalbicans Candida (two Candida tropicalis and one Candida krusei). Gram‑negative isolates were least resistant to tigecycline and colistin. All Gram‑positive cocci were sensitive to linezolid. Conclusion: Monitoring of data regarding the prevalence of microorganisms and its resistance patterns would help in currently prescribing antimicrobial regimens and improving the infection control practices by formulating policies for empirical antimicrobial therapy.

Key words: Bloodstream infections, coagulase negative staphylococci, colistin, Klebsiella pneumoniae sub spp. pneumoniae, linezolid, nonalbicans Candida

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Website: www.ijhas.in

DOI: 10.4103/2278-344X.194083

How to cite this article: Dash M, Panda RK, Mohapatra D, Paty BP, Sarangi G, Chayani N. Bacteriological profile and antimicrobial resistance patterns of bloodstream infections in a tertiary care hospital, Eastern India. Int J Health Allied Sci 2016;5:210-4.

This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms.

For reprints contact: reprints@medknow.com

Address for correspondence: Dr. Muktikesh Dash, Department of Microbiology, Shri Ramachandra Bhanj Medical College and Hospital, Utkal University, Cuttack ‑ 753 007, Odisha, India. E‑mail: mukti_mic@yahoo.co.in

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diagnosis is crucial to avoiding delay in treatment.[4‑6] Blood culture is paramount to identify causative agents of BSIs to choose an appropriate antimicrobial therapy. In the Intensive Care Unit, the main causative agents of BSIs are Staphylococcus sp., Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Enterococcus faecalis, Acinetobacter baumannii, and Candida spp.[7,8] The use of automated culture system for monitoring blood cultures increases the speed and improves efficiency in detection of blood borne pathogens. The system monitors the consumption of carbon dioxide by calorimetric method, generally detecting positive growth after 48 h.

The infections caused by multidrug‑resistant organisms are more likely to be associated with prolonged hospital stay, increased mortality and thus requires treatment with more expensive antimicrobials. In almost all cases, antimicrobial therapy is initiated empirically before the results of blood culture are available. Monitoring and analyzing the antimicrobial resistance pattern of most frequently isolated microorganisms help the clinicians to choose effective antimicrobial therapy as well as empirical antimicrobials. Therefore, the present study was undertaken to analyze the various microorganisms causing BSIs and study their antimicrobial resistance patterns in a tertiary care hospital, Eastern India to guide the clinicians for formulating antimicrobial policies for empirical therapy.

MATERIALS AND METHODS

A total of 239 blood specimens from clinically suspected cases of septicemia were studied at a tertiary care hospital of Eastern India for 6 months from July 2015 to December 2015. Septicemia is defined as a systemic disease caused by the spread of microorganisms and their toxins via the circulating blood. Patients presented with sepsis showed a diversity of clinical signs, i.e. body temperature higher than 38°C (100.4°F) or lower than 36°C (96.8°F), heart rate >0 beats/min, respiratory rate >20/min, hyperventilation (PaCO

2 <32 mmHg), and white blood

cell count >12,000/µl or <4000/µl were included as cases.[9] The study was conducted after due approval from Institutional Review Board. Single blood specimen was collected from inpatients admitted in our hospital during the study, and the specimens were processed in clinical microbiology laboratory. The contaminated, duplicate, and repeat specimens were excluded from the study. Before the collection of blood samples, verbal informed consent was sought. Blood sample was collected aseptically from each patient before the start of antimicrobial therapy. In case of adults, 5–10 ml (average 7 ml) and pediatrics

1–5 ml (average 3 ml) were inoculated in BacT/ALERT® FA and PF plus‑aerobic bottles (bioMerieux, Durham, NC, USA), respectively. The microorganisms were detected as per manufacturer’s instructions.[10] In brief, after inoculation, these bottles were immediately incubated in BacT/ALERT® 3D system (bioMerieux, Durham, NC, USA) a fully automated blood culture system for detection of aerobic growth in blood samples. The blood specimens were incubated for a maximum period of 7 days, and if there was no growth, the result was read as negative. While in case of positive growth, the BacT/ALERT® system (bioMerieux, Durham, NC, USA) automatically showed an alert. Then the positive blood culture bottles were taken out and subcultured on blood agar and MacConkey agar plates. From the colonies that were grown on blood agar and MacConkey agar, 0.5% McFarland suspension was prepared and which was then subjected to identification and antimicrobial susceptibility testing on VITEK® 2 (bioMerieux, Durham, NC, USA) as per Clinical Laboratory Standards Institute (CLSI) guidelines and manufacturer’s instructions.[11] The antimicrobial resistance was determined by VITEK®2 system (bioMerieux, Durham, NC, USA) as per CLSI guidelines.

RESULTS

During the study of 6 months, a total of 239 blood culture specimens were received from various clinical wards. Out of 239 specimens, 41 (17.2%) yielded growth of different microorganisms [Table 1]. From these isolates, 20 (48.8%) were Gram‑negative bacilli, 18 (43.9%) were Gram‑positive cocci and rest 3 (7.3%) were yeasts. Out of 20 Gram‑negative and 20 Gram‑positive respectively negative isolates, 14 (70%) were K. pneumoniae sub spp. pneumoniae and rest 6 were single isolate each of Acinetobacter lwoffii, Acinetobacter haemolyticus, A. baumannii, Burkholderia cepacia, Pantoea agglomerans, and P. aeruginosa. From 18 g positive isolates, 7 (38.9%) were Staphylococcus hominis sub spp. hominis, 5 (27.8%) were Staphylococcus haemolyticus, 4 (22.2%) were S. epidermidis and rest were single isolates each of S. aureus and Enterococcus faecium [Table 2]. The antimicrobial resistances patterns of Gram‑negative bacilli showed, the majority of isolates were resistant to ß‑lactam antibiotics, followed by aminoglycosides and quinolones. These isolates were least resistant to tigecycline and colistin [Figure 1]. The antimicrobial resistances patterns of Gram‑positive cocci showed most of the isolates were resistant to penicillin, oxacillin, and erythromycin followed by clindamycin, rifampicin, daptomycin, and quinolones. The Gram‑positive cocci were least resistant to vancomycin, teicoplanin, and tigecycline and all isolates were sensitive to linezolid [Figure 2]. Similarly, all three nonalbicans Candida

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were sensitive to voriconazole, caspofungin, micafungin, and amphotericin B [Figure 3].

DISCUSSION

BSI is a major cause of morbidity and mortality worldwide. Antimicrobial therapy is the mainstay of treatment of BSI along with management of severe sepsis and septic shock.[12] During last few years, clinicians have witnessed a growing incidence of BSIs along with resistance against commonly used antimicrobials.[13] Therefore, this present study was undertaken to detect the prevalence of microorganisms isolated from blood and study their antimicrobial resistant patterns in a tertiary care hospital, Eastern India.

From 239 blood specimens (201 pediatric and 38 adults) cultured in automated blood culture system, our study detected 41 (17.2%) growth of different microorganisms. Although the reason for more number of pediatric patients were tested for BSIs not quite clear, one of the reasons may be due to fact that in pediatric age group both the innate and adaptive immune functions are not immunologically mature thus they are susceptible to infections.[14] The prevalence rate of BSIs in our hospital was 17.2%. The similar prevalence rate of 16% BSIs was observed by Fayyaz et al. in a tertiary

care setting in Rawalpindi, Pakistan.[15] In contrast, the high prevalence rate of 28.9% and 42% were reported by Parihar et al. and Ramana et al. from Western Rajasthan, India, and South India, respectively.[16,17] Prevalence rate varies among different geographical regions as well as the type of antimicrobials prescribed. The majority of patients reported to our tertiary care hospital were referred by primary and secondary care hospitals and private hospitals, and most of these patients were already received antimicrobials elsewhere before they reached our hospital. Furthermore, the patients those were admitted to emergency sometimes had received antimicrobials before collection of blood for

Table 1: Overall adult and pediatric blood culture results (n=239)Result Adults (%) Pediatrics(%) Total (%)Growth of microorganisms

5 (2.1) 36 (15.1) 41 (17.2)

No growth (sterile) 33 (13.8) 165 (69) 198 (82.8)Total 38 (15.9) 201 (84.1) 239 (100)

Table 2: Distribution of microorganisms isolated from blood cultures (n=41)Gram reaction Microorganisms n (%)Gram‑negative bacilli

Klebsiella pneumoniae sub spp. pneumoniae

14 (34.2)

Acinetobacter lwoffii 1 (2.4)Acinetobacter haemolyticus 1 (2.4)Acinetobacter baumannii 1 (2.4)Burkholderia cepacia 1 (2.4)Pantoea agglomerans 1 (2.4)Pseudomonas aeruginosa 1 (2.4)

Gram‑positive cocci

Staphylococcus hominis sub spp. hominis

7 (17.2)

Staphylococcus haemolyticus 5 (12.3)Staphylococcus epidermidis 4 (9.8)Staphylococcus aureus 1 (2.4)Enterococcus faecium 1 (2.4)

Gram‑positive yeasts

Candida tropicalis 2 (4.9)Candida krusei 1 (2.4)

Total 41 (100)

Figure 1: Drug‑resistant patterns of Gram‑negative bacilli (%)

Figure 2: Drug‑resistant patterns of Gram‑positive cocci (%)

Figure 3: Drug‑resistance patterns of yeast isolates (%)

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culture. From 41 microorganisms isolated in our study, 20 (48.8%) were Gram‑negative bacilli, 18 (43.9%) were Gram‑positive cocci (most commonly isolated were coagulase negative staphylococci [CONS]) and 3 (7.3%) were yeasts. Out of 20 g negative bacilli, 14 (70%) isolates were K. pneumoniae sub spp. pneumoniae. From 18 g positive cocci, 16 (88.9%) were CONS. All three yeast isolates were nonalbicans Candida. Similar distributions of microorganisms were noted by Fayyaz et al. and Parihar et al. respectively.[15,16] In comparison, Ramana et al. detected a higher percentage of Candida spp., i.e., 34% in their study.[17] Other studies have reported CONS being the most commonly isolated species among Gram‑positive cocci.[15,17] The CONS have been isolated from blood cultures among patients with increased use of intravascular devices which could serve as portal of entry to the bloodstream.

The Gram‑negative K. pneumoniae sub spp. pneumoniae were 100% resistant to ampicillin, ceftazidime, cefixime, and ceftriaxone followed by cefoperazone + sulbactam, piperacillin + tazobactam, imipenem, meropenem, gentamicin, ciprofloxacin, and levofloxacin. They were least resistant to amikacin, tigecycline, and colistin. One B. cepacia isolate was resistant to both tigecycline and colistin. Similar to our study, Fayyaz et al. have reported higher resistance to third generation cephalosporins and quinolones. On the other hand, imipenem and amikacin yielded better activity against Gram‑negative isolates.[15] Gohel et al. have demonstrated very poor sensitivity to penicillins, cephalosporins, and quinolones. Least resistance was observed with carbapenems, aminoglycosides, tigecycline, and colistin.[18]

This study revealed that most of the CONS were resistant to penicillin, oxacillin, and erythromycin, followed by clindamycin, tetracycline, ciprofloxacin, levofloxacin, co‑trimoxazole, daptomycin, rifampicin, and gentamicin. The CONS were least resistant to tigecycline, vancomycin, and teicoplanin. All isolates were sensitive to linezolid. Fayyaz et al. in their study have reported all the CONS isolates were sensitive to linezolid, which is comparable with our study.[15] Ramana et al. have revealed 20% of CONS were resistant to vancomycin, and all CONS were sensitive to imipenem and linezolid.[17]

In this study, all three Candida spp. isolated were nonalbicans Candida (two Candida tropicalis and one Candida). C. tropicalis were sensitive to all antifungal agents tested, whereas Candida krusei was resistant to fluconazole and flucytosine. Similarly, Ramana et al. have reported in their study that all Candida isolates were susceptible to amphotericin B and nystatin but Candida spp. were resistant to fluconazole and

clotrimazole.[17] There is the emergence of nonalbicans Candida and resistant to most commonly used antifungal agents have been reported in different parts of India.[19,20]

There were few limitations in this present study. The sample size was less due to short study period. Only single blood culture specimen could be collected from each patient. Beside blood specimen other specimens from different sites were not collected.

CONCLUSION

K. pneumoniae sub spp. pneumoniae and CONS were the predominant blood borne pathogens isolated in our region. Most of the Gram‑negative bacilli were sensitive to tigecycline and colistin. The majority of Gram‑positive cocci were sensitive to vancomycin, teicoplanin, tigecycline, and linezolid. There is the emergence of antimicrobial resistance in almost every corner of the world pointing toward active microbial surveillance in all clinical settings. Such monitoring of data regarding the prevalence of microorganisms and its resistance patterns would definitely benefit the current prescribed antimicrobial regimens, especially in resource‑limited countries. This also helps in improving the infection control practices by formulating policies for empirical antimicrobial therapy.

Financial support and sponsorshipNil.

Conflicts of interestThere are no conflicts of interest.

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