Journal of Laboratory Physicians
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Year : 2010  |  Volume : 2  |  Issue : 1  |  Page : 14-16 Table of Contents   

Metallo-beta-lactamase producing Pseudomonas aeruginosa in neonatal septicemia

Microbiology Department, Pt.BDS PGIMS, Rohtak, Haryana, India

Date of Web Publication23-Jul-2010

Correspondence Address:
Madhu Sharma
Microbiology Department, Pt.BDS PGIMS, Rohtak, Haryana
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0974-2727.66701

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Gram-negative bacilli are important agents causing neonatal sepsis. The organisms isolated are often resistant to multiple antimicrobials specially which are metallo-beta-lactamases (MβL) producers. Therefore, the present study was conducted with the objective to examine the incidence of MβL producing strains in multidrug resistant (MDR) Pseudomonas aeruginosa from cases of neonatal sepsis. Between January-December 2006, 1994 cases of neonatal sepsis were investigated. The isolates obtained were identified and tested for susceptibility to various antimicrobial agents. The multidrug resistant P. aeruginosa0 isolates were screened for the presence of MβL by imipenem-EDTA disc method. Five hundred and ninety three (29.73%) isolates were obtained from culture of neonates. Most frequent offender was P. aeruginosa (48.2%). There was an overall predominance of gram-negative organisms. MβL production was seen in 69.5% of imipenem-resistant P. aeruginosa isolates. MβL producing P. aeruginosa is an emerging threat in neonatal septicemia and a cause of concern for physicians treating such infections.

Keywords: MβL, neonatal sepsis, Pseudomonas

How to cite this article:
Sharma M, Yadav S, Chaudhary U. Metallo-beta-lactamase producing Pseudomonas aeruginosa in neonatal septicemia. J Lab Physicians 2010;2:14-6

How to cite this URL:
Sharma M, Yadav S, Chaudhary U. Metallo-beta-lactamase producing Pseudomonas aeruginosa in neonatal septicemia. J Lab Physicians [serial online] 2010 [cited 2019 Dec 8];2:14-6. Available from:

   Introduction Top

Septicemia is a clinical syndrome associated with considerable morbidity and mortality. In India, neonatal septicemia is responsible for one-fourth to nearly half of the neonatal deaths next to perinatal hypoxia. [1] Infections with Pseudomonas aeruginosa is usually late in onset, nosocomial in origin and epidemic in pattern. P. aeruginosa, exhibit intrinsic resistance to various antimicrobial agents including β-lactam antibiotics. In recent years, there has been an increase in carbapenem resistance which is acquired metallo-beta-lactamases (MβL) and reported mainly for P. aeruginosa and Acinetobacter spp. in several countries. Therefore, P. aeruginosa must be considered in all neonatal infections, regardless of the age of onset, so that early, appropriate and often life-saving antibiotic therapy may be instituted. [2] Thus, the present study was designed to know the incidence of neonatal septicemia, sepsis caused by P. aeruginosa, their antibiotic susceptibility pattern and to detect the presence of MβL among the imipenem-resistant isolates of P. aeruginosa.

The present study was undertaken during January-December 2006 at Pt.B.D.S, PGIMS, Rohtak (Haryana). A total of 1994 blood cultures were received in the Microbiology Deptartment., from clinically suspected cases of neonatal septicemia. The blood culture bottles were incubated at 37C for 7 days. Subcultures were done first at 24 h, then at 48 h, 72 h and on the seventh day onto the blood agar and MacConkey's agar plates. Organisms isolated were identified by standard methods of identification. [3] P. aeruginosa were Gram-negative bacilli, strictly aerobic, oxidase positive, motile, with positive arginine dihyrolase reaction, growth at 42C and able to reduce nitrates to nitrogen gas. Antibiotic sensitivity tests of the isolates were performed by the Kirby Bauer disc diffusion method for commonly used antibiotics. [4] All the multi-drug-resistant(MDR) isolates of P. aeruginosa were then tested for the sensitivity to imipenem (10μg, HiMedia) and the imipenem-resistant isolates were screened for the production of MβL by the imipenem-EDTA disc method as described by Yong et al.[5] The inhibition zone with imipenem-EDTA disc were <14 mm for MβL-negative isolates and >17 mm for MβL-positive isolates considering the inhibition zone with imipenem to be 6-16 mm.

Of the 1994 blood cultures from neonates, 593(29.73%) showed bacterial growth. Most cases were detected in the first 10 days of life (77.90%). Gram-negative septicemia was encountered in 81.28% cases; Gram-positive cocci were isolated in 18.71% cases. P. aeruginosa (48.22%) was the predominant pathogen [Table 1] in Gram-negative isolates, whereas coagulase negative Staphylococci (CoNS) was the most common among Gram-positive cocci. P. aeruginosa was mostly resistant to gentamicin(92.3%), amikacin(91.2%), and piperacillin (88.8%). One hundred and eighty two (63.6%) isolates of P. aeruginosa were found to be MDR. Of these, 113(62%) were imipenem-sensitive and 69(37.9%) were imipenem resistant. MβL production was observed in 69.5% of imipenem-resistant isolates.

Blood culture is the most important investigation to confirm the diagnosis of neonatal septicemia. In the present study, the incidence of septicemia was 29.73%. This was comparable to 30-75% positivity reported in earlier studies. [6],[7] Most of the cases detected by blood culture occurred in the first 10 days of life (77.90%), a fact that has been reported previously and probably relates to immaturity of the immune system. This warrants the need for close monitoring of the newborns.

A rising incidence of Gram-negative bacteremia has been reported in recent years in neonates. [6],[7] The present study isolated 81.28% of Gram-negative bacilli with P. aeruginosa (48.22%) as the predominant pathogen. P. aeruginosa has also been reported to be the most common etiological agent of neonatal septicemia by other workers. [8],[9],[10]

Almost all Gram-negative organisms showed resistance to chloramphenicol (70-95%) and gentamicin (50-95%). Reduced chloramphenicol sensitivity (20-44%) [11],[12] and gentamicin sensitivity (23-30%) [13] have been documented by other workers. The overall resistance rate of P. aeruginosa to all antimicrobial agents in our study was also significant and accounted for 62% MDR isolates which correlates with the study by Moniri and colleagues (73.9%). [10] Multi-drug resistance caused by a variety of resistance mechanisms implies that there are few therapeutic options. Carbapenems are often used as antibiotics of last resort against this organism. Our study showed 37.9% imipenem resistance which is in concordance with Sarkar et al (36.36%). [14]

With increasing the use of carbapenems in hospital settings, the problem of MβL production is also increasing. In our study, 69.5% isolates were found to be MβL producers. This is an emerging threat and a matter of concern for treating physicians. The remaining imipenem resistant isolates may have other mechanisms of resistance such as reduced levels of drug accumulation or increased expression of pump efflux.

To conclude, P. aeruginosa is an important Gram-negative bacilli which cause neonatal septicemia and should be borne in mind while dealing with such cases. The MDR strains can cause considerable morbidity and mortality. The study also highlights that MβL incidence is increasing in our region. The wide spread occurrence of MβL producing P. aeruginosa isolates poses a great therapeutic problem. The resistance may spread rapidly to various species of Gram-negative bacilli; therefore, to prevent the further spread of MβL producers, it is essential to rapidly detect MβL-positive isolates to aid infection control.

   References Top

1.Sharma A, Kutty KC, Sabharwal U, Rathee S, Mohan H. Evaluation of sepsis screen for diagnosis of neonatal septicemia. Indian J Pediatr 1993;60:559-63.  Back to cited text no. 1      
2.Barton LL, Lustiq RH, Fong CT, Walentic CA. Neonatal septicemia due to Pseudomonas aeruginosa. Am Fam Physician 1986;33:147-51.  Back to cited text no. 2      
3.Collee JG, Duguid JP, Fraser AG, Marmion BP, Simmons A. Laboratory strategy in diagnosis of infective syndromes. In: Collee JG, Fraser AG, Marmion BP, Simmons AC, editors. Mackie and McCartney Practical Medical Microbiology. 14 th ed. Singapore: Churchill Livingstone; 1996. p. 53-94.  Back to cited text no. 3      
4.Bauer AW, Kirby WM, Sherns JC, Turck M. Antibiotic susceptibility testing by a standard single disc method. Am J Clin Pathol 1966;45:493-6.  Back to cited text no. 4      
5.Yong D, Lee K, Yum HJ, Shin HB, Rossolini GM, Chong Y. Imipenem-EDTA disk method for differentiation of metallo-β-lactamases producing clinical isolates of Pseudomonas spp. and Acinetobacter spp. J Clin Microbiol 2002;40:3798-801.   Back to cited text no. 5      
6.De A, Saraswathi K, Gogate A, Fernandes AR. Bacteremia in hospitalized children: A one year prospective study. Indian J Med Microbiol 1995;13:72-5.  Back to cited text no. 6      
7.Sharma M, Goel N, Chaudhary U, Aggarwal R, Arora DR. Bacteremia in children. Indian J Pediatr 2002;69:1029-32.  Back to cited text no. 7      
8.Kulkarni A, Vigneswaran R. Acquired neonatal sepsis: Are surveillance cultures helpful? Asian J Pediatr Pract 2000;4:11-3.  Back to cited text no. 8      
9.Bhattacharjee A, Sen MR, Prakash P, Gaur A, Anupurba S. Increased prevalence of extended spectrum beta lactamase producers in neonatal septicemic cases at a tertiary referral hospital. Indian J Med Microbiol 2008;26:356-60.   Back to cited text no. 9  [PUBMED]  Medknow Journal  
10.Moniri R, Mosayebi Z, Movahedian AH, Mousavi GA. Emergence of multidrug resistant Pseudomonas aeruginosa isolates in neonatal septicemia. J Infect Dis Antimicrob Agents 2005;22:39-44.  Back to cited text no. 10      
11.Kuciikates E, Kocazeybek B. High resistance rate against 15 different antibiotics in aerobic Gram-negative bacterial isolates of cardiology intensive care unit patients. Indian J Med Microbiol 2002;20:208-10.  Back to cited text no. 11      
12.Okesola AO, Oni AA. Antimicrobial resistance among common bacterial pathogens in South-west Nigeria. American Eurasian J Agri Env Sci 2009;5:327-30.  Back to cited text no. 12 A, Deodhar LP. Sensitivity of common bacterial isolates to netilmycin: A potent aminoglycoside. Indian Practitioner 1992;45:599.  Back to cited text no. 13      
14.Sarkar B, Biswas D, Prasad R. A clinic microbiological study on the importance of Pseudomonas in nosocomially infected ICU patients with special reference to metallo-β-lactamase production. Indian J Pathol Microbiol 2006;49:44-6.  Back to cited text no. 14  [PUBMED]    


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[Pubmed] | [DOI]


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