ABSTRACT
Background and Objectives: Acinetobacter baumannii has emerged as a major organism accounting for hospital acquired infections particularly in intensive care units. Due to production of different kinds of beta lactamases these bacteria have developed drug resistance rendering the treatment of such infections very difficult and expensive. Rapid identification of A. baumannii producing such beta-lactamases is the need of the hour in reducing morbidity and mortality associated with A. baumannii infections. Materials and Methods: A. baumannii was isolated from clinical samples like endotracheal aspirates, sputum, urine, exudates using standard culture techniques. Identification and drug sensitivity was done using Vitek 2 system. All the isolates were subjected to detection of ESBLs using phenotypic confirmatory test, plasmid mediated AmpC beta-lactamase by AmpC disc test, Carbapenemase production by CarbAcineto NP Test and Modified hodge method. Results: 149 A. baumannii isolates were analysed for antimicrobial susceptibility and various beta-lactamase production. Results were evaluated for statistical significance using Chi-Square and P value. 81.8% of isolates were from male patients with majority of them above 50 years of age. 88.5% of samples were from ventilator associated pneumonia patients. 83.8% of isolates were sensitive to tigecycline. Only 10% to 12% of isolates were sensitive to carbapenems. 23.4% of isolates were ESBL producers and 46.9% of them were AmpC producers. Modified Hodge test method identified 63.7% of A. baumannii as carbapenemase producers where as CarbAcineto NP test identified 63% and exibiting 94.74% sensitivity, 93.22% specificity when compared to Modified Hodge test. Conclusion: Multidrug resistant Acinetobacter spp. is on the rise. Present study showed that high percentage of drug resistance in A. baumannii could be due to production of ESBLs, AmpC and carbapenemases. Among all beta lactamases carbapenemase producers are more and quickly raising in A. baumannii. Rapid, cost effective assay which can be adopted in all clinical laboratories is critical to prevent their further transmission particularly in hospital environment.
ABSTRACT
PURPOSE: Multidrug-resistant organisms causing community-acquired and hospital-acquired infections are increasing at a dangerous rate. Carbapenemase-producing Enterobacteriaceae and Pseudomonas species are an important source of concern since these organisms are not only resistant to beta-lactam antibiotics but also show cross-resistance to other groups of antibiotics. In the present study, rapid detection of these carbapenemase-producing Enterobacteriaceae and Pseudomonas species by carbapenemase Nordmann-Poirel (Carba NP) test was evaluated by comparing with modified Hodge test (MHT). MATERIALS AND METHODS: Imipenem-resistant Enterobacteriaceae and Pseudomonas species isolated from various samples such as pus, blood, sputum, urine, and endotracheal aspirates were processed for carbapenemase detection by MHT and Carba NP test. Kappa analysis was done to evaluate the percentage agreement between the two tests. RESULTS: Seventy imipenem-resistant Enterobacteriaceae and Pseudomonas isolates were analyzed in the present study for carbapenemase production. 63.41% of Enterobacteriaceae and 34.48% of Pseudomonas species were carbapenemase producers considering both the methods. By MHT, 36 (51.42%) isolates and, by Carba NP test, 35 (50%) isolates were positive for carbapenemase production out of the 70 isolates. CONCLUSION: Carba NP test when compared to MHT is a simple, rapid, cost-effective biochemical test which can be used in all laboratories in the identification of life-threatening carbapenemase-producing Gram-negative bacteria.
ABSTRACT
BACKGROUND AND OBJECTIVES: Neonatal septicemia can be rapidly fatal if not treated promptly. A speedy laboratory diagnosis would improve the outcome. The BacT/ALERT 3D system (bioMerieux, Durham, North Carolina) is currently being used for laboratory diagnosis of blood stream infections. In the present study, a modified protocol was employed in which the broth was subcultured into two nutrient broth tubes and these tubes were used for biochemical tests and antimicrobial susceptibility testing to decrease the turnaround time. MATERIALS AND METHODS: A prospective study was conducted in the Department of Microbiology, SDM College of Medical Sciences and Hospital, Dharwad from October 2010 to July 2012 after receiving clearance from the institutional ethics committee. Automated blood cultures of 250 neonates admitted to the Neonatal Intensive Care Unit (NICU), clinically diagnosed to have septicemia, were performed using BacT/ALERT 3D. Bottles flagged positive within 72 hours of loading were processed for identification and antibiotic susceptibility testing using a modified protocol. The results were assessed for time saved in reporting in comparison with standard protocol. Student's t test was used for statistical analysis. RESULTS: Of the 250 cases studied, 117 cases yielded a positive blood culture giving a yield of 46.8%. The number of cases yielding monomicrobial growth were 73, which were included for further analysis. Of the remaining samples, 133 did not show growth, 11 were polymicrobial while 33 samples were flagged positive after 72 hours. Candida spp. grew in 34 cases, Gram negative bacilli grew in 28 cases and Gram positive cocci grew in 11 cases. In four cases, 66 hours were saved, 60 and 54 hours were saved in 18 cases each, 48 hours were saved in 27 cases, and 24 hours were saved in 6 cases. Methicillin resistant Staphylococcus aureus and Klebsiella pneumoniae were the most common isolates among Gram positive cocci and Gram negative bacilli, respectively, while C. guilliermondii was the most common Candida isolate. All Gram positive isolates were susceptible to vancomycin and linezolid. Most of the Gram negative isolates were susceptible to imipenem. CONCLUSION: This method can be employed in peripheral laboratory settings where there is no complete automation. Modification in processing blood culture can provide speedy identification and sensitivity report in blood stream infections. Time saved in reporting would play a crucial role in improving morbidity and mortality rates in neonatal septicemia.
