Javaid Usman

Evaluation of different detection methods of biofilm formation in the clinical isolates

BACKGROUND Microorganisms growing in a biofilm are associated with chronic and recurrent human infections and are highly resistant to antimicrobial agents. There are various methods to detect biofilm production like Tissue Culture Plate (TCP), Tube method (TM), Congo Red Agar method (CRA), bioluminescent assay, piezoelectric sensors, and fluorescent microscopic examination. OBJECTIVE This study was conducted to compare three methods for the detection of biofilms. METHOD The study was carried out at the Department of Microbiology, Army Medical College, National University of Sciences and Technology, Pakistan, from January 2010 to June 2010. A total of 110 clinical isolates were subjected to biofilm detection methods. Isolates were identified by standard microbiological procedures. Biofilm detection was tested by TCP, TM and CRA. Antibiotic susceptibility test of biofilm producing bacteria was performed by using the Kirby-Bauer disc diffusion technique according to CLSI guidelines. RESULTS The TCP method was considered to be superior to TM and CRA. From the total of 110 clinical isolates, TCP method detected 22.7% as high, 41% moderate and 36.3% as weak or non-biofilm producers. We have observed higher antibiotic resistance in biofilm producing bacteria than non-biofilm producers. CONCLUSION We can conclude from our study that the TCP method is a more quantitative and reliable method for the detection of biofilm forming microorganisms as compared to TM and CRA methods, and it can be recommended as a general screening method for detection of biofilm producing bacteria in laboratories.

Current status of vancomycin susceptibility against methicillin resistant Staphylococcus aureus (MRSA) strains: A study at two tertiary care hospitals of Pakistan

Vancomycin has been considered mainstay treatment of infections caused by methicillin-resistant Staphylococcus aureus. The reports of the emergence of vancomycin intermediate and vancomycin resistant S. aureus from various parts of the world have been of great clinical concern. This study was performed to monitor the status of glycopeptide susceptibility against methicillin resistant S. aureus in our set up. All non-duplicate methicillin resistant Staphylococcus aureus (MRSA) isolates recovered during the period of study from various wards of Military Hospital Rawalpindi and PAEC General Hospital Islamabad, were subjected to the detection of minimum inhibitory concentrations of vancomycin using E-strips. Results were analyzed to evaluate the possible presence of vancomycin intermediate and resistant strains in the set up. A total of 276 methicillin-resistant S. aureus isolates were studied. The range of vancomycin minimum inhibitory concentrations (MIC) was 0.19 to 3 ug/mL. MIC 50 came out to be 0.75 ug/mL whereas the MIC 90 was 1.5 ug/ mL. 128 out of 276 (46%) isolates had vancomycin MIC equal to or greater than 1 ug/mL. Majority of the isolates (69%) were from pus samples. No vancomycin resistant or intermediate strain of MRSA was isolated during the study but there were a significant number of isolates having ≥ 1 µg/ml MIC of vancomycin.

PP-209 In vitro efficacy of ceftriaxone and cefixime against respiratory pathogens

a periodic domain during 198

PP-023 Minimum inhibitory concentration of colistin against multi-drug resistant Acinetobacter baumannii isolated from a tertiary care hospital in Pakistan

Objective: To investigate the prevalence of nosocomial infection (NI) in the same hospital in the past three years. Methods: The survey form of personal case was filled by adopting the method of combining clinical investigation and consulting inpatients medical records. Results: The average rate of nosocomial infection (NI) was 4.8%; rate of NI was different in the different; there were not significant difference among age, hospitalization, invasive operation, infection sites, antibiotics using in the past three years, but, the rate of NI were changing in the different department in the three years. Conclusions: The rate of NI were changing in the different hospitals and departments. The survey and control of NI should be strengthened in the department and the season with high rate of nosocomial infection.

PP-025 Amp C beta-lactamases among extended spectrum beta-lactamases producing Enterobacteriaceae

Introduction/background: Amp C beta lactamases are cephalosporinases which confer resistance to cephamycins, narrow-, expandedand broad-spectrum cephalosporins, beta-lactam/beta-lactamases inhibitor combination and aztreonam. ESBLs and Amp C beta lactamases may coexist in isolates. Presence of Amp C beta-lactamases goes undetected in presence of ESBLs. This may lead to treatment failure and poses diagnostic and therapeutic challenge. Objective: To detect the prevalence of Amp C beta lactamases among ESBL producing Enterobacteriaceae isolated from a tertiary care hospital of Pakistan. Place and duration of study: The study was carried out from October 2009 to March 2010, at the Department of Microbiology, Army Medical College/National University of Sciences and Technology, Rawalpindi, Pakistan. Methods: Clinical specimens were received from various wards. Organisms were identified by standard microbiological procedures. ESBL detection was done by double disk approximation method by Jarier et al and confirmed by Etest (ceftazidime, ceftazidime/clavulanic acid). ESBL producing organisms were subjected to three dimensional extract test (3DET) for detection of Amp C beta lactamases. Antimicrobial susceptibility of isolates against aminoglycosides, cephalosporins, monobactams, fluoroquinolones, carbapenems and beta-lactam/betalactamase inhibitor combination was tested by using Kirby Bauer disc diffusion technique, according to CLSI guidelines. Results: We evaluated 58 ESBL producing Enterobacteriaceae for Amp C production (32 E. coli, 18 K. pneumoniae, 6 Enterobacter spp, 2 K. oxytoca). 34 were positive for Amp C beta lactamase production. 68% E. coli, 32.3% K. pneumoniae and 5.8% Enterobacter spp are positive for Amp C beta lactamases. Overall prevalence of Amp C in ESBL producing isolates was 58.6%. Conclusion: This study shows the high prevalence of Amp C beta lactamase producing isolates, which may lead to serious therapeutic problems. Three-dimensional extract test is a reliable method for detection of Amp C betalactamases.

PP-003 Determination of vancomycin minimum inhibitory concentrations against methicillin resistant Staphylococcus aureus to find out its efficacy in our set up

Background: Staphylococcus aureus is a facultatively anaerobic, Gram-positive coccus. It is a major pathogen associated with serious community and hospitalacquired infections. By designation methicillin resistant Staphylococcus aureus (MRSA) is a strain of Staphylococcus aureus that is resistant to all beta-lactams, including penicillins, cephalosporins and carbapenems. Vancomycin has a narrow spectrum of activity, restricted to most Gram-positive bacteria, and is the drug of choice for the treatment of methicillin resistant Staphylococcus aureus. This agent, however, requires intravenous administration, and occasionally patients experience unacceptable side effects. Linezolid, a member of the new oxazolidinone class of antibiotics, has shown very good activity against methicillin resistant Staphylococcus aureus, has excellent oral bioavailability and is inexpensive as compared to vancomycin. Aims and Objectives: Comparison of in vitro activities of vancomycin and linezolid against methicillin resistant Staphylococcus aureus. Materials and Method: The study was conducted over a period of 6 months. Fifty Methicillin resistant Staphylococcus aureus isolated from the clinical isolates of Military hospital Rawalpindi were subjected to the determination of Minimum inhibitory concentrations of linezolid and vancomycin using E-strips. Minimum inhibitory concentrations 50 and minimum inhibitory concentrations 90 were calculated. Results: All the isolated organisms were uniformly susceptible to both the antibiotics. Vancomycin showed higher minimum inhibitory concentrations (MICs) as compared to linezolid MICs. Conclusion: This study suggests that linezolid and vancomycin have similar in vitro efficacy for methicillin resistant Staphylococcus aureus infections. Linezolid’s oral dosing option can allow earlier discharge of hospitalized patients and its low cost reduces health care expenses.

PP-014 Antibiogram of carbapenem resistant Acinetobacter (CRA) isolated from a tertiary care hospital

Background: Acinetobacter has emerged as a significant nosocomial pathogen. It has developed resistance against major groups of antibiotics. Acinetobacter resistance to broad spectrum antibiotics like carbapenems posing an additional threat. Objective: We have conducted this study to find out the antibiotic susceptibility pattern of carbapenem resistant Acinetobacter (CRA). This will help our clinicians in prescribing appropriate treatment against CRA. Place and duration of study: The study was conducted from June 2009 to December 2009 at the Department of Microbiology, Army Medical College Rawalpindi, affiliated with 100 bedded tertiary care hospital. Materials and Method: Clinical specimens were received form various wards. Acinetobacter species were identified by using standard microbiological procedures. Acinetobacter species resistant to carbapenems were identified by using Kirby Bauer disc diffusion technique according to Clinical and Laboratory Standard (CLSI) guidelines. Fourteen antibiotics were used against CRA (gentamicin, amikacin, tobramycin, tetracycline, minocycline, doxycycline, tigecycline, levofloxacin, ciprofloxacin, trimethoprim-sufmethoxazole, ceftriaxone, ampicillin-sulbactam, cefoperazone-sulbactam, piperacillin-tazobactam). Antimicrobial susceptibility test was performed according to CLSI guidelines using KirbyBauer disc diffusion techniques. Results: A total of 61 carbapenem resistant Acinetobacter were isolated. Majority of the isolates were sensitive to minocycline, tigecycline, tobramycin and cefoperazone sulbactam. Doxycycline and piperacillin tazobactam showed moderate activity against majority of CRA. Tetracycline, ciprofloxacin, ceftriaxone and ampicillin sulbactam were least effective. Conclusion: Emergence of carbapenem resistant Acinetobacter is a challenge for our clinicians. Antibiotics like minocycline, tigecycline, tobramycin and cefoperazone sulbactam provide effective treatment options against CRA.

PP-015 Detection of biofilm producing Gram-positive and Gram-negative bacteria isolated from clinical specimens and their antibiotic susceptibility pattern

Background: Acinetobacter has emerged as a significant nosocomial pathogen. It has developed resistance against major groups of antibiotics. Acinetobacter resistance to broad spectrum antibiotics like carbapenems posing an additional threat. Objective: We have conducted this study to find out the antibiotic susceptibility pattern of carbapenem resistant Acinetobacter (CRA). This will help our clinicians in prescribing appropriate treatment against CRA. Place and duration of study: The study was conducted from June 2009 to December 2009 at the Department of Microbiology, Army Medical College Rawalpindi, affiliated with 100 bedded tertiary care hospital. Materials and Method: Clinical specimens were received form various wards. Acinetobacter species were identified by using standard microbiological procedures. Acinetobacter species resistant to carbapenems were identified by using Kirby Bauer disc diffusion technique according to Clinical and Laboratory Standard (CLSI) guidelines. Fourteen antibiotics were used against CRA (gentamicin, amikacin, tobramycin, tetracycline, minocycline, doxycycline, tigecycline, levofloxacin, ciprofloxacin, trimethoprim-sufmethoxazole, ceftriaxone, ampicillin-sulbactam, cefoperazone-sulbactam, piperacillin-tazobactam). Antimicrobial susceptibility test was performed according to CLSI guidelines using KirbyBauer disc diffusion techniques. Results: A total of 61 carbapenem resistant Acinetobacter were isolated. Majority of the isolates were sensitive to minocycline, tigecycline, tobramycin and cefoperazone sulbactam. Doxycycline and piperacillin tazobactam showed moderate activity against majority of CRA. Tetracycline, ciprofloxacin, ceftriaxone and ampicillin sulbactam were least effective. Conclusion: Emergence of carbapenem resistant Acinetobacter is a challenge for our clinicians. Antibiotics like minocycline, tigecycline, tobramycin and cefoperazone sulbactam provide effective treatment options against CRA.