Frequency and Antibiogram of Isolates from Surgical Units of a Tertiary Care Hospital in Quetta.

OBJECTIVE: To determine the frequency and antibiogram of the isolates from infected patients in surgical units of a tertiary care hospital. STUDY DESIGN: Cross-sectional, descriptive study. PLACE AND DURATION OF STUDY: Department of Microbiology, Combined Military Hospital, Quetta, from March to October 2015. METHODOLOGY: Clinical samples from the surgical units received in Department of Microbiology for culture and sensitivity were analyzed by Gram stain, culture and biochemical tests for identification of the isolates; and the antibiotic susceptibility was determined by modified Kirby Bauer disc diffusion method. Data was analyzed by Statistical Package for Social Sciences (SPSS) version 19. RESULTS: The commonest isolate was Acinetobacter baumannii (22%) followed by Escherichia coli (20%), Pseudomonas spp. (15%) and Methicillin-resistant Staphylococcus aureus (MRSA) (11%). Acinetobacter baumannii showed highest susceptibility to doxycycline (41%), Enterobacteriaceae to meropenem (96%), Pseudomonas spp. to polymyxin-B (100%) and Gram positive bacteria to linezolid (100%). Seventy-two percent of the isolates were found to be multi-drug resistant. CONCLUSION: There was a high infection rate in surgical patients with Acinetobacter baumannii, Eschericia coli, Pseudomonas spp. and MRSA being the commonest isolates. Acinetobacter baumannii showed highest susceptibility to doxycycline, Enetrobacteriaceae to meropenem, Pseudomonas spp. to polymyxin-B and Gram positive bacteria to linezolid.

Methicillin resistant coagulase negative staphylococcus: From colonizer to a pathogen.

The objective of our study was to determine the frequency of methicillin resistance in coagulase negative Staphylococcus (CoNS) and to determine its in-vitro antimicrobial susceptibility to various other routinely used antibiotics. It was a cross sectional study conducted at the department of Microbiology, Army Medical College, Rawalpindi, Pakistan from June 2011 to May 2012. The organisms were identified on the basis of colony morphology, Gram staining, catalase, DNAase and slide/tube coagulase tests. The organisms were considered to be methicillin resistant when the diameter of zone of inhibition was less than 25mm around 30µg cefoxitin disc. Antibiotic sensitivity was determined using the Modified Kirby-Bauer disc diffusion method. From a total of 337 CoNS, 201 were methicillin resistant and were included in the study. All were resistant to Penicillin, followed by Erythromycin (93•1%), Ciprofloxacin (77%), Co-trimoxazole (74•8%), Gentamicin (68•3%), Clindamycin (51•06%), Tetracycline (44•6%), Fusidic acid (40%), Rifampicin (39•5%), Chloramphenicol (19•3%), Linezolid (2%), Minocycline (1•1%), and Vancomycin (0%). More than half of CoNS were methicillin resistant. Vancomycin is the only drug to which all of the MRCoNS were sensitive, with more than 98% of the isolates being sensitive to Linezolid and Minocycline.

In vitro Efficacy of Meropenem, Colistin and Tigecycline Against the Extended Spectrum Beta-Lactamase Producing Gram Negative Bacilli.

OBJECTIVE: To compare the in vitro efficacy of meropenem, colistin and tigecycline against extended spectrum Betalactamase producing Gram negative bacilli by minimal inhibitory concentration. STUDY DESIGN: Cross-sectional descriptive study. PLACE AND DURATION OF STUDY: Department of Microbiology, Army Medical College, National University of Sciences and Technology, Rawalpindi, from June to December 2010. METHODOLOGY: Routine clinical specimens were subjected to standard microbiological procedures and the isolates were identified to species level. Extended spectrum ß-lactamase producing Gram negative bacilli were detected by Jarlier disc synergy method and confirmed by ceftazidime and ceftazidime-clavulanate Etest. Minimum Inhibitory Concentration (MIC(90)) of meropenem, colistin and tigecycline was determined by Etest (AB BIOMERIUX) and the results were interpreted according to the manufacturer's instructions and Clinical and Laboratory Standards Institute guidelines and Food and Drug Authority recommendations. Results were analyzed by using Statistical Package for the Social Sciences version 20. RESULTS: A total of 52 non-duplicate extended spectrum Beta-lactamase-producing Gram negative bacilli were included in the study. The MIC(90) of tigecycline (0.75 µg/ml) was lowest as compared to the meropenem (2 µg/ml) and colistin (3 µg/ml). CONCLUSION: Tigecycline is superior in efficacy against the extended spectrum Beta-lactamase producing Gram negative bacilli as compared to colistin and meropenem.

IN VITRO SUSCEPTIBILITY PATTERN OF EXTENDED SPECTRUM ß-LACTAMASE PRODUCING GRAM NEGATIVE BACILLI AGAINST TETRACYCLINES.

BACKGROUND: Extended Spectrum ß-lactamases (ESBLs) are emerging as common nosocomial pathogens and important cause of mortality and morbidity, if not treated properly. The need of the hour is to find effective treatment options for dealing with ESBL producing organisms. This study was aimed to evaluate in vitro susceptibility pattern of extended spectrum ß-lactamase producers against tetracyclines. METHODS: This descriptive cross-sectional study was carried out in the department of Microbiology, Army Medical College, Rawalpindi, National University of Sciences and Technology over a period of 6 months. Seventy eight non-duplicate isolates were included in the study. ESBL detection was done using Jarlier et al method. In vitro susceptibility of tetracyclines like tetracycline, doxycycline, minocycline and tigecycline was then tested using Modified Kirby Bauer disc diffusion method. The zones of inhibition were measured after completion of incubation period and interpreted as per CLSI and FDA guidelines. RESULTS: Approximately 56.4% of the isolates were Escherichia coli, 28.2% were Klebsiella pneumoniae, 10.26% were Enterobacter species, and 2.6% were each Klebsiella oxytoca and Acinetobacter species. ESBLs were found to be most sensitive to tigecycline, intermediate in susceptibility to minocycline while least sensitive to doxycycline and tetracycline. CONCLUSION: Among tetracyclines, tigecycline has best in vitro susceptibility against ESBL producing Gram negative rods.

Frequency and antibiogram of vancomycin resistant enterococcus in a tertiary care hospital.

OBJECTIVE: To determine the frequency of Vancomycin Resistant Enterococcus (VRE) in a tertiary care hospital of Rawalpindi, Pakistan. STUDY DESIGN: Observational, cross-sectional study. PLACE AND DURATION OF STUDY: Department of Microbiology, Army Medical College, Rawalpindi, from May 2011 to May 2012. METHODOLOGY: Vancomycin resistant Enterococcus isolated from the clinical specimens including blood, pus, double lumen tip, ascitic fluid, tracheal aspirate, non-directed bronchial lavage (NBL), cerebrospinal fluid (CSF), high vaginal swab (HVS) and catheter tips were cultured on blood agar and MacConkey agar, while the urine samples were grown on cystine lactose electrolyte deficient agar. Later the antimicrobial susceptibility testing of the isolates was carried out using the modified Kirby-Bauer disc diffusion method on Mueller Hinton agar. RESULTS: A total of 190 enterococci were isolated. Of these, 22 (11.57%) were found to be resistant to vancomycin. The antimicrobial sensitivity pattern revealed maximum resistance against ampicillin (86.36%) followed by erythromycin (81.81%) and gentamicin (68.18%) while all the isolates were 100% susceptible to chloramphenicol and linezolid. CONCLUSION: The frequency of VRE was 11.57% with the highest susceptibility to linezolid and chloramphenicol.

Evaluation of different phenotypic methods for detection of amp C Beta-lactamase producing bacteria in clinical isolates.

OBJECTIVE: To compare the sensitivity and specificity of different phenotypic methods for detection of Amp C betalactamase producing bacteria. STUDY DESIGN: Analytical study. PLACE AND DURATION OF STUDY: Department of Microbiology, Army Medical College / National University of Sciences and Technology (NUST), Islamabad, Pakistan, from June 2010 to December 2010. METHODOLOGY: A total of 150 clinical isolates were screened for presence of Amp C beta-lactamase by using the cefoxitin disc. The confirmatory methods evaluated were inhibitor based assay (boronic acid), Amp C disc test and Amp C Etest. Three dimensional enzyme extract assay was used as the reference method for determining the sensitivity and specificity. RESULTS: Among the total isolates tested, 62.8% bacteria showed the presence of Amp C beta-lactamase by standard three dimensional enzyme extract assay. Among the three methods compared, boronic acid disk test found out to be highly sensitive (88%) and specific (92%) for the detection of Amp C beta-lactamase producing bacteria. CONCLUSION: Detection of Amp C production is crucial in order to establish the antibiotic therapy and to attain the favourable clinical outcomes. Implementation of simple tests like boronic acid disk tests in the laboratories will help to alleviate the spread of Amp C beta-lactamase harboring organisms.

Frequency and antibiogram of multi-drug resistant Pseudomonas aeruginosa.

OBJECTIVE: To find out the frequency and susceptibility pattern of multi-drug resistant (MDR) Pseudomonas aeruginosa in clinical specimens. STUDY DESIGN: Cross-sectional observational study. PLACE AND DURATION OF STUDY: Department of Microbiology, Army Medical College, National University of Sciences and Technology (NUST), Rawalpindi, from January to September 2010. METHODOLOGY: Routine clinical specimens were subjected to standard microbiological procedures and the isolates were identified to the species level. The antibiotics susceptibility was determined by Kirby Bauer Disc diffusion method and the results were interpreted according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. RESULTS: The frequency of MDR Pseudomonas aeruginosa among all the Pseudomonas aeruginosa strains isolated was found to be 22.7%. These isolates were most sensitive to Colistin followed by Piperacillin-Tazobactam and Cefoperazone-Sulbactum. CONCLUSION: Increasing fequency of infections due to MDR Pseudomonas aeruginosa is an emerging threat in our set up which an be prevented by prescribing antibiotics judiciously and by adopting proper disinfection measures.