Endogenous methicillin resistant staphylococcus aureus as a source of post-operative surgical site infections.

OBJECTIVE: To determine frequency of Endogenous Methicillin Resistant Staphylococcus aureus (MRSA) in pre-operative patients and its frequency in Surgical Site Infections (SSIs) post operatively. METHODS: It was a descriptive cross sectional conducted at Department of Microbiology, Fauji Foundation Hospital Rawalpindi (FFH), Pakistan. Samples were collected from 1st November-31st May 2018. Total 75 samples were collected during the period. Consecutive non-probability sampling technique was utilized. Specimens were collected from nose, axilla and groin of preoperative patients. Methicillin Resistant Staphylococcus aureus was identified if only isolated from these sites. Patients were followed till his/her discharge from the hospital and if they developed infection post operatively, pus specimen from infected site was also collected and identified. RESULTS: Out of 75 specimen preoperatively, 11(14.7%) were identified as endogenous MRSA. From these, 33(44%) developed Surgical site infections (SSIs), among them 19(57%) were MRSA (09 endogenous, 10 exogenous), 7(21.2%) were Escherichia coli, 3(9.1%) were Klebsiella pneumoniae, 3(9.1%) were Enterococcus faecalis and 1(3%) was Methicillin Sensitive Staphylococcus aureus. CONCLUSIONS: The results of this study determined that Endogenous Methicillin Resistant Staphylococcus aureus (MRSA) could be isolated from patients going for surgery if microbiological screening was done at the time of admission. This could prevent patients from Surgical Site Infection Post operatively by these endogenous MRSA. This search and wipe out strategy is able to curtail the events of outbreak, reduce hospital stay and decrease budget of the hospital by providing guidance in choice of empirical therapy for infection.

Reciprocal benefit to senior and junior peers: An outcome of a pilot research workshop at medical university.

A study was planned to explore and evaluate the role of senior peers in the learning process of their juniors during a Research Methodology workshop, and to assess educational advantages for seniors in leading roles. Twenty medical students participated with 15 juniors (1st to 3rd year) and 5 seniors (final/fourth year) divided into 5 groups with one senior student each at Foundation University Medical College, Islamabad, Pakistan. The seniors supervised and engaged the groups to develop research questions, formulate objectives, review literature, outline study designs, develop study tools/questionnaire and finally shape their projects in synopsis. Overall advantages to both juniors and seniors through this peer-assisted learning model were assessed by feedback proformas with open and closed-ended questions. Senior peers' facilitation was effective in the learning process of junior peers. Senior peers also gained academic benefit by exercising their leadership qualities through teaching and maintaining group dynamics.

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.

In vitro efficacy of colistin against multi-drug resistant Pseudomonas aeruginosa by minimum inhibitory concentration.

Multi-drug resistant bacteria are an important cause of mortality and morbidity. In the management of various infections, timely detection and appropriate treatment, in accordance with the culture and sensitivity reports can help improve the treatment outcome. Colistin is a bactericidal antibiotic which is emerging as a reliable solution for treating infections with multi-drug resistant Gram negative bacilli. The aim of this study was to find out the in-vitro efficacy of colistin against multidrug resistant Pseudomonas aeruginosa isolates by minimum inhibitory concentration. This cross sectional, descriptive study was conducted in the Department of Microbiology, Army Medical College, National University of Sciences and Technology, Islamabad from February 2010 to January 2011. Antimicrobial sensitivity testing was done on Pseudomonas aeruginosa isolated from routine clinical specimens received and the strains which appeared resistant to at least one antimicrobial agent in three or more anti-pseudomonal antimicrobial categories were subjected to the Colistin Etest. The MIC endpoint of colistin was read, as per manufacturers instructions (AB Biodisk, Solna, Sweden). The isolates showing MIC of 2µg/ml or less were considered sensitive, those with 4-6µg/ml as intermediate and >µg/ml as resistant. MIC(50) and MIC(90) of colistin against MDR Pseudomonas aeruginosa was determined. A total of 52 MDR Pseudomonas aeruginosa strains were isolated during the period of the study. The highest percentage was isolated from urine (36%) followed by respiratory tract infections (18%) and pus specimens (20%). The highest percentage of these isolates was found to be susceptible to colistin followed by piperacillin-tazobactam and cefoperazone-sulbactam. A total of 36(69%) isolates were sensitive, 10(20%) were intermediate and 6(11%) were resistant to colistin by Kirby Bauer disc diffusion method. MIC(50) was found to be 1.0µg/ml while MIC(90) was 3.0µg/ml. Colistin is a reliable solution in cases of infections with MDR, XDR or PDR Pseudomonas aeruginosa.

Reviving the role of mecillinam against extended spectrum beta-lactamase producing enterobacterales.

Background and Objectives: This study was designed to determine the in vitro efficacy of mecillinam against extended spectrum beta lactamse producing Enterobacterales. Materials and Methods: After proper permission from Ethical Review Committee of the Institute, all samples yielding growth of ESBL producing Enterobacterales were part of the study and were processed according to routine microbiological procedures. Routine antibiotic sensitivity testing was done on Muller Hinton Agar by Modified Kirby Bauer Method. All Gram negative isolates were subjected to concomitant detection of ESBL production by double disc synergy method. All ESBL producers were then subjected to the mecillinam Minimum Inhibitory Concentration (MIC) determination by E test. The results were interpreted as per CLSI Guidelines. Results: A total of 120 ESBL producing Enterobacterales isolates were included in the study. The mean age of patients with ESBL infection was 45 ± 18.7 years. There were 44% male and 55% female patients. Majority of the ESBL producing Enterobacterales were isolated from urine samples (56%), followed by pus. Among the isolated organisms, Escherichia coli (45%) was the most frequently isolated organism followed by Klebsiella spp. (22%). Overall 83% of the isolates turned out to be sensitive to mecillinam. MIC50 of mecillinam against ESBL producing Gram negative rods (GNR) turned out to be 1 ug/ml and MIC90 turned out to be 2 ug/ml. Conclusion: Mecillinam shows good in vitro efficacy against ESBL producing Enterobacterales in our study. Further studies with more sample size and from diverse areas across the country should be done to evaluate its efficacy.

Comparison of in vitro efficacy of linezolid and vancomycin by determining their minimum inhibitory concentrations against methicillin resistant Staphylococcus aureus (MRSA).

OBJECTIVES: To compare the in vitro activities of vancomycin and linezolid against methicillin resistant Staphyloccus aureus in our set up to help in formulating a better empirical treatment and reduce the emergence of vancomycin resistant Staphylococcus aureus. METHODS: The study was conducted over a period of 6 months (1st July 2009-31st Dec 2009). 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. 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 Staphyloccus aureus infections.

Extended-spectrum ß-lactamase production in Shigella flexneri.

Emergence of multidrug-resistant strains of Shigella is a growing concern across the globe. Third-generation cephalosporins are used for treating infections caused by multidrug-resistant Shigellae. However, resistance to these cephalosporin antibiotics due to extended-spectrum ß-lactamases, has emerged as a new problem. So far extended-spectrum ß-lactamases producing Shigella has not been reported from Pakistan. We report such a case in Shigella flexneri from an 8-year old girl with acute dysentery.

Outbreak Of Extensively Drug Resistant Stenotrophomonas Maltophilia In Burn Unit.

Stenotrophomonas maltophiliais an emerging cause of nosocomial infections. We report an outbreak of XDR-Stenotrophomonas maltophilia infection from burn unit of a tertiary care hospital in July 2016. The strain isolated was resistant to all antimicrobials tested but colistin. Outbreak investigation was carried out which subsided after timely intervention. Patients were treated adequately by Colistin.

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.

Incidence and susceptibility pattern of methicillin resistant coagulase-negative staphylococci isolated from a tertiary care hospital of pakistan.

BACKGROUND: Methicillin resistant coagulase-negative Staphylococci are resistant organisms causing infections associated with high morbidity and mortality. Methicillin resistant Staphylococcus epidermidis (MRSE), is especially important with respect to admitted patients with indwelling catheters and other installed invasive devices where these organisms are known to be found. As a result, such lifesaving measures may prove fatal from subsequent infection and sepsis by these pathogens. Therefore, to limit such conditions in patients, the spread of MRSE and related organisms in the hospitals have to be effectively controlled. OBJECTIVES: This study was carried out to determine the frequency of methicillin resistant organisms among all isolated coagulase negative Staphylococci (CoNS) and to find effective antibiotics against these microorganisms. PATIENTS AND METHODS: All samples sent to the lab were routinely processed according to standard microbiological procedures and the cultures yielding growth of CoNS were selected for the study. All samples containing CoNS collected over a 2 year-period, were included irrespective of patients' age and gender. The antibiogram of the organisms was recorded according to CLSI guidelines and the ratio of methicillin resistant organisms determined. RESULTS: From a total of 299 isolated coagulase negative Staphylococci (CoNS), 40.1% were methicillin resistant. A high proportion of these organisms (more than 50%) were resistant to cephalosporins, aminoglycosides and quinolones while only a small number were found to show resistance to linezolid, minocycline, chloramphenicol and rifampicin. There were no resistant organisms against vancomycin. CONCLUSIONS: A considerable amount of methicillin resistant organisms found among CoNS in our region. The above stated antibiotics would prove effective in limiting these infections. Clinicians should keep these facts in mind while treating their patients.

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.

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.

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.

Frequency and susceptibility pattern of metallo-beta-lactamase producers in a hospital in Pakistan.

INTRODUCTION: The rapid spread of acquired metallo-beta-lactamases (MBLs) among major Gram-negative pathogens is an emerging threat and a matter of particular concern worldwide. METHODOLOGY: This descriptive study was conducted between January and August 2009 in the department of Microbiology, Army Medical College, National University of Sciences and Technology, Rawalpindi, to determine the frequency and susceptibility patterns of MBL-producers among carbapenem-resistant Gram-negative rods (GNRs) from clinical isolates of a tertiary care hospital. All clinical samples were processed according to standard microbiological methods. Isolated GNRs were subjected to susceptibility testing against various antibiotics by disc diffusion method according to the Clinical and Laboratory Standards Institute (CLSI) guidelines.  Carbapenem-resistant isolates were subjected to the detection of MBL production by the E-test MBL strip method. RESULTS: Out of 50 carbapenem resistant isolates, 39 (78%) of were confirmed to be MBL producers by the E-strip method.  Acinetobacter baumannii were the most frequent MBL producers, followed by Pseudomonas aeruginosa. A total of 19 (37%) of the MBL producers were susceptible to cefoperazone-sulbactam. CONCLUSION: The findings strongly suggest that there is a need to track the detection of MBL producers and that judicious use of carbapenems is necessary to prevent the further spread of these organisms.

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 percent as high, 41 percent moderate and 36.3 percent 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.