ABSTRACT
To determine the in vitro susceptibility of chloramphenicol against methicillin-resistant Staphylococcus aureus. Cross-sectional study. Department of Microbiology, Armed Forces Institute of Pathology, Rawalpindi, from January to June 2012. One hundred and seventy four isolates of methicillin-resistant Staphylococcus aureus were included in this study using cefoxitin [30 microg] disc for detection. Minimum inhibitory concentration [MIC] of chloramphenicol against MRSA was determined by using E-strip [AB BIO DISK]. The susceptibility was determined by swabbing the Mueller-Hinton agar [MHA] plates with the resultant saline suspension of MRSA and applying E-strip of chloramphenicol from AB Biodisk Sweden and determining the MIC of chloramphenicol [in microg/ml]. Clinical and Laboratory Standards Institute [CLSI] recommendations of /= 32 microg/ml as resistant were followed in interpreting the results. Out of the 174 MRSA isolates, 132 [75.86%] isolates were susceptible to chloramphenicol with MICs of A[2] 8 microg/ml, 38 [21.84%] were resistant >/= 32 microg/ml while 4 [2.30%] were in intermediate range with MIC of 16 microg/ml. Chloramphenicol has shown good in vitro activity against MRSA and is likely to have a key role in the treatment of MRSA infections providing us a good alternative to newer expensive antimicrobials in resource limited countries
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To determine the susceptibility pattern of extended spectrum betal-lactamase [ESBL] producing Gram negative isolates from various clinical specimens. Descriptive study. Microbiology Department, Armed Forces Institute of Pathology, Rawalpindi, from January 2008 to January 2009. A total of 308 ESBL producing isolates from various clinical specimens sent to AFIP for culture and sensitivity were identified using standard microbiological techniques and tested for antimicrobial susceptibility. At the same time screening for ESBL production was also done. ESBL production was confirmed by combination disc synergy method. The susceptibility pattern of isolates was then recorded in frequency percentages. Out of the 308 ESBL producing isolates more than 99% were susceptible to carbapenems, 84% to tazobactam/ piperacillin, 81% to sulbactam/cefoperazone, 12% to fluoroquinolones, 13% to cotrimoxazole, 59% to amikacin and 18% to gentamicin. Among the urinary isolates 49% were susceptible to Nitrofurontoin and only 5% to Pipemidic acid. Antibiotic choices in case of ESBL producing isolates are limited and at present only carbapenems can be regarded as treatment of choice. As empirical agents, beta-lactam/beta lactamase inhibitor combinations should be used cautiously for serious infections. Fluoroquinolones showed very poor efficacy. Amikacin can be used alternatively in such cases. Nitrofurantoin is still a good oral agent for treating UTI
ABSTRACT
To determine the in vitro efficacy of Piperacillin/Sulbactam, Piperacillin/Tazobactam and Cefoperazone/Sulbactam against clinical isolates of Pseudomonas aeruginosa. Cross-sectional study Department of Microbiology, Armed Forces Institute of Pathology from January 2010 to September 2010. A total of 287 isolates of Pseudomonas aeruginosa recovered from various clinical specimens were taken under consideration. Routine microbiological methods were used to identify the organism. Susceptibility of the isolates was carried out by modified Kirby-Bauer disc diffusion method against piperacillin 100/sulbactam 30 [SPR130micro g], cefoperazone 75/sulbactam 30 [SCF105micro g] and piperacillin 100/tazobactam 10 [TZP110micro g], according to the guidelines provided by Clinical and Laboratory Standards Institute [CLSI]. The highest numbers of Pseudomonas aeruginosa isolates were found in pus swabs, followed by urine and endobronchial washings. Seventy five percent of clinical isolates of P. aeruginosa were susceptible to tazobactam/piperacillin, 71% to piperacillin/sulbactam and 70% to cefoperazone/sulbactam. The difference between the susceptibility of isolates to these three antimicrobials was statistically not significant [p>0.05]. We conclude that there was very little difference in the antimicrobial susceptibility of P. aeruginosa to the three beta-lactam/beta-lactamase inhibitor combination drugs studied. Periodic susceptibility testing should be carried out over a period of two to three years, to detect the current resistance trends. Moreover, a rational strategy on the limited and prudent use of anti-Pseudomonal agents is urgently required
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To determine the role and pattern of non-dermatophyte moulds as causative agents of onychomycosis. Case series. Department of Microbiology, Armed Forces Institute of Pathology [AFIP], Rawalpindi, from November 2009 to July 2010. Nail clippings and nail scrapings were obtained from abnormal looking nails with treatment and detection failure for onychomycosis. Microscopic [40% potassium hydroxide mounts] examination and culture on Sabouraud's dextrose agar [SDA], SDA containing chloramphenicol, and SDA containing actidione and chloramphenicol were used for species identification. Non-dermatophyte moulds were isolated from 32 out of the total 47 culture positive cases [68%]. Alternaria alternata was the commonest species [46%]. Dermatophytes were isolated from only 7 patients [15%] belonging to genus Trichophyton. Yeasts were isolated in 8 [17%]. There was no fungal growth in 53% of cases. The non-dermatophytes should be considered important in evaluating the culture negative cases for dermatophytes as well as those cases ending up in treatment failure after empirical treatment for dermatophyte infections
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To determine the spectrum and antimicrobial susceptibility pattern of pathogens isolated from bone marrow transplant centre and to examine the evolution of bacterial resistance to antibiotics in these patients. It was a retrospective study conducted in the department of Microbiology, Armed Forces institute of Pathology [AFIP] from January 2004 to December 2009. Isolation, identification and antimicrobial susceptibilities were performed by standard methods. Gram negative bacterie accounted for 50.4% of the total isolates and Gram positives 49.6%. Escherichia coli was the most common isolate among the gram negative rods followed by Pseudomonas spp and Acinetobacter spp. Amongst the Gram positive organisms staphylococcus aureus and coagulase negative staphylococci followed by enterococci were the predominant organisms. The susceptibility of methicillin resistant staphylococcus aureus remained 100% for Vancomycin and Linezolid, while those of minocycline, fusidic acid and doxycycline were at an acceptable level of above 60%. Imipenem remained the most effective antibiotic for Gram negative rods. Acinetobacter spp. was the most problematic organism as only 62% isolates were susceptible to imipenem. Linezolid, vancomycin and tigecycline were very effective for enterococci. Ciprofloxacin sensitivity has been reduced among most of the bacteria isolated. The spectrum of isolates from neutropenic patients in our population appears to be changing with a shift towards Gram-positive microorganisms. At the same time resistance to most of the commonly used antimicrobials is increasing. Continuous surveillance of their susceptibility patterns is essential for formulation of empiric therapeutic regimens for these patients
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To determine the in vitro efficacy of tigecycline against methicillin resistant Staphylococcus aureus [MRSA]. Department of Microbiology Army Medical College and Armed Forces Institute of Pathology Rawalpindi, from Feb 2008 to Jan 2009. One hundred clinical isolates of MRSA were taken, Detection of MRSA was done using 30 microg disc of cefoxitin as recommended by Clinical laboratory Standard Institute [CLSI]. Susceptibility of the isolates to tigecycline was done by employing modified Kirby Bauer disk diffusion technique, according to the guidelines provided by the Food and Durg Administration [FDA]. Minimum inhibitory concentrations [MICs] of the isolates were determined by using E-strips [bioMerieux] of tigecycline. Results were interpreted according to FDA recommendations. All MRSA isolates were susceptible to tigecycline by disc diffusion method. The MICs of tigecycline revealed that all MRSA isolates were in sensitive range. In an era of rapidly growing antibiotic resistance, tigecycline has been found to have very good in vitro efficacy against MRSA isolates
Subject(s)
Methicillin-Resistant Staphylococcus aureus/drug effects , Minocycline/analogs & derivatives , Methicillin-Resistant Staphylococcus aureus/isolation & purification , Microbial Sensitivity Tests , Staphylococcal Infections/drug therapyABSTRACT
To compare the accuracy of Mueller-Hinton agar and Isosensitest agar using cefoxitin disc for detecting methicillin resistant Staphylococcus aureus using mecA gene PCR assay as gold standard. Comparative study. Department of Microbiology, Armed Forces Institute of Pathology, Rawalpindi, from May 2006 to January 2007. One hundred clinical isolates of Staphylococcus aureus were evaluated; 64 MRSA [methicillin resistant Staphylococcus aureus] and 36 MSSA [methicillin sensitive Staphylococcus aureus] by mecA PCR assay All the isolates were tested with cefoxitin 30 micro g disc using semi-confluent growth on Mueller-Hinton agar as well as on Iso-sensitest agar in ambient air at 35-37°C after an overnight incubation as per recommendations of Clinical and Laboratory Standard Institute. Following diameters provided the best sensitivity and specificity without substantial overlapping between the zones of resistant and sensitive isolates; Mueller-Hinton agar: R /= 22 mm [sensitivity 97.2% and specificity 100%], and Iso-sensitest agar: R /= 26 mm [sensitivity 100% and specificity 100%]. High accuracy was obtained with cefoxitin disc on both media. Performance of both media was equally convincing for reliable prediction of methicillin resistance in Stapfylococcus aureus by placing cefoxitin 30 micro g disc on either of these in routine susceptibility testing