Comparative in vitro efficacy of doripenem and imipenem against multi-drug resistant pseudomonas aeruginosa

Objective: to compare the in vitro efficacy of doripenem and imipenem against multi-drug resistant [MDR] Pseudomonas aeruginosa from various clinical specimens

Study Design: descriptive cross-sectional study

Place and Duration of Study: department of Microbiology, Armed Forces Institute of Pathology, Rawalpindi, from November 2012 to November 2013

Methodology: MDR Pseudomonas aeruginosa isolates from various clinical samples were included in the study. Susceptibility of Pseudomonas aeruginosa against doripenem and imipenem was performed by E-test strip and agar dilution methods. The results were interpreted as recommended by Clinical Laboratory Standard Institute [CLSI] guidelines

Results: the maximum number of Pseudomonas aeruginosa were isolated from pure pus and pus swabs. In vitro efficacy of doripenem was found to be more effective as compared to imipenem against MDR Pseudomonas aeruginosa with both E-test strip and agar dilution methods. Overall, p-values of 0.014 and 0.037 were observed when susceptibility patterns of doripenem and imipenem were evaluated with E-test strip and agar dilution methods

Conclusion: in vitro efficacy of doripenem was found to be better against MDR Pseudomonas aeruginosa as compared to imipenem when tested by both E-test and agar dilution methods

Extensively and pre-extensively drug resistant tuberculosis in clinical isolates of multi-drug resistant tuberculosis using classical second line drugs [levofloxacin and amikacin]

To find out the frequency of Extensively Drug Resistant [XDR] and pre-XDR tuberculosis in clinical isolates of Multi-Drug Resistant [MDR] Tuberculosis [TB] by determining the susceptibilities against Levofloxacin and Amikacin [classical second line antituberculosis drugs]. A descriptive cross-sectional study. Microbiology Department, Armed Forces Institute of Pathology [AFIP], Rawalpindi, from September 2011 to August 2013. Amikacin [AK] and Levofloxacin [LEVO] were obtained in chemically pure form from Sigma [Taufkirchen, Germany]. The breakpoint concentration used for AK was 1.0 microg/ml and for LEVO 2.0 microg/ml. Mycobacterial Growth Indicator Tube [MGIT] 960 system was used to carry out drug susceptibility testing as per recommended protocol. A total of 3 MDR-TB isolates [3%] turned out to be XDR-TB based upon simultaneous resistance to injectable second line antituberculosis drug AK and one of the fluoro-quinolones [LEVO]. A total of 24 MDR-TB isolates [24%] were found to be pre-XDR based upon resistance to LEVO alone. Treatment status record of patients with XDR and pre-XDRTB isolates revealed that majority of patients had received fluoroquinolones [FQs] during the course of treatment. XDR-TB has started to emerge in MDR-TB isolates in our set up. The worrying sign is the high frequency of pre-XDR tuberculosis. Urgent steps need to be taken to stem the tide of pre-XDR-TB in our population. It is thus recommended to develop facilities to carry out drug susceptibility testing to monitor the status of pre-XDR and XDR-TB in our population

Frequency and antimicrobial susceptibility pattern of Acinetobacter species isolated from pus and pus swab specimens

To evaluate the frequency and antimicrobial susceptibility pattern of Acinetobacter species isolated from pus and pus swab specimens at a tertiary care setting. Cross-sectional observational study. Department of Microbiology, Armed Forces Institute of Pathology, Rawalpindi, from July 2008 to July 2012. Data regarding positive culture and antimicrobial sensitivity pattern was retrieved from the pus and pus swab culture records of the Microbiology Department, AFIP, Rawalpindi. Only those pus and pus swab specimens which yielded the growth of Acinetobacter species were included in the study. Out of 2781, 1848 were of pure pus while 933 were pus swab specimens. Out of 2538 culture positive isolates, 276 [10.9%] were identified as Acinetobacter species. Among 276 Acinetobacterspp., 245 [88.8%] were Acinetobacter baumannii and 31 [11.2%] were Acinetobacter johnsonii. Male/female ratio of the affected patients was 5.6:1. Doxycycline was the most sensitive antibiotic to which 45% of the tested isolates were sensitive. Sensitivity to all other antimicrobials was 15% or less. About 11% of soft tissue and wound infections are caused by Acinetobacter species in our set up particularly in male. Doxycycline was the most sensitive antibiotic. Sensitivity to all other antimicrobials was 15% or less. In vitro sensitivity to carbapenems is very low

In vitro evaluation of linezolid and meropenem against clinical isolates of multi drug resistant tuberculosis by mycobacterial growth indicator tube [MGIT] 960

To evaluate the in vitro effectiveness of multiple breakpoint concentrations of newer antituberculosis agents [Linezolid and Meropenem] against Multi Drug-Resistant Tuberculosis [MDR-TB] isolates. A descriptive cross-sectional study. Microbiology Department, Armed Forces Institute of Pathology [AFIP], Rawalpindi, from September 2011 to August 2013. A total of 100 MDR-TB isolates recovered during the study period were subjected to susceptibility testing against multiple breakpoint concentrations of Linezolid [LZD] and Meropenem [MER]. The breakpoint concentration used for LZD were 0.5, 1.0 and 2.0 microg/ml, while for MER were 4.0, 8.0 and 16 microg/ml. Mycobacterial Growth Indicator Tube [MGIT] 960 system was used to carry out drug susceptibility testing as per recommended protocol. At break point concentration of 0.5 microg/ml, 80 out of 100 [80%] MDR-TB isolates were susceptible to LZD while at breakpoint concentration of 1.0 microg/ml and 2.0 microg/ml, 96/100, [96%] of MDR-TB isolates were susceptible. For MER, at breakpoint concentrations of 4.0 microg/ml no MDR-TB isolate was susceptible, while at 8.0 microg/ml 3/100, [3%] and at 16.0 microg/ml 11/100, [11%] of MDR-TB isolates were susceptible. LZD was found to have excellent in vitro efficacy as 96% of MDR-TB isolates were susceptible at breakpoint concentration of 1.0 microg/ml or more. In case of MER it was found that in vitro susceptibility improved as the break point concentrations were increased

Antimicrobial susceptibility pattern of bacteria isolated from patients with urinary tract infection

To determine the antimicrobial susceptibility pattern of bacterial pathogens in the patients of urinary tract infection reporting at a tertiary care hospital. Laboratory based study. Department of Microbiology, Armed Forces Institute of Pathology, Rawalpindi, from January to December 2012. A total of 440 culture positive bacterial isolates from 1110 urine samples; submitted over a period of one year were included in this study. Identification of bacterial isolates was done by standard biochemical profile of the organisms. The antimicrobial susceptibility of culture positive bacterial isolates was performed by disk diffusion method as recommended by Clinical Laboratory Standard Institute guidelines [CLSI]. Out of the 440 culture positive urine samples, 152 [34.6%] were from indoor patients whereas 288 [65.4%] from outdoor patients. Gram negative bacteria accounted for 414 [94%] of the total isolates while rest of the 26 [6%] were Gram positive bacteria. The most prevalent bacterial isolate was Escherichia [E.] coli 270 [61.3%] followed by Pseudomonas [P.] aeruginosa 52 [12%] and Klebsiella [K.] pneumoniae 42 [9.5%]. The susceptibility pattern of E. coli showed that 96.2% of the bacterial isolates were sensitive to imipenem, 85.1% to amikacin, 80.7% to piperacillin/tazobactam and 72.6% to nitrofurantoin. In case of P. aeruginsosa, 73% bacterial isolates were sensitive to tazobactam/piperacillin, 69.2% to sulbactam/cefoperazone and 65.38% to imipenem. The antibiogram of K. pneumoniae has revealed that 76.1% of the bacterial isolates were sensitive to imipenem and 52.3% to piperacillin/tazobactam. Nitrofurantoin and imipenem were the most effective antimicrobials amongst the Enterococcus spp. as 92.3% showed susceptibility to this bacterial isolate. Majority of the bacterial isolates were sensitive to imipenem and piperacillin/tazobactam while susceptibility to most of the commonly used oral antibiotics was very low. Among the oral antimicrobials, nitrofurantoin showed good susceptibility against Enterobacteriaceae family and Gram positive organisms

In vitro activity of fosfomycin tromethamine against extended spectrum beta-lactamase producing urinary tract bacteria

To determine the in vitro activity of Fosfomycin tromethamine against extended spectrum beta-lactamase producing uropathogens. Experimental study. Department of Microbiology, Armed Forces Institute of Pathology, Rawalpindi, from October 2011 to October 2012. A total of 381 culture positive ESBL producing isolates from 2400 urine samples submitted over a period of one year were included in this study. Identification of isolates was done by standard biochemical profile of the organisms. The antimicrobial susceptibility of culture positive isolates was performed by disk diffusion method as recommended by Clinical Laboratory Standard Institute guidelines [CLSI]. The antimicrobial activity of Fosfomycin to various isolates revealed that 93% of E. coli, 64% Klebsiella spp. 50% Proteus spp. 75% Enterobacter cloacae, 100% Citrobacter freundii, 100% Burkholderia spp. 100% Serratia spp. and 50% Stenotrophomonas maltophilia were susceptible to this chemical compound. Fosfomycin showed excellent effectiveness to most of the common ESBL producing bacteria such as E. coli, Klebsiella and Proteus spp

Pathogens causing blood stream infections and their drug susceptibility profile in immunocompromised patients

To determine the types of pathogens causing blood stream infections and their drug susceptibility profile in immunocompromised patients. Cross-sectional, observational study. Department of Microbiology, Armed Forces Institute of Pathology, Rawalpindi, from January to September 2012. Blood culture bottles received from immunocompromised patients were dealt by two methods, brain heart infusion [BHI] broth based manual method and automated BACTEC system. The samples yielding positive growth from either of two methods were further analyzed. The identification of isolates was done with the help of biochemical reactions and rapid tests. Antimicrobial susceptibility of the isolates was carried out as per recommendations of Clinical and Laboratory Standards Institute [CLSI]. Out of the 938 blood culture specimens received from immunocompromised patients, 188 [20%] yielded positive growth. Out of these, 89 [47.3%] isolates were Gram positive and Gram negative each, while 10 [5.3%] isolates were fungi [Candida spp.]. In case of Gram positive isolates, 75 [84.3%] were Staphylococcus spp. and 51 [67%] were Methicillin resistant. Amongst Gram negative group 49 [55.1%] isolates were of enterobacteriaceae family, while 40 [44.9%] were non-lactose fermenters [NLF]. In vitro antimicrobial susceptibility of Staphylococci revealed 100% susceptibility to vancomycin and linezolid. The enterobacteriaceae isolates had better susceptibility against amikacin 85.7% compared to tigecycline 61.2% and imipenem 59.2%. For NLF, the in vitro efficacy of aminoglycosides was 72.5%.The frequency of Gram positive and Gram negative organisms causing blood stream infections in immunocompromised patients was equal. Vancomycin in case of Gram positive and amikacin for Gram negative organisms revealed better in vitro efficacy as compared to other antibiotics.

In vitro susceptibility of chloramphenicol against methicillin-resistant staphylococcus aureus

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

Antimicrobial susceptibility pattern of methicillin resistant staphylococcus aureus in a tertiary care setting-latest trend

To determine antimicrobial susceptibility pattern of methicillin resistant Staphylococcus aureus in a tertiary care setting. Descriptive study. Microbiology Department, Armed Forces Institute of Pathology, Rawalpindi from March 2011 to April 2012. Two hundred isolates of MRSA recovered from various clinical specimens sent to AFIP for culture and sensitivity were identified using standard microbiological techniques and the antimicrobial susceptibility was carried out employing Kirby-Bauer disc diffusion technique as recommended by Clinical and Laboratory Standards Institute. The Susceptibility pattern of isolates was recorded in percentages. Of the 200 MRSA isolated, all[100%] were susceptiblr to vancomycin and Linezolid followed by 88% to tigecycline, 81% to chloramphenicol, 66% to amikacin, 62.5% to clindamycin, 52.5% to doxycycline, 36% to trimethoprim-sulfamethoxazole, 29% to gentamicin, 28.5% to erythromycin and 26.5% to ciprofloxacin. The results show that linezolid and vacomycin hold excellent in vitro efficacy against MRSA whereas doxycyline, clindamycin, trimethoprim-sulfamethoxazole, gentamicin, erthromycin and ciprofloxacin have poor sensitivity.

Spectrum and antimicrobial susceptibility of bacterial organisms isolated from patients in a bone marrow transplant centre-A review of 6 years

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

Non-dermatophyte moulds as pathogens of onychomycosis

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

Susceptibility pattern of extended specturm beta-lactamase producing isolates in various clinical specimens

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

In vitro efficacy of piperacillin/sulbactam, piperacillin/ tazobactam and cefoperazone/sulbactam against clinical isolates of pseudomonas aeruginosa - a comparative study

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

Evaluation of BACTEC MGIT 960 system for recovery of Mycobacterium tuberculosis complex in Pakistan

We evaluated the performance of MGIT 960 system in terms of recover rate, detection time of mycobacteria and contamination rate from various human clinical specimens and compared it with already in use BACTEC 460 TB system and conventional LJ medium. This is the first reported study on MGIT 960 and its comparison with BACTEC 460 system in Pakistan. A total of 260 different clinical specimens received for the culture of mycobacteria were dealt during the six months study period. All the specimens were digested and decontaminated according to the standard N-acetyl-Lcysteine NaOH method. All the processed specimens were inoculated on both the liquid systems and solid medium and incubated for six weeks and eight weeks consecutively. A total of 44 mycobacterial isolates (Mycobacterium tuberculosis, n=43; Mycobacteria other than tuberculosis, n=1) were recovered from 260 clinical specimens. The recovery rate of M. tuberculosis complex was 97.6% on BACTEC MGIT 960 system and 93.0% on BACTEC 460 system and 83.7% on LJ medium. The mean detection time of mycobacteria on BACTEC MGIT 960 system was 11.2 days in smear positive cases, 14.2 days in smear negative cases and 14.8 days in smear positive cases on BACTEC 460 system. Contamination rates were 9.6% and 5.6% and 3.4% for BACTEC MGIT 960, BACTEC 460 system and LJ medium respectively. The non-radiometric, fully automated BACTEC MGIT 960 system has better diagnostic ability as compared with radiometric, semi-automated BACTEC 460 system and LJ medium, so it can be used as a reliable alternative in over burden laboratories.

Microbiology of Chronic suppurative otitis media - experience at Bahawalpur

To determine the aerobic microorganisms involved and their antibiotic sensitivity pattern in patients with chronic suppurative otitis media [CSOM] to provide a guideline for making a protocol for empirical antibiotic therapy. Descriptive study. The study was conducted from Sept 2005 to April 2007 at the department of ENT and Microbiology, Combined Military hospital Bahawalpur. A total of 178 patients with unilateral or bilateral active chronic suppurative otitis media attending the outpatient clinic were included in the study. All the patients were evaluated through detailed clinical history and clinical examination. Pus samples were collected from the discharging ear[s] and sent to microbiology section of hospital laboratory where aerobic cultures were done. Antibiotic sensitivity testing was done with standard antibiotic discs using Kirby-Bauer disk diffusion method as per National Committee for Clinical Laboratory Standards recommendations. From the clinical specimens of 178 patients enrolled in the study, microbiological culture was yielded from 130 [73%] specimens. There were 116, [89%] bacterial isolates and 14, [11%] fungi. Pseudomonas aeruginosa 58 [45%] was the most common isolate, followed by Staphylococcus aureus 52 [40%] including two isolates of Methicilliresistent Staphylococcus Aureus [MRSA]. Antibiotic sensitivities of Pseudomonas aeruginosa showed that 100% isolates were sensitive to Piperacillin/Tazobactam, where as 86% isolates were sensitive to ceftazidime and 83% to ciprofloxacin. Only 45% of Pseudomonas aeruginosa isolates were sensitive to gentamicin and 48% to amikacin. For Staphylococcus aureus [other than MRSA], 100% isolates were sensitive to cloxacillin, 80% to ciprofloxacin and 68% to gentamicin. Only 60% isolates were sensitive to chloramphenicol and 32% to cotrimoxazole. Pseudomonas aeruginosa was the most common isolate followed by Staphylococcus aureus. More than 80% of the two organisms were sensitive to quinolones. It is therefore concluded that the topical preparation of quinolones should be included in the formulary to cover the most common aerobic isolates involved in CSOM