Management of Chronic Osteomyelitis and Antibiotic Stewardship; An Effort to Delay the Post-Antibiotic Era.

OBJECTIVE: To develop an effective antimicrobial strategy for the management of chronic osteomyelitis. STUDY DESIGN: Observational study. Place and Duration of the Study: Departments of Microbiology and Orthopaedics, Combined Military Hospital Malir, Karachi, Pakistan, from January 2021 to February 2022. METHODOLOGY: Bone biopsies of 45 enrolled participants were taken for microbiological evaluation. Intravenous antibiotic therapy was begun as per empirical therapy based on the local antibiogram and antibiotic policy. Once the susceptibility pattern was available, targeted therapy started and continued for 28 to 42 days. Patients were evaluated based on inflammatory markers and clinical conditions for a minimum of six months to a maximum of one year. RESULTS:  Out of the 45 patients, the majority 29% were soldiers, 40% belonging to the age group of 31-60 years. The common predisposing factor was trauma/fractures followed by diabetes and implants leading to chronic sinus discharge and decubitus ulcers. The most commonly isolated organism was Staphylococcus aureus (38%) followed by Methicillin-resistant Staphylococcus aureus (MRSA) (31%). Cotrimoxazole and Rifampicin turned out to be good treatment options. Only 4.4% showed unsatisfactory prognosis, nonetheless, no mortality was observed during the course of treatment. CONCLUSION: In this study, highly resistant strains were observed with limited treatment options for chronic osteomyelitis, however, effective stewardship programmes with accurate diagnostic reporting and judicious use of antimicrobials can prevent overuse of the valuable resources. KEY WORDS: Antimicrobial stewardship, Osteomyelitis, Methicillin-resistant Staphylococcus aureus, Empirical therapy, Antimicrobial resistance.

Herpes Simplex Virus Encephalitis: An Unexpected Outcome in a Polytrauma Patient.

An 84-year male was brought in the emergency after a road traffic accident leading to polytrauma with deteriorating consciousness. Prolonged unexplained unconsciousness led to cerebrospinal fluid examination. The polymerase chain reaction (PCR) of cerebrospinal fluid (CSF) was found to be positive for HSV-1 DNA. The patient was started on intravenous acyclovir and the consciousness level of the patient improved gradually. In this case, encephalitis was not suspected initially, because of the multiple traumatic injuries that needed management. Moreover, no features suggestive of encephalitis were present at the time of presentation, except for the non-specific symptom of drowsiness at the time of the accident. The patient was also diabetic and had chronic kidney disease as predisposing factors. It was primarily encephalitis which led to impaired consciousness that resulted in the road traffic accident in a very unlikely situation, i.e., hit by an ambulance inside the hospital. The reasons to suspect herpes simplex virus encephalitis (HSE) in this case were unexplained worsening level of consciousness, CSF findings suggestive of viral encephalitis along with highly deranged alanine aminotransferase (ALT) levels. This case highlights the importance of keeping a high index of suspicion for viral encephalitis in patients with risk factors, even in such a scenario of polytrauma. Key Words: Herpes simplex virus, Polytrauma, Viral encephalitis, Polymerase chain reaction.

Antimicrobial susceptibility pattern and genotypic characterisation of quinolone and ceftriaxone resistant genes among Salmonella typhi from various regions of Pakistan.

OBJECTIVE: To determine the current antibiotic resistance patterns and identification of quinolone and ceftriaxone resistant genes among Salmonella enterica subspecies serovar Typhi. METHODS: The prospective study was conducted from September 2018 to March 2019 and comprised samples collected from major hospitals and laboratories in Karachi, Quetta, Lahore, Kharia, Rawalpindi, Islamabad and Peshawar after approval from the institutional ethics review board of Hazara University, Mansehra, Pakistan. Antimicrobial susceptibility of isolates collected from the health facilities was checked using the Kirby Bauer disc diffusion method in line with the Clinical and Laboratory Standards Institute guidelines at the Department of Microbiology, Armed Forces Institute of Pathology (AFIP), Rawalpindi, Pakistan. All isolates were subjected for identification of genes responsible for quinolone and ceftriaxone resistance using polymerase chain reaction followed by gel-electrophoresis. RESULTS: Among the 96 isolates, phenotypically, ceftriaxone was found resistant in 31(32.29%) and ciprofloxacin in 95(99%). Genotypically, blaCTX-M-15 (beta lactamase, CTX as its acronym, -M from Munich) gene for ceftriaxone resistance was found in all phenotypically resistant 31(32.29%) isolates, while QnrS (Quinolone resistance, S group), GyrA (DNA gyrase subunit A), and GyrB (DNA gyrase subunit B) genes responsible for ciprofloxacin resistance were found in different frequencies (percentages given in table 2). CONCLUSIONS: The spread of extensively drug-resistant Salmonella enterica subspecies serovar Typhi strain to many big cities calls for urgent preventive measures.

Invasive fungal disease in critically ill and Immunocompromised patients.

OBJECTIVE: To study the frequency and type of invasive fungal disease in critically ill and immunocompromised patients. Method: The prospective, cross-sectional, descriptive study was conducted at the Armed Forces Institute of Pathology, Rawalpindi, Pakistan, from January 2017 to December 2020, and comprised pathological samples from immunocompromised and critically ill patients for fungal culture. Data regarding demographics, comorbidities, results of direct microscopy and fungal culture was recorded. Data was analysed using SPSS 22. RESULTS: Of the 8285 patients' specimens, 4722(57%) belonged to males and 3563(43%) to females. The mean age of the patients was 48.32±5.42 years (range: 14-98 years). Out of total 8285, 3465(41.82%) were related to blood, 2640(32%) endobronchial washing, 837(10%) sputum, 623(7.5%) tissue, 332(4%) body fluids, 288(3.5%) bronchoalveoar lavage and 100(1.2%) cerebrospinal fluid. Aspergillus flavus (20.7%) and candida albicans (14.5%) were the two most commonly isolated fungal species. CONCLUSIONS: A high index of suspicion for invasive fungal disease should be maintained in immunocompromised and critically ill patients.

Diagnostic Accuracy Of Rapid Fosfomycin Np Test For Detection Of Fosfomycin Resistance In Escherichia Coli In A Tertiary Care Hospital In Pakistan.

BACKGROUND: Emergence of resistance among Escherichia coli (E.coli) isolates against therapeutic options for UTIs (Urinary tract infections) has led to renewed interest in older antibiotics like Fosfomycin. In this study we evaluated diagnostic accuracy of Rapid Fosfomycin NP test based on glucose metabolism for rapid Fosfomycin susceptibility testing among urinary E.coli isolates. METHODS: In a cross-sectional validation study conducted in the Microbiology Department, Armed Forces Institute of Pathology, Rawalpindi, Pakistan from 15th March to 15th September 2020, 149 consecutive urine specimens were included as per selection criteria. Rapid Fosfomycin NP test was performed as per protocol of Nordmann P et al on urinary E.coli isolates for detection of Fosfomycin resistance and results were compared with reference modified Kirby-Bauer disk diffusion method. RESULTS: Out of total 149 E.coli isolates from 149 urine specimens, 80 were classified as Fosfomycin susceptible and 69 as Fosfomycin resistant by reference disk diffusion method. Sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy of rapid Fosfomycin NP test was found to be 94.2%, 98.75%, 98.48%, 95.2% and 96.64%, respectively. In our study reliable results were achieved after 2.5 hours of incubation. CONCLUSIONS: The rapid Fosfomycin NP test is valid and user-friendly technique which can be performed with minimal technical expertise. It is less time consuming than disk diffusion and Etest strips and easy to perform as compared to agar dilution method. It can be useful as alternative to agar dilution in urinary E.coli isolates which would help in selecting appropriate therapeutic option for UTIs.

Superficial Thrombophlebitis caused by Extensively Drug-resistant Salmonella Enterica Serovar Typhi.

Salmonella enterica serovar typhi causes one of the most common blood stream infections, the typhoid fever. However, it can cause pyogenic infections involving different sites as well. Extensively drug resistant (XDR) strains of Salmonella typhi are resistant to all first line anti-typhoidal drugs (chloramphenicol, ampicillin and trimethoprim-sulfamethoxazole) as well as ciprofloxacin and ceftriaxone. XDR-strains were first reported from Pakistan in 2016, and since then the strains have been spreading. These XDR Salmonella cases not only pose a therapeutic challenge but also predispose to complications as a result of prolonged illness and delayed treatment. Here, we report a case of superficial thrombophlebitis at intravenous cannula site in a 49-year male, who was being treated for XDR-typhoid fever. To the best of our knowledge, thrombophlebitis of a superficial vein is an unusual complication of Salmonella typhi, not previously reported in literature. Key Words: Bacteremia, Thrombophlebitis, Extensively drug-resistant, Typhoid fever, Salmonella typhi.

Antimicrobial susceptibility patterns among community and health care acquired carbapenem resistant Enterobacteriaceae, in a tertiary care hospital of Lahore.

OBJECTIVE: To compare the disk susceptibility pattern of healthcare acquired carbapenem-resistant enterobacteraceae with that of community-acquired isolates and their associated clinical presentations. METHODS: The cross-sectional study was conducted at the Department of Microbiology, Combined Military Hospital, and the Institute of Dentistry, Lahore, Pakistan, from November 2017 to July 2018. Patients with positive carbapenem-resistant enterobacteraceae cultures from clinical specimens were included. All the isolates were identified through conventional methods and standard biochemical tests. Antibiotic susceptibility testing was performed by Kirby Bauer Disk Diffusion method on Muller Hinton Agar plates. Data was analysed using SPSS 23. RESULTS: Of the 123 isolates identified, 97(79%) were healthcare acquired and 26(21%) were community-acquired. Statistically significant susceptibility patterns (p<0.001) of community acquired isolates were observed against cefoperazone-sulbactum and amikacin, while a low significance was observed with gentamycin (p<0.05). Significant results were obtained in case of colistin against both the groups (p<0.001). CONCLUSIONS: There was low antimicrobial resistance in community acquired carbapenem-resistant enterobacteraceae isolates.

Chryseobacterium Indologenes as a Novel Cause of Bacteremia in a Neonate.

Chryseobacterium indologenes is a rare human pathogen. It is an emerging species, least frequently reported from pediatric age group and known to cause pneumonia, bacteremia, and meningitis. The inherent resistant of one of the species to commonly prescribed broad-spectrum antibiotics makes it formidable challenge in the hospital settings. We report the first case of C. indologenes bacteremia from Pakistan, diagnosed in a preterm newborn in an intensive care setting.

Current Trends of Antimicrobial Susceptibility of Typhoidal Salmonellae Isolated at Tertiary Care Hospital.

OBJECTIVE: To determine the current trend of antimicrobial susceptibility of typhoidal Salmonellae. STUDY DESIGN: Descriptive cross-sectional study. PLACE AND DURATION OF STUDY: The study was carried out in the Department of Microbiology, PNS Shifa Hospital, Karachi, from January 2014 to December 2015. METHODOLOGY: Blood culture samples received from the wards and outpatient departments were included. Isolates of Salmonella were dealt with standard microbiological procedures. The antimicrobial sensitivity against the typhoidal Salmonellaewas determined using Kirby-Bauer disc diffusion method as per the guidelines of Clinical and Laboratory Standards Institute (2013). RESULTS: Atotal of 460 typhoidal Salmonellaewere isolated; out of which 270 were Salmonella typhiand 190 were Salmonella paratyphiA. The percentage of MDR isolates of S. typhiwas 57% and that of S. paratyphiAwas 42%. None of the isolates were resistant to ceftriaxone, while sensitivity to ciprofloxacin (07% and 0% for S. typhiand S. paratyphiA, respectively) was very low. CONCLUSION: There is high percentage of MDR isolates of typhoidal Salmonellaein our region. The antimicrobial sensitivity of typhoidal Salmonellaeto conventional agent has not improved enough to recommend their empirical use. There is almost complete resistance to fluoroquinolones as well, leaving very limited available treatment options.

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 aeruginosaas compared to imipenem when tested by both E-test and agar dilution methods.

In Vitro Evaluation of Linezolid and Meropenem Against Clinical Isolates of Multi Drug Resistant Tuberculosis By Mycobacterial Growth Indicator Tube (MGIT) 960.

OBJECTIVE: 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. STUDY DESIGN: A descriptive cross-sectional study. PLACE AND DURATION OF STUDY: Microbiology Department, Armed Forces Institute of Pathology (AFIP), Rawalpindi, from September 2011 to August 2013. METHODOLOGY: 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 µg/ml, while for MER were 4.0, 8.0 and 16 µg/ml. Mycobacterial Growth Indicator Tube (MGIT) 960 system was used to carry out drug susceptibility testing as per recommended protocol. RESULTS: At break point concentration of 0.5 µg/ml, 80 out of 100 (80%) MDR-TB isolates were susceptible to LZD while at breakpoint concentration of 1.0 µg/ml and 2.0 µg/ml, 96/100, (96%) of MDR-TB isolates were susceptible. For MER, at breakpoint concentrations of 4.0 µg/ml no MDR-TB isolate was susceptible, while at 8.0 µg/ml 3/100, (3%) and at 16.0 µg/ml 11/100, (11%) of MDR-TB isolates were susceptible. CONCLUSION: LZD was found to have excellent in vitro efficacy as 96% of MDR-TB isolates were susceptible at breakpoint concentration of 1.0 µg/ml or more. In case of MER it was found that in vitro susceptibility improved as the break point concentrations were increased.

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

OBJECTIVE: 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). STUDY DESIGN: Adescriptive cross-sectional study. PLACE AND DURATION OF STUDY: Microbiology Department, Armed Forces Institute of Pathology (AFIP), Rawalpindi, from September 2011 to August 2013. METHODOLOGY: Amikacin (AK) and Levofloxacin (LEVO) were obtained in chemically pure form from Sigma (Taufkirchen, Germany). The breakpoint concentration used for AK was 1.0 µg/ml and for LEVO 2.0 µg/ml. Mycobacterial Growth Indicator Tube (MGIT) 960 system was used to carry out drug susceptibility testing as per recommended protocol. RESULTS: 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. CONCLUSION: 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.

OBJECTIVE: To evaluate the frequency and antimicrobial susceptibility pattern of Acinetobacter species isolated from pus and pus swab specimens at a tertiary care setting. STUDY DESIGN: Cross-sectional observational study. PLACE AND DURATION OF STUDY: Department of Microbiology, Armed Forces Institute of Pathology, Rawalpindi, from July 2008 to July 2012. METHODOLOGY: 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 Acinetobacterspecies were included in the study. RESULTS: 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 Acinetobacterspecies. Among 276 Acinetobacterspp., 245 (88.8%) were Acinetobacter baumannii and 31 (11.2%) were Acinetobacterjohnsonii. 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. CONCLUSION: About 11% of soft tissue and wound infections are caused by Acinetobacterspecies 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 activity of fosfomycin tromethamine against extended spectrum beta-lactamase producing urinary tract bacteria.

OBJECTIVE: To determine the in vitro activity of Fosfomycin tromethamine against extended spectrum beta-lactamase producing uropathogens. STUDY DESIGN: Experimental study. PLACE AND DURATION OF STUDY: Department of Microbiology, Armed Forces Institute of Pathology, Rawalpindi, from October 2011 to October 2012. METHODOLOGY: 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). RESULTS: 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. CONCLUSION: Fosfomycin showed excellent effectiveness to most of the common ESBL producing bacteria such as E. coli, Klebsiella and Proteus spp.

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

OBJECTIVE: To determine the antimicrobial susceptibility pattern of bacterial pathogens in the patients of urinary tract infection reporting at a tertiary care hospital. STUDY DESIGN: Laboratory based study. PLACE AND DURATION OF STUDY: Department of Microbiology, Armed Forces Institute of Pathology, Rawalpindi, from January to December 2012. METHODOLOGY: 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). RESULTS: 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. CONCLUSION: 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.

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

OBJECTIVE: To determine the types of pathogens causing blood stream infections and their drug susceptibility profile in immunocompromised patients. STUDY DESIGN: Cross-sectional, observational study. PLACE AND DURATION OF STUDY: Department of Microbiology, Armed Forces Institute of Pathology, Rawalpindi, from January to September 2012. METHODOLOGY: 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). RESULTS: 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%. CONCLUSION: 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.

OBJECTIVE: To determine the in vitro susceptibility of chloramphenicol against methicillin-resistant Staphylococcus aureus. STUDY DESIGN: Cross-sectional study. PLACE AND DURATION OF STUDY: Department of Microbiology, Armed Forces Institute of Pathology, Rawalpindi, from January to June 2012. METHODOLOGY: One hundred and seventy four isolates of methicillin-resistant Staphylococcus aureus were included in this study using cefoxitin (30 µg) 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 µg/ml). Clinical and Laboratory Standards Institute (CLSI) recommendations of ≤ 8 µg/ml being sensitive, 16 µg/ml as intermediate and ≥32 µg/ml as resistant were followed in interpreting the results. RESULTS: Out of the 174 MRSA isolates, 132 (75.86%) isolates were susceptible to chloramphenicol with MICs of ≤ 8 µg/ml, 38 (21.84%) were resistant ≥32 µg/ml while 4 (2.30%) were in intermediate range with MIC of 16µg/ml. CONCLUSION: 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.

Prevalence and molecular characterization of Enterobacteriaceae producing NDM-1 carbapenemase at a military hospital in Pakistan and evaluation of two chromogenic media.

The aim of this study was to assess the frequency and genotypic diversity of carbapenemase-producing Enterobacteriaceae (CPE) in stool samples from patients attending a military hospital in Pakistan. Further aims included the identification of factors that might predispose to faecal carriage and evaluation of 2 chromogenic culture media: Brilliance CRE and chromID CARBA. Of 175 patients, 32 (18.3%) had faecal carriage of CPE and all produced NDM-1 carbapenemase. All of these 32 patients were detected using chromID CARBA compared with 20 patients (62.5%) detected using Brilliance CRE (P = 0.0015). Duration of hospitalization and treatment with co-amoxyclav were statistically associated with a higher likelihood of carriage of CPE (P ≤ 0.05). The majority of NDM-1-producing Enterobacteriaceae co-produced CTX-M-1 group extended spectrum ß-lactamase, and one third produced armA-type methylase. NDM-1 carbapenemase was most commonly found amongst commensal types of Escherichia coli, especially phylogenetic group B1.