Direct susceptibility testing on MGIT 960 TB system: a rapid method for detection of drug resistant tuberculosis

Objective: To evaluate direct drug susceptibility testing on MGIT 960 system for detection of multidrug resistant tuberculosis from smear positive pulmonary specimens

Study Design: Cross-sectional analytical study

Place and Duration of Study: Microbiology Department, Armed Forces Institute of Pathology, Rawalpindi, from July 2016 to September 2017

Methodology: Smear positive specimens were pretreated according to guidelines and then tested on MGIT 960 TB system for direct drug susceptibility testing [DST] of isoniazid and rifampin. Samples were also processed by gold standard indirect method, which comprises culture and then DST from positive growth by MGIT 960 TB system

Results: Out of 108 specimens, 95 [88%] DST results were reportable. Out of 95 reportable specimens, 17 isolates were resistant to both isoniazid [INH] and rifampin [RIF] by direct DST. The sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy for INH were 92%, 93%, 82%, 97% and 92.6%, respectively; and 95%, 96%, 86.3%, 98.6% and 95.7%, respectively for RIF. Average time to report DST by indirect method was 23.6 +/-3.9 days, while it was 11.4 +/- 2.7 days for the direct method

Conclusion: Direct susceptibility testing on MGIT 960 system showed very good agreement when compared with indirect method. Time saving is crucial factor in initiation of early effective therapy, especially in drug resistant cases. Further studies on large scale are required for more accurate evaluation of this method

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

Rapid mycobacterium tuberculosis dna detection on fine needle aspirates from extra pulmonary lymph nodes

To evaluate the diagnostic efficacy of two rapid methods i.e. Mycobacterium tuberculosis [MTB] Polymerase Chain Reaction [PCR] on Fine Needle Aspiration [FNA] samples by comparing with cytology of respective site sample. Cross-sectional comparative study. Department of Microbiology, Armed Forces Institute of Pathology [AFIP], Rawalpindi, Pakistan, from July 2010 through November 2013. A total of 105 extra pulmonary lymph nodes aspirates obtained through fine needle aspiration were processed. Cytology and PCR were done on each specimen. Cytology was taken as gold standard. Out of the total 105 samples, 71 [67.6%] were positive for the MTB PCR while 34 [32.4%] showed negative status. According to FNA cytology [FNAC] results, 72 [68.6%] cases were positive for the disease while 33 [31.4%] were negative. Sensitivity of PCR was 90.3%, specificity 81.8%, positive predictive value [PPV] 91.5%, negative predictive value [NPV] 79.4%, with diagnostic accuracy of 87.6%. Area under the curve was 0.860 [p < 0.001]. PCR is a sensitive tool for detection of MTB on FNA samples from EPTB cases. The results are available within few hours which is helpful for the clinicians to initiate therapy

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

Frequency of dyslipidaemia in young patients with acute myocardial infarction

To study the frequency of dyslipidaemia in young patients aged between 20-40 years, with Acute Myocardial Infarction in our population. Descriptive study. Coronary Care Unit [CCU] of Armed Forces Institute of Cardiology [AFIC]/ National Institute of Heart Diseases [NIHD], Rawalpindi from December 2008 to May 2009. One hundred patients of acute myocardial infarction [AMI] fulfilling the World Health Organization [WHO] diagnostic criteria of AMI, having ages between 20-40 years, were included in the study after full informed consent using non-probability consecutive sampling. Blood samples for serum lipid profile were taken after 12 hours fasting [within 24 hours of presentation], and analyzed in laboratory of AFIC. Individual patients' results were compiled with respect to age, gender, serum total cholesterol, serum triglycerides, serum low density lipoprotein [LDL] cholesterol, serum very low density lipoprotein [VLDL] cholesterol and serum high density lipoprotein [HDL] cholesterol. The data was entered in SPSS [version 11.0] and analyzed. Of the 100 patients with AMI, 47 were found to have dyslipidaemia. Hypertriglyceridaemia was the most common lipid abnormality as it was found in 32 [68.1%] patients; followed by raised serum VLDL, hypercholesterolemia, raised serum LDL and low serum HDL found in 25 [53.2%], 16 [34.0%], 4 [8.5%] and 2 [4.3%] patients respectively. Out of 47 patients with dyslipidaemia, 28 [59.6%] had more than one lipid abnormality. Frequency of dyslipidaemia in young patients with AMI in our population is high.

Bone marrow infection with Mycobacterium fortuitum in a diabetic patient

Incidence and prevalence of Mycobacterium fortuitum infection vary greatly by location and death is very rare except in disseminated disease in immunocompromised individuals. We present what we believe is the first case of bone marrow infection with Mycobacterium fortuitum in an HIV negative patient. Bone marrow examination revealed presence of numerous acid fast bacilli which were confirmed as Mycobacterium fortuitum on culture and by molecular analysis. Patient was managed successfully with amikacin and ciprofloxacin

Ambu bag as a source of Acinetobacter baumannii outbreak in an intensive care unit

This case report describes an outbreak of multidrug resistant Acinetobacter baumannii in the intensive care unit of a tertiary care hospital. Three patients were infected on the same day from an Ambu bag which was used on all the patients. The outbreak was immediately identified and the source was traced within one week. Appropriate measures were taken and a continuous surveillance was carried out resulting in reporting of no such case from the intensive care unit in the last 6 months

Efficacy of zinc as an antibacterial agent against enteric bacterial pathogens

Background: Diarrhoea is a serious threat all over the world with great economic implications especially evident in the developing world. This study was aimed at determining in vitro efficacy of Zinc [Zn] against common enteric bacterial pathogens. Method: A total of 100 bacterial enteric pathogens: Salmonellae [n=16], enteropathogenic Escherichia coli [EPEC] [n=26], Shigellae [n=28] and Vibrio cholerae [n=30] were isolated from diarrhoeal stool specimens at Department of Microbiology, Armed Forces Institute of Pathology Rawalpindi during Aapril 2009 to Jan 2010. These isolates were tested against various concentrations of Zn supplemented in Mueller Hinton [MH] agar using a multipoint inoculator. A minimum inhibitory concentration of active Zn in ZnSO4.7H2O ranging from 0.03 mg/ml to 1 mg/ml was used. Results: Zn completely inhibited the growth of all the tested pathogens and most of them were inhibited at a concentration of 0.06 mg/ml to 0.5 mg/ml of Zn. Conclusions: Zinc has an excellent antibacterial activity against enteric bacterial pathogens common in our setup which may provide basis for treatment of diarrhoea. Clinical study based on these findings is recommended. Keywords: Diarrhoea, zinc, antibacterial, Enteric Pathogens, Cholera, Salmonella, E. coli, Shigella

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.

Pulmonary cryptosporidiosis in a bone marrow transplant recepient

Cryptosporidium, a protozoan parasite of Phylum Apicomplexa, causes acute short term intestinal infection in immunocompetent individuals. However, in immunocompromised patients, it causes prolonged and life threatening watery diarrhea, rarely with extra-intestinal involvement. We present a case of Cryptosporidium parvum with pulmonary involvement who was managed with azithromycin and co-trimoxazole combination. This is the second reported case in the world in HIV negative patient undergoing bone marrow transplantation

Invasive infection in a young immunocompetent soldier caused by scytalidium dimidiatum

Scytalidium dimidiatum is mainly responsible for human skin and nail infections but the mould has also been reported for invasive infections in immunocompromised individuals. We report a young immunocompetent individual diagnosed with invasive non-traumatic Scytalidium dimidiatum infection involving the left orbital cavity and maxillary sinus