Reflection on bacterial resistance to antimicrobial agents at a major tertiary care center in Lebanon over a decade

Antimicrobial resistance has been inflecting deleterious health and economic consequences locally and globally. This study addresses the patterns and trends of bacterial resistance to antimicrobial agents over a decade, at a major tertiary care center in Beirut. Data on bacterial susceptibility patterns at the CAP accredited Clinical Microbiology Laboratory is analyzed from January 2000 to November 2011, along with related different studies conducted during this period. Increasing rates of ESBL-producing isolates were noted for Escherichia coli, Klebsiella pneumoniae, Salmonella spp. and Shigella spp. Resistance to carbapenems remains problematic in Acinetobacter spp. and Pseudomonas aeruginosa, and started emerging in E. coli and K. pneumoniae. Tigecycline and colistin maintained excellent activity against most ESBL and carbapenem resistant bacteria relevant to the treatment by these agents. Resistance to quinolones is being encountered in Streptococcus pneumoniae, Haemophilus influenzae, Salmonella spp. and Shigella spp. Methicillin resistant Staphylococcus aureus [MRSA], though remaining relatively high, showed decreasing trends of resistance, while vancomycin maintain uniform activity. Rare and sporadic vancomycin resistant strains in enterococci are encountered. Macrolide and clindamycin increasing rates of resistance is noted in S. pneumoniae, group A streptococci, S. aureus, viridans streptococci and some others. Physicians should be aware of the local epidemiology of antimicrobial resistance to properly guide the initial therapy. These resistance problems can be attributed to uncontrolled use of antimicrobial agents, thus, highlighting the need for antimicrobial stewardship to curb this threat

[Efficacy of bactec TB in the rapid confirmatory diagnosis of mycobacterial infections. A lebanese tertiary care center experience]

Rapid detection of Mycobacterium tuberculosis [MTB], especially multidrug-resistant strains, is of importance for prompt clinical management and initiation of public health control measures. Culture remains the "gold" standard in the confirmatory laboratory diagnosis of mycobacterial infections. The reliability of the automated radiometric BACTEC 460 TB [BAC:, TEC] system for the rapid detection of mycobacteria in clinical specimens was evaluated and compared to the conventional culture on Lowenstein-Jensen [LJ] medium. All clinical specimens submitted for mycobacterial culture were processed and simultaneously cultured on both BACTEC broth medium and Li solid medium. Acid-fast bacilli [AFB] smears were also performed on the sediments. Differentiation of mycobacterial isolates as MTB or Mycobacterium sp. other than tuber-culosis [MOTT] was based on the BACTEC NAP test. All positive culture findings recovered between January 1997 and December 2003 were analyzed in this study.A total of 3300 specimens were tested of which 355 [10.7%] yielded positive cultures consisting of 233 [65.6%] MTB and 122 [34.4%] MOTT. The percentages of AFB smear-positive were 45% and 49% in clinical speci-mens yielding MTB and MOTT, respectively. Though several types of specimens were cultured, most isolates [72% of MTB and 91% of MOTT] were recovered from respiratory specimens. Overall, the BACTEC showed significantly higher mycobacteria recovery rate [91%] than LJ [77%]. In terms of times to detection, BACTEC showed significantly shorter detection time of isolates than L.1 for the overall [mean 9.6 days for BACTEC vs 22.8 days for Li] and for each category of AFB smear finding. The detection time is shortened for BACTEC with the increasing grade of smear positivity. BACTEC is substantially more sen-sitive, efficient and rapid than LJ in the laboratory diagnosis of mycobacterial infections. This system also provides rapid differentiation of MTB from MOTT and susceptibility test results on MTh. However, the simultaneous use of BACTEC and LJ is recommended to provide maximum optimal recovery of isolates from clinical specimens. The time-saving in BACTEC provides an excellent facility for physicians in patient management and to public health personnel for prompt initiation of infection control measures

Molecular fingerprinting of multidrug-resistant mycobacterium tuberculosis strains in Beirut reveals genetic diversity and father to daughter transmission

The typing of six consecutive multidrug-resistant Mycobacterium tuberculosis strains isolated from patients with tuberculosis [TB] at the American University of Beirut Medical Center, was performed by touchdown double-repetitive-element [DRE]-PCR. The isolates exhibited four distinct patterns in DRE-PCR with three isolates exhibiting unique patterns and three isolates yielded similar DNA fragment patterns [cluster pattern]. Only two of the three cluster isolates exhibited identical patterns as revealed by restriction fragment length polymorphism [RFLP] targeting specific mutations in the rpoB and katG genes that confer resistance to rifampin and isoniazid, respectively. A direct epidemiological linkage for the two isolates exhibiting genotypic relatedness was also established as the isolates were recovered from a 33-year-old man and his 8-year-old daughter. The data show that transmission of multidrug-resistant M. tuberculosis strains is contributing to the emergence of drug-resistant TB in Beirut. Combining DRE-PCR with RFLP at the rpo B and katG genes could provide a powerful means for investigating the spread of multidrug-resistant M. tuberculosis strains in Lebanon