Nationwide study of drug resistance among acid-fast bacilli positive pulmonary tuberculosis cases in Lebanon.

OBJECTIVE: To assess the prevalence of drug resistance among smear-positive sputum specimens from pulmonary tuberculosis (TB) cases in Lebanon. DESIGN: Between July 2002 and April 2004, 224 newly diagnosed TB cases and 21 previously treated TB cases were collected nationwide. Mycobacterium tuberculosis isolates were tested against isoniazid (INH), rifampicin (RMP), streptomycin (SM) and ethambutol (EMB) using the BACTEC-TB system. RESULTS: M. tuberculosis and non-tuberculous mycobacteria (NTM) isolates were recovered from 190 and 15 new cases, respectively, and from 16 and 1 previously treated cases, respectively. Overall drug resistance among new TB vs. previously treated TB cases was 19.5% and 75%, and for single drugs it was INH (12% vs. 63%), RMP (3% vs. 56%), SM (12% vs. 44%) and EMB (3% vs. 44%). The overall rate of multidrug resistance (MDR) was 5.8% (1% vs. 62.5%). The male:female ratio was 1.3:1; most were young adults. CONCLUSION: Relatively moderate single drug resistance and very low MDR rates were found among new TB cases, while among previously treated TB cases very high resistance and MDR resistance rates were detected. Such findings underline the need for ongoing stringent control measures to curb the spread of M. tuberculosis and its deleterious effects.

Comparative performance of PCR-based assay versus microscopy and culture for the direct detection of Mycobacterium tuberculosis in clinical respiratory specimens in Lebanon.

SETTING: American University of Beirut Medical Center, Lebanon. OBJECTIVE: To assess the performance of a polymerase chain reaction (PCR) using primers that flank 542 bp within IS6110 in Mycobacterium tuberculosis (TB) vs. microscopy and BACTEC culture, in the diagnosis of tuberculosis. DESIGN: A total of 82 clinical respiratory pulmonary specimens and 73 samples from BACTEC vials were tested by the three methods. RESULTS: Of 24 smear-positive culture-positive (SP-CP) and 11 smear-negative culture-positive (SN-CP) TB specimens, PCR detected 83% and 64%, respectively. Among 17 specimens yielding mycobacteria other than tuberculosis (MOTT), the PCR was positive in 33% SP-CP and 14% SN-CP specimens. Among the 73 BACTEC vials, PCR was positive in 36 of 38 (95%) yielding culture-positive TB, and in one of 20 (5%) yielding culture positive MOTT. None of the 30 smear-negative culture-negative (SN-CN) clinical specimens and 15 of the CN vials were positive by PCR. The overall sensitivity of PCR was 77% and 95% for TB detection in respiratory specimens and BACTEC vials, respectively, and the specificity was 94% in both. CONCLUSIONS: Because a substantial number of TB cases are missed, especially in SN-CP specimens, a PCR-based assay utilizing these primers cannot be used reliably, alone, in clinical laboratory diagnosis of mycobacterial respiratory infections.

Comparative study of antituberculous drug resistance among Mycobacterium tuberculosis isolates recovered at the American University of Beirut Medical Center: 1996-1998 vs 1994-1995.

PURPOSE: To study the overall current prevalence of antituberculous drug resistance among M. tuberculosis isolates recovered at the American University of Beirut Medical Center (AUBMC) between 1996-1998 in comparison to those reported on isolates recovered in 1994-1995. MATERIALS AND METHODS: Seventy-four consecutive M. tuberculosis isolates recovered from the same number of newly diagnosed cases of tuberculosis (TB), between January 1996 and December 1998 (referred to as 1998), were tested against isoniazid (INH), rifampicin (RIF), streptomycin (STM) and ethambutol (ETH), using the BACTEC-TB susceptibility procedure and system. The results were compared to those reported on the isolates recovered in 1994-1995 (referred to as 1995). RESULTS: A comparison between the results obtained in 1998 vs 1995 showed the following, respectively: The male to female ratio was 3.1:1 vs 2:1 and the mean ages were almost similar in males, 33.4 vs 34.1 years but were slightly higher in females 38.2 vs 32.7 years. Children (< or = 15 yrs) represented 10.8% vs 8.3% of the study population. The prevalence of resistance, to one or more drugs, was almost the same, 24% vs 26% but the overall percentages of single drug resistance were generally higher in 1998 vs 1995 against all the tested drugs except INH: INH (20.2% vs 23.9%), RIF (16.2% vs 12.5%), STM (13.5% vs 7.3%) and ETH (8.1% vs 3%). Among the resistant isolates, the profiles of resistance indicated decrease in resistance to one and two drugs, 6.7% vs 11.5% and 5.4% vs 10.4%, respectively, but showed increase in resistance to three and four drugs, 8.1% vs 2.1% and 4% vs 2.1%, respectively. Increase in resistance to two or more drugs was also observed, 17.6% vs 14.6%, and the prevalence of multidrug resistance, defined as resistance to at least both INH and RIF, was also increased, 14.7% vs 11.4%. CONCLUSIONS: This study shows a high prevalence and persistence of TB drug resistance tested in our Medical Center in Lebanon. In addition, the shift in the increase of resistance from one and two drugs to three and four drugs are very ominous and should be considered when treating patients in this country. Moreover, such information calls for scrutinizing the existing local TB control programs as part of the global efforts to minimize the incidence of this highly morbid infectious disease.

Drug-resistant Streptococcus pneumoniae in the Lebanon: implications for presumptive therapy.

A total of 50 consecutive clinical isolates of Streptococcus pneumoniae, collected between 1996 and 1998, were tested against six antimicrobial agents using the E-test. The percentages of fully resistant (R) and intermediately-R strains, respectively, were: benzyl penicillin 18 and 38%, amoxycillin-clavulanate 6 and 12%, cefuroxime 22 and 16%, ceftriaxone 2 and 16%, and clarithromycin 10%. Fully and or intermediately multidrug-resistance (two or more drugs) was seen in 44% of the isolates, 18% being fully resistant. The MIC breakpoint for cefaclor is not defined by the National Committee for Clinical Laboratory Standards (NCCLS) but MICs showed that: 76% of the isolates had an MIC of < or = 8 mg/l, 4% had an MIC of 16 mg/l and 20% had an MIC of > or = 32 mg/l. There was agreement between the E-test Pen MIC results and the 1 microg oxacillin (oxa) disk diffusion screen test for the 22 susceptible and the nine fully R strains but not for the 19 strains with Pen MICs between 0.1 and 1 mg/l; this shows the importance of MIC determination in such isolates. Penicillin and multiply antibiotic-resistant pneumococci are spreading in Lebanon, emphasizing the necessity to reconsider current treatment regimens in this country.