RESUMEN

Information is limited about the drug resistance patterns in extrapulmonary tuberculosis (EPTB) in Iran. This study aimed to determine the prevalence of EPTB and to investigate the drug-resistance pattern in Mycobacterium tuberculosis strains collected from extrapulmonary samples at the Tehran regional TB reference laboratory. Extrapulmonary specimens from individuals with suspected TB referred to the TB reference laboratories in five cities of Iran were collected. Both standard conventional methods (culture and direct smear microscopy) and Xpert MTB/RIF assay were used for the identification of mycobacteria. Drug susceptibility testing was done using Xpert MTB/RIF. The proportion method on Lowenstein-Jensen medium was performed for confirmation. Between 2016 and 2020, a total of 12 050 clinical specimens from individuals with suspected TB were collected, of which 10 380 (86%) were pulmonary specimens and 1670 (14%) were extrapulmonary. Of the extrapulmonary specimens, 85 (5.0%) were positive for M. tuberculosis, and the remaining 1585 (95.0%) samples were negative by standard methods. Of 85 M. tuberculosis isolates, drug susceptibility testing was performed for 32 isolates, of which 1 (3.1%, 95% CI 0.0%-9.4%) was rifampin resistant and 31 (96.9%, 95% CI 90.1%-100%) were pan-susceptible. The rifampin-resistant isolate was also resistant to isoniazid, so was assigned as a multidrug-resistant TB. Our study indicated the frequency of drug-resistance among EPTB in Iran. Establishing rapid diagnostic methods for detection of drug-resistance in EPTB, performing drug susceptibility testing for all EPTB cases to provide effective treatment, and continuous monitoring of drug resistance, are suggested for prevention and control of drug resistance in EPTB in Iran.

RESUMEN

In this study, we evaluated the existence of classes A, B and D ß-lactamases among Pseudomonas aeruginosa (P.aeruginosa) and Acinetobacter baumannii (A.baumannii) strains isolated from burn patients in Tehran during the years 2012 and 2013. From these strains, the frequency of MBL (metallo-beta-lactamase) and ESBL (extended-spectrum beta-lactamase) producers were evaluated using CDDT (Combined Disk Diffusion Tests). The prevalence of some related genes, including blaIMP, blaVIM, blaSPM, blaKPC, blaGIM, blaDIM, blaBIC, blaOXA-48, blaCTX-M-15 and blaNDM genes, was evaluated using PCR and sequencing methods. Of the 75 non-fermenter isolates, 47 P.aeruginosa and 28 A.baumannii were isolated and identified. A high rate of resistance to common antibiotics was detected among A.baumannii isolates in particular, showing 100% resistance to 9 tested antibiotics. CDDT showed that 21 (28%) and 25 (34.25%) of the non-fermenter isolates were ESBL and MBL producers respectively. The prevalence of blaCTX-M-15 and blaIMP genes among the 75 non-fermenter isolates was 7 (9.3%) and 1 (1.3%), respectively. Fortunately, no other genes were detected in either of the non-fermenters. The mortality rate due to MBL-producing isolates was 5 (20%). This study showed specific resistance genes exist among some MBL and ESBL gram-negative non-fermenters which were isolated from burn patients in Tehran.

Dans cette étude, nous avons évalué l'existence des classes A, B et D de ß-lactamases chez les souches de Pseudomonas aeruginosa (P.aeruginosa) et Acinetobacter baumannii (A.baumannii) isolées des patients brûlés à Téhéran pendant les années 2012 et 2013. La fréquence des producteurs du MBL (métallo-bêta-lactamase) et du BLSE (bêta-lactamase à spectre étendu) a été évaluée par les tests de diffusion sur les disques combinées, et la prévalence de certains gènes liés (y compris les gènes blaIMP, blaVIM, blaSPM, blaKPC, blaGIM, blaDIM, blaBIC, blaOXA-48, blaCTX-M-15 et blaNDM) a été vérifiée avec des tests pour réaction en chaine à la polymérase et les méthodes de séquençage. Un totale de 75 isolats non-fermenteurs ont été isolés et identifiés : 47 étaient P.aeruginosa et 28 étaient A.baumannii. Un taux élevé de résistance aux antibiotiques communs a été détecté parmi les isolats d'A.baumannii en particulier, avec une résistance de 100% aux 9 antibiotiques testés. Les tests de diffusion des disques combinés a montré que 21 (28%) et 25 (34,25 %) des isolats non-fermenteur étaient producteurs du BLSE et du MBL respectivement. La prévalence des gènes blaCTX-M-15 et blaIMP parmi les 75 isolats non-fermenteurs était 7 (9,3%) et 1 (1,3%), respectivement. Heureusement, d'autres gènes n'ont pas été détectés. Le taux de mortalité due aux isolats producteurs des MBL était 5 (20%). Cette étude a montré que des gènes avec des résistances spécifiques existent parmi certains non-fermenteurs MBL et BLSE Gram-négatifs qui ont été isolés des patients brûlés à Téhéran.