Evaluation of a Molecular Test for Detection of Mycobacterium tuberculosis Isolates Resistant to Rifampicin and Isoniazid.

BACKGROUND: Multidrug-resistant tuberculosis (MDR-TB) is increasing worldwide and is a major cause of death in many countries. It has become a major challenge for national tuberculosis control programs. Therefore, rapid identification of MDR strains of Mycobacterium tuberculosis and monitoring of their transmission could contribute significantly to the fight against tuberculosis. The GenoType MTBDRplus assay has been recommended by the World Health Organization to identify rifampicin (RIF)- and isoniazid (INH)-resistant M. Tuberculosis isolates. The objectives of this study were to evaluate the performance of the GenoType MTBDRplus test in the detection of rifampicin and isoniazid resistance of M. tuberculosis isolates in a Moroccan hospital and then to determine the frequency of mutations associated with resistance to these two major anti-tuberculosis drugs. METHODS: This is a retrospective study conducted at the bacteriology department of the Mohammed V military hospital over a period of one year from 01/01/2018 to 12/31/2019. A total of 92 isolates of M. tuberculosis from pulmonary and extra-pulmonary specimens were evaluated for drug susceptibility by MGIT™ 960 AST system and compared to the GenoType MTBDRplus assay. The MGIT™ 960 AST system was used as the gold standard for the evaluation of the GenoType MTBDRplus assay. RESULTS: Sensitivity and specificity of the GenoType MTBDRplus assay for the detection of RIF-resistant M. tuberculosis isolates were 83.33% and 100%, respectively. Its sensitivity and specificity for the detection of INH-resistant M. tuberculosis were 88.23% and 100% respectively. The concordances of the GenoType MTBDRplus assay and the MGIT™ 960 AST system for the detection of sensitivity to RIF and INH were 99% (1/92) and 98% (2/92), respectively. Among the five RIF-resistant isolates, the MUT3 mutation in the rpoB gene (codon S531L mutation) was present in 80% of isolates, whereas mutations in the rpoB MUT1 gene were present in only one (20%) RIF-resistant isolate. INH resistance was detected in 15 isolates, of which nine isolates (60%) had specific mutations of the katG gene (codon S315T1) and conferred a high level of resistance to INH. CONCLUSIONS: The results of this study have shown that the GenoType MTBDRplus test has a high sensitivity and specificity for the detection of resistance to RIF and INH.

A Case of Colonic Tuberculosis Revealed by Polymerase Chain Reaction.

BACKGROUND: The authors report a case of tumor-like colonic tuberculosis revealed by PCR in a 32-year-old patient with a low-level peritoneal effusion on CT scan with negative histological study on colonic biopsy. METHODS: The colonic biopsy received at the laboratory after grinding in a porcelain mortar, was the object of a molecular study by GeneXpert MT/RIF (Cepheid, Sunnyvale, CA, USA) using the automated real-time PCR technique and a conventional study based on Ziehl-Nielsen staining and culture on Lowenstein-Jensen® solid medium (LJ) and Mycobacteria Growth Indicator Tube (MGIT®) liquid medium. RESULTS: The patient was a 32-year-old male without any personal or family history of tuberculosis and without signs of tuberculosis impregnation. He had a story of ingestion of non-pasteurized dairy products including milk and cheese. For 45 days he had constipation with abdominal pain and feeling of heaviness. Physical examination of the patient revealed abdominal tenderness without adenopathy. The laboratory workup showed a normal blood count, CRP, liver and kidney function tests. The HIV test was negative. Medical imaging revealed a low-level peritoneal effusion that could not be punctured. Colonoscopy showed a thickening of the colon. The colonic biopsy, after crushing and sonication, was searched for the Mycobacterium tuberculosis complex by both molecular biology and conventional methods. Molecular research by GeneXpert MTB/RIF (Cepheid, Sunnyvale, CA, USA) using the automated real-time PCR technique, revealed the presence of the Mycobacterium tuberculosis complex without detection of rifampicin resistance. On the other hand, the direct examination after special Ziehl-Nielsen staining was positive (Figure 2) and the cultures on Lowenstein-Jensen® solid medium (LJ) and Mycobacteria Growth Indicator Tube (MGIT®) liquid medium were also positive after two and three weeks, confirming the molecular diagnosis. The histology study showed moderate non-specific chronic colitis with no histological arguments for tuberculosis or malignancy. The patient was placed on curative tuberculosis treatment according to the national protocol, with a favorable clinical-radiological course. CONCLUSIONS: Colonic tuberculosis is a disease that may mimic many other diseases; therefore, a correct approach is necessary for the correct diagnosis and treatment.

Septic arthritis of the ankle: Do not forget Pasteurella pneumotropica.

Pasteurella pneumotropica is an important bacterial pathogen in both animals and humans. Most reported Pasteurella infections in humans involve skin and soft tissues, often after an animal bite, scratch, or lick to an open wound. We report a case of septic arthritis with Pasteurella pneumotropica in a diabetic and cardiopathic patient who was the victim of a rat bite in the street, with a good evolution after medical and surgical treatment.

In Vitro Activities of Ertapenem and Imipenem against Clinical Extended Spectrum Beta-Lactamase-Producing Enterobacteriaceae Collected in Military Teaching Hospital Mohammed V of Rabat.

Objective. To study the sensitivity level of extended spectrum beta-lactamase-producing Enterobacteriaceae to Carbapenems (Imipenem, Ertapenem) marketed in Morocco and discusses the place of Ertapenem in the treatment of extended spectrum-beta-lactamase-producing. Materials and Methods. A retrospective study of 110 extended spectrum beta-lactamase-producing Enterobacteriaceae. Isolates obtained from blood cultures, superficial and deep pus, and catheters were conducted. The minimum inhibitory concentrations of Imipenem and Ertapenem were done by the E-test. The modified Hodge test was conducted for resistant or intermediate strains. Results. 99.1% of isolates were susceptible to Imipenem. For Ertapenem, 4 were resistant and 4 intermediate. The modified Hodge test was positive for all 08 isolates. A minimum inhibitory concentration comparison of K. pneumoniae, E. cloacae, and E. coli for Imipenem has noted a significant difference between E. cloacae on one hand and E. coli, K. pneumoniae on the other hand (P < 0.01). No significant difference was noted for minimum inhibitory concentration of Ertapenem. Conclusion. Our results confirm in vitro effectiveness of Ertapenem against extended spectrum beta-lactamase-producing Enterobacteriaceae as reported elsewhere. However, the emergence of resistance to Carbapenems revealed by production of carbapenemases in this study confirmed a necessary bacteriological documented infection before using Ertapenem.