Community-Acquired Uropathogenic Escherichia coli, Antimicrobial Susceptibility, and Extended-Spectrum Beta-Lactamase Detection.

INTRODUCTION: Urinary tract infection is the second-leading reason for consults in primary health care. Bacterial urinary tract infections are the most common, of which Escherichia coli is the main etiologic agent. Antimicrobial resistance and multidrug resistance complicate effective community treatment, especially if resistance is caused by extended-spectrum beta-lactamase production. WHO recommends that antimicrobial susceptibility be evaluated in different regions of the world at different times. Community-acquired E. coli's susceptibility to colistin has not yet been studied in Cuba, and mcr-1 gene screening is necessary. OBJECTIVE: Evaluate community-acquired uropathogenic E. coli isolates' susceptibility to antibiotics, including colistin, and identify extended-spectrum beta-lactamase-producing bacteria. METHODS: We conducted a descriptive cross-sectional study that included 281 community-acquired uropathogenic E. coli isolates (153 from the Isle of Youth Special Municipality's Hygiene, Epidemiology, and Microbiology Center and 128 from Microbiology Laboratories of 7 institutions in Havana) from June 2016 through July 2018. We used the disk diffusion method to determine susceptibility to ampicillin, ampicillin/sulbactam, cefazolin, trimethoprim/sulfamethoxazole, ciprofloxacin, nitrofurantoin and fosfomycin. The disk elution method was used to determine susceptibility to colistin. The combined disk method was used to identify extended-spectrum beta-lactamases. Estimates were made regarding the frequency and percentages of antimicrobial susceptibility and resistance, as well as multidrug-resistance patterns. RESULTS: Of the 281 isolates, 68.3% (192/281) were resistant to ampicillin, 54.8% (154/281) were resistant to ciprofloxacin, and 49.5% (139/281) were resistant to trimethoprim/sulfamethoxazole. Resistance to colistin was not detected. On the other hand, 14.2% (40/281) were susceptible to the 8 antibiotics we evaluated, 22.1% (62/281) showed resistance to only 1 antibiotic, and 63.7% (179/281) were resistant to 2 or more antibiotics. In the extended-spectrum beta-lactamase determination, 34.5% (97/281) had inhibition zones ≤14 mm with cefazolin. Of those with inhibition zones, 64.9% (63/97) were positive in the phenotype test, and 35.1% (34/97) were negative. In extended-spectrum beta-lactamase-producing bacteria, 1.6% (1/63) were resistant to fosfomycin, and 3.2% (2/63) were resistant to nitrofurantoin. The most common multidrug-resistance pattern (22.9%; 30/131) was to ampicillin/sulbactam, ampicillin, cefazolin, ciprofloxacin, and trimethoprim/sulfamethoxazole. CONCLUSIONS: Uropathogenic E. coli resistance to the antibiotics most frequently used in community medical practice is quite common, and extended-spectrum beta-lactamase-producing bacteria is the mechanism for beta-lactam antibiotic resistance. Multidrug-resistance patterns include resistance to the antibiotics most used in community-acquired infections. Fosfomycin and nitrofurantoin are the most active in extended-spectrum beta-lactamase producing bacteria. All the isolates were susceptible to colistin.

Biofilm and Planktonic Antibiotic Resistance in Patients With Acute Exacerbation of Chronic Rhinosinusitis.

INTRODUCTION: The recalcitrant nature of patients with acute exacerbation of chronic rhinosinusitis (AECRS) potentially involves persisting colonization of the sinonasal mucosa by bacterial biofilms. Biofilms are known to be highly resistant to antibiotics, which may trigger or maintain chronic inflammation in the sinonasal mucosa. However, little is known about the relationship between the minimum inhibitory concentration (MIC) and antibiofilm concentrations of bacteria obtained from AECRS patients. MATERIAL AND METHODS: Thirty bacterial strains from 25 patients with AECRS were identified and underwent MIC determination (VITEK® 2). The planktonic isolates were submitted to an in vitro formation of biofilms (Modified Calgary Biofilm Device) and determination of minimum biofilm inhibitory concentration (MBIC) and minimum biofilm eradication concentration (MBEC) for amoxicillin, amoxicillin/clavulanic acid, clarithromycin, and levofloxacin. MIC of the planktonic forms was compared with MBIC and MBEC levels, according to the breakpoints established by the Clinical Laboratory Standards Institute guidelines. RESULTS: The main bacteria retrieved was S. aureus (60%), followed by other Gram-positive and Gram-negative bacteria in lower frequencies. 76.7% of strains formed biofilm in vitro (n=23/30). The planktonic isolates presented high rates of resistance for amoxicillin (82.6%) and clarithromycin (39.1%), and lower rates for amoxicillin/clavulanic acid (17.4%). The biofilm-forming bacteria counterparts presented higher levels of MBIC and MBEC compared to the MIC levels for amoxicillin, amoxicillin/clavulanic acid, and clarithromycin. Levofloxacin was highly effective against both planktonic and biofilm forms. Planktonic resistant forms were associated with levels of antibiofilm concentrations (MBIC and MBEC). CONCLUSIONS: Biofilm-forming bacteria from AECRS patients are prevalent, and biofilm forms are highly resistant to antibiotics compared to their planktonic counterparts. Antibiotic resistance observed in planktonic forms is a good indicator of biofilm resistance, although near 20% of susceptible planktonic bacteria can produce antibiotic tolerant biofilms.

Determination of minimum bactericidal concentration, in single or combination drugs, against Mycobacterium tuberculosis.

Aim: To evaluate an assay to detect minimum bactericidal concentration (MBC) in Mycobacterium tuberculosis, using as single model rifampicin, isoniazid, levofloxacin (LVX) and linezolid (LNZ) and in combination. Material & methods: MBCs were carried out directly from resazurin microtiter assay plate and 3D checkerboard in M. tuberculosis H37Rv and five resistant clinical isolates. Results: The proposed MBC assay showed similar values to those determined by MGIT™, used as control. LVX and LNZ's MBC values were close to their MIC values. LNZ or LVX combined with isoniazid and rifampicin showed MBC value reduced in 63.7% of the assays. Conclusion: The proposed assay to determine MBCs of drugs can be applied to the study of new compounds with anti-M. tuberculosis activity to detect their bactericidal effect and also in laboratory routine for clinical dose adjustment of drugs according to the patient's profile.

Species distribution and antifungal susceptibility to vulvovaginal Candida spp. in southern Mato Grosso State, Brazil / Distribuição de espécies e suscetibilidade a antifúngicos de Candida spp. vulvovaginais no sul de Mato Grosso, Brasil

ABSTRACT INTRODUCTION: Vulvovaginal candidiasis is a prevalent opportunistic mucosal infection, caused predominantly by Candida albicans. Candida species vary in their susceptibility to the antifungal agents, thus, the susceptibility tests have clinical significance in determining the appropriate therapeutic choice. OBJECTIVE: To investigate the distribution of vulvovaginal yeasts and the susceptibility pattern to azoles antifungal isolated in southern Mato Grosso State, Brazil. MATERIAL AND METHODS: Clinical samples from 166 patients were obtained regardless signs and symptoms of vulvovaginal candidiasis. Vaginal swabs were collected, seeded onto plates containing Sabouraud Dextrose agar and incubated at 35ºC, for five days. A pool of colonies that grown on each plate was subcultured in CHROMagar Candida medium. On the basis of a pure culture, the yeasts were identified using traditional phenotypic identification methods. Susceptibility tests for antifungal fluconazole and ketoconazole were performed using the broth microdilution method according to the reference protocol M27A3 of the Clinical Laboratory Standards Institute (CLSI). RESULTS: The frequency of Candida spp. in the study population was 30%, of which 28% were in the group of asymptomatic women and 35% among symptomatic. Among the isolated strains were C. albicans (50%), C. glabrata (33%) and C. tropicalis (17%). The minimum inhibitory concentration (MIC) for fluconazole ranged from 0.5 μg/ml to 16 μg/ml and for ketoconazole from 0.03 μg/ml to 4 μg/ml. The resistance rates were 1.7% for fluconazole and 3.4% for ketoconazole. CONCLUSION: C. albicans was the predominant species. We observed a high susceptibility of Candida spp. to fluconazole and ketoconazole antifungal.

RESUMO INTRODUÇÃO: A candidíase vulvovaginal é uma prevalente infeccção mucosa oportunista, causada predominantemente por Candida albicans. As espéceis de Candida variam de acordo com a suscetibilidade aos agentes antifúngicos, assim os testes de sensibilidade têm importância clínica para uma adequada escolha terapêutica. OBJETIVO: Investigar a distribuição de leveduras vulvovaginais e o padrão de suscetibilidade a antifúngicos azólicos em isolados do sul de Mato Grosso. MATERIAL E MÉTODOS: Foram obtidas amostras clínicas de 166 pacientes, independentemente de sinais e sintomas para candidíase vulvovaginal. Swabs vaginais foram coletados, semeados em placas contendo ágar Sabouraud e incubados a 35ºC. Uma amostra das colônias que cresceram em cada placa foi subcultivada em meio CHROMagar Candida. Partindo de uma cultura pura, as leveduras foram identificadas por métodos fenotípicos clássicos. Os testes de suscetibilidade aos antifúngicos cetoconazol e fluconazol foram realizados, usando o método de microdiluição de acordo com o protocolo de referência M27A3 do Clinical Laboratory Standards Institute (CLSI). RESULTADOS: A frequência de Candida spp. na população em estudo foi de 30%, sendo 28% no grupo de mulheres assintomáticas e 35% entre as sintomáticas. As espécies isoladas foram C. albicans (50%), C. glabrata (33%) e C. tropicalis (17%). A concentração inibitória mínima (CIM) para o fluconazol variou de 0,5 μg/ml a 16 μg/ml e para o cetoconazol, de 0,03 μg/ml a 4 μg/ml. A frequência de resistência ao fluconazol foi de 1,7% e ao cetoconazol, de 3,4%. CONCLUSÃO: C. albicans foi a espécie predominante. Observamos elevada sensibilidade de Candida spp. aos antifúngicos fluconazol e cetoconazol.