A reply to "Relevant factors in the eutrophication of the Uruguay River and the Río Negro".

A recent paper by Beretta-Blanco and Carrasco-Letelier (2021) claims that agricultural eutrophication is not one of the main causes for cyanobacterial blooms in rivers and artificial reservoirs. By combining rivers of markedly different hydrological characteristics e.g., presence/absence and number of dams, river discharge and geological setting, the study speculates about the role of nutrients for modulating phytoplankton chlorophyll-a. Here, we identified serious flaws, from erratic and inaccurate data manipulation. The study did not define how erroneous original dataset values were treated, how the variables below the detection/quantification limit were numerically introduced, lack of mandatory variables for river studies such as flow and rainfall, arbitrary removal of pH > 7.5 values (which were not outliers), and finally how extreme values of other environmental variables were included. In addition, we identified conceptual and procedural mistakes such as biased construction/evaluation of model prediction capability. The study trained the model using pooled data from a short restricted lotic section of the (large) Uruguay River and from both lotic and reservoir domains of the Negro River, but then tested predictability within the (small) Cuareim River. Besides these methodological considerations, the article shows misinterpretations of the statistical correlation of cause and effect neglecting basic limnological knowledge of the ecology of harmful algal blooms (HABs) and international research on land use effects on freshwater quality. The argument that pH is a predictor variable for HABs neglects overwhelming basic paradigms of carbon fluxes and change in pH because of primary productivity. As a result, the article introduces the notion that HABs formation are not related to agricultural land use and water residence time and generate a great risk for the management of surface waterbodies. This reply also emphasizes the need for good practices of open data management, especially for public databases in view of external reproducibility.

Characterization of resistance genes in 68 ESBL-producing Klebsiella pneumonia in Lebanon.

AIM: We studied 68 ESBL-producing Klebsiella pneumoniae strains isolated in Lebanon, determined their profile of resistance to antibiotics, and identified 6 ESBL genes. METHODOLOGY: The susceptibility to antibiotics was determined by the disk diffusion method. The MIC of carbapenems and cefepime was determined by the agar dilution method. ESBL genes were detected by PCR. RESULTS: A percentage of 88.2% and 86.7% of isolates carried the SHV and CTX-M gene respectively; combinations of more than 1 gene of resistance were detected in several isolates. Five strains were resistant to carbapenems; 4/5 carried the OXA-48 gene. CONCLUSION: Our study revealed the emergence of K. pneumoniae ESBL (+) strains carrying several types of genes involved in this phenotype; we also identified carbapenem-resistant strains due to the OXA-48 gene, which are a real threat for public health, especially in Lebanon.

Prevalence of type b Haemophilus influenzae and antibiotic resistance in 52 clinical isolates in north Lebanon.

The aim of this study was to determine the capsular typing and type b prevalence of clinical Haemophilus influenzae strains in north Lebanon in both invasive and non-invasive disease and to determine the susceptibility pattern and the mechanism of resistance to ß-lactams [ß-lactamase-producing strains and ß-lactamase-negative ampicillin resistant (BLNAR) strains]. Fifty-two strains of clinical H. influenzae were isolated from 312 clinical specimens; the resistance pattern to ß-lactams of these strains was determined by using the disc diffusion and E-test methods followed by molecular methods such as PCR of blaTEM et blaROB genes. Nine (17.4%) of the 52 strains were resistant to ampicillin; all of them produced type TEM-1 ß-lactamase. In the susceptible strains 15.3% were not fully susceptible to ß-lactams or considered low BLNAR strains. Slide agglutination serotyping showed that 30.7% of the strains were type b.

Glycopeptide intermediate Staphylococcus aureus and prevalence of the luk-PV gene in clinical isolates, in Northern Lebanon.

OBJECTIVES: The aim of our study was to confirm the identification of 113 meticillin-resistant Staphylococcus aureus (MRSA) strains by pyrosequencing, to determine the susceptibility of these clinical isolates to various classes of antibiotics, to determine the minimum inhibitory concentration (MIC) to glycopeptides, and to detect mecA and luk-PV genes. METHODOLOGY: The Staphylococcus species was identified by pyrosequencing of the variable region (V3) of the 16SrRNA. The susceptibility of these 113 strains of MRSA to antibiotics was determined by the disk diffusion method on Mueller-Hinton agar. The MIC of glycopeptides was determined by using the dilution method on solid media. mecA gene and luk-PV gene were detected by PCR. RESULTS: The disk diffusion method proved full susceptibility to vancomycin, teicoplanin, and linezolid; whereas MIC (dilution method) indicated that 5/113 strains were resistant to teicoplanin, giving a probability of having heterogeneous glycopeptide intermediate S. aureus (hGISA) strains. The mecA gene was detected in all MRSA strains ruling out the probability of having new variants of this gene in the tested strains. The luk-PV gene was detected in 28 out of 113 MRSA strains (24.8%). CONCLUSION: The originality of this study was the detection of hGISA strains knowing that they were susceptible to glycopeptides according to the diffusion method. Thus it is necessary to check the level of susceptibility of MRSA clinical isolates to glycopeptides for immunodeficient patients, by determining the MIC.