Although polyomavirus JC (JCV) is the proven pathogen of progressive multifocal leukoencephalopathy, the fatal demyelinating disease, this virus is ubiquitous as a usually harmless symbiote among human beings. JCV propagates in the adult kidney and excretes its progeny in urine, from which JCV DNA can readily be recovered. The main mode of transmission of JCV is from parents to children through long cohabitation. In this study, we collected a substantial number of urine samples from native inhabitants of 34 countries in Europe, Africa, and Asia. A 610-bp segment of JCV DNA was amplified from each urine sample, and its DNA sequence was determined. A worldwide phylogenetic tree subsequently constructed revealed the presence of nine subtypes including minor ones. Five subtypes (EU, Af2, B1, SC, and CY) occupied rather large territories that overlapped with each other at their boundaries. The entire Europe, northern Africa, and western Asia were the domain of EU, whereas the domain of Af2 included nearly all of Africa and southwestern Asia all the way to the northeastern edge of India. Partially overlapping domains in Asia were occupied by subtypes B1, SC, and CY. Of particular interest was the recovery of JCV subtypes in a pocket or pockets that were separated by great geographic distances from the main domains of those subtypes. Certain of these pockets can readily be explained by recent migrations of human populations carrying these subtypes. Overall, it appears that JCV genotyping promises to reveal previously unknown human migration routes: ancient as well as recent.

Some beta-lactam antibiotics are active in vitro against Mycobacterium tuberculosis. There are anecdotal reports of successful treatment of tuberculosis caused by multiple-drug-resistant strains of M. tuberculosis with regimens that included amoxicillin/clavulanate. Reduction of M. tuberculosis in the sputum of patients with pulmonary tuberculosis during administration of amoxicillin/clavulanate was measured by a quantitative culture method to determine the activity in vivo. Patients were randomized to receive isoniazid, ofloxacin, or amoxicillin/clavulanate for 7 days. Isoniazid was the most effective agent, reducing M. tuberculosis after 2 days at a mean rate (+/- standard deviation) of 0.60 +/- 0.30 log10 cfu/mL per day, compared with 0.32 +/- 0.05 and 0.34 +/- 0.03 for ofloxacin and amoxicillin/clavulanate, respectively. The early bactericidal activity of amoxicillin/clavulanate was comparable to that reported for antituberculous agents other than isoniazid. Further studies of beta-lactam antibiotics with in vitro activity against M. tuberculosis are warranted to define their role in treatment of tuberculosis.

The ongoing coronavirus disease 2019 (COVID-19) pandemic continues to threaten public health systems all around the world. In controlling the viral outbreak, early diagnosis of COVID-19 is pivotal. This article describes a novel method of voltammetrically determining severe acute respiratory syndrome coronavirus 2019 (SARS-CoV-2) with a newly designed sensor involving bovine serum albumin, SARS-CoV-2 spike antibody and a functionalised graphene oxide modified glassy carbon electrode (BSA/AB/ f -GO/GCE) or screen-printed electrode (BSA/AB/ f -GO/SPE). The oxidation reaction based on the antibody–antigen interaction was evaluated as a response to SARS-CoV-2 spike antigen at -200 mV and 1430 mV with the BSA/AB/ f -GO/SPE and BSA/AB/ f -GO/GCE, respectively. The developed sensors, BSA/AB/ f -GO/SPE and BSA/AB/ f -GO/GCE, could detect 1 ag/mL of virus spike protein in synthetic, saliva and oropharyngeal swab samples in 5 min and 35 min, and both sensors demonstrated a dynamic response to the SARS-CoV-2 spike antigen between 1 ag/mL and 10 fg/mL. Real-time polymerase chain reaction (RT-PCR), rapid antigen test and the proposed method were applied to saliva samples. When compared to RT-PCR, it was observed that the developed method had a 92.5% specificity and 93.3% sensitivity. Moreover, BSA/AB/ f -GO/SPE sensor achieved 91.7% accuracy compared to 66.7% accuracy of rapid antigen test kit in positive samples. In view of these findings, the developed sensor provides great potential for the diagnosing of COVID-19 in real samples.

Brucellae survive acidic pHs in phagolysosomes. Azithromycin, streptomycin, and quinolones were active against Brucella melitensis at pH 7.0 but not at pH 5.0; rifampin and doxycycline retained activity at pH 5.0. Regardless of pH, azithromycin-rifampin and ofloxacin-rifampin showed less synergy than established streptomycin-doxycycline and rifampin-doxycycline combinations.

In Staphylococcus aureus, penicillin-binding protein 2 (PBP 2) has been implicated in non-PBP 2a-mediated methicillin resistance. The PBP 2 gene (pbpB) was cloned from an expression library of a methicillin-susceptible strain of S. aureus (209P), and its entire sequence was compared with that of the pbpB gene from strains BB255, BB255R, and CDC6. Point mutations that resulted in amino acid substitutions near the conserved penicillin-binding motifs were detected in BB255R and CDC6, two low-level methicillin-resistant strains. Penicillin binding to PBP 2 in both BB255R and CDC6 is altered, and kinetic analysis indicated that altered binding of PBP 2 by penicillin was due to both lower binding affinity and more rapid release of bound drug. These structural and biochemical changes may contribute to the strains' resistance to ␤-lactam antibiotics.Penicillin-binding proteins (PBPs) catalyze the cross-linking of the peptidoglycan subunits in the bacterial cell wall, and their transpeptidase activity is essential for the cell's structural integrity (31). With ␤-lactamases, PBPs form a superfamily of penicillin-interacting serine D,D-peptidases. These enzymes have a lysine residue downstream from the active site serine that is required for their catalytic activity (14). This S-X-X-K sequence is a conserved motif in the transpeptidase domain of this class of enzymes. S-X-N and K(H)-T(S)-G sequences downstream of the active site serine are also conserved and are instrumental to the penicillin-binding reaction. ␤-Lactam antibiotics are structural analogs of the PBP substrate, and their mechanism of action involves covalently binding the active site of the enzyme, thus preventing its function. The sensitivity of prokaryotes to these antibiotics is primarily due to their PBPs having a high affinity for the drugs.Seven PBPs have been identified in Escherichia coli, and most have been sequenced. The low-M r E. coli PBPs (no. 4, 5, and 6) appear to have carboxypeptidase, rather than transpeptidase, activity and to be nonessential for growth (29,31). The high-M r PBPs (1A, 1B, 2, and 3) are bifunctional enzymes with a penicillin-insensitive transglycosylase domain as well as a penicillin-sensitive transpeptidase domain (15-17). ␤-Lactams exert their lethal effects by inactivating one or more of these high-M r PBPs.The genes from Streptococcus pneumoniae PBP 1A (21), Streptococcus oralis PBP 1A (21), and Bacillus subtilis PBP F (11, 25) were recently cloned, and the peptides from their translated nucleotide sequences are homologous to the transpeptidase domains of PBPs 1A and 1B from E. coli. Unlike the bifunctional enzymes in E. coli, these high-M r PBPs from gram-positive organisms do not appear to have transglycosylase activity.Four PBPs (no. 1 to 4) with M r s of 85, 81, 75, and 45, respectively, have been identified in susceptible strains of Staphylococcus aureus (8). In addition to PBPs no. 1 to 4, mecA-encoded PBP 2a is produced by methicillin-resistant staphylococci, and its production mediates most methicillin resistance ...