Months-long seismicity transients preceding the 2023 MW 7.8 Kahramanmaras earthquake, Türkiye.

Short term prediction of earthquake magnitude, time, and location is currently not possible. In some cases, however, documented observations have been retrospectively considered as precursory. Here we present seismicity transients starting approx. 8 months before the 2023 MW 7.8 Kahramanmaras earthquake on the East Anatolian Fault Zone. Seismicity is composed of isolated spatio-temporal clusters within 65 km of future epicentre, displaying non-Poissonian inter-event time statistics, magnitude correlations and low Gutenberg-Richter b-values. Local comparable seismic transients have not been observed, at least since 2014. Close to epicentre and during the weeks prior to its rupture, only scarce seismic activity was observed. The trends of seismic preparatory attributes for this earthquake follow those previously documented in both laboratory stick-slip tests and numerical models of heterogeneous earthquake rupture affecting multiple fault segments. More comprehensive earthquake monitoring together with long-term seismic records may facilitate recognizing earthquake preparation processes from other regional deformation transients.

Gas and seismicity within the Istanbul seismic gap.

Understanding micro-seismicity is a critical question for earthquake hazard assessment. Since the devastating earthquakes of Izmit and Duzce in 1999, the seismicity along the submerged section of North Anatolian Fault within the Sea of Marmara (comprising the "Istanbul seismic gap") has been extensively studied in order to infer its mechanical behaviour (creeping vs locked). So far, the seismicity has been interpreted only in terms of being tectonic-driven, although the Main Marmara Fault (MMF) is known to strike across multiple hydrocarbon gas sources. Here, we show that a large number of the aftershocks that followed the M 5.1 earthquake of July, 25th 2011 in the western Sea of Marmara, occurred within a zone of gas overpressuring in the 1.5-5 km depth range, from where pressurized gas is expected to migrate along the MMF, up to the surface sediment layers. Hence, gas-related processes should also be considered for a complete interpretation of the micro-seismicity (~M < 3) within the Istanbul offshore domain.

Serovars and serum resistance of Neisseria gonorrhoeae from disseminated and uncomplicated infections.

Two hundred and seventy-four gonococcal strains isolated from patients with either disseminated (DGI) or uncomplicated (UG) infection were examined to determine their serotypes/serovars by two typing systems as well as their resistance to the bactericidal action of normal human serum. The bactericidal assays were performed in particular to determine whether isolates from patients with the clinical syndrome of DGI but negative systemic cultures (suspected DGI) were serum-susceptible. When strains containing protein IA in their outer membranes and having auxotypes other than the arginine-hypoxanthine-uracil requirement were serotyped, a significant difference was found in the distribution of serovars among strains from DGI and suspected DGI compared with UG. The two typing systems revealed both antigenic similarities and differences of gonococci from Chicago and isolates from Germany reported in another study. Like DGI strains, most suspected DGI strains contained protein IA and were resistant to the bactericidal action of serum.

Auxotypes, penicillin susceptibility, and serogroups of Neisseria gonorrhoeae from disseminated and uncomplicated infections.

We examined auxotypes, penicillin susceptibility, and outer membrane serogroups of 137 strains of Neisseria gonorrhoeae isolated from patients with disseminated gonococcal infection (DGI) and 137 control strains from patients with uncomplicated gonorrhea. We analyzed separately the data for strains isolated from systemic sites in patients with DGI and for strains from local sites in patients with the clinical syndrome of DGI (SDGI) who had negative systemic cultures. We found the nutritional requirement for arginine, hypoxanthine, and uracil (AHU auxotype) significantly more often among DGI strains than among SDGI strains. By using commercially available serogrouping reagents to detect outer membrane protein antigens, we found that regardless of strain auxotype, dissemination correlated best with the presence of protein IA antigens. We did not find that gonococci isolated from DGI are highly susceptible to penicillin. Susceptibility to low concentrations of penicillin correlated only with the AHU requirement, not with serogroup or isolation from a patient with DGI or SDGI.

Evaluation of the RIM-N, Gonochek II, and Phadebact systems for the identification of pathogenic Neisseria spp. and Branhamella catarrhalis.

Methods for identifying Neisseria spp. include conventional and modified carbohydrate degradation procedures, chromogenic enzyme substrate tests, and immunologic coagglutination tests for Neisseria gonorrhoeae. In this study, we evaluated the abilities of the RIM-N carbohydrate degradation system (American MicroScan, Campbell, Calif.), the Gonochek II enzymatic identification system (Du Pont Co., Wilmington, Del.), and the Phadebact Gonococcus coagglutination test (Pharmacia Diagnostics, Piscataway, N.J.) to identify pathogenic Neisseria spp. and Branhamella catarrhalis. Both stock strains and clinical isolates, including 176 N. gonorrhoeae, 173 Neisseria meningitidis, 48 Neisseria lactamica, and 12 B. catarrhalis strains, were tested. The RIM-N identified 98% of the gonococci, 99% of the meningococci, 94% of the N. lactamica strains, and 100% of the B. catarrhalis strains within 1 h. The Gonochek II system identified 99% of the gonococci, 97% of the meningococci, 100% of the N. lactamica strains, and 100% of the B. catarrhalis strains within 30 min. Phadebact coagglutination provided clearly positive results for only 77% of the N. gonorrhoeae strains, producing negative or equivocal results with 23% of the strains. The RIM-N and Gonocheck II tests generally produced clear-cut reactions. An additional advantage of the Gonocheck II system was the small inoculum required for the performance of the test compared with the other systems, thus allowing the identification of N. gonorrhoeae directly from the primary isolation medium.

Use of the API NeIdent system for identification of pathogenic Neisseria spp. and Branhamella catarrhalis.

The API NeIdent system (Analytab Products, Plainview, N.Y.) was evaluated for identifying Neisseria spp. and Branhamella catarrhalis commonly isolated from clinical specimens. The system identified 90% of 303 Neisseria gonorrhoeae isolates, 71% of 113 Neisseria meningitidis isolates, and 63% of 16 Neisseria lactamica isolates but failed to identify any of 22 B. catarrhalis isolates. Testing of gonococcal strains of various auxotypes revealed no relationship between nutritional requirements and NeIdent profile numbers. With the Neisseria species, interpretation of the cinnamaldehyde-coupled beta-naphthylamine reactions was difficult and resulted in profile numbers not listed in the Profile Register. Positive resazurin-glucose reactions resulted in unlisted numbers for all B. catarrhalis strains. Inconsistent results were also obtained when 62 N. gonorrhoeae isolates were tested more than once on the strip. In all cases, profile variability and failure to identify these organisms were related to the beta-naphthylamide substrate tests. Expansion of the data base and modification of the substrate formulations or their interpretive criteria may increase the reliability of the NeIdent system for identifying Neisseria spp. and B. catarrhalis.

Characteristics of pathogenic Neisseria spp. isolated from homosexual men.

Oropharyngeal, urethral, and rectal cultures for pathogenic Neisseria spp. were collected from 815 homosexual men attending a community clinic in Chicago. Meningococci were characterized by serogrouping and antimicrobial susceptibility testing. Gonococci were auxotyped, and susceptibilities to penicillin and tetracycline were determined. Of the 815 men tested, 42.5% carried meningococci in the oropharynx. Gonococci were recovered from the urethra, rectum, and oropharynx of 18.5, 16.3, and 5.6%, respectively. Meningococci were also recovered from the urethra (6 patients) and the rectum (15 patients). Some of these isolates were identical to the isolates from the oropharynges of the same patients, whereas others were distinct from the oropharyngeal isolates by serogroup or antimicrobial susceptibilities. Serogroups B, W135, and C comprised over 90% of the meningococci. Almost 80% of the gonococcal strains required minimal inhibitory concentrations greater than 0.06 micrograms of penicillin per ml, whereas greater than 90% of the meningococci were inhibited at this concentration. Auxotyping demonstrated three major auxotypes: Zero (required none of the nutrients tested), 60%; arginine requiring, 19.4%; and proline requiring, 12.3%. Only four strains (1.2%) required arginine, hypoxanthine, and uracil.

Susceptibility of Neisseria meningitidis and Neisseria gonorrhoeae isolates to N-formimidoyl thienamycin.

A diverse collection of 123 meningococcal and 126 gonococcal isolates was tested for susceptibility to N-formimidoyl thienamycin (N-F-thienamycin; MK0787) and to penicillin G (PEN). All of the meningococci were susceptible to both of these, as well as to rifampin. Among gonococci, beta-lactamase-producing strains, which were resistant to PEN, were susceptible to N-F-thienamycin. Among non-beta-lactamase-producing strains, the minimal inhibitory concentrations of N-F-thienamycin and PEN were less than or equal to 1.28 micrograms/ml. Of these, the strains with PEN minimal inhibitory concentrations toward the higher end of the range were likely to be more susceptible to N-F-thienamycin, whereas the strains that were highly susceptible to PEN were likely to have higher minimal inhibitory concentrations of N-F-thienamycin.

Absence of acetohydroxy acid synthetase in a clinical isolate of Neisseria gonorrhoeae requiring isoleucine and valine.

A clinical isolate of Neisseria gonorrhoeae with an unusual growth requirement for isoleucine and valine lacked the activity of acetohydroxy acid synthetase, one of the enzymes required for the biosynthesis of these amino acids. A spontaneous mutant which no longer required isoleucine and valine had acquired this enzymatic activity.

Characteristics of atypical Neisseria gonorrhoeae from disseminated and localized infections.

Approximately 6% of 1,200 clinical isolates of Neisseria gonorrhoeae were atypical because they produced smaller than normal colonies on conventioal chocolate agar and fermented glucose weakly. Auxotyping studies indicated that these atypical strains required for growth arginine, uracil, and, in most instances, hypoxanthine. In addition, all of them were susceptible to 0.02 U of penicillin/ml. None of the normal colony isolates, including those susceptible to the same low concentration of penicillin, had the same nutritional characteristics. Atypical strains comprised almost half of the isolates from disseminated infections, but only 5% of those from localized infections. Auxotyping was used to identify the contact of a patient who became reinfected nine times with an atypical gonoccal strain. In addition to its usefulness in such epidemiological studies, this technique has enabled us to distinguish a subgroup of gonococci with apparent increased pathogenicity.

Plasmid deoxyribonucleic acid in clinical isolates of Neisseria gonorrhoeae.

Two different sizes of circular covalently closed deoxyribonucleic acid plasmids have been identified in four independent clinical isolates of Neisseria gonorrhoeae. All four strains contained a small plasmid with a molecular weight of 2.8 X 10-6 and two of the four stains also contained a large plasmid with a molecular weight of 24.5 X 10-6. The avirulent derivative of each of these four strains had the same plasmid complement as its virulent parent. There was no correlation between the presence of these plasmids and antibiotic resistance, piliation, and colony type associated with virulence, or ability to grow without seven specific amino acid supplements.

Experimental infection with parent and L-phase variants of Neisseria meningitidis.

Thirty-six strains of Neisseria meningitidis, including groups A, B, and C, produced L forms in vitro in the presence of an osmotic stabilizer and high concentrations of horse serum using penicillin as the transforming agent. Transformation to L growth occurred most readily among strains recently isolated from patients, and an unusually high rate of transformation was observed in 7 of the 36 strains. Revertant L strains developed diplococcal colonies on blood-agar and L colonies on sucrose-serum-penicillin-agar-always in a ratio of approximately 10 to 100 diplococcal colonies to 1 L colony. Using mucin as a host depressant, comparison was made between parent and revertant L strains of their initial pathogenicity and development of virulence by serial mouse passage. In general, revertant L strains showed the same pathogenic characteristics as the parent. Heart blood cultures from mice dying of infection with revertant L strains retained their ability to grow as L forms on penicillin media. Three stable L strains were completely avirulent for mice, although persistence of L forms could be demonstrated in peritoneal exudate for 6 days after inoculation.