Drug resistance in Detroit River gram-negative bacilli.

Detroit River Gram-negative bacilli were examined for resistance to agents of interest to public health. The total recoverable population and the lactose-fermenting organisms existed at approximately 10(5) and 10(2) colony forming units per litre, respectively. Lactose-nonfermenting and lactose-fermenting isolates demonstrated resistance to six and four of nine antimicrobial agents, respectively, when tested by a paper disc procedure. Multiple resistance in lactose-nonfermenting organisms included up to five agents. Lactose-fermenting isolates produced multiple resistance to two antibiotics. Only 7% of antibiotic resistance strains were proven to contain plasmids. Biochemical testing indicated that the most common group of resistant bacteria was Pseudomonas fluorescens. Comparison of protein profiles produced by polyacrylamide gel electrophoresis indicated that there was variation between P. fluorescens strains demonstrating the same multiple resistance.

Genetic analysis of lipopolysaccharide core biosynthesis by Escherichia coli K-12: insertion mutagenesis of the rfa locus.

Tn10 insertions were selected on the basis of resistance to the lipopolysaccharide (LPS)-specific bacteriophage U3. The majority of these were located in a 2-kilobase region within the rfa locus, a gene cluster of about 18 kb that contains genes for LPS core biosynthesis. The rfa::Tn10 insertions all exhibited a deep rough phenotype that included hypersensitivity to hydrophobic antibiotics, a reduction in major outer membrane proteins, and production of truncated LPS. These mutations were complemented by a Clarke-Carbon plasmid known to complement rfa mutations of Salmonella typhimurium, and analysis of the insert from this plasmid showed that it contained genes for at least six polypeptides which appear to be arranged in the form of a complex operon. Defects in two of these genes were specifically implicated as the cause of the deep rough phenotype. One of these appeared to be rfaG, which encodes a function required for attachment of the first glucose residue to the heptose region of the core. The other gene did not appear to be directly involved in determination of the sugar composition of the core. We speculate that the product of this gene is involved in the attachment of phosphate or phosphorylethanolamine to the core and that it is the lack of one of these substituents which results in the deep rough phenotype.

Adult children of alcoholics--a treatable entity: an aviation case report.

This is a case report of a male naval aviator, raised in an alcoholic environment, and the impact of that environment on his development and adult functioning. A review of the adult children of alcoholics syndrome is presented to help familiarize the reader with this evolving entity and its probable impact on aviation personnel. In the United States, current estimates indicate that parental alcoholism affects 27 million children. Only about 5% of these children are receiving any evaluation, supportive care, or treatment. This case of a naval aviator affected by this syndrome illustrates the need for its recognition and potential for treatment and modification of maladaptive behavior. As a treatment entity, recognition of the adult children of alcoholics syndrome will hopefully have a positive effect upon aviation safety and will help save a valuable national asset, our trained aviation personnel.

Sequence-specific DNA uptake in transformation of Neisseria gonorrhoeae.

Piliated, competent gonococci are known to preferentially take up homologous transforming DNA into the cell. We examined the mechanism for DNA uptake with pFA10, a hybrid 11.5-kilobase (kb) penicillin-resistant (Pcr) plasmid composed of heterologous DNA from a 7.2-kb Pcr plasmid and homologous DNA from a 4.2-kb gonococcal cryptic plasmid. The presence of the gonococcal cryptic plasmid DNA in the hybrid resulted in markedly increased transformation efficiencies in isogenic crosses as compared with the parent 7.2-kb Pcr plasmid. Uptake of 32P-end-labeled MspI or TaqI restriction fragments of the hybrid was limited to fragments entirely derived from the 4.2-kb gonococcal cryptic plasmid, indicating that DNA uptake was probably dependent on the presence of a specific DNA sequence. Since Haemophilus DNA did not inhibit transformation by the hybrid Pcr plasmid, the gonococcal DNA uptake sequence is different from the known sequence involved in homologous DNA uptake by Haemophilus spp.

Marker rescue by a homologous recipient plasmid during transformation of gonococci by a hybrid Pcr plasmid.

A 42-kilobase hybrid Pcr plasmid (pFA14) was formed when the naturally occurring 7.2-kilobase Pcr plasmid pFA3 was introduced by transformation into a competent gonococcal recipient containing the 36-kilobase conjugative plasmid pFA2 (Sox et al., J. Bacteriol. 138:510-518). Analysis of the structure of pFA14 showed that it was a stable recombinant between pFA3 and pFA2. The transformation efficiency of pFA14 was increased 300- to 10,000-fold by the presence in isogenic recipients of the homologous plasmid pFA2. The presence of a homologous plasmid in the recipient also markedly increased the likelihood of recovery of intact donor-size Pcr plasmids in the transformants. The presence of pFA2 had no effect on the competence of piliated or nonpiliated gonococci for transformation by either linear chromosomal DNA or a nonhomologous Pcr plasmid. Increased transformation efficiency of the hybrid Pcr plasmid pFA14 may have been due to recombination between the nicked or linearized donor plasmid and the homologous recipient plasmid (marker rescue).

Anaerobic transfer of antibiotic resistance from Pseudomonas aeruginosa.

Pseudomonas aeruginosa, an opportunistic pathogen that often initiates infections from a reservoir in the intestinal tract, may donate or acquire antibiotic resistance in an anaerobic environment. Only by including nitrate and nitrite in media could antibiotic-resistant and -sensitive strains of P. aeruginosa be cultured in a glove box isolator. These anaerobically grown cells remained sensitive to lytic phage isolated from sewage. After incubation with a phage lysate derived from P. aeruginosa 1822, anaerobic transfer of antibiotic resistance to recipients P. aeruginosa PS8EtBr and PS8EtBrR occurred at frequencies of 6.2 x 10(-9) and 5.0 x 10(-8) cells per plaque-forming unit, respectively. In experiments performed outside the isolator, transfer frequencies to PS8EtBr and PS8EtBrR were higher, 1.3 x 10(-7) and 6.5 x 10(-8) cells per plaque-forming unit, respectively. When P. aeruginosa 1822 was incubated aerobically with Escherichia coli B in medium containing nitrate and nitrite, the maximum concentration of carbenicillin-resistant E. coli B reached 25% of the total E. coli B population. This percentage declined to 0.01% of the total E. coli B population when anaerobically grown P. aeruginosa 1822 and E. coli B were combined and incubated in the glove box isolator. The highest concentration of the recipient population converted to antibiotic resistance occurred after 24 h of aerobic incubation, when an initially high donor/recipient ratio (>15) of cells was mixed. These data indicate that transfer of antibiotic resistance either by transduction between Pseudomonas spp. or by conjugation between Pseudomonas sp. and E. coli occurs under strict anaerobic conditions, although at lower frequencies than under aerobic conditions.

Serotype and sulphonamide sensitivity of meningococci isolated from 1966 to 1971.

From 1966 to 1971, 298 cultures of meningococci from clinical material (cerebrospinal fluid or blood) were examined. Eighty-nine cultures were from the Manchester area and the remainder from other parts of England or Northern Ireland. Five per cent of strains were group A, 57% group B, and 31% group C; 6% were untypable. Eighteen strains (6%) had an MIC of 6.4 mug/ml or more of sodium sulphadiazine and 10 of these (3.5%) an MIC of 50 to 100 mug/ml. The incidence of sulphonamide resistance was higher in group A strains than in group B or group C strains.