Barbara A. Peddie

Natural and synthetic betaines counter the effects of high NaCl and urea concentrations

Escherichia coli was used as a model system to evaluate a range of betaines for their ability to protect against salt and urea stresses. Betaine structure determined the salt and urea protective effects. Dimethylthetin conferred salt protection similar to glycine betaine, whereas dimethylsulfoniopropionate (DMSP) was less effective than either glycine betaine or dimethylthetin, but similar to propionobetaine (its nitrogen analogue). Hydrophobic alpha-substituents altered salt tolerance. Valine betaine with an aliphatic side group conferred salt tolerance similar to glycine betaine. Betaines containing phenyl groups (phenylglycine, phenylalanine and N-phenylglycine betaines) did not confer salt protection, growth being similar to, or less than the control (no betaine). Hydrophobic groups decreased the ability to protect against urea stresses; valine betaine conferred poor urea tolerance. The addition of an hydroxyl group increased the ability of a betaine to protect against urea denaturation. Proline betaine, an effective salt protector, conferred poor urea tolerance. Increasing the charge separation in the betaine molecule decreased the ability to confer urea tolerance. Thiolanium, pyridinium and triethylglycine betaines, with larger cationic functions, conferred no urea tolerance to E. coli.

Competitive accumulation of betaines by Escherichia coli K-12 and derivative strains lacking betaine porters.

Escherichia coli was grown in hyperosmotic media containing both glycine betaine and one other betaine. E. coli K-12 derivative WG439 (putP- proP- proU-) did not accumulate any of 15 betaines. Strains WG445 (putP- proP- proU+), WG443 (putP- proP+ proU-) and the control strains all accumulated less betaine, (CH3)3N(+)-(CH2)n-COO-, when n was greater than 1. Accumulation was not detectable when n = 5. Both L- and D-isomers of alpha-substituted betaines were accumulated by both strains WG443 and WG445, the D-isomers more slowly. Hydroxylated alpha-substituted betaines were accumulated relatively more through the osmoregulated transport protein ProU than through ProP. In actively growing cultures glycine betaine appeared to be the preferred substrate for accumulation, but the proportion of the second accumulated betaine increased as cultures approached stationary phase.

Relationship Between Contraceptive Method and Vaginal Flora

Summary: This study was undertaken to assess whether the vaginal flora was affected by the method of contraception, and in particular as to whether the incidence of vaginal candidiasis increased when oral contraceptives were used. One thousand and two consecutive vaginal or cervical swabs from women attending a family planning centre were cultured. Candida albicans was isolated from 13% of women using no contraception, 16% using oral contraceptives, and from 9%, 19% and 18% of those using diaphragms, intrauterine contraceptive devices (IUCD) and condoms respectively. These differences were not statistically significant. Women using an IUCD had significantly more Gram‐positive cocci cultured than women in any other group, while those using diaphragms had significantly more Gram‐negative bacilli. Our clinical impression that the use of oral contraceptives led to an increase in vaginal candidiasis, was not confirmed by this study.

Comparison of ciprofloxacin with netilmicin for the treatment of acute pyelonephritis.

A prospective, randomised trial was undertaken to compare the efficacy of ciprofloxacin and netilmicin for the treatment of acute pyelonephritis. Forty-three patients were enrolled and 34 (29 women) completed the protocol. Fifteen of 17 patients treated with ciprofloxacin and 15 of 17 treated with netilmicin were cured. All patients were treated for five days. One patient relapsed after ciprofloxacin and another had a reinfection, while two relapsed after netilmicin. Five of six patients with a urinary tract abnormality were cured. Side effects were generally mild and rapidly reversible. Patients treated with ciprofloxacin spent a mean of 3.7 days in hospital compared with 5.3 days for those treated with netilmicin. The difference in duration of hospital stay was statistically significant (p less than 0.01). Both drugs proved highly effective and safe for the treatment of severe acute pyelonephritis.

Sexual Acquisition of Urinary Tract Infection in a Man

A man was admitted with acute pyelonephritis due to Escherichia coli. Three days prior to the onset of his symptoms his wife presented with a 7-day history of cystitis due to E. coli. Before the wife developed her symptoms the couple were having vaginal intercourse every night, and this continued for the first 3 days of her symptoms. The organisms isolated from the urine of both patients were found to have the same biotype, an identical antibiogram, and the same serotype. The temporal sequence of events and the bacteriological findings strongly suggest the sexual transmission of this organism from the wife to her husband.

Osmoprotective activity, urea protection, and accumulation of hydrophilic betaines in Escherichia coli and Staphylococcus aureus.

The hydrophilic betaines, deanol betaine, triethanol betaine, diethanolthetin and methylethanolthetin, and also thioxanium betaine and citrulline betaine, were accumulated by Escherichia coli. All betaines tested had significant osmoprotective activity for E. coli and, with the exception of citrulline betaine and diethanolthetin, also demonstrated urea protection. Staphylococcus aureus accumulated only methylethanolthetin, deanol betaine and thioxanium betaine: the first two had an osmoprotective effect but conferred no urea protection. Diethanolthetin and thioxanium betaine significantly decreased urea tolerance for S. aureus.

Is the ability of urinary tract pathogens to accumulate glycine betaine a factor in the virulence of pathogenic strains

The regulation of intracellular concentrations of organic solutes, including glycine betaine, is an important adaptive response to osmotic stress for Escherichia coli. The clinical significance of glycine betaine to uropathogens is not clear. Clinical isolates of E. coli, Klebsiella pneumoniae, Enterobacter species, Pseudomonas aeruginosa, Proteus mirabilis, Staphylococcus aureus, S. saprophyticus, and Enterococcus faecalis accumulated glycine betaine from hyperosmotic media. The addition of glycine betaine to hyperosmotic minimal medium accelerated the growth rates of all species tested except P. mirabilis. However, when clinical strains of E. coli were transferred from urine with low osmolality to hyperosmotic urine, there was no slowing of the growth rate. There was no difference in growth rates of E. coli isolates from acute pyelonephritis, cystitis, and asymptomatic bacteriuria nor from fecal isolates. The ability to accumulate osmolytes, although it may be a factor in the adaptation to hypertonic environments, was not related to virulence.

Inhibitors of bacterial growth in urine: what is the role of betaines?

It has long been recognised that some individuals produce urine that is inhibitory to uropathogens. This may be partly explained by inhibitors. Several inhibitors have been identified in urine including urea and organic acids. Bacteria adapt to high osmolarity by activating osmoregulated betaine porters and accumulating organic osmolytes intracellularly. The preferred substrate is glycine betaine, which is present in urine, and promotes rapid growth by balancing osmotic forces and stabilising macromolecular structures against the toxicity of urea and low pH. Other dietary betaines such as trigonelline may also be taken but enhance urea toxicity. The importance of such compounds in vivo is unknown.

Comparison of Single Dose with a 5‐day Course of Co‐trimoxazole for Asymptomatic (Covert) Bacteriuria of Pregnancy

Summary: Forty‐four pregnant women with covert (asymptomatic) bacteriuria proven by suprapubic bladder aspiration were randomly allocated to treatment with either a single 1.92g dose or a standard 5‐day course of co‐trimoxazole. Twenty‐one of 24 women were cured with a single dose. Seven of these 21 women were reinfected later in the pregnancy. All 20 women treated with a 5‐day course of co‐trimoxazole were cured, and 2 became reinfected later in the pregnancy. There were no side‐effects of treatment, and no detrimental effects on the outcome of pregnancy. Single dose therapy should be considered as the treatment of choice for covert bacteriuria in pregnancy.

Assessment of antimicrobial activity of hydrophilic betaines in osmotically stressed bacteria.

A series of hydrophilic aromatic and semi-aromatic betaines related to trigonelline was synthesized and tested for antimicrobial activity. 4-Methylthiazolium betaine was the only one that showed significant antibacterial activity towards Escherichia coli under hyperosmotic conditions. None of the tested betaines showed any evidence of osmoprotection or urea protection.