657 The results of M.LC. determinations for

benzylpenicil-

lin, ampicillin, cephaloridine, and cefuroxime are shown in the table. There was a striking inoculum effect with the first three antibiotics, but not with the fourth. With very small inocula the organism did not seem especially

to penicillin, but was a little more resistant to ampicillin and cephaloridine than isolates that we have previously studied. However, with the large inocula, including our standard inoculum of 104 c.F.u., the organism was much more resistant to benzylpenicillin and ampicillin than any isolate of N. gonorrhϾ previously studied. It was also somewhat more resistant to cephaloridine, but was fully sensitive to cefuroxime.5 The organism was resistant to streptomycin (> 128 mg/1) and, like all gonococci, moderately resistant to trimethoprim (32 mg/1) among the other antibiotics. It was sensitive to erythromycin (003mg/1), tetracycline (025 mg/l), sulphamethoxazole (4 mg/1), kanamycin (4 mg/1), and spectinomycin (16 mg/1). In the tests for p-lactamase production, the resistant gonococcus produced within a few minutes a deep-red colour in the chromogenic cephalosporin test, while the control gonococci produced no change. In the B. subtilis

viewpoint, to determine whether other gonococci exist, and if they do, what is their geographical distribution, and finally whether we have now reached the stage at which gonorrhoea may be truly untreatable with penicillin.

from such

a

clinical

resistant

inhibition test there was no zone around the well containing the penicillin solution that had been incubated with ultrasonicate of the gonococcus, in contrast with a large zone around that containing penicillin alone. Both tests indicated a considerable degree of -lectamase ac-

I thank Dr K. P. Shannon and Miss C. Warren for their help in the investigation of the organism, Dr A. E. Wilkinson of the Venereal Diseases Reference Laboratory for confirming its identification, and Prof. J. D. Williams of the London Hospital Medical College for the results of the determinations of the isoelectric point of the p-lactamase by isoelectric focusing. REFERENCES 1.

Phillips, I., Humphrey, D., Middleton, A., Nicol, C. Br. J. vener. Dis. 1972, 48, 287. 2. Wilkinson, A. E., Turner, G. C., Rycroft, J. A. in Laboratory Diagnosis of Venereal Disease (Publ. Hlth Lab. Serv. Monogr. Ser. no. 1) (edited by A. T. Willis and C. H. Collins); p. 38. London, 1972. 3. O’Callaghan, C. H., Morris, A., Kirby, S. M., Shingler, A. H. Antimicrob. Ag. Chemother. 1972, 1, 283. 4. Matthew, M., Harris, A. M., Marshall, M. J., Ross, G. W. J. gen. Microbiol.

1975, 88, 169. 5.

Phillips, I., King, A., Warren, C., Watts, B., Stoate, M. W. J. antimicrob. Chemother. 1976, 2, 31. 6. Matthew, M., Harris, A. M. J. gen. Microbiol. 1976, 94, 55. 7. Sykes, R. B., Matthew, M. J. antimicrob. Chemother. 1976, 2, 115. 8.

Sykes, R.

B. Personal communication.

PENICILUNASE-PRODUCING NEISSERIA GONORRHή

tivity, Isoelectric focusing of the &bgr;-lactamase bands of activity at pH 5 4 and pH 5.5.

produced

two

DISCUSSION

The first important question about this organism is whether it is a gonococcus. Tests in this laboratory, to be reported later in more detail, and in the V.D. Reference Laboratory, have shown that it is. The second important question concerns its resistance to penicillin and ampicillin. Disc testing showed that the organism was more resistant to penicillin than any isolate previously studied in this laboratory. The determination of M.LCS for different inocula of the organism showed that it behaved like a typical &bgr;-lactamase producer in that the M.l.C. increased with increasing inoculum size. The third important question concerns the mechanism of resistance. There can be little doubt from the results of the tests that we performed that it was indeed lactamase production that was responsible for the unusual resistance to penicillins and cephaloridine. In fact, lactamase has already been demonstrated in small amounts in gonococci by the highly sensitive isoelectric focusing technique.6 7 It has been suggested that in these quantities the primary function of the enzyme might be m cell-wall synthesis: it certainly has not been shown to affect the penicillin susceptibility of the gonococcus.8 Our resistant isolate is, so far as we are able to ascertain, unique in both the degree and the mechanism of resistance,

Clearly, further investigation

of the strain is needed, to characterise the &bgr;-lactamase and compare it with the Mzvme found normally in minute amounts in gono:occi, and to determine whether it is controlled by a plasmid or by a chromosome. It will be most important,

ROMAN G. GOLASH WINSTON A. ASHFORD VAL G. HEMMING

Microbiology Section, Department of Pathology, David Grant Medical Center, Travis Air Force Base, California 94535, U.S.A.

failure of penicillin G treatwith gonorrhœal urethritis prompted penicillin sensitivity testing of the responsible strain of Neisseria gonorrhœœ. Disc diffusion sensitivity testing showed complete resistance to 10 µg of

Summary

Repeated

ment

in

a man

penicillin G. The organism produced penicillinase. INTRODUCTION

CLINICIANS have lately been confronted with strains of Hæmophalus influenzæ which are resistant to ampicillin. The mechanism for this resistance is the production of penicillinase.Perhaps Neisseria gonorrhœæ could similarly become resistant to penicillin G. Our isolation of a penicillin-resistant strain of N. gonorrhœæ at David Grant U.S.A.F. Medical Center prompts this report. Since then 42 additional strains of N. gonorrhcece have been recovered in our laboratory, 5 of these isolates have also proved to be penicillin resistant. CASE-REPORT

25-year-old male, lately back from South-east Asfa, was April 17, 1976, complaining of dysuria and penile discharge. Urethral smears revealed gram-negative intracellular A

seen on

diplococci. The patient was treated with 1 g probenecid and 4.8 megaunits of procaine penicillin G given intramuscularly. Probenecid and procaine penicillin G therapy was repeated on April 20 because of persistent symptoms and positive urethral smears. His symptoms continued unabated. On April 26 urethral smears remained positive and cultures revealed N.

658

gonorrhϾ resistant to penicillin G by disc diffusion sensitivity testing. Between April 27 and May 6 he received erythromycin, 500 mg by mouth four times daily, with little decrease in his urethral symptoms. On May 8 he was again treated with 1 g of probenecid and 4.8 megaunits of procaine penicillin G. Smears and cultures were still positive on May 10, at which time he received 4 g of spectinomycin intramuscularly. Bacteriological and symptomatic cure were confirmed on May 14.

USE OF NASAL CONTINUOUS POSITIVE AIRWAY PRESSURE TO TREAT SEVERE RECURRENT APNŒA IN VERY PRETERM

INFANTS* PETER M. DUNN

BRIAN D. SPEIDEL

University of Bristol, Department of Child Health, Southmead Hospital, Bristol BS10 5NB

MATERIALS AND METHODS

The isolation and identification of N. gonorrhϾ were performed by standard laboratory methods. A gonococcal agar plate (G.C. agar base, Difco Laboratories, Detroit, Michigan)

containing 1% haemoglobin (Difco Laboratories), supplemented with ’Iso-Vitalex’ enrichment (B.B.L. Division of Becton, Dickinson and Company, Cockeysville, Maryland), vancomycin, colistin, and nystatin, was inoculated and incubated for 18 h in a candle jar containing 3-7% carbon dioxide at 36°C. Tubes of cystine tryptic agar (Difco Laboratories) media containing 1% each of glucose, maltose, sucrose, and lactose were prepared, and a heavy inoculum of bacteria was placed on the surface of the medium. Identification procedures included direct fluorescent-antibody procedure colonial morphology,3 oxidase reaction (tetramethyl-p-phenylenediamine dihydrochloride, Eastman Kodak Company, Rochester, N.Y.) and gram stain. RESULTS

The direct

fluorescent-antibody procedure,

colonial

morphology, oxidase reaction, and gram-stain morphology all corroborated the identification of the isolate as N. gonorrhϾ. This organism, however, failed to ferment any of the sugars. Further, the 10 fJ-g penicillin G disc produced no detectable zone of growth inhibition. As a consequence of these findings, the organism was forwarded to the venereal disease control unit at the Center for Disease Control, Atlanta, Georgia, which confirmed our observations.4 Utilisation of the chromogenic cephalosporin test for &bgr;-lactamase5 suggested the mechanism of resistance to be the production of a

penicillinase enzyme. DISCUSSION

The isolation of a

penicillinase-producing strain of N. number of important questions gonorrhϾ poses regarding therapeutic recommendations for the treatment of gonorrhoea. How widely disseminated is this resistant organism? Does penicillin G remain the drug of choice in the treatment of gonorrhoea? Is the developa

ment

of resistance R-factor mediated? Should antimicro-

susceptibility testing be done on strains of N. gonorrhϾ acquired from patients not cured by currently recommended penicillin G therapy? Studies under way at our institution should help answer these and other important questions. bial

We thank F. Moore, T. Waller, J. Bettinger, and C. Presley laboratory assistance, and Betty Corbin for secretarial assistance. Requests for reprints should be addressed to V. G. H.

for

REFERENCE S 1. Khan, W., Ross, R., Rodriguez, W., Controni, G., Saz, A. K. J. Am. med. Ass. 1974, 229, 298. 2. White, L. A., Kellog, D. S., Jr. Appl. Microbiol. 1965, 13, 171. 3. Kellog, D. S., Jr., Cohen, I. R., Norins, I. C., Schroeter, A. L., Reising, G. J. Bact. 1968, 95, 596. 4. Center for Disease Control Morbid. Mortal. wkly Rep. 1976, 25, 261. 5. O’Callaghan, C. H., Morris, A., Kirby, S. M., Shindler, A. H. Antimicrob. Ag Chemother. 1972, 1, 283.

Nasal continuous positive airway pressure (C.P.A.P.) of 2-3 mm Hg abolished or reduced the incidence of severe apnœic attacks in 5 very preterm newborn infants. It is postulated that C.P.A.P. provides a respiratory drive by reflexly stimulating the infant’s pulmonary stretch receptors.

Summary

INTRODUCTION

INFANTS of very short

gestational

apnceic attacks.Although these may

age

are

prone to

in association with a variety of disorders, often no explanationis found other than immaturity. The condition has a high mortality2 and is likely to be a possible cause of hypoxic brain damage among survivors.3 4Although individual apnœic attacks frequently respond to superficial stimulation, positive pressure ventilation may be required for refractory cases. The use of a raised ambient oxygen has been advocatedS but is often ineffective and may expose the infant to the risk of hyperoxia between attacks and consequent retrolental fibroplasia. Theophylline has also been recommendedbut we have not ourselves been overimpressed by its effectiveness. Continuous positive airway pressure (C.P.A.P.) has been used by us in the treatment of severe respiratory distress syndrome of the newborn since 197I.7 Besides improving arterial oxygenation, C.P.A.P. also affects the pattern of breathing in this condition.s The typically irregular respiration rapidly becomes regular with little breath-to-breath variation. In addition, we found that sudden withdrawal of C.P.A.P. often led to immediate apncea which in turn, was usually abolished by the reapplication of C.P.A.P. We have applied this effect of C.P.A.P. to the management of apnoeic attacks of immaoccur

turity. PATIENTS AND METHODS

The effect of C.P.A.P. on the frequency of apnceic attacksm 5 preterm infants was studied. An apnreic attack was defined as the absence of breathing for a period of more than 20 s Attacks were monitored using a 4-electrode transthoracic impedance pneumograph8 and the diagnosis was confirmed b’ direct observation and the need for intervention. A chart was kept of the frequency of attacks. In 2 infants a polarographic intra-arterial oxygen electrode (G. D. Searle Ltd.) was usedto provide a continuous recording of arterial oxygen tension (Pao2). The catheter was inserted into an umbilical arten until the oxygen electrode tip was in the lower aorta. The accuracy of this in-vivo Pa02 recording was regularly checked against the in-vitro Pa02 of intermittent blood-samples withdrawn through the catheter. The environmental oxygen level was recorded using a continuous-reading oxygen analyser, Ihc infants were nursed in servo-controlled incubators set to mair tain abdominal skin temperature at 36.5°C. C.P,A.P, was applied through bilateral soft-rubber nasopharyngeal ca:’Y eters.

The clinical details of the infants *Based

on a

paper given

to

the Neonatal

tal, London, on Feb. 5, 1976.

are

given in table i. The’

Society,

St.

Thomas Hosp-

Penicillinase-producing Neisseria gonorrhoeae.

657 The results of M.LC. determinations for benzylpenicil- lin, ampicillin, cephaloridine, and cefuroxime are shown in the table. There was a striki...
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