Serratia ficaria isolated from a human clinical specimen

Vol. 14, No. 2

JOURNAL OF CLINICAL MICROBIOLOGY, Aug. 1981, p. 234-236 0095-1 137/81/080234-03$02.00/0

Serratia ficaria Isolated from a Human Clinical Specimen V. J. GILL,'* J. J. FARMER II1,2 P. A. D. GRIMONT,3 M. A. ASBURY,2 AND C. L. McINTOSH4 Microbiology Service, Clinical Pathology Department, National Institutes of Health, Bethesda, Maryland 202051; Enteric Section, Centers for Disease Control, Atlanta, Georgia 303332; Service des Enterobacteries, Unite INSERM 199, Institut Pasteur, F- 75724 Paris Cedex 15, France3; and Clinic of Surgery, National Heart, Blood, and Lung Institute, Bethesda, Maryland 202054

Received 27 January 1981/Accepted 13 April 1981

The first isolation of Serratia ficaria from a human source is reported. Investigation into the eating habits of the patient revealed the probable source as figs, which are one of the natural reservoirs of this organism. How this and other normally saprophytic Serratia species can be distinguished from Serratia marcescens is reviewed.

Serratia ficaria is a new species of Serratia that was recognized and identified by Grimont et al. in 1979 (4). They reported on 14 strains isolated from figs, caprifigs, and fig wasps collected in California and Tunisia and also from a small black ant in France. S. ficaria isolation has been confined almost exclusively to the Smyrna-type figs (Calimyrna in California)-fig wasp ecosystem; however, the case below indicates that it can also be encountered in clinical microbiology laboratories. A gram-negative rod, isolated from a sputum specimen, was tested by the National Institutes of Health Microbiology Laboratory and found not to fit the characteristics of any of the Enterobacteriaceae usually seen in clinical materials. The isolate was then forwarded to the Centers for Disease Control, where it was identified as S. ficaria (CDC no. 2721-79). This identification was confirmed by one of us (P.A.D.G.) with both carbon source assimilation and DNA-DNA hybridization (4). This is the first known isolate from a human source. Case report. The patient was a 59-year-old white female who, in September of 1969, underwent an aortic and mitral valvulotomy for stenotic, presumably rheumatic, heart disease. In 1970 a Starr-Edwards valve was placed in the aortic area, and a porcine xenograft was made in the mitral area because of progressive stenosis. Just before surgery in October 1979, she had an episode of upper respiratory tract infection, accompanied by cough and scant clear sputum. A sputum sample from 22 October 1979 contained alpha-hemolytic streptococci, species of Neisseria, Corynebacterium, and Haemophilus, a light growth of Escherichia coli, and a light growth of S. ficaria. On 23 October 1979, she underwent reoperation, subsequently recovered uneventfully, and was discharged about a month 234

later. More patient information was obtained after receiving notification of the identification of the organism as S. ficaria. The patient has lived in Binghamton, N.Y. for most of her adult life. She said, upon questioning, that she enjoys eating fresh figs and has them whenever they are available; she recalled that during the weeks before her latest hospitalization she had eaten fresh frozen figs grown in the Lake Charles, Louisiana area. During her hospitalization, she was visited by a relative from California who brought her fresh California figs. She ate one of these 2 to 3 days before her surgery. As noted above, the sputum containing the S. ficaria was obtained the day before surgery. In this particular case, the S. ficaria probably represented nothing more than transient colonization of the mouth or upper respiratory system following the ingestion of a fig. Discussion. Initial laboratory identification using the API 20E (Analytab Products, Plainview, N.Y.) yielded a profile number of 1206773. Possible identifications suggested by the API computer service at that time were Enterobacter agglomerans, Serratia liquefaciens, and Serratia rubidaea. Test tube biochemical tests yielded the results shown in Table 1. These are compared to the reactions of S. ficaria as well as those of other Serratia. The most notable characteristic of the isolate was its very strong odor, which resembled that of potatoes or other vegetable matter. A similar odor was described by Grimont et al. as "38-like" (2), and was eventually shown to be characteristic of S. odorifera (3). The odor has since been found in all strains of S. ficaria (4) and a few strains of S. rubidaea

(3). Antibiotic susceptibilities of this isolate were similar to those of the 14 strains tested by Gri-

VOL. 14, 1981

NOTES 235 TABLE 1. Characteristics ofpatient isolate 2721- 79 and biochemical differentiation of the seven species of Serratia currently recognizeda Biochemical test

Patient isolate 2721-79

thica

cescens

S. liquefaciens

S. ficaria S. plymu-

S. mar-

S. rubidaea (S.

marinoru-

S. odorifera

S. fonticola

Deoxyribonuclease at 250C

+

+

+

+

+

bra) +

Lipase (corn oil)

+

+

V

+

(3

+

V

Gelatinase at 220C

+

+

V

+

+

i)

+

Lysine decarboxylaseMollers

-

-

-

+

+

V

+

+

Ornithine decarboxylase-

-

-

-

+

+

-

V

+

Odor of S. odorifera

+

+

-

-

-

0

+

Red, pink or orange pigment

-

-

V

V

-

V

+

Mollers

Fermentation of: + + + + + + + L-Arabinose + + D-Arabitol + _ + _ + V + + D-Sorbitol + + + V V Adonitol + + + Dulcitol a Symbols: +, 90 to 100% positive; ), 75 to 89% positive; V, 26 to 74% positive, ), 11 to 25% positive; -, 0 to 10% positive. The percentage data for all of the Serratia species were tabulated from the computer records of the Enteric Section, Centers for Disease Control, and all data are based on reactions within 2 days (most are within 24 h) at 36°C unless otherwise indicated. The reactions for the patient isolate are within 48 h.

mercial systems used in the identification of micin, nalidixic acid, and tobramycin; resistance Enterobacteriaceae, arabinose may be acidified to cephalothin was also similar. Our isolate dif- by S. marcescens. This has resulted in S. marfered in that it was moderately resistant to chlor- cescens being identified incorrectly as S. liqueamphenicol and kanamycin and resistant to faciens (or occasionally as another Serratia spestreptomycin, whereas the isolates of Grnmont cies). Since the vast majority of Serratia from et al. were susceptible to these antibiotics. Of clinical specimens will be S. marcescens, we taxonomic interest was this isolate's resistance suggest that all arabinose-positive (based on to colistin, which in the Enterobacteriaceae is miniaturized systems) Serratia be confirmed by generally seen only with the Proteus group and testing in a standard tube test for L-arabinose species of Edwardsiella, Serratia, and some- fermentation. This should avoid the problem of times of Yersinia. incorrect identification which has led to reports We encourage clinical laboratories to do a of S. liquefaciens outbreaks which were really complete identification of all Enterobacteria- just endemic strains of S. marcescens. Over the past 3 years, members of the genus ceae, and Table 1 should prove useful in differentiating the seven Serratia species. However, Serratia have been carefully defined (1-4) so for those laboratories which cannot do complete that the clinical microbiology laboratory needs identification, we suggest Serratia species as a to be aware of species other than just pigmented report for all arabinose-positive strains. This and nonpigmented Serratia marcescens. Incompromise differentiates the very important creased laboratory awareness of the currently human pathogen S. marcescens (arabinose neg- recognized species of Serratia may lead to more ative) from the six other Serratia species (ara- clinical isolates of Serratia ficaria, Serratiaplybinose positive) of more doubtful clinical signif- muthica, and Serratia fonticola, which are icance. However, some caution is necessary with thought to be exclusively plant, soil, or water this approach. In some of the miniaturized com- organisms. Our case report illustrates how an mont et al. (4) to amikacin, carbenicillin, genta-

236

NOTES

unusual clinical isolate can be traced to its logical source simply by asking the patient questions about eating figs. We thank the patient for a very cooperative interview, Sylvia Gersch and the National Institutes of Health microbiology technologists for recognizing the uniqueness of the organism, and James MacLowry for review of this manuscript.

LITERATURE CITED 1. Gavini, F., C. Ferragut, D. Izard, P. A. Trinel, H. Leclerc, B. Lefebvre, and D. A. A. Mossel. 1979. Serratia fonticola, a new species from water. Int. J.

J. CLIN. MICROBIOL. Syst. Bacteriol. 29:92-101. 2. Grimont, P. A. D., F. Grimont, H. L. C. Dulong de Rosnay, and P. H. A. Sneath. 1977. Taxonomy of the genus Serratia. J. Gen. Microbiol. 98:39-66. 3. Grimont, P. A. D., F. Grimont, C. Richard, B. R. Davis, A. G. Steigerwalt, and D. J. Brenner. 1978. Deoxyribonucleic acid relatedness between Serratia plymuthica and other Serratia species, with a description of Serratia odorifera sp. nov. (type strain; ICPB 3995). Int. J. Syst. Bacteriol. 28:453-463. 4. Grimont, P. A. D., F. Grimont, and M. P. Starr. 1979. Serratia ficaria sp. nov., a bacterial species associated with Smyrna figs and the fig wasp Blastophaga psenes. Current Microbiol. 2:277-282.