HEMOLYTIC ACTIVITY OF STAPHYLOCOCCUS HYICUS AND STAPHYLOCOCCUS CHROMOGENES

S k a 1 k a B.: Hemolytic activity of Staphylococcus hyicus and Staphylococcus chromogenes. Acta vet. Bmo, 57, 1988: 3-11. Hemolytic activity of 135 ~ hyicus and 75 ~ chromogenes strains was examined on sheep, rabbit, human, horse and chicken blood agars. The agar bases were supplemented with 5 % washed erythrocytes of the corresponding animal species. The strains of both staphylococcal species under study produced a wide zone of complete hemolysis on rabbit blood agar and a narrow one on media containing h9~se~rythrocytes. ~e hemolytic effects always appeared after 48 h incubation at 37 C. Neither species produced hemolysis on agar containing sheep or chicken erythrocytes, and no synergistic hemolytic effect was observed on sheep blood agar. A direct hemolysis was exhibited by 92 (68 %) ~ hyicus strains on human blood agars. The remaining ~ hyicus strains and ~ chromo genes did not produce hemolysis of human erythrocytes. Hemolytic effects of the staphylococci used as controls were expressed just after 24 h incubation on all kinds of blood agar. We recOllllleJld inclusion of the hemolysis of rabbit erythrocytes among the characteristic properties of ~ hyicus and ~ chromogenes. Staphylococcus hyicus, Staphylococcus chromogenes, hemolytic activity, blood agar, sheep, rabbit, huI:Dan, horse and chicken


Staphylococcus hYitUS (B a i r d -Par k e r
1965), origina.lly named Micrococcus hyicus S 0 m p o l i n• sky 1953), was subdivided in two subspecies, namely subsp.hyicus and subsp.chromogenes (D e v r i e s e et• a!.1978; K 1 0 0 s and S chi e i fer 1986), but these were later elevated to species status.: ~ hyicus and ~ chromogenes (H a j e k et ale 1986).Lack. of hemolysis of sheep red blood cells is one of the most important properties of both ~ hyicus and ~ ch;omogenes (D e v J."i e s e 1977; D e v r i e s e et a!.1978; H a j e k et ale 1986; K 1 0 0 s and S c h 1 e i f e r 1986; S k a 1 k a 1987).It is well established that intact sheep erythrocytes are relatively insensitive to hemolysins elaborated by staphylococci of both coagulase-positive and coagulase-negative speCies (M a r k s and V aug han 1950; B ern h e i mer et ale 1968; W i s e man 1975).Nevertheless, their subceptibility increases remarkably if the cell _brane sphingomyelin is disintegrated by the beta-toxin of ~ ~ (C h r i s t i e and G ray don 1941; A dam c z y k and B 1 a u roc k 1963; S k a 1 k a et a1.19.79a;1979b;Boy c e 1985), or by the toxin of CorynebacterilDD pseudotuberculosis (S 0 u C e k et al.

1967;
S k a 1 k a et a1. 1979b; 1980).Such a phospholipase-conditioned hemolysis, called synergistic hemolysis, is characteristic of staphylococcal delta-lysin (C h r i s t i e and G ray don 1941; A da m c z y k and

Erythrocytes
Sheep, rabbit, human, horse and pultry (Gallus domesticus) erythrocytes were used.For detection of hemolysis, the agar base described above was supplemented with 5 % (v/v) .erythrocytes, washed three times, of the corresponding animal species.

Bacteria
The identification procedure described by K 10 0 s and S chI e i fer (1986) was used for all staphylococcal strains.Strain for the synergistic (phospholipase-conditioned) hemolysis Staphylococcus ~ CCM 6188 producing beta toxin (phospholipase C) was employed for disintegration of sphingomyelin of sheep erythrocytes.

Investigated organisms
The assays were carried out with 135 Staphylococcus hyicus strains, including CCM 2368, 75 Staphylococcus chromogenes strains, including CCM 3387, and 5 strains which were not allocated to any staphylococcal species.The properties of the strains of both species corresponded with those described by K 1 0 0 s and S c h 1 e i f e r (1986)  at 37 0 C, and the result was-read after 24 h, 48 h, and 72 h.The direct hemolysis and the hemolytic effect on phospholipase-treated erythrocytes were evaluated on sheep blood agar as described previously (5 k a 1 k a et al. 1979a; 1979b).The other blood agars served merely for demonstration of the direct hemolysis.
Result.sThree S. aureus strains, including CCM 2351, proved to be strongly hemolytic on sheep blood agar, as appeared in the direct effect, but the wide hemolysis surrounding the streaks was reduced in the zone of the beta-hemolysin.Such antagonism of hemolysis is characteristic of those ~ aureus strains which produce alpha-toxin and only a negligible amount of delta-hemolysin.Seven ~ aureus strains, including CCM 2512, produced narrower, sometimes indistinct, hemolytic zones as a direct effect, and these zones were always considerably enhanced when erythrocytes were affected by the beta-hemolysin.This synergistic hemolysis is characteristic of staphylococcal delta-hemolysin.The hemolytic activity of 7 ~ epidermidis strains, 8 ~ haemolyticus 2 ~ cap rae , 2 ~ hominis, 2 ~ simulans, and 1 ~ warneri strain was the same as of ~ au reus delta-hemolysin producing strains.These hemolytic effects were apparent just after 24 h incubation (Fig.

1).
The remaining strains of coagulase-negative staphylococcal species grew without any direct or synergistic hemolysis (non-hemolytic group -NHG) on sheep blood agar.The strains of ~ hyicus , ~ chromo genes , and of the non-allocated staphylococci did not show direct or synergistic hemolysis on sheep blood agar after 24 h, 48 h, and 72 h incubation (Fig. 1).However, after 48 to 72 hours' incubation, a narrow zone of incomplete clearing appeared around inoculation streaks of some strains under study in the zone of activity of the staphylococcal beta -hemolysin.The occurrence of this phenomenon was occasional and its reproducibility was very low.
A wide zone of complete hemolysis appeared around the streaks of three alpha-toxin positive S. aureus strains on rabbit blood agar after 24 h incubation, and the diameter -of the hemolytic effect increased considerably with further incubation (Fig. 2; Fig. 3).The remaining control strains of ~ aureus and those of coagulase-negative specIes, which were hemolytic on sheep blood agar, also hemolyzed rabbit.blood agar, producing narrower zones of hemolysis than the alpha-toxin strains, with only a slight increase in diameter on prolonged incubation (Fig. 2; Fig. 3).The NHG strains did not produce hemolysis on rabbit blood agar•.An unusual phenomenon was observed when the strains of ~ hyicus, .~chromogenes, and of the group of non-allocated staphylococci grew on rabbit blood agar.No hemolysis appeared around the streaks of the strains under study after 24 h incubation (Fig. 2; Fig. 4).However, a broad zone of complete hemolysis .was produced by all strains within a further 24 h (Fig. 3 ; Fig. 5) .This singular delayed hemolysis, appearing after 48 h incubation, was reproducibly shown by all strains under study.
A complete hemolysis of human erythrocytes developed around the growth of ~ aureus strains and of coagulase-negative staphylococci, which were hemolytic on sheep and rabbit blood agars.The effect was shown after 24 h incubation.The zone of clearing produced by three alpha-toxin strains was less intense than that caused by the producers of delta-hemolysin and the coagulase-negative strains with hemolytic properties (Fig. 6).The NHG strains did not hemolyze on human blood agar.The hemolytic reaction was seen with 92 (68 %) strains of ~ hyicus after 48 h incubation.The hemolysis was not as wide as the zones produced by other hemolytic staphylococci (Fig. 6).The remaining strains of ~ hyicus, and all strains of .§.:.chromogenes, did not show hemolysis on human blood agar.
On agar containing horse erythrocytes, a wide zone of complete hemolysis with sharp edges .surrounded as the streaks of delta-hemolysin ~ aureus strains, as the growth of the hemolytic coagulase-negative staphylococci.A smaller zone with blurred edges surrounded the streaks of three alpha -toxin strains.Both effects were developed after 24 h incubation.
~ hyicus, ~ chromogenes, and. the non-allocated strains produced a very narrow complete hemolysis on this medium after 48 h incubation (Fig. 7).The NHG strains grew without hemolysis on horse blood agar.
All hemolytic strains of staphylococci used as contrds produced wide zone of complete hemolysis on agar containing chicken .erythrocytes.~ hyicus, ~ chromo genes , the non-allocated strains, and the NHG staphylococci grew .without hemolysis on this blood agar (Fig. 8).

Discussion
The detection of hemolytic activity, especially on sheep blood agar, is a significant component of detailed diagnosis of many bacterial species, or of some strains within a species.The production of hemolysin(s) provides an important marker in the identification of staphylococci.In view of this fact, it is therefore important to specify which of the known hemolysins is produced (M ark s and V aug han 1986; W a t t sand 0 wen s 1987).Nevertheless, hemolytic inactivity constitutes a feature of diagnostic value, for example for §.:.. hyicus and §.:.. chromogenes (D e v r ie s e et at.1978; H Ii j e k et.a1.1986; K I 0 0 sand S c h i e i fer 1986).Some strains of S. aureus, however, especially those of the 'ecovar B, do not produce hemolysin either, and lack of hemolysis of some §.:.. intermedius strains has also been described (S k a I k a et al. 1979a; 1980) .. In addition, hemolytic strai.ns in many coagulase-negative species are known (C h r i s tie and G ray don 1941 ; Owe n s 1987) and with our prevjous experience as well (S k ark a ,et al. 1979a; 1979b; 1980).
The inaQility . of §.:.. ..       was confirmed by us in the present paper.In addition, we did not observe a', marked hemolytic effect when strains of both species were assayed on sheep erythrocytes treated by staphylococcal beta-toxin.A positive synergistic hemolysis of ~ hyicus and ~ chromogenes was described (H e b e r t and Han c 0 c k 1985; W a t t sand 0 wen s 1987), and the authors took for granted the production of delta-hemolysin (H e b e r t and Han c 0 c k 1985) or of cytolysin, which acts synergistically with ~ aureulS beta-toxin (W a t t sand 0 wen s 1987), by some strains of both species.A narrow zone of incomplete clearing around streaks of some strains under study, observed by us in synergistic hemolytic assays, resembles the description of D e v r i e s e (1977), who described as hemodigestion the direct effect of some ~ hyicus strains on sheep blood agar, explaining it as a consequence of strong proteolytic activity.A close relation of proteolytic activity and the clearing phenomenon observed by us could not be shown, because even some non-proteolytic ~ hyicus strains showed this phenomenon~ On the contrary, a great number of proteolytic strains did not produce it.
The use of rabbit erythrocytes in the detection of hemolytic properties of ~ hyicus and ~ chromo genes has not been previously described.These red blood cells were hemolyzed by all strains of the both species, and the hemolysis appeared generally after 48 h of incubation.Such delayed hemolysis distinguishes ~ hyicus and ~ chromogenes from the alphaand delta-hemolysin producing ~ aureus strains and from the coagulase-negative staphylococci with hemolytic properties.Strains of these groups always produce hemolysis on rabbit blood agar just after 24 h incubation.
The  1976).The production of gamma-hemolysin by'~ hyicus and ~ chromogenes was described (G 0 0 d f ell 0 w ' et al. 1987).But gamma-hemolysin produces a complete hemolysis of sheep erythrocytes and its activity is apparently inhibited by agar(J a c k son 1962).The nature ~f he~olytic activity of §..:.. hyicus and §..:.. chromoge?es,descrIbed In ~he present study, thus remains to be explained, although relatIon to the staphylococcal gamma-hemolysin is perhaps possible.
The strains previously non-allocated to §..:.. hyicus because of their failure to produce hyaluronidase displayed hemolytic patterns like those of S. hyicus.We suggest that these strains are S. hyicus and-presume that a limited number of hyaluronidase-negative strains exists in this species.
observed some synergistic hemolytic phenomenon produced by a limited number of ~ hyicus and ~ chromogenes strains.On the other hand, the red blood cells of other animal species show greater susceptibility to some bacterial hemolytic substances, so that human (W i s e man and C a i r d 1968; W i s e man 1975; K 1 0 o s and S c h 1 e i fer 1986), rabbit (C 0 0 per et a1.1964; B e r n h e i mer 1965; W i s e man 1975; F a c k r e l l and W i s e man 1976), horse (G u yon net and P 10m met 1970), and poultry erythrocytes (M 0 1 1 b Y and Wad s t rom 1971) are recommended for detection of the hemolysins produced by staphylococci.The present paper is devoted to study the behaviour of ~ hyicus and ~ chromogenes in media supplemented with red blood cells of different animal species and to examine the possible synergistic hemolysis of ~ hyicus and ~ chromogenes against sheep erythrocytes.Mat e r i a 1 s a n d Met hod s Agar medilDD Brain heart infusion agar CM 375 (Oxoid Ltd) was used.
1950; A dam c z y k and B 1 a u roc k 1!J63; B ern he i mer et a!.1968; W i s e man 1975; S k a 1 k aet al. 1979a; 1979b; H e be' r t and Han c 0 c k 1985; K 1 0 0 s and S chI e i f e r 1986; W a t t sand 0 wen s 1987).Hemolysis. of those strains on sheep blood agar is usually weak, but• becomes stronger if red blood cells of other animal' species (M a r k s and V a u .(! han 1950) or the synergistic (phospholipase-conditioned) hemolysis (A damc z y k and B 1 a u roc k 1963) ~re employed. .The hemolytic effects of coagulase-positive and coagulase--negative staphylococci used for control in the present study agreed with the descriptions of other authors (M a r k s and V aug han 1950; J a c ks 0 n 1962; A damc z Y k and B 1 a u roc k 1963; Coo p ,e r et al. 1964; B e r n h e i mer 1965; W i s e man 1975 ; W i s e man and C a i r d 1976; Boy c e 1985; H e b e r t and Han c 0 c k 1985; W a t t sand Fig. 1.Agar with sheep erythrocytes (S).Vertical streak of S. aureus producing beta-hemolysin (B) • Horizontal streaks: S. aureus producing alpha-toxin (A); S. hyicus (H); S. aureus producing delta-hemolysin (D); S. chromogenes (C).Effects after 48 h incubation.