This article was downloaded by: [Michigan State University] On: 11 February 2015, At: 07:03 Publisher: Taylor & Francis Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK
New Zealand Veterinary Journal Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/tnzv20
The bacterial flora of the respiratory tract of normal and pneumonic sheep M.R. Alley B.V.Sc
a
a
Department of Veterinary Pathology and Public Health , Massey University , Palmerston North Published online: 23 Feb 2011.
To cite this article: M.R. Alley B.V.Sc (1975) The bacterial flora of the respiratory tract of normal and pneumonic sheep, New Zealand Veterinary Journal, 23:6, 113-118, DOI: 10.1080/00480169.1975.34211 To link to this article: http://dx.doi.org/10.1080/00480169.1975.34211
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://www.tandfonline.com/page/terms-and-conditions
1975
NEW
ZEALAND
VETERINARY JOURNAL
113
THE BACTERIAL FLORA OF THE RESPIRATORY TRACT OF NORMAL AND PNEUMONIC SHEEP M. R. ALLEY*
Downloaded by [Michigan State University] at 07:03 11 February 2015
INTRODUCTION
FOR MANY YEARS chronic and subacute pneumonia has been recognized as a common finding in the lungs of lambs at slaughter throughout New Zealand. While the effect of the disease on weight gain is not clear, there can be no doubt that residual pleuritis is an important cause of 'economic loss through high condemnation rates of carcasses. Previous. bacteriological investigations have been confined to outbreaks of acute enzootic pneumonia (Salisbury, 1957). In these cases the lungs examined were from sheep of all ages and Pasteurella haemolytica was invariably isolated. No studies have been reported on the bacterial flom of chronic and subacute pneumonia in lambs in New Zealand. The p,resent survey was undertaken to compare the bacterial flora of the nasal cavity, trachea and lungs of normal sheep with that of pneumonic sheep at slaughter. A limited investigation of the bacteria present in pneumonic lesions of various pathological types is also included. MATERIAL AND METHODS
COLLECTION OF SPECIMENS Specimens were collected at 7- or 14day intervals from a local slaughterhouse from lambs aged 5 to 10 months during the December to May period of the years 1969-70 .and 1970-71. On each occasion 10 lungs were selected on the basis of their gross appearance and the corresponding heads identified and collected. Nasal swabs were obtained by cutting the head sagitally, slightly to one side of the mid-line with a band saw and removing the nasal *M. R. Alley, B.V.Sc., Department of Veterinary Pathology and Public Health, Massey University, Palmerston North.
septum with bone forceps. A sterile swab was then drawn over the exposed turbinate and inserted into both the dorsal and ventral nasal meatus. Tracheal swabs were collected by incising the trachea transversely midway along its length and inserting a sterile swab distally as far as the bifurcation of the main bronchi. Samples of lung were collected in sterile petri dishes. From the majority of penumonic lungs a 4 cm2 area of right apical lobe was removed with forceps and scissors as this was· the area most consistently affected. A slice of pneumonic tissue immediately adjacent to this was routinely collected in 10% fonnol-saline for subsequent histological examination. Samples of normal lung were collected from the right apical lobei in a similar manner. LABORATORY
PROCEDURES
Nasal and tracheal swabs were plated out initially on to sheep blood agar and MacConkey's agar. The surface of all lung samples was seared before plating out in the same way. Gram-stained direct smears were made from all samples. In the early stages of the survey, plates were incubated both aerobically and with 10% C(h; however, after 100 lungs had been processed, the latter was found to be non-productive and was discontinued. Identification of bacteria was based on the methods outlined by Wilson and Miles (1964) and Cowan and Steel (1965) with the exception of Enterobacteriaceae which were identified by the keys of Ewing (1968). Suspect Pasteurella failing to show haemolysis on sheep blood agar were subcultured on to horse blood agar and tested with the indole reaction. Lung samples for histological examination were 'embedded in paraffin, cut and stained routinely with haematoxylin and eosin.
114
NEW ZEALAND VETERINARY JOURNAL
RESULTS
Downloaded by [Michigan State University] at 07:03 11 February 2015
THE DISTRIBUTION OF BACTERIA IN THE NORMAL AND PNEUMONIC RESPIRATORY TRACT
The results summarized in Table 1 show a high rate of carriage of several bacteria in the nasal cavity of both normal and pneumanic sheep. Bacteria of the same type were also isolated in large numbers from the trachea and lungs of pneumonic sheep but were only rarely recovered from nonna! lungs and tracheae.
TABLE 1: NUMBER OF BACTERIAL ISOLA· TIONS FROM NORMAL AND PNEUMONIC SHEEP RESPIRATORY TRACTS OVER TWO SEASONS, 1969·70 AND 1970-71 (Total examined: 184 nonnal sheep, 246 pneumonic sheep)
Nasal
Cavity P. haemolytica: Normal 135 (73%) 193 (78%) Pneumonic N. catarrhalis: Normal Pneumonic
72 (39%) 114 (46%)
Trachea
Lung
9 (5%) 133 (54%)
11 (6%) 144 (59%)
2 (1%) 55 (22%)
3 (1.6%) 54 (22%)
VO.l..23
The predominant organism isalated from both the normal and pneumonic respiratory tract was Pasteurella haemolytica. This organism was most frequently isolated from the nasal cavity of pneumonic sheep although its prevalence here was anly slightly higher than in the nasal cavity of normal sheep. It was recovered in pure aerobic culture from only 20% of all nasal cavities examined but was found in combinatian with! Neisseria catarrhalis in 40% of animals and in cambinatian with other organisms in a further 16%. In the pneumonic lung! P. haemolytica was most frequently isolated in pure culture, being recovered alone from 45 % of all pneumonic lungs and in combination with N. catarrhalis in a further 14%. The se.cond mast commonly recavered organism in this study was an organism )dentified as N. catarrhalis (Alley et al., 1970). This organism was isolated most aften in cambination with P. haemoiytic(lJ 'and could be gra'wn in pure aerobic culture from only 3 % of all nasal cavities examined. Neisseria catarrhalis was also commonly isolate.d from the pneumonic lung and trachea (Table 1) but was recovered in pure culture from only 6% of pneumonic lungs.
Escherichia coli, Staphylococcus. and a-haemolytic Streptococcus were alsO' E. coli frequently isolated from the nasal cavity; 22 (12%) 1 (0.5%) 1 (0.5%) Normal however, only rarely were these argan4 (2°Ic,) 31 (13%) 2 (1%) Pneumonic isms recovered from the trachea or lung. Although staphylococci were more comStaphylococcus: monly isolated from the nasal cavity and 2 (1%) 8 (4%) 2 (1%) Normal 2 (1%) Pneumonic 23 (9%) 10 (4%) trachea of pneumonic sheep there appearStreptococcus ed to be little difference in the recovery (a·haemolytic) : rate of the other two organisms between 2 (1%) 21 (11%) Normal 0 (0%) the respiratory tracts of normal and 0 (0%) 0 (0%) Pneumonic 23 (9%) pneumanic sheep. Mixed growths in the nasal cavity were more commonly seen Corynebacterium: in those animals sampled during the o (001c;,) 1 (0.5%) Normal 4 (2%) December-J anuary-February periad of o (0%) o (0%) Pneumonic 2 (1 %) both seasons. Later during the autumn months, P. haemalytica and N. catarrhalis No growth: appeared to dominate the nasal flora of Normal 30 (16%) 169 (92%) 167 (91%) both normal and pneumanic sheep. Only 83 (34%) 95 (39%) Pneumonic 21 (9%) rarely was P. haemolytica or N. catarOther bacteria isolated from nasal cavHy were rhalis isolated from pneumonic lungs and Actinobacillus (6 isolations), micrococci (4 isola- not found to be present concurrently in tions) and Bacillus (3 isolations). the nasal cavity.
1975
NEW ZEALAND VETERINARY JOURNAL
Downloaded by [Michigan State University] at 07:03 11 February 2015
THE PREVALENCE OF BACTERIA IN DIFFERENT TYPES OF PNEUMONIC LESION
F or the purposes of this study the pneumonic lungs examined were divided intO' four categDries on the basis of the gross and histological appearance of the lesions. A brief description of the pathological cri teria for this classification is included below. These categories dO' not re.present the full spectrum of lesions seen in chronic pneumonia in New Zealand sheep and a more detailed pathological deSCription of the! disease will be published at a later date.
Type 1: The gross lesions consisted Df dull red consolidation in the ventral areas of the apical and cardiac IDbes of both lungs. The lesiDns were sunken below the surface of the adjacent normal lung and were of homogeneous. appearance with a smooth pleural surface. The most prominent histological feature was alveolar collapse. Small numbers of macrophages were sometimes present in alveoli and occasional bronchioles contained a neutrophilic exudate. Type 2: In this category the gross lesions were usually more extensive and took the! form of red-grey consolidation of ventral apical, cardiac and interm.ediate lobes. They. were sharply delineated from the normal lung tissue but did not sink below its surface. On close 'examination numerous grey-white 1 to 2 mm foci could often be seen within the consoli,dated tissue and the pleural surface had an uneven granular appearance in reflected light. Histologically, the main feature was severe infiltration of neutrophils into groups of alveolar spaces disseminated throughout the lung. Macrophages were present in moderate numbers and early proliferative changes including, bronchiolar epithelial hyperplasia and peribronchial lymphoid hyperplasia were common. The majority of bronchioles contained neutrophilic plugs.
Type 3: The lungs in this group showed. extensive grey-red consolidation which! usually involved whole lobes. In the least severe cases the lesions involved the right apical lobe but often they extended into both apical and cardiac lobes,
115
the intermediate lobe and ventral parts of both diaphragmatic lobes. The consolidated tissue had a finely granular mottled appearance, firm consistency, and affected lobes were thicker than normal. Both exudative and proliferative changes were present histo,logically but proliferative changes predominated. There was hyperplasia of bronchiolar and alveolar epithelium together with variable peribronchial lymphoid hyperplasia. Large! numbers of macrophages and lessoc number of neutrophils filled the alveolar spaces. Type 4: In this group were placed lungs with severe grey consolidation which varied in extent but was always confined to the anteroventral parts of the lungs. The consolidated tissue was very firm and affected lobes thicker than normal. The cut surface had a finely mottled! texture or was homogeneous and pale grey in appearance. Occasionally fibrous adhesions were present on the pleuraU surface. Chronic proliferative lesions predominated microscopically. Severe hyperplasia of both bronchiolar and alveolar epithelium were constant findings. Peri~ bronchiolar fibrosis and alveolar interstitial thickening were also common and peribronchial lymphoid hyperplasia was variable though often severe in extent. Alveolar macrophages were present in large numbers but neutrophils were rare. The prevalence of bacteria in theSe! four types of lesion is shown in Table 2. I t can be seen that lesions in the first categO'ry in which the main feature was, alveolar cO'llapse were much less likely, to yield bacteria than lungs in the other three groups (NO' growth X2 = 30.5, P < 0.(01). The lungs in which the most extensive lesions were present usually showed grey-re.d consolidation and were placed in the third category. It was frO'm this type of lesion that bacteria were re~ covered mO'st consistently, being present in 83 % of the lungs examine.d. PasteurellaJ haemolytica was recO'vered most O'ften from lesions of the second category in which cellular exudation predominated (P. haemolytica x2 = 11.3, P
New Zealand Veterinary Journal Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/tnzv20
The bacterial flora of the respiratory tract of normal and pneumonic sheep M.R. Alley B.V.Sc
a
a
Department of Veterinary Pathology and Public Health , Massey University , Palmerston North Published online: 23 Feb 2011.
To cite this article: M.R. Alley B.V.Sc (1975) The bacterial flora of the respiratory tract of normal and pneumonic sheep, New Zealand Veterinary Journal, 23:6, 113-118, DOI: 10.1080/00480169.1975.34211 To link to this article: http://dx.doi.org/10.1080/00480169.1975.34211
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://www.tandfonline.com/page/terms-and-conditions
1975
NEW
ZEALAND
VETERINARY JOURNAL
113
THE BACTERIAL FLORA OF THE RESPIRATORY TRACT OF NORMAL AND PNEUMONIC SHEEP M. R. ALLEY*
Downloaded by [Michigan State University] at 07:03 11 February 2015
INTRODUCTION
FOR MANY YEARS chronic and subacute pneumonia has been recognized as a common finding in the lungs of lambs at slaughter throughout New Zealand. While the effect of the disease on weight gain is not clear, there can be no doubt that residual pleuritis is an important cause of 'economic loss through high condemnation rates of carcasses. Previous. bacteriological investigations have been confined to outbreaks of acute enzootic pneumonia (Salisbury, 1957). In these cases the lungs examined were from sheep of all ages and Pasteurella haemolytica was invariably isolated. No studies have been reported on the bacterial flom of chronic and subacute pneumonia in lambs in New Zealand. The p,resent survey was undertaken to compare the bacterial flora of the nasal cavity, trachea and lungs of normal sheep with that of pneumonic sheep at slaughter. A limited investigation of the bacteria present in pneumonic lesions of various pathological types is also included. MATERIAL AND METHODS
COLLECTION OF SPECIMENS Specimens were collected at 7- or 14day intervals from a local slaughterhouse from lambs aged 5 to 10 months during the December to May period of the years 1969-70 .and 1970-71. On each occasion 10 lungs were selected on the basis of their gross appearance and the corresponding heads identified and collected. Nasal swabs were obtained by cutting the head sagitally, slightly to one side of the mid-line with a band saw and removing the nasal *M. R. Alley, B.V.Sc., Department of Veterinary Pathology and Public Health, Massey University, Palmerston North.
septum with bone forceps. A sterile swab was then drawn over the exposed turbinate and inserted into both the dorsal and ventral nasal meatus. Tracheal swabs were collected by incising the trachea transversely midway along its length and inserting a sterile swab distally as far as the bifurcation of the main bronchi. Samples of lung were collected in sterile petri dishes. From the majority of penumonic lungs a 4 cm2 area of right apical lobe was removed with forceps and scissors as this was· the area most consistently affected. A slice of pneumonic tissue immediately adjacent to this was routinely collected in 10% fonnol-saline for subsequent histological examination. Samples of normal lung were collected from the right apical lobei in a similar manner. LABORATORY
PROCEDURES
Nasal and tracheal swabs were plated out initially on to sheep blood agar and MacConkey's agar. The surface of all lung samples was seared before plating out in the same way. Gram-stained direct smears were made from all samples. In the early stages of the survey, plates were incubated both aerobically and with 10% C(h; however, after 100 lungs had been processed, the latter was found to be non-productive and was discontinued. Identification of bacteria was based on the methods outlined by Wilson and Miles (1964) and Cowan and Steel (1965) with the exception of Enterobacteriaceae which were identified by the keys of Ewing (1968). Suspect Pasteurella failing to show haemolysis on sheep blood agar were subcultured on to horse blood agar and tested with the indole reaction. Lung samples for histological examination were 'embedded in paraffin, cut and stained routinely with haematoxylin and eosin.
114
NEW ZEALAND VETERINARY JOURNAL
RESULTS
Downloaded by [Michigan State University] at 07:03 11 February 2015
THE DISTRIBUTION OF BACTERIA IN THE NORMAL AND PNEUMONIC RESPIRATORY TRACT
The results summarized in Table 1 show a high rate of carriage of several bacteria in the nasal cavity of both normal and pneumanic sheep. Bacteria of the same type were also isolated in large numbers from the trachea and lungs of pneumonic sheep but were only rarely recovered from nonna! lungs and tracheae.
TABLE 1: NUMBER OF BACTERIAL ISOLA· TIONS FROM NORMAL AND PNEUMONIC SHEEP RESPIRATORY TRACTS OVER TWO SEASONS, 1969·70 AND 1970-71 (Total examined: 184 nonnal sheep, 246 pneumonic sheep)
Nasal
Cavity P. haemolytica: Normal 135 (73%) 193 (78%) Pneumonic N. catarrhalis: Normal Pneumonic
72 (39%) 114 (46%)
Trachea
Lung
9 (5%) 133 (54%)
11 (6%) 144 (59%)
2 (1%) 55 (22%)
3 (1.6%) 54 (22%)
VO.l..23
The predominant organism isalated from both the normal and pneumonic respiratory tract was Pasteurella haemolytica. This organism was most frequently isolated from the nasal cavity of pneumonic sheep although its prevalence here was anly slightly higher than in the nasal cavity of normal sheep. It was recovered in pure aerobic culture from only 20% of all nasal cavities examined but was found in combinatian with! Neisseria catarrhalis in 40% of animals and in cambinatian with other organisms in a further 16%. In the pneumonic lung! P. haemolytica was most frequently isolated in pure culture, being recovered alone from 45 % of all pneumonic lungs and in combination with N. catarrhalis in a further 14%. The se.cond mast commonly recavered organism in this study was an organism )dentified as N. catarrhalis (Alley et al., 1970). This organism was isolated most aften in cambination with P. haemoiytic(lJ 'and could be gra'wn in pure aerobic culture from only 3 % of all nasal cavities examined. Neisseria catarrhalis was also commonly isolate.d from the pneumonic lung and trachea (Table 1) but was recovered in pure culture from only 6% of pneumonic lungs.
Escherichia coli, Staphylococcus. and a-haemolytic Streptococcus were alsO' E. coli frequently isolated from the nasal cavity; 22 (12%) 1 (0.5%) 1 (0.5%) Normal however, only rarely were these argan4 (2°Ic,) 31 (13%) 2 (1%) Pneumonic isms recovered from the trachea or lung. Although staphylococci were more comStaphylococcus: monly isolated from the nasal cavity and 2 (1%) 8 (4%) 2 (1%) Normal 2 (1%) Pneumonic 23 (9%) 10 (4%) trachea of pneumonic sheep there appearStreptococcus ed to be little difference in the recovery (a·haemolytic) : rate of the other two organisms between 2 (1%) 21 (11%) Normal 0 (0%) the respiratory tracts of normal and 0 (0%) 0 (0%) Pneumonic 23 (9%) pneumanic sheep. Mixed growths in the nasal cavity were more commonly seen Corynebacterium: in those animals sampled during the o (001c;,) 1 (0.5%) Normal 4 (2%) December-J anuary-February periad of o (0%) o (0%) Pneumonic 2 (1 %) both seasons. Later during the autumn months, P. haemalytica and N. catarrhalis No growth: appeared to dominate the nasal flora of Normal 30 (16%) 169 (92%) 167 (91%) both normal and pneumanic sheep. Only 83 (34%) 95 (39%) Pneumonic 21 (9%) rarely was P. haemolytica or N. catarOther bacteria isolated from nasal cavHy were rhalis isolated from pneumonic lungs and Actinobacillus (6 isolations), micrococci (4 isola- not found to be present concurrently in tions) and Bacillus (3 isolations). the nasal cavity.
1975
NEW ZEALAND VETERINARY JOURNAL
Downloaded by [Michigan State University] at 07:03 11 February 2015
THE PREVALENCE OF BACTERIA IN DIFFERENT TYPES OF PNEUMONIC LESION
F or the purposes of this study the pneumonic lungs examined were divided intO' four categDries on the basis of the gross and histological appearance of the lesions. A brief description of the pathological cri teria for this classification is included below. These categories dO' not re.present the full spectrum of lesions seen in chronic pneumonia in New Zealand sheep and a more detailed pathological deSCription of the! disease will be published at a later date.
Type 1: The gross lesions consisted Df dull red consolidation in the ventral areas of the apical and cardiac IDbes of both lungs. The lesiDns were sunken below the surface of the adjacent normal lung and were of homogeneous. appearance with a smooth pleural surface. The most prominent histological feature was alveolar collapse. Small numbers of macrophages were sometimes present in alveoli and occasional bronchioles contained a neutrophilic exudate. Type 2: In this category the gross lesions were usually more extensive and took the! form of red-grey consolidation of ventral apical, cardiac and interm.ediate lobes. They. were sharply delineated from the normal lung tissue but did not sink below its surface. On close 'examination numerous grey-white 1 to 2 mm foci could often be seen within the consoli,dated tissue and the pleural surface had an uneven granular appearance in reflected light. Histologically, the main feature was severe infiltration of neutrophils into groups of alveolar spaces disseminated throughout the lung. Macrophages were present in moderate numbers and early proliferative changes including, bronchiolar epithelial hyperplasia and peribronchial lymphoid hyperplasia were common. The majority of bronchioles contained neutrophilic plugs.
Type 3: The lungs in this group showed. extensive grey-red consolidation which! usually involved whole lobes. In the least severe cases the lesions involved the right apical lobe but often they extended into both apical and cardiac lobes,
115
the intermediate lobe and ventral parts of both diaphragmatic lobes. The consolidated tissue had a finely granular mottled appearance, firm consistency, and affected lobes were thicker than normal. Both exudative and proliferative changes were present histo,logically but proliferative changes predominated. There was hyperplasia of bronchiolar and alveolar epithelium together with variable peribronchial lymphoid hyperplasia. Large! numbers of macrophages and lessoc number of neutrophils filled the alveolar spaces. Type 4: In this group were placed lungs with severe grey consolidation which varied in extent but was always confined to the anteroventral parts of the lungs. The consolidated tissue was very firm and affected lobes thicker than normal. The cut surface had a finely mottled! texture or was homogeneous and pale grey in appearance. Occasionally fibrous adhesions were present on the pleuraU surface. Chronic proliferative lesions predominated microscopically. Severe hyperplasia of both bronchiolar and alveolar epithelium were constant findings. Peri~ bronchiolar fibrosis and alveolar interstitial thickening were also common and peribronchial lymphoid hyperplasia was variable though often severe in extent. Alveolar macrophages were present in large numbers but neutrophils were rare. The prevalence of bacteria in theSe! four types of lesion is shown in Table 2. I t can be seen that lesions in the first categO'ry in which the main feature was, alveolar cO'llapse were much less likely, to yield bacteria than lungs in the other three groups (NO' growth X2 = 30.5, P < 0.(01). The lungs in which the most extensive lesions were present usually showed grey-re.d consolidation and were placed in the third category. It was frO'm this type of lesion that bacteria were re~ covered mO'st consistently, being present in 83 % of the lungs examine.d. PasteurellaJ haemolytica was recO'vered most O'ften from lesions of the second category in which cellular exudation predominated (P. haemolytica x2 = 11.3, P
