Figure 1. Fibrin stranding in peritoneal cavity

Figure 2. Intestinal haemorrhages

Background

Between July and September 2011, six separate outdoor breeding herds were diagnosed with septicaemia in pre-weaned pigs due to infection with Klebsiella pneumoniae sub-species pneumoniae.

Klebsiella pneumoniae subsp. pneumoniae is recognised as a cause of sporadic disease in individual pigs often concurrent with other diseases. In addition, the organism is an opportunistic pathogen causing mastitis in cows and sows. Klebsiella pneumoniae is a commensal of the healthy porcine alimentary tract and is present within the environment both in soil and water sources.

Whilst Klebsiella pneumoniae can cause human infections including pneumonia, urinary tract infections and neonatal septicaemia, it is not a recognised zoonosis. Instead, infections in humans are commonly hospital-acquired and tend to affect immune compromised patients.

Case Definition

Based on consistent findings in the six cases, the case definition is as follows: ‘Pigs found dead with lesions consistent with septicaemia and pure/predominant growths of Klebsiella pneumoniae subsp. pneumoniae isolated from internal sites in multiple pigs’.

Clinical Signs

The disease has been diagnosed in preweaned pigs, aged 17 to 28 days old, and in good bodily condition. The predominant presentation is of pigs found dead although occasional piglets are seen in extremis, recumbent, cyanosed and mouth breathing followed by death in less than 30 minutes. All of the cases occurred on commercial outdoor breeding units between July and September. Mortality is estimated at between one and four per cent, with one piglet to all of the affected litter dying. The duration of herd disease is variable with two herds having short-lived duration of disease from seven to 10 weeks and four herds experiencing losses for more than 12 weeks, at a reducing rate over time.

Diagnosis

Lesions at post-mortem examination are non-specific and seen in cases of septicaemia due to other porcine pathogens. The most consistent finding has been the presence of fibrin strands in the abdominal cavity. Other findings include ventral skin reddening, serosal haemorrhages, pleural effusions and reddened lymph nodes. Klebsiella pneumoniae subsp. pneumoniae is isolated from a number of visceral sites by standard aerobic bacterial culture.

Disease Control

The cause of the emergence of Klebsiella pneumoniae subsp. pneumoniae resulting in outbreaks of disease in piglets rather than sporadic disease has not yet been elucidated and therefore no specific advice is available on control measures. All of the laboratory isolates of Klebsiella pneumoniae from these cases have an innate ampicillin resistance.

The use of antimicrobials in litter mates of affected pigs appears to prevent further cases. However, case control studies have not been undertaken to confirm this. Interestingly, once weaned, there are no reports of continuing disease at rearing sites. The investigation is on-going with the collation of farm epidemiological data and analysis of bacterial isolates using molecular techniques.

What should I do if I suspect a case of Klebsiella septicaemia?

The clinical signs of sudden death are non-specific and further investigation is essential to establish a diagnosis of Klebsiella septicaemia. The recommended approach in GB is for pig producers to contact their veterinary surgeons in the first instance. Where the problem needs further investigation, the veterinary surgeon should contact their local AHVLA or SAC Laboratory, to arrange the submission of up to three freshly dead, typical untreated cases for full post-mortem examination and diagnostic investigation.

October 2012