Table 2.
Pooled prevalence of Klebsiella spp. in milk samples from dairy cows with mastitis worldwide including risk factors and meta-regression.
| No. studies | No. tested | No. positive | Positive percentage (95% CIa) | Heterogeneity | Univariate meta-regression | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| χ2 | p -value b | I2 (%) | p -value | Coefficient (95% CI) | ||||||
| Sampling years | 0.0004 | 0.1339 (0.0599–0.2079) | ||||||||
| Before 2013 | 25 | 26,171 | 536 | 3.85% (2.67–5.21%) | 505.76 | < 0.01 | 94.9% | |||
| 2013 or later | 28 | 24,752 | 1,735 | 12.16% (8.08–16.90%) | 2,725.28 | 0 | 99.0% | |||
| Detection methods | 0.0099 | 0.1565 (0.0376–0.2754) | ||||||||
| Biochemical tests | 32 | 64,699 | 1,626 | 6.97% (4.93–9.31%) | 2,705.81 | 0 | 98.9% | |||
| 16SrDNA identification | 9 | 12,770 | 806 | 11.04% (4.01–20.82%) | 1,550.65 | 0 | 99.5% | |||
| MALDI-TOF MS | 8 | 4,154 | 315 | 4.56% (1.51–9.01%) | 188.45 | < 0.01 | 96.3% | |||
| Automatic analysis systems | 6 | 5,090 | 615 | 17.14% (10.33–25.17%) | 126.76 | < 0.01 | 96.1% | |||
| Continents | 0.00240 | −0.2169 (−0.4053 to −0.0285) | ||||||||
| Africa | 7 | 2,251 | 139 | 8.72% (3.75–15.32%) | 67.02 | < 0.01 | 91.0% | |||
| Asia | 24 | 12,616 | 1,581 | 14.26% (10.49–18.48%) | 789.51 | < 0.01 | 97.1% | |||
| Europe | 9 | 40,651 | 257 | 0.73% (0.20–1.49%) | 159.78 | < 0.01 | 95.0% | |||
| North America | 7 | 3,145 | 159 | 7.52% (2.99–13.73%) | 160.46 | < 0.01 | 96.3% | |||
| South America | 6 | 18,383 | 321 | 4.48% (2.14–7.61%) | 325.69 | < 0.01 | 98.5% | |||
| Oceania | 2 | 2,806 | 21 | 0.67% (0.38–1.03%) | 0.10 | 0.76 | 0.0% | |||
| Longitude | < 0.0001 | −0.2229 (−0.3097 to −0.1362) | ||||||||
| 0–20°E | 7 | 35,955 | 167 | 0.70% (0.28–1.26%) | 64.72 | < 0.01 | 90.7% | |||
| 20–40°E | 10 | 7,174 | 262 | 7.72% (4.00–12.42%) | 199.63 | < 0.01 | 95.5% | |||
| 40–60°E | 1 | 200 | 80 | 40.00% (33.30–46.89%) | 0.00 | — | — | |||
| 80–100°E | 1 | 48 | 30 | 62.50% (48.27–75.75%) | 0.00 | — | — | |||
| 100–120°E | 18 | 7,580 | 649 | 10.11% (7.43–13.13%) | 209.11 | < 0.01 | 91.9% | |||
| 140–160°E | 1 | 2,572 | 20 | 0.78% (0.47–1.16%) | 0.00 | — | — | |||
| 0–20°W | 2 | 447 | 65 | 15.23% (0.00–50.98%) | 67.24 | < 0.01 | 98.5% | |||
| 40–60°W | 3 | 6,075 | 61 | 2.60% (0.15–7.67%) | 113.26 | < 0.01 | 98.2% | |||
| 60–80°W | 4 | 8,516 | 166 | 12.59% (2.29–28.79%) | 168.56 | < 0.01 | 98.2% | |||
| 80–100°W | 2 | 953 | 21 | 6.22% (0.00–29.58%) | 6.81 | < 0.01 | 85.3% | |||
| Latitude | 0.0001 | 0.2421 (0.1189–0.3652) | ||||||||
| 0–10°S | 3 | 1,870 | 132 | 13.37% (1.30–34.48%) | 78.94 | < 0.01 | 97.5% | |||
| 10–20°S | 1 | 1,547 | 28 | 1.81% (1.20–2.54%) | 0.00 | — | — | |||
| 20–30°S | 2 | 4,528 | 33 | 3.23% (0.00–20.37%) | 83.49 | < 0.01 | 98.8% | |||
| 30–40°S | 1 | 2,454 | 19 | 0.77% (0.46–1.16%) | 0.00 | — | — | |||
| 40–50°S | 1 | 118 | 1 | 0.85% (0.00–3.60%) | 0.00 | — | — | |||
| 0–10°N | 4 | 8,260 | 115 | 2.33% (0.63–4.86%) | 9.52 | 0.02 | 68.5% | |||
| 10–20°N | 1 | 174 | 11 | 6.32% (3.12–10.48%) | 0.00 | — | — | |||
| 20–30°N | 4 | 415 | 84 | 24.13% (6.02–48.96%) | 73.14 | < 0.01 | 95.9% | |||
| 30–40°N | 16 | 7,375 | 719 | 12.91% (8.93–17.46%) | 349.68 | < 0.01 | 95.7% | |||
| 40–50°N | 10 | 6,918 | 155 | 6.20% (2.81–10.68%) | 299.14 | < 0.01 | 97.0% | |||
| 50–60°N | 6 | 35,106 | 207 | 0.60% (0.01–1.73%) | 122.70 | < 0.01 | 95.9% | |||
| Economic development level | < 0.0001 | 0.1561 (0.0840–0.2282) | ||||||||
| Developed countries | 21 | 51,658 | 838 | 3.31% (1.89–5.08%) | 1,296.66 | < 0.01 | 98.5% | |||
| Developing countries | 34 | 28,194 | 1,640 | 11.76% (8.25–15.77%) | 2,596.12 | 0 | 98.7% | |||
| Mastitis type | 0.0447 | 0.0987 (0.0023–0.1951) | ||||||||
| Clinical | 31 | 16,990 | 1,233 | 11.99% (8.62–15.79%) | 1,222.44 | < 0.01 | 97.5% | |||
| Subclinical | 13 | 14,627 | 420 | 6.42% (2.97–10.98%) | 770.04 | < 0.01 | 98.4% | |||
| Population density | 0.0141 | −0.1021 (−0.1837 to −0.0206) | ||||||||
| < 50 | 17 | 29,768 | 610 | 4.13% (2.70–5.83%) | 595.21 | < 0.01 | 97.3% | |||
| 50–100 | 2 | 1,848 | 159 | 19.00% (0.00–62.04%) | 153.85 | < 0.01 | 99.4% | |||
| 100–250 | 24 | 12,121 | 968 | 9.58% (5.64–14.37%) | 1,222.15 | < 0.01 | 98.1% | |||
| 250–500 | 6 | 33,479 | 563 | 8.88% (2.18–19.07%) | 1,336.36 | < 0.01 | 99.6% | |||
| >500 | 6 | 2,636 | 178 | 10.28% (2.73–21.58%) | 149.23 | < 0.01 | 96.6% | |||
| Scores of study quality | 0.8368 | −0.0087 (−0.0920 to 0.0745) | ||||||||
| 2–3 | 14 | 39,846 | 572 | 8.20% (4.72–12.49%) | 1,222.17 | < 0.01 | 98.9% | |||
| 4–5 | 41 | 40,006 | 1,906 | 7.88% (5.67–10.39%) | 2,643.54 | 0 | 98.5% | |||
| Total | 55 | 79,852 | 2,478 | 7.95% (6.07–10.06%) | 4,584.55 | 0 | 98.8% | |||
aCI, confidence interval.
bp-value: p < 0.05 is statistically significant.